ED 259 928

AUTHORTITLE

INSTITUTION

SPONS AGENCY

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ABSTRACT

DOCUMENT RESUME

Miller, BarbaraWindow Insulation: How to Sort Through theOptions.National Center for Appropriate Technology, Butte,Mont.Department of Energy, Washington, DC. AppropriateTechnology Program.DOE/CE/15095-12Mar 84DE-AC01-82CE1509539p.Superintendent of Documents, U.S. Government PrintingOffice, Washington, DC 20402.Reports - General (140) -- Reference Materials -Geneeal (130)

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SE 045 899

MF01 Plus Postage. PC Not Available from EDRS.Energy; *Energy Conservation; Heat; *TechnologicalAdvancement; Technology; *tlindows*Appropriate. Technology; *Insulation

This two-part report explores the eflorts ofbusinesses and individuals to improve the thermal performance ofwindows. Part I discusses the basics of what makes a window productinsulate or save energy. Topic areas addressed include saving energylost through windows, key components of window insulation, threebasic types of window insulation, amount of energy window insulationcan save, and ways to improve the performance of existing windowtreatments. Part II discusses whether or not to put insulation insideor outside a window, which sealing systems are available and make themost sense to use, and how to operate products used on heat-gainingwindows. In addition, choices for new construction and retrofit areexplained. Information on how to calculate heat losses throughwindows, a reading and resource list, and descriptions of Departmentof Energy appropriate technology grants (reviewed in researching andpreparing this document) are included in appendices. (ML)

************************************************************************ Reproductions supplied by EDRS are the best that can be made *

* from the original document. *

***********************************************************************

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WINDOW INSULATIONHow To Sort Through the Options

PREFACE

From 1978 to 1981, the U.S.Department of Energy (DOE)awarded more than 2,000 smallgrants to individuals, organiza-tions and small businesses acrossthe nation to research anddemonstrate appropriatetechnologies. Grants were givenin the general areas of conserva-tion, solar, biomass, wind,geothermal and hydro power.

This booklet is part of a seriesof publications that focuses onappropriate technologies andtheir application in the home andthe work place. These publica-tions combine a qualitativeassessment of the DOE grantprojects with the results of cur-rent research for the particu'technology highlighted in L..;document. A list of pertinentprojects reviewed in preparationof this document appears in .

Appendix C.

Prepared for:U.S. Department of EnergyAssistant Secretary, Conservationand Renewable EnergySmall Scale Technology BranchAppropliate Technology ProgramUnder Contract No.DE- ACO1- 82CE15095

Prepared by:

Nthe Nedonel feedntermottowriAPProPrietsP.O. Box 3838Butte, MT 59702

ACKNOWLEDGEMENTS

The following individuals and organizations are recognized for their special contributions in the pro-duction of this publication: Barbara A. Miller, author; George Everett and John McBride, editorialassistance; Hans Haumberger, illustrations. Special thanks is offered to those who reviewed thispublication: Michael R. McSorley, energy specialist, Idaho Department of Water Resources; MikeMahlurr, program specialist, North Dakota Office of Federal Aid Coordinator; Jesse Moore and staffat the Indiana Department of Commerce, Office of Energy Policy; Tricia Ryan, window insulationspecialist, Montana; and Dr. Gautam Dutt, Center for Energy and Environmental Studies, PrincetonUniversity. Thanks are also offered tb grantees who provided photos used as the basis for illustrationsfor this publication: Energy Research and Information Foundation, Linda Nicholson, Director; JonAverill of Shades of West Virginia Sewing Cooperative; Dr. Robert Wehrli, AIA, architect and privateconsultant; and John Pierre Stephens.

DISCLAIMER

This report ..vas prepared as an account of work sponsored by an agency of the United States Govern-ment. Neither the United States Government nor any agency thereof, nor any of their employees,makes any warranty, expressed or implied, or assumes any legal liability o: responsibility for the ac-curacy, completeness, or usefulness of any information, apparatus, product, or process disclosed, orrepresents thai its use would not infringe on privately owned rights. Reference herein to any specificcommercial product, process or service by trade name, trademark, manufacturer, or otherwise, doesnot necessarily constitute or imply its endorsement; recommendation, or favoring by the UnitedStates Government or any agency thereof. The views and opinions of authors expressed herein donot necessarily state or reflect those of the United States Government or any agency thereof.

INTRODUCTION 2

PART I: What Is "Window Insulition," and How Does It Compare WithNon-insulating Window Coverings? 3

Saving Energy Lest Through Windows 3

The Key Components 4

Window Insulation Comes in Three Basic Types 5

How Much Energy Can Window Insulation Products Save? 6

Does Window In ,ulation Make Economic. Sense in Your Situation? 7

Movable Insulation May Require Attention to Avoid 13- oblemsImproving the Performance of Existing Window Treatments 8

PART II: Sorting Through The Options 10

Movable, Seasonal or Fixed Window Insulation? 10

Examining Other Options 11

More Glazings or Other Types of Window Insulation? 11

Interior or Exterior Window Insulation? 14

Sealing System Options 16

How Do the Sealing Systems Compare? 16

Do- it- yourself or Hire a Contractor? 18

Sorting Through Product Claims 20

Managing The Windows Through All the Seasons 20

What Options Are Available for Remodeling or New Construction? 21

What About Automated Control of Window Insulation? 23

Avoid Window Insulation Products that AreDifficult to Operate 24Substituting Sealed Window Treatments for StormWindows in Moderate Climates 24

The Windows of the Future 25

APPENDIX A: How To Calculate Heat Losses Through Your Windows 27

APPENDIX B: Reading and Resource List 31

APPENDIX C: DOE Appropriate Technology Grants Related ToWindow Insulation 32

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Each year, Americans spendseveral billions of dollars coveringtheir windows with drapes,shades and blinds. Yet, only asmall fra tion of these expen-ditures are on products that canconserve the substantial amountof energy that is routinely lostthrough windows.

Window coverings are alreadyexpected to play many roles.They are used to control lightand glare, provide privacy, servev; decoration, protect windowsand sometimes improve homesecurity. Yet, devices that servethese same tunctibns can also in-sulate, as well a!; provide areturn on the investment and im-prove comfort in the home. Moreimportant, perhaps, is the factthat in many instances a devicethat saves energy will cost nomore than many consumers hadplanned to spend on non-insulating window coveringsanyway.

However, several obstacles re-main in the path of the con-sumer who wishes to achieve thebenefits that stem from windowinsulation. Additional informa-tion on available products andassistance in using these prod-ucts is needed. Few businessesoffer a truly comprehensive ap-proach to helping consumers sortthrough the options, and a lackof information and training hasstopped many existing windowtreatment businesses from adop-ting the goal of insulating. aswell as decorating, windows. Theresult has been that the con-sumer, in many cases, must at-tempt to solve problems without

INTRODUC.TION

professional advice or servicehelp.

The work of the many granteeswho researched anddemonstrated window insulationoptions in the course of theDepartment of Energy's Ap-propriate Technology SmallGrants Program gives further in-dication that many people wantto improve the thermal perfor-mance of their windows, andthat a potentially large market isawaiting businesses who can of-fer quality assistance with thiswork.

Grantees took on the challengeof reducing window energylosses in many ways. Projects fellin a wide variety of areas, rang-ing from materials testing andresearch to studies of how wellhomeowners adapt to using win-dow insulation devices.

Some grantees concentratedtheir efforts on providing con-sumer information and training,while others developed andtested low-cost, do-it-yourseifdevices. Some organizationsdesigned and manufacturedseveral types of window insula-tion, to learn which was theeasiest to make and had themost user appeal.

Window insulating devices,both homemade and commercial,were employed in a number ofpassive solar and conservationprojects. Several new smallbusiness ventures grew fromwork with window insulation,and existing small businessesdeveloped products that are nowcommercialized. Still othergrantees developed and patented

products that have yet to hit themarket.

Just as grantees explored aseemingly endless number ofways to reduce energy losses dueto windows, consumers currentlyface a confusingly large array ofoptions. Although the windowinsulation industry has grownduring the last five years, manyconsumers remain baffled by thechoices.

By reviewing the grantees'work, consumers cart learn howto sort through the optionsavailable for residential settings,including:

how to identify window in-sulating devices that can savea significant amount ofenergy, including a discus-sion of components andtypes;how operating window in-sulating devices compareswith using conventional,non-insulating windowcoverings;how to choose a product thatcan serve all the functionstraditionally required of win-dow coverings;how to avoid problems withdo-it-yourself projects; andhow to estimate costs andsavings with windowinsulation.

In addition, this publicationprovides information on windowchoices for new construction, andan overview of current researchin window insulation. The ap-pendices provide summaries ofselected grant projects, and areading list is presented for thosewho want more information onwindow insulation.

Interior Shutters Exterior Shutters.

Roman Shades,Drapes And Curtains

Interior StormWindow

Interior Panels

ExteriorRollDownSystems

Exterior SunscreenAnd Tinted Gists

Exterior StormWindow

Interior Film

FIGURI- 1: Product- Mot can save eliersv are available inpi:am/ ditturclit fille%. MUM, of leitIch resemble non-msuialms

cozvrt,N. The mator diffettliCe is that insulating pro-folfure a sealing system, which stops 9,/r ttiot'e-

,,h.lit limit the insulation

Saving Energy Lost ThroughWindows

Because window insulation isnew, the window treatment in-dustry still has not adopted aworking name for insulatingproducts. Often referred to as"movable insulation," "windowenergy treatments," "solar windowtreatments," or "night insulation,"the concept of window insulationcan be difficult to pin down. Also,devices and products that can saveenergy come in many styles(Figure 1).

To define a product that reducesenergy consumption, one firstshould note how energy is lostthrough windows. In colderweather, loose-fitting windows can'lead to heat losses through infiltra-tion, which describes air passinginto and out of the house throughcracks and leaks around the win-dow. Infiltration is mainly a func-tion of temperature differencesbetween the indoors and outdoorsand of wind speed. It is often ex-perienced as cold drafts of air.

In a proce's described as convec-tion, a cold window pane sets air inmotion downward, with warm air

ing pulled from above to thewidow, where it is cooled. Thus,

a loop of air is constantly passingover the window.

Heat also passes directlythrough the glass and the windowframe to the cold outdoors throughconduction. Conduction and con-vection go hand-in-hand.

Finally, warmer objects naturallyradiate energy toward colder ob.

3

jests, and the cold window pane isoften the coolest surface in mosthouses. Heat losses through radia-tion losses typically make for dis-comfort; people feel chilled whenbody heat is being radiated towarda cold surface.

On the other hand, windows cancontribute to cooling costs when,in hot weather, unwanted solarradiation passes into the housethrough the windows.

Some window devices will re-duce heat losses or heat gains inone way, but not others. For exam-ple, glass is probably the mostcommon "window insulation." Anextra layer of "glazing" (anotherterm for glass or plastic films thatact like glass) provides an in-sulating layer of air between thelayers of glass, which helps reducelosses through conduction. Yet, or-dinary glass does little to preventheat losses through convectionand radiation.

A thin layer of inexpensive poly-ethylene plastic taped to the win-dow frame may reduce infiltration,but it will do little to conserve en-ergy lost in other ways. Other de-vices that shade windows, such asreflective or tinted glass, films,screens or fabrics can reduce cool-

ing costs that stem from unwantedheat gains from sunshine, but,alone, they won't do much to stopheat losses.

The most effective type of win-dow insulation will save energyyear round. It will reduce heatlosses in winter and prevent un-wanted heat gains in the summer.In this publication, the term "win-dow insulation" rei °rs to devicesand products that can save asignificant amount of energygenerally 40 percent or more of theenergy lost through windows,whether it be due to unwantedheat losses or heat gains.

The Key ComponentsHighly effective window insula-

tion has several components thatdistinguish it from its ineffectivecounterpart. The most importantcomponent in effective window in-sulation is usually the sealingsystem. This system, which tightlyseals the window covering to thewindow on all sides, is the key toreducing heat loss through infil-tration, convection, and conduc-tion.

A sealing system is critical instopping the convective loop of air

that naturally occurs when tt.ecold window pane chills room air,and this convective loop helpscause heat losses through both in-filtration and conduction.

Research in the 1970's has illus-trated the importance of stoppingair movement around any type ofinsulation. If air can freely passaround or through insulation,whether it is in the attic, walls orover the windows, the insulatingpower is diminished, sometimesdramatically. If insulation is Lo per-form as expected, air movementaround it must be reduced, andthis is one of the reasons why seal-ing systems are critical to the per-formance of many window in-sulating products.

The effect of air mov-..mentaround window treatments is themajor reason why conventionalwindow treatments do little to in-sulate (Figure 2). In studies of thethermal performance of conven-tional blinds, drapes and shades,the material the window treatmentwas made of had less effect on theproduct's insulating ability thanthe tightness of the fit and sealaround the window. Thick butloose-fitting products providedwell under 10 percent savings over

FIGURE 2: An uninsulated window loses valuable energy through radiation, convection, and conduction. Infiltration is anotherway in which heat is lost through windows. An unsealed window covering does virtually nothing to stop these neat losses, whilea ,ealeil window-insulating device can reduce all types of heat loss.

4

one pane of glass, while conven-tional roman shades (shades thatfold up vertically in an accordion-like fashion) that formed a sort ofseal around a window casing pro-vided as much as 30 percent sav-ings, mainly because of the reduc-tion of air movement. A number ofgrantees saw the ootential of retro-fitting standard window treat-ments with sealing systems to en-hance thermal performance. (See:IMPROVING THE PERFORMANCE OFEXISTING WINDOW TREATMENTS.)Sealing systems are covered indetail in Part II.

Insulating materials slow conduc-tive heat losses, usually by trap-ping air between layers or withinthe material itself. Materials usedin window insulation are diverse,ranging from a single layer ofhighly reflective, aluminized plas-tic and layered batts of air-trappinginsulating fabrics to a variety ofrigid insulating boards.

Highly reflective materials, likeopaque aluminized films, are veryeffective at reducing heat lossesthrough radiation, if there is an airspace (at least 1/8-inch) that sepa-rates the reflective material fromthe window pane or from other in-sulating materials.

Although research is continuingon the issue, it is generally thoughtthat heat losses through radiationalone are as great as losses throughthe combination of convection andconduction. Radiant heat loss canbe somewhat reduced by any tight-ly wov:n material that covers thecold window pane, but opaquereflective materials are much moreeffective. In fact, a single laver ofreflective material may be more ef-fective at stopping heat loss than aone inch thick layer of some typesof insulating board.

Insulation is typically describedin terms of "R-value," which is ameasure of how resistant a mate-rial is to heat transfer. The higherthe R-value, the greater the insu-lating power of the material. TheR-value of a single layer of glass isslightly under 1, while 31/2 inchesof standard fiberglass batt has anR-value of about 11. Generally, pro-ducts that have R- values of under 1art not considered to be windowin,,tilators, except, perhaps, in the

case of sun rejection devices,whose performance is notmeasured in terms of R-value.

Window insulation specialistshave generally agreed that windowinsulation should cut heat loss (orunwanted gain) by at least 50 per-cent to be considered a "good"window insulation choice. Suchreductions can usually be ac-complished with relatively low R-values, and most of the windowinsulation products on the markethave R-values in the R-2 to R-5range.

As with other insulatior invest-ments, the "law of diminishingreturns" sets in after about R-5 inmany cases, making greater levelsof insulation less economic. In ad-dition, some researchers reportthat it is difficult to get materialswith high R-values to perform asexpected on windows; the R-valueof the material has been proven tobe high when tested alone, yetwhen it is used over windows, itsR-value is less than expected. Thereasons for this problem are stillunclear.

While R-value is one measure ofthe insulating power of a device,effectiveness is often more de-pendent on the performance of thesealing system than how powerfulan insulator the material is. For ex-ample, a product may have a testedR-value of 3, but if edge seals arelacking, the actual R-value of theproduct would probably be muchlower.

Another common feature inmany window insulation productsis an integral vapor barrier. Unlikethe sealing system or the insula-ting material, the lack of a vaporbarrier usually doesn't significant-ly affect the product's ability tosave energy. A vapor barrier pre-vents moisture' frcm passingthrough the insulation. In ex-tremely cold weather, this mois-ture can be cooled to the pointwhere it condenses on the windowor within the window insulationitself. Vapor barriers are usuallymade of plastics or aluminizedfilms that are highly impervious tomoisture transfer. Some insulatinghoards are quite impervious tomoisture, without the addition of aseparate vapor-stopping layer.

Window Insulation Conies inThree Basic: Types

Window insulation products cangenerally be grouped into threebasic types: movable, seasonal andfixed (Figure 3 ). They can be trans-parent, translucent or opaque.Each type may be used on the in-side or the outside of the window.

One of the first tasks facing theconsumer . designer is tc correct-ly choo, -rig movable, sea-sonal of ) ions to window

.s to achieve the mostenergy saviiigs and the greatestdegree of overall benefits fromother features of the windowinsulation.

Movable insulation describes de-vices that can be easily opened endclosed over the window. In thiscategory are roll-up 01 iold-up(Roman) shades, sealed drapery orcurtains, folding or movable shut-ters, and movable sun-screenshades. A standard component ofpassive solar heating systems,movable insulation is opened orremoved to admit daytime solarradiation, and closed at night orduring cloudy, cold weather toconserve heat gains from the sun.Because it is operable, movable in-sulation is often more expensivethan seasonal or fixed devices.Thus, movable insulation tends tomake the most sense economicallywhen used on windows that re-ceive a significant amount of sun-shine.

Movable insulation is the closestinsuiating counterpart to tradi-tional non-insulating windowtreatments, because it often canserve the same functions. Yet, un-like conventional window cover-ings, movable insulating devicesusually demand some manage-ment by the occupants to achievemaximum energy savings and toprevent potential damage to thewindow.

Seasonal window insulation de-scribes insulation that is installedduring the heating (or wiling)season, and is not regularlyopened or Moved. In this catagorymight be translucent or opaquepanels that cover windows thatdon't receive sun in winter, or per-haps .1 sun-reflecting exterior

5

DAYTIME NIGHT

i

Closed

Movable Window insulition

.

SUMMER WINTER

Seasonal Windo,1414141410,,,

INSTALLED ONCE REMAINS INSTALLED ALL YEAR

Final Window Insolation

FIGURE 3: Improved consumer satisfaction and cost savingscan be achieved by choosing the right typemovable, seasonal,or ft veti window insulation for each window in the house.

1

screen in hot climates to preventunwanted heat gain. In manyhouseholds, storm windows areseasonal window insulation, in-stalled for the colder season andremoved in the summer to allowventilation.

Because they have no mechani-cal or moving parts, seasonal insu-lation devices can be quite inex-pensive, and they often work wellwith (..isting window coverings. In

. they demand littleattention

lived ietrid();( insulation describesproducts that are installed perma-nently. Extra glazings might fall in-

fi

to this category, as do many typesof solar control film, which are per-manently attached to glass to rejecsolar heat gains. Most fixed pro-ducts are transparent so that theview is not obstructed.

The permanent' nature of fixed;nsulation can be an advantage; in-sulation that is always in place de-mands virtually no attention fromthe occupants. But, permanencealso can be a disadvantage. Thedevice may not be able to maxi-mize savings related to seasonalchanges. And, some types of fixedwindow insulation can make win-dows difficult or impossible toopen for ventilation purposes.

How Much Energy CanWindow Insulation Products

Save?

Window heat loss and solar gaindepend on the climate, the orienta-tion of the house, the current con-dition of the windows, and theamount of solar energy the win-dows receive.

Whether your climate demandsheating, cooling or substantialamounts of both, windows can bea major energy expense in yourhousehold budget. Generally, thecolder the climate, the greater theenergy loss through the windows.For most households, heat lossthrough windows during coldweather has been estimated torange from about 15 to 35 percentof the total annual cost of heating.In passive solar houses, this heatloss can be as much as 40 percent,because of the large expanses ofglas5 that are often employed inpas-sive designs.

Wintertime heat losses are themain concern in most climates, butcooling costs that stem from un-wanted solar radiation also can bea major expense in some house-holds. Cooling is most often pow-ered by electricity, and in someregions, peak pricing can makeelectricity very expensive duringthe warmest times in the summer.

Products aimed at stopping bothwinter and summertime energylosses can save from 60 to 80 per-cent of the total energy lost due tothe windows. How this translatesto dollar savings depends on theamount of window space, the cli-mate and the cost of fuel.

For example, in a climate like thatof Chicago, a double-glazed win-dow may lose more than $1 worthof energy per square foot of glassper year, assuming that electricityis used for heat and costs 711 perkilowatt-hour. If the house has 200square feet of glass, this adds up toa cost of $200 per year of heat lossthrough the windows. In 1979,

trade and industry groupsestimated the dollar value of heatloss through single-pane glass tobe anywhere from 40¢ to $1.50 persquare foot per year, and energyprices have risen substantiallysince then. (For details on how toroughly calculate heat losses for

9

your climate and window condi-tions, see Appendix A.) If the Chi-cago homeowner installs windowinsulation that reduces heat loss by80 percent, as much as $160 a yearcould be saved.

Another important point to noteis that, on art annual basis, unob-structed, south-facing double-glazed windows can be net heatgainers in all climates, if the win-dows receive regular sunlight. Inother words, south-facing win-dows have the potential to gainmore heat in the daytime than theylose at night or during cloudyweather over the course of theyear. But, in many climates theseheat-gaining windows will be netlosers during the coldest two orthree months of the year.

East- and west-facing windowsalso have the potential to gainheat, although in much smallerquantities than south-facing win-dows. East- and west-facing win-dows often cause overheatingduring warm, sunny weather,however, because roof overhangsrarely can provide the neededshading during summer becausethey would have to be so large.

Except for heat rejection devices andextra glazing, window insulation onheat-gaining windows should be easilymovable to control heat gain effec-tively. If managed properly,movable window insulation canturn all windows that get somesunlight into net gainers, andmake south-facing windows amore permanent "free" heatsource, especially during very coldweather.Does Willi low Insulate °, Make

Economic Sense In ourSituation ?

With the recent growth of thewindow insulation industry andthe new developments with glaz-ings and low-emittance films (heatmirrors), it is probably possible formany consumers to purchase win-dows or window coverings that in-sulate for no more money thanthey were planning to spend inany case. Window insulation thatprovides light control, privacy anddecoration can be substituted forconventional window treatments,sometimes even at a savings overwhat the consumer planned tospend.

The decision to invest in energyconservation for windows is usu-ally quite different from mostother types of conservation im-provements. Unlike wall or ceilinginsulation, window insulation canplay many roles. Also, wall insula-tion demands no managementfrom the occupant, while sometypes of window insulation re-quire that the buyer make a com-mitment to operate the devicesproperly to achieve the expectedenergy savings and avoid prob-lems. Another major differencewith window insulation is that noother insulating or energy-savingdevice in the home is so ,subject tothe occupants' tastes and prefer-ences.

At present, a broad range ofproduct types, styles, colors anddesigns are available in non-insu-lating window coverings to meetthe many different tastes of con-sumers. With this broad range ofproduct offerings, costs for non-insulating window treatmentsrange from as low as 30C persquare foot to well over $30 persquare foot of window covered.

Yet, consumers do not expectnon-insulating window treat-ments to provide a return on in-vestment. Instead, these productsare accepted as an integral compo-nent of most houses, providingshading, privacy and other func-tions.

Consumers fall into many cate-gories, as far 35 conventional win-dow treatment goes, based on in-come, tastes and preferences andthe needs of the house in ques-tion. To some people, the ap-pearance of the window treat-ments is much more importantthan that of the other furnishings,while other people don't wanttheir windows covered at all.

For example, if the homeownerwas planning to spend $800 onnew drapery anyway, it is possibleto spend a similar amount on aes-thetically similar window insula-tion and get "instant" returns onthe investment. If the homeownerplanned to spend under $100 on anumber of s:riple, vinyl roll-downshades, it is now possible to pur-chase vinyl roll-down shades inthis same price range that have in-tegral edge seals. Again, this

10

would be an instant return on theinvestment.

For homeowners who like tneirexisting, non-insulating windowtreatments and don't plan to re-place them in the near future, theeconomics of the situation aresomewhat different. Lower-costwindow insulation products thatwork with existing window treat-ments may be a good choice thatcan enhance comfort and providesubstantial economic return. Or,in some cases, an effective sealingsystem can be added to existingwindow coverings that will turnthem into energy savers.

For those who don't need orwant any conventional windowtreatments, the benefits of win-dow insulation lie mainly in howmuch energy the products cansave and the potential for im-proved comfort. In some house-holds, privacy and .shading aretaken care of by exterior vegeta-tion or by where the house issited. For some people, an unob-structed view is the most impor-tant consideration, and these con-sumers may demand that any win-dow insulation purchased doesnot interfere with this view in theslightest. For those consumerswho have no need or desire forwindow covering of any kind, theeconomics of window insulationshould explored more completely.

Movable Insulation MayRequire Attention to Avoid

Problems

Consumers should be awarethat movable types of window in-sulation may need special atten-tion to avoid problems, such asoverheating from sunshine, ther-mal shock during cold weather incolder climate regions and damagefrom excessive moisture conden-sation.

Overheating can occur when aninsulating device is left in place,sealed over the window when thesun is shining on the window. Theinsulation can turn the window in-to a type of solar collector, but theheat has no way to escape. Thewindow panes can expand andcrack.

Thermal shock is a similar phe-nomenon to pouring hot water in-

7

to a chilled glass. When a coldwindow is suddenly exposed toheat, it may crack. Thermal shockappears to be an unlikely occur-rence in most cases, but it can be aproblem in colder climate regions.Specialists in Idaho have reportedthat it may be a particular problemin homes heated with woodstoves. For example, on extremelycold mornings, the occupant firstfires the wood stove, which usual-

ly increases the indoor tempera-ture to a high level. Then, whenwindow insulation on windowsnear the wood stave is removed,very hot air rushes to the win-dows, causing them to crack. If thewindow insulation was openedbefore the wood stove was fired,the problem could be easilyavoided.

Moisture condensation prob-lems can occur when the sealing

system isn't tight enough or whenthe idow doesn't have stormwindows. Moisture problems aremost likely to occur in householdswhere indoor relative humidity isconstantly high.

Minor changes in daily habitscan overcome most of these poten-tial problems, and simple manage-ment strategies are discussed inPart II of this publication.

IMPROVING THE PERFORMANCE_OFIXI6TINP WINDOW TREATMENTS

At least one grantee explored the possibility of im-proving the performance of existing windowtreatments in the cour .,e of work with new, movableinsulation products.

John Pierre Stephens and Barbara Wezelman,working in the moderate climate of Davis, California,designed and fabricated nine interior movable insul-tion options, which were installer: in a demonstrationhouse managed by the Solar Community HousingAssociation of Davis, a non-profit cooperative.

The nine types of products ranged from traditional-looking draperies and simple, roll-down shades toheavy, wood-framed fiberglass board shutters andwood-sheathed pop-in panels. Stephens and Wezel-man then produced a booklet that describes each oftheir designs, which are aimed at do-it-yourselfers.(See Appendix B for details on how to get thisbooklet.)

DOUBLE LAYER FOYLON DRAPERY ON TRAVERSE ROD

Front slew

This double layer Insulating curtainoperates behind a decorative drapery.allowing a COnventionally appearing*MO* to be well insulated.

Highlight*

Sonvintional appearanceEasy OperationReq s qonsidersblksewIngTotal cost: 83.701112Rvalue: 3.5Fabrication time: 20.hrWindow size: (2) 3' x 6.7'

14,

sate111/1111-11.1

Compen

Fab* lc boo to, :I seal

Traverse ads

Valance

Foylon drapery (double layer)

Decorative drapery

Window

Sand-weighted boltdm hent

Side stew

Material costs for the products range from 951/4 to$4.90 per square foot (1981 prices), and R-valuesranged from R-2 to R-8. The pair concluded that inDavis (a 2,800 heating degree day climate), con-sumers could get a positive economic benefit fromspending an extra $2 to $4 a square foot on windowinsulation, over and abo_ me cost they would bewilling to spend on conventional window coverings.

The first design described in their booklet (Figures4 and 5) shows that traditional draperies can be retro-fitted at a low cost by adding a reflective drapery linerthat employs a tight sealing system. ThE. sealing sys-teM entails adding a tightly woven fabric "loop" fora top seal, sand-weighted bottom hem and a low-costwooden clamp for a side seal on one side and a per-manent, tacked-down seal on the other side. Thematerials cost of this insulating drape option is listedas $1.60 per square foot, while the decorative-front

Top Oew of olds Guts

Cost bomitagi

Insisting drops. rod and edge'seals

Decorative drape. rod end edge seals

Total coat

Side clamp: Ise board mountedon spring loaded hinges (Manuallyoperated)

Foylon drape

Decorative drape

Payton drape tufted to aide

$63 St .60(h2

85 2 .1 Oil t2

$3.70/1t2$148

CenstbsClie0 Tip*

Leave at toast 4.5" between the two curtains.

Mount rod at exact sameHang Foylon curtain that bottom Ism rest, on Door.

t above floor on both ends.Allow cleerance for curtains Nide valance.A double layer curtain takes considerable swing time.

Use lightweight reflective fatal (Payton 7001 or Aetrolon VIII)Cut febric wder acmes bottom to show for slight folds in bottom when curtain isclosed.

Top width eaCurtain Alter

Bottom widths' curtain width+ 2-4"

Cut and sew very carefully so that the resulting curtain is straight and evenSew 2" wide itrOs Of batting In betivein the layers on the top and ends. to createan sir gap in the middle.Edges of Foylon should be protected by hemming with other %wit:Sewing a large drapery requires a very targe work area.

FIGURE 4: This design, taken from the publication developed by Stephens and Wezelman, illustrates one way to Improve thethermal per,'Ormance of existing drapery. The key components in this design arc highly reflective material and a sealing system.

8 BEST COPY AVAILABLE11

drape cost an additional $2.10 per square foot. TheR-value is listed as R-3.5.

If the liner as tacked to existing drapery, this de-sign could be adapted for an even lower cost (about95c per square foot), by saving the cost of buying anextra curtain rod. (The hardware and rods con some-times be more expensive than the draperies them-selves.) For best results, this liner material should bequite impermeable to moisture transfer, as well asdurable.

The grantees reported that making this type of win-dov.. insulation yourself requires a very large workarea and plenty of time. However, because it is simi-lar to drapery products that are currently being pro-duced in custom shops across the country, it may bepossible to get this work professionally done at an af-fordable cost.

As for the other movable insulation designs,Stephens noted that some insulation boards may betoo heavy for use in shutters. In particular, he said,the fiberglass board shutters are so heavy that opera-tion can be difficult.

Looking back on the project, Stephens reportedthat the conventional-looking curtains were well re-ceived by those who toured the demonstration houseand by the current occupants of the house. Hewarned, however, that consumers should look for avery durable lining mater;a1; some materials he andhis partner' tried delaminated after being installed.

This project illustrates that existing conventional-looking products can be transformed into window in-

FIGURE 5: This drawing shows the finished insulatingdrapery system as it looks in the demonstration house inDavis, California. When open, the reflective liner can be com-pletely hidden behind the decorative drapery.

sulators, and that this work can be low-cost and ex-tremely cost-effective.

12 9

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11:1111i

1. Deno Ws 'Wow got &lot sunlight?

S. Should it be oassiblo to evilly openthis wink* tor mastics 1 n ohHasoew?

I. is it highly dostrobts to possorso thenew dtutng wow% ood him

inima/4W window?

L Would this window _he needed kw ashIn the use si ow

4. Would say window oweerlie on IANwindow be trandesent se Vet therosei4s)

FIGURE 6: To choose among the options requires that the oc-cupant reinm, all the uses of the windows.

10

13

Movable, Seasonal or FixedWindow Insulation?

Much expense and many prob-lems can be avoided by choosingthe right product for your windowin the first place. The first step inmaking the right decision is to de-termine the uses of each of thewindows (Figure 6). The followingquestions should be answered inall climate regions:

1. Does this window receivedirect sunshine?

2. Would this window be need-ed for exit in case of a fire?

3. Should this window be easyto open for ventilation in allseasons?

4. Should any window coveringon this window be translu-cent so that the room getssome light during the daywhen the product is in place?

5. Is it highly desirable to pre-serve the view during all sea-sons, and still have an insu-lated window?

By reviewing the answers tothese questions, the homeownercan decide which windows arecandidates for the various types ofwindow insulation. Let's gothrough each question separately.1. Does this window get directsunlight?

IF YES: This winnow should inmost cases have movable insula-tion or a fixed insulation thateither admits or rejects solar ener-gy, depending on climate. Mova-ble insulation will demand opera-tion, while fixed insulation re-quires no attention.

Movable insulation should betruly easy to operate. It may bewise to avoid opaque, one-piecepop-in panels that may be bulky orinconvenient to store or cause anyother type of difficulty in opera-tion. Effective operation is criticalbecause sun-gaining windows canoverheat when window insulationisn't removed when the sun is shin-ing. The heat can build up, and, insevere cases, this can result inbreakage of glass and warpage of%,iindow casings.

Seals on movable insulation onNeat- gaining windows shouldallow ease of summer operation toensure proper escape of heatbuildup. Also, sealing mecha-nisms should be able to withstandhigh temyeratures without prob-lems.

If the occupants cannot or do notwant to operate the window insu-lation, movable insulation may notbe the best choice. More glazingmight be the answer in this case,or else automated control of thewindow treatment. (Automatedcontrols are discussed later in thispublication.)

IF NO: If the window receivesno sunlight and isn't important forventilation or fire egress, movableinsulation may be an unnecessaryexpense. Low-cost, pop-in panelsare perfect choices for windowsthat get no sunshine. Window in-sulation for this purpos may betranslucent or opaque. It may beinstalled during the winter and leftin place all season, making for24-hour heat savings. Panels de-mand no attention and tend tohave high returns on investmentwhen used throughout the heat-ing season. (See: AVOID INSU-

rING PRODUCTS THAT ARE DIE-1:1(LIT To OPERATE.)2. Would this window br needed forexit in the case of a fire?

IF YES: This window must havewindow insulation that is veryeasy to open (even in the clark),which speaks for movable insula-tion. Seasonal window insulatiun,such as non-operable storm win-dows or pop-in 'Panels, can blockeasy e\it tram a window. Notethat codes often require operablewindows in sleeping areas.

IF NO: Any sort of fixed or sea-sonal window insulation workin this case.

3. Should this window he easy to openfor ventilation in all seasons?

IF YES: Movable insulationwould be the best choice. Win-dows are the main source of need-ed ventilation in most households,although..not every window needbe operable. it makes sense to findthe windows that provide the bestcross-ventilation, and designatethem to be fully operable, no mat-ter what the season. Ventilationneeds are not seasonal.

IF NO: Any type of fixed orseasonal window insulation willwork in this case.4. Should any window covering onthis window be translucent so that theroom in question gets some light dur-ing the day when the product isclosed?

IF YES: Don't settle for windowinsulation that is of the black-outtype if you want to retain somelight. Translucent window insula-tion products are available, forboth seasonal and movablemodes. If the product allowsenough light to come through toavoid turning on room lights, en-ergy can be saved.

IF NO: The lower-cost productstend to be "black-out" types. Ifyou don't need translucent win-dow coverings, you might be infor some savings. In bedrooms,black-out products may be de-sirable.5. Is it highly desirable to preserve theview during all seasons, and still havean insulated window?

IF YES.. More glazings may bethe bt s, approach in this case, or acombination of another glazinglayer and movable insulation thatwon't obscure view when it isopened. Seasonal insulation,whether opaque or translucent, isout of the question here. Extrawork may be needed to ensurethat the movable insulation fullyexposes the window when it isopen, if ycu want to fully preservethe view. This aspect also may ruleout some movable insulation de-signs. Note mounting details care-fully as you explore the variousoptions.

IF NO: Any type of window in-sulation will be suitable, and thiswindow may be a candidate for alow-cost product.

14

Examining Other OptionsWith the answers to these first

questions concerning the use ofthe windows will come a prelimi-nary assessment of what types ofproducts might work best in eachsituation. Next, you'll need to de-termine whether more glazings orother types of window insulationwould suit the need, and whetheryou want interior or exterior prod-ucts. But, before a discussion ofthese decision points, let's first ex-plore some more unusual, butlow-cost, options for windows inall climate regions.

Some energy specialists start outa window insulation consultingjob by noting whether any win-dows can be insulated by beingboarded up permanently. Thisusually entails removing the win-dow sashes and adding exteriorgrade board, regular insulation,and an interior surface. If a househas too many windows, thiscourse may be an excellent option.

However, this course should beavoided in the case of historicbuildings or buildings located infederally designated historic land-mark districts. In this case, win-dows should be carefu:ly retrofit-ted to retain the architectural fea-tures as well as improve thermalperformance. (For guidelines onthis job, see Appendix B..)

Another low-cost option oftensuggested by researchers is to ret-rofit inexpensive vinyl rollershades with a thin exterior layer ofhighly reflective aluminized mate-rial. For ease of operation, thealuminized layer should be at-tached to the shade only at the topof the roller, ana left free at thebottom. This option works wellwhen it is difficult or impossible toretrofit existing drapery or cur-tains, yet you want to retain thesecurtains and improve the thermalperformance of the windows at alow cost.

More Glazings or Other Typesof Window Insulation?

The answer to whether youshould attempt substituting othertypes of window insulation for ex-tra glazing layers depends on your

11

NORMAL NUMBER. OF DIGNEEDAYS PER,, YEAR

FIGURE 7.: The first map illustrates "heating degree days," while the second map shows "cooling degree days." The maps helpindic,..'e how cold or how hot a particular region is, on the average. Degree days represent the difference between the average out-aoor temperature for a particular day and the base reference temperature for the indoors. (These degree-day averages use an in-door reference temperature of 65°F to calculate heating degree days, and 75°F for cooling degree days.) The more degree days inyour location, the greater your energy usage for heating or cooling is likely to be.

climate (Figure 7) and your pocket-book. You may be able to get moreinsulating power for your moneyif you avoid extra glazings, butyou also may be asking for troublein some cases.

Storm windows are a standardpart of most weatherization ef-forts, in all but the warmest partsof the nation. Extra layers of glassserve as extra insulation mainlythrough the creation of a "dead"air space between the layers ofglass. These extra glazings alsohelp tighten up windows, thus re-ducing infiltration.

Other measures to reduce infil-tration through the existing win-dows ought to be accomplished asa first course in any energy-savingprogram concerning the windows:weatherstripping and caulking thewindows, replacing any crackedglass, and resetting the glazingcompound around the glass, ifneeded.

12

Most energy conservation spe-cialists recommend these energy-saving steps and adding stormwindows before making any fur-ther investment in window insula-tion. However, some grantees ex-plored the possibilities of forego-ing storm windows and usingsealed window treatments in-stead. (See: SUBSTITUTING SEALEDWINDOW TREATMENTS FOR WIN-DOWS IN MODERATE CLIMATES.)

The decision to add more sub-stantial insulation or to go with anextra layer of glazing depends onthe current condition of the win-dow, tastes and preferences, andthe climate.

A minimum of two layers ofglazing is recommended for cli-mates with 4,000 heating degreedays or more. In colder climates, itoften makes sense from an eco-nomic standpoint to add extraglazing over single-pane windows

as well as other types of windowinsulation.

In more moderate climates, (un-der 4,000 heating degree days)skipping the storm windows infavor of a movable insulation mayseem to make economic sense.But, in this case the product mustseal very tigl.tly to avoid potentialmoisture condensation, andmovable insulation must be oper-ated on a regular basis if the win-dow receives sunlight.

One of the main differences be-tween the two ourses of action isthat storm windows or extra glaz-ing layers are usually fixed or sea-sonal. These devices save energyon a 24hour basis, while a mova-ble window insulation productmay be in place only 14 hours aday. However, if a window getssignificant sunshine, the overallsavings can be greater with themovable insulation that has a

15

BEST COPY AVAILABLE

AVERAGE ANNUAL 'MIA' 141,1MIER OF COTOLING DEGREE-DAYS,rptieit 'p31.1 s% bid.. km amain Mill 40

. I . (1

Fleoroduced with permission from Handbook of Air Conditioning, Hootirig itnd Ventitation;Third Edition by Eygene Stamper and Richard 1...Korai.01979 by Industrial Prins Inc.

Amal=higher R-value than an extra singlelayer of glazing.

Another mportant difference isthat the glazing or storm windowmight have a longer lifespan andrequire less maintenance than themovable insulation. Movable insu-lation may need periodic cleaningor laundering, and it will needmanagement.

The most important point to noteabout adding storm windows or moreglazings is that in climates whereheating is predominant, the room-sidewindow should be tightest to avoidunwanted moisture condensation be-tween the layel ()f glass. In climateswhere winter temperatures fall to35') F or below, window surfacescan get cold enough that warm,moist room air will condense onthe window pane (Figure 8). Thewarmer the window surface is, theless likely it is that moisture willcon dense.

Thus, if your inside layer of glaz-ing is looser than the outer glazinglaver, warm, moist inside air will

move around the inner sash andcondense on the outer pane,which can obscure the view andcause significant damage to win-dow sills and other components.This same problem can occur withloose-fitting drapes or ill-fitting in-terior window insulation prod-ucts. The rule of thumb then be-comes: Any interior window insulaLion in colder climates must fit tightlyto avoid excess moisture condensation.

Products in a wide price rangeare available for use as interiorstorm windows. Interior stormwindows can be operable, fixed orseasonal. When adding an interiorstorm, make sure the fit and sealare excellent. With an exteriorstorm, the fit and seal are still im-portant, but if the exterior storm istighter than the primary window,condensation might become aproblem.

If your home has consistentlyhigh indoor relative humidity, theseals on your interior storm win-dows or other window insulation

16

will have to be extremely tight toprevent moist air from reachingthe window pane. On sunnysouth-facing windows, this con-densation may still harm the sills.You will be less likely to sufferfrom moisture damage if you firstinstall tight storm windows, anddo the needed weatherizationwork on the existing windows.

It should be noted that whenmovable insulation products areused, a minor level of moisturecondensation is common andshouldn't cause concern. Thus,don't worry if your windows areslightly fogged when you openmovable products in the morning.after a cold night. However, if thewindows become heavily iced andwater runs down the glass whenthe ice melts, corrective action is inorder. This problem indicates thateither indoor relative humidity istoo high or that there is a problemwith the storm windows or thelack of them. Excess moisture con-densation is more likely when the

13

COLD

FIGURE 8: To avoid excess moisture condensation during coldweather, all interior window insulating devices, includingstorm windows or extra glazings, must be tightly sealed.

m. vable insulation has a highclue because the window be-

comes much colder.Any type of additional window

insulation will appear to be morecost-effective over single-glazedwindows than over double- ortriple-pane windows. The reasonis simple: single-glazed windowslose the most heat. In warmer cli-mates, where co sensation maybe less likely to a problem, itmay be acceptable to avoid goingto double glazing and instead optfor some other type of insulatingwindow treatment. But, remem-ber that the single-glazed windowis more Ilk, lv to fog or ice up thana double-paned window (Figure9).

G.ng from double to triple glaz-ing can be a cost-effective move,even in moderate climates whenfuel costs are high. Yet, the cost ofgoing tp triple glazing may meanthat votk;:annot afford to add any

14

additional window insulation,which might be desirable strictlyfrom a comfort standpoint inwinter.

Triple-glazing Lan cut solar gainssomewhat, as well (Figure 10). Atpresent, most experts recommendtriple glazing on all but south-facing windows where heatingdegree days ex-eed 6,000 andabove, and tripe glazing nowcommands more than 20 percentof the total sales of new windows.

Again, money can be saved bygoing to some other type of win-dow insulation with more insulat-ing power than glass, especially ifnew window coverings are need-ed or desired for other reasons. Incold climates, you may wish toadd both glazing and additionalwindow insulation. If you mustdecide between the options, how-ever, you can roughly figure outthe difference in savings by con-sulting Appendix A.

Interior or Exterior WindowInsulation?

Climate affects the choice oe-tween interior and exterior insula-tion, as well as concerns over theappearance of the outside of thehouse. The majority of window in-sulation products are for interioruse, with many meant to replaceconventional window treatments.

Exterior products have both ad-vantages and disadvantages (Fig-ure 11). In hot climates where thereduction of solar gain is impor-tant, it makes sense to install heat-rejecting devices on the outside.This way the unwanted solar ener-gy is rejected before it can warmup the window and, eventually,the house. In cold climates, ex-terior treatments can help avoidmoisture condensation problems,by keeping the window panes orglazing warm. In all climates,some types of exterior treatmentscan help make the house more se-cure; it is more difficult to breakinto a house with a locking exte-rior window treatment.

But exterior products must 'beable to stand up to the elements;wind, rain and snow can damagethem, as several grantees discov-ered. In northern climates, mova-ble exterior products may be diffi-cult to open and close in winter,yet overheating won't be a prob-lem with them because the suncan't reach the window. Movableexterior products are inappropri-a :e on hard-to-reach windows, un-less they are mechanically oper-ated.

Many of the available exteriorproducts and do-it-yourself win-dow insulation schemes will rath-er dramatically affect the exteriorappearance of the home, Nthichsome consumers don't like. Interi-or products with reflective appear-ance can strike a bad chord withsome consumers, as well.

The main features to look for inan exterior product are: ability towithstand high winds withoutdamage or noise from vibration,effectiveness of the sealing system(for cold-climate products) andease of operation and mainte-nance. Other questions to askyourself include: Will I like thelooks of the produC. when it's in

17

RELATIVE HUMIDITY AT WHICH VISIBLE CONDENSATIONWILL APPEAR ON INSIDE SURFACE FOR VARIOUS U.VALUES

(BASED ON INSIDE SURFACE CONDUCTANCE VALUE OF 1.65)

100% .

90%

80%e 70%

zz w 60%tai X 50%

it 40%a °0 30%cc ao 20%O it.

%z 10

. no/30° 20 10, 0°

OUTDOOR TEMPERATURE IN °F(Adapted from ASHRAE Handbooks 1977 Fundamentals)

10° 20° 30° 40°

(U = 0.2)R3.3 (U = 0.3)0.6 (UR2.0 (U 0.58.1.6 (U = 0.6)

(U = 1.0)

FIGURE 9: The level of insulation on the window will determine the probability of moisture condensing on the glass during coldweather. With a single-glazed window, moisture will condense at lower indoor relative humidity than if the window has doubleglazing. The higher your indoor relative humidity, the more insulation will be needed to avoid visible condensation. Note fromthe chart above that when the temperature outdoors is 0°F, condensation will occur on a single-glazed window (R-1) when indoorhumidity is only 19 percent. If the window's R-value was increased to R-2, however, condensation wouldn't .occur until relativehumidity reaches 47 percent. This chart can be helpful in makin Me decision on whether more glazings would be desirable toavoid moisture condensation.

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FIGURE 10: Triple glazing can cut heatgains from solar radiation. For thisreason, triple glazing is often avoided onsouth-facing windows that receiveregular sunlight. However, triple glazingmakes economic sense on windows thatface north, east, or west in cold climatesor in locations where fuel costs are high.

place, bot't from the interior andthe exterior? Can this produci,,.w-place traditional window treat-ments or is it meant to be used inconjunction with them?

In general, exterior productsprobably make the most sense inwarm climates. Transparent sunscreens that are clamped to the ex-terior (so they shouldn't be af-fected by winds) can make for anexcellent solar-rejection strategy,particulary when used seasonally.

15

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INTERIOR PRODUCTS: .

can NON), IridNiallall wind*treatments at via* tvilh

docanbotae==gotiuramlii...,_ales but may fletiftscilve to aVoltodebeesiten.can be Ng etteolive as inettlationdurlpg ewe member, bet notexameely effective for shading.

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FIGURE 11: Interior and exterior products both have advantages and disadvantages.

Exterior products can be reason-able choices in cold climates if theyare used seasonally. For example,north-facing windows in a mois-ture-prone area of the home maybe treated with a tight-fitting exte-rior product that would preventmoisture condensation on theglass. The product can be employ-ed for the winter season and for-gotten, and then removed in thespring. Most available strategiesand products for exterior use incolder climates are opaque prod-ucts, however, so this should benoted if some light is desirable.

On east- and west-facing win-dows that receive some sunlight,an exterior product can work welland won't demand operation toavoid overheating. Some "xteriorproducts allow for interior opera-tion, of course, but these productswill be more expensive because oftheir (Terabit? nature.

BeLause of the drawbacks withsome (hut not ail) of the exteriorproducts. most people in climatesrequiring some winter heating

I Es)

111111111

tend to choose insulation that isinstalled inside the house. Interiorinsulation can replace a traditionalwindow treatment, it is handy andcan be easy to operate, and itneedn't be strong enough to with-stand rain, wind and snow.

Sealing System OptionsGrantees used a wide variety of

products and components toachieve tight seals around win-dow- insulating devices (Figure12). Work done during these proj-ects reveals that the design of thewindow insulation can make a bigdifference on how well the prod-uct can be sealed, and that eachsealing system has its drawbacksand advantages.

How tight the sealing systemmust be depends on what condi-tion the primary window k in andwhere the insulating device is tobe mounted. Products mountedover single-glazing should be ex-tremely tight to avoid moisturecondensation problems, while

windows with double or tripleglazing may be somewhat moreforgiving.

If the product is to be mounted bypressing it directly against the glass,seals around the edges are unneces-sary. The seal in this case isachieved by the fact that no signifi-cant air movement can occurbehind a plate that is within1/4 -inch of the window surface. Anon-the-glass seal is fairly easy witheither exterior or interior seasonalpanels, whicll can be wedged intoposition and held tight against theglass by putting shims around theedges.

However, the majority of win-dow insulation products are notmounted in this manner. Flexiblepioducts are often sealed aroundthe window casing or the sur-rounding wall. Some designs 'em-ploy side tracks of various types,while others use seals achievedwith hook-and-loop tape, flexiblemagnetic tape or wooden side 4

clamps operated on spring-loadhinges. Shutters and rigid panelsare fit between the jambs, withseals of soft foam, "v-strip"weatherstripping or other similarmethods.

When the product is more thanV.-inch away from the windowpane, seals around the edges ofthe prOduct become imperative.Further, most specialists note thatgaps greater than 118-inch in theseedge seals can significantly reducethe effectiveness of the product.Also, if the window itself allowsmuch infiltration the seal on thewindow insulation must be ex-tremely tight and strong.

Ilow Do the Sealing SystemsCompare?

In most retrofit situations, it isqially easier achieve an effec-

t ve seal with a soft, flexible prod-uct than with a rigid panel or shut-ter. The reason for this is that thefit with rigid products often mustbe exacting, because many aredesigned to fit between the jambsof the window. The problem isthat many older windows are notperfectly in square. (At least twomanufacturers of do-it-yourselfpanel kits have overcome this fit-ting problem by providing sealing

19

systems that can make up for aninexact fit of the rigid panel itself.

Some sealing systems may be af-fected by heat or moisture. For in-stance, one grantee found thatsome varieties of hook-and-looptape will stretch out if exposed tomoisture. This grantee concludedthat these tapes should probablybe washed and dried once beforebeing installed to avoid this poten-tial problem. Some plastic trackingsystems will warp and expand if

III=IMar

exposed to,. heat or sunlight, andsome varieties of magnetic tapecan lose their magnetic powerwhen exposed to heat or directsunlight.

The general rule is: Don't try tocut costs too much with sealingsystem components. Higher quali-ty products may cost quite a bitmore, but the performance willeasily be worth the money. A sealthat doesn't work can ruin yourproject and reduce the insulating

value of your product to the pointwhere it is nearly worthless aswindow insulation.

Adhesives used to apply sealingcomponents also must be of highquality, able to withstand heat andmoisture. "Self-adhesive" tapeshave sometimes given way (dur-ing washing or dry cleaning orduring regular use), and quite anumber of these products demandan extra layer of additional adhe-sive to be truly effective. Trying a

Hook.And Loop Taps

Flexible Magnetic Tape

L--- Side Tracks

Bottom Seel Weights

FIGURE 12: TiltNe .4ealin.SZ SVSteMS are among the many options available for window insulating devices.

2017

FIGURE 13: Grantees in the Shades of West Virginia SewingCooperative designed this drapery shade, which seals at thebottom with a wooden rod that is held securely in place by sidebrackets. The rod is attached with a spring, to ensure easyoperation and hold it in place when not in use.

',est ,ection with this type of prod-uct is a good idea before doing theentire job. Try the self-adhesiveproduct in an inconspicuousplace, and test the hold of the ad-hesive by tugging the strip repeat-edly.

Perhaps the simplest and mosttrouble-free sealing system usedby grantee.; was the wooden sidelamp system. This system is use-

ful ith all types of soft, flexibleinsulation materials for interioruse. and it is an excellent sealingoption for existing drapery

One aspect of th;s type of seal isthat it must be manually operated;the insulating product is closed

Ifi

over the window, and the sideclamps are snapped into placeover the edges of the insulation.Unlike other types of sealing sys-tems that are 'somewhat "automa-tic," this manually operated sealmay prevent inadvertent sealingof the product at an inappropriatetime. This type of seal allows theproduct to be in place for shadingor light control on a heat-gainingwindow without employing theseals, which can help avoid over-heating.

Sealing folding shutter productsproved difficult for several grant-ees. Foam tapes and viiiy1weather-stripping may break

down due to friction caused dur-ing operation. Also, there aremore edges to seal than with aone-piece product. Shutters mayneed some additional hardware tokeep them snugly in place; if thefit is less-than-exact, the shuttersmay have a tendency to pop awayfrom their seals.

Seals for the bottoms of flexibleproducts usually rely on addingweight to the bottom of the win-dow insulation. Grantees usedmetal weight bars of steel, sand,standard weight chains (which areoften used in conventional, non-insulating drapery), small marblesand rods that are clamped over thebottom-of the window insulation.(Figure 13). Magnetic tapes alsocan work well for bottom seals.

The top seal can be achieved in anumber of ways, depending onthe design of the product. For con-ventional-looking draperies andcurtains, grantees used valancesand soft, flexible materials tobridge the gap between the walland the drapery rod. Shades thatoperate vertically are often perma-nently tacked to the top of thewindow, or lightweight shadescan be mounted with hook-and-loop tape. At least cne manufac-turer offers top and bottom seals .for horizontally operated shadesthat employ tracking devices.

Just as the grantees used a varie-ty of sealing systems with theirprojects, consumers have 'anumber of choices to make when itcomes to achieving an adequateseal with window insulation.Manufacturers and small busi-nesses .:ontinue to work on sealingsystems, and innovations in thisarea will continue in the future.

Perhaps no other part of thewindow insulation field bafflesconsumers as much as sealingsystems do, yet no other compo-nent is as essential to the perform-ance of these products. Nev. -comers to window insulation man-ufacturing and sales sometimesoverlook the importance of thesealing system, and unwary con-surncrs can be left to fend forthemselves.

Do It Yourself or I tire aContractor?

The most popular products intoday's window insulation market

21

are do-it-yourself products. Con-siderable savings await the occu-pant who wants to use skills ineither sewing or carpentry (orboth) to make and install windowinsulation. But, zs one grantee dis-covered in the course of a surveyof potential users of window in-sulation, many people don't havethe ability to complete a do-it-yourself project succ.?ssfully.

If the device is a shade or cur-tain, sewing skills and a sewingmachine will be needed, while ifthe product is a shutter that foldsopen, considerable carpentry skillswill be necessary to ensure a tightfit.

Yet, some do-it-yourself prod-ucts demand few skills or tools.Probably the most popular in thisregald are simple, pop-in panelsthat fit between the jambs of the

window (Figure 14). In the sim-plest of cases, the occupant pur-chases standard insulation boardfrom the lumber. yard and a kitfrom another firm that suppliesthe instructions and sealing sys-tem. In the more difficult circum-stance, the occupant buys theinsulation board and fends forhimself when it comes to the seal-ing system.

As with any do-it-yourself pro-ject, your chances of success :Iremuch greater if you follow an es-tablished, proven plan and avoidimprovising when it comes to thedetails, especially with the sealingsystem.

For several years, consumershave demanded window insula-tion at a faster rate than firms havebeen able to supply it. In themeantime, passive solar advocate%

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FIGURE 14: A pop -in panel is one 0: the easiest options forthe ao-it-vourselfer. Kit:, that include a flexible edge sealingsti,:tem can help ozmome the problem of out-of-squarezenulou.,

j

22

and practitioners tried to get infor-mation to consumers on do-it-yourself schemes and products.Yet, many consumers were start-ing out without the basic informa-tion they needed to ensure suc-cess. This has led to numerouscomplaints about the "difficult"features of window insulation: theproducts blocked light, were dif-ficult to open, allowed excessmoisture condensation due topoor sealing systems and, in manycases, were unsatisfactory simplybecause they were so differentfrom the conventional windowtreatments that are familiar tomost people.

A number of do-it-yourselfproducts were introduced that hadlittle chance of success becauseconsumers didn't have the skills toovercome such obstacles as out-of-square windows. Billed as,"simpleto make and install," these prod-ucts sometimes produced a mas-sive headache for the consumer,who was expecting an easy-to-tackle project. In addition, someproducts advertised as "insulat-ing" products made little or noprovision for effective sealing sys-tems.

The greatest difference betweenmaking standard window treat-ments and insulating products isthat the insulators usually must fitwell; there is little margin for errorif a good seal is to be achieved.

If you are contemplating a do-it-yourself project with window ici-sulation, first determine whatskills and tools will be needed todo the job and be realistic aboutyour ability to handle the task. Tryto estimate how many hours it willtake to do the job and whether youare willing J put in the time. Ifyou feel confider t that you:

understand the design of theproduct and how it will workand seal on your window;have the tools and skills to dothe tasks, or can hire out theparts that you can't do;have the time to devote to theprcject;trust the insti actions and de-sign to do a good job;

°' a:A understand how you willmanage and maintain theproduct when the job is fin-ished,

19

then you're probably ready toundertake the job of making yourown window insulation. Other-wise, try to find a local dealer orcontractor who has these sameskills, has a thorough understand-ing of the product(s) and canguarantee the work.

In many parts of the country,"energy conservation" businesseshandle the bulk of the window in-sulation work in their areas.Sometimes pre -lucts and servicesare available at major departmentstores or at interior furnishings ordecoration businesses. Also, archi-tects who specialize in passivesolar work are likely to haveknowledge of window insulationstrategies and products.

A reputable contractor generallywill need to visit the house to lookat the windows and help the cus-tomer choose the best products tomeet the demands of the situation.Because window insulation oftendemands a good fit, hiring a con-tractor usually means a customjob. Measurements often must beexact to make sure the seal islocated in a place where it won'tbe hampered by the design of thewindow or the casings. Also thecontractor should be able todiscuss and explain managementand maintenance of the products.

Many contractors handle onlyone type or design of window in-sulation, and this design mightnot meet your needs. Don't hesi-tate to shop around and comparedifferent designs -4nd operationalfeatures. For example, because ofdecorative trim on your window,one type of window insulationmay not be able to be tightlysealed at the bottom of the win-dow, while another would workfine.

Another level of do-it-yourselfactivity may come in buying a fin-ished product and installing ityourself. In this case, you usuallysupply the measurements, and thefinished produce is delivered witha sealing systei for your installa-tion. If you go u s route, be sure,again, that you fully understandhow the product will be sealedand will operate bOore you buy.Carefully think through how theproduct will be mounted andwhether you will able to suc-cessfully mount the product.

20

Installing insulating productscan be extremely simple or verydifficult. For example, mounting abasic, vinyl roll-down shade withmagnetic sealing system can besimple, while installing bi-foldingshutters can sometimes try the pa-tience of a seasoned carpenter.

Many of the problems associatedwith do-it-yourself projects can beavoided if you first think throughthe sealing system and the mount.Many a disappointed homeownerhas learned this painful lessonwhen trying to install a finishedproduct in a situation that is reallyimpossible, because of windowdesign or other unforeseen"hitches."

Sorting Through ProductClaims

A frequent complaint about win-dow insulation relates to inflatedor inconsistent claims as to howmuch energy the product willsave. Some manufacturers havelabeled conventional windowtreatments as "energy savers,"when there is little t9 indicate thatthe products are capable of anymergy savings because of inade-quate or missing sealing systems.

Manufacturers of products withan R-value (based on acceptedengineering practice) of less thanR-2 may claim the product worksat an R-10 level. Many productsare described in terms of what the"total" R-value will be over singleor double glazing, whi:h is a dif-ficult thing to bank on, becausethe thermal effectiveness of win-dows varies, depending on howtight the window is and how greatthe air space is between the layersof glazing.

At least one trade association ispushing for an acceptable indus-try-wide standard of testing thatwill overcome these inconsist-encies and help clear up false ormisleading claims. Until this hap-pens, however, the consumershould beware

Reputable contractors or dealersshould be able to give a reasonableestimate of the R-value of theirproducts, discounting the existinginsulating power of the windows.Some manufacturers have hadtheir products tested at reputablelaboratories, and they are usually

willing to show you a copy of thelab's report or a summary.

If you have any doubt about thetruth of claim; made by a manu-facturer or dealer, keep shop-ping.

Managing the WindczosThrough All the Seasons

When managing movable insu-.lation, the main goals are to pro-duce the greatest energy savings,and avoid overheating, thermalshock, and excessive moisturecondensation. Obviously, mova-ble insulation will produce thebest benefit on south-facing win-dows if it is faithfully openedwhen the sun is shining andclosed during cloudy weather andat night. Such operation is easilypossible if someone is home toopen and close the products, butin many households, everyone isaway from home during part ofeach day. Yet, simple habits can beadopted to allow for near-optimaluse of interior window insulation.Some rules of thumb include:1) If you are routinely away fromthe house during the daytime,open any interior movable insula-tion on all heat-gaining windowsbefore you leave for the day. It'snot necessary to open the prod-ucts completely if you wish to ob-scure view into your windows forsecurity reasons, Lut you shouldopen them sufficiently to avoidheat buildup behind the insula-tion. (The same holds true if youare leaving the house for severaldays or for a long period of time.)2) During the coldest weather,open movable insulation slowly toavoid thermal shock. Just breakthe seal a bit at first, and let thewindow temperature changeslowly. If you heat with a woodstove, open movable productsbefore firing your stove in themorning.

3) In wintertime, the effective-ness of the seal at the bottom ofthe window is the most important;in summertime, the top seal is themost effective (Figure 15). In thesummer, an alternative to leavingan insulating device unsealed atthe bottom (to allow some escapeof hew in:o the worn) is to openthe windo% sufficiently to encour-

23

FIGURE 15: In winter, the bottom seal is critical, while insummer, the seal at the top of the window is the mostimportant.

+111Mi=1111111111

FIGURE 16: When using sealed window insulation products toprevent unwanted heat gains. it is important to either open thewindow covering or the window to avoid damaging heatbuildup.

age heat to return to the outdoors(Figure 16).

tVhat Options Are Availablefor Remodel* or New

Cortstruction?Consumers now have more op-

tions in new windows for remod-eling or new construction. For ex-

ample, one manufacturer makes awindow unit that includes a built-in, high-R shutter that slides into apocket in the wall. Another makesa triple-pane window with a shadethat slides down between thelayers of glazing.

Many effective products and de-vices have been developed in thelast ten yeors to help consumers

24

save the energy lost through win-dows. Yet, there is still 4he needfor significant innovation in thisindustry, and research is continu-ing in a number of promisingareas. (See: THE WINDOW OF THEFUTURE.)

Heat 1vfirrortiRecent research has led to one

striking development in windowinsulation: low-emittance films(also called "heat mirrors") thatdramatically enhance the perform-ance of windows. Heat mirrorsspent more than a decade in thelaboratory before entering thenew-window market in the early1980s.

Heat mirrors consist of an ex-tremely fine layer of metal, so finethat it is not visible to the nakedeye. The metal is embedded in alayer of clear synthetic material,that is sealed between two layersof glass.

Heat mirrors allow a double-glazed window to perform morelike a window with four panes ofglass, yet they do not cut heatgains, from sunlight as much as aquadruple-paned window (Figure17). Thus, solar radiation is trans-mitted by day, but the window isinsulated at night or during cloudyweather.

On the other hand, heat mirrorscan also be designed to reduce so-lar radiation, in a manner similarto conventional reflective films,but they insulate much more effec-tively than a clear, reflective filmor a tinted glass. Thus, heat mir-rors make sense in all climateregions.

The breakthrough in heat mir-rors allows the occupant to foregoadditional window insulation, ifdesired. This can be especiallyhelpful in passive solar applica-tions, such as greenhouses, whichhave traditionally posed manyproblems with window insulation.For example, it has been difficultto find a movable insulation prod-uct that works well on slantedglass. In addition, when the insu-lation is pulled up during the day-time, it can sometimes obstruct de-sirable sunlight from overheadglazing.

Because the new windowswhich incorporate the heat mirrors

21

1111M10111111,

FIGURE 17: Low-emittance films, or "heat mirrors," canallow solar radiation to pass through the glass to enhance solarheating, yet heat mirrors insulate a double-glazed window sothat it performs better than a window with four panes of glass.For climates where heat gain is a problem, heat mirrors havebeen developed that cut solar gains, while still insulating theglass to a level of about R-5. The film is sealed between twopanes of glass.

FIGURE 18: Solar rejection films or tinted glass are for use on-ly where heat gains are the major problem. Unless solar rejec-tion devices are movable or seasonal, they will also cut solargains that may be desirable in the winter.

are in place 24 hours a day, andbecause they don't substantiallyreduce solar gains, they can beeconomically competitive withdouble-glazing combined withmovable insulation. They have theextra advantage of saving the oc-cupant time and trouble, becauseno window management is neces-sary.

Some observers have noted thatthese new windows may make

22

movable insulation and othertypes of window insulation obso-lete. However, this observation ig-nores the fact that some con-sumers will still want interior win-dow treatments of some kind forother reasons. The overall cost ofnew i:idows plus additional window treatments could be muchhigher than if the homeowner hadchosen basic double-glazing and

an interior, movable window insu-lation.

Reflective Films and TintedGlass

In contrast to heat mirrors,reflective films and tinted glass aresuitable only when excess solargains are the primary concern(Figure 18). Because solar gainsmay be desirable in most house-holds during the winter (even inwarmer climates), these optionsare more commonly recommend-ed for commercial rather than resi-dential applications.

Reflective films should not beadded to existing windows if thewindows are sealed double-panedunits. Temperature difference canmake the two panes expand andcontract at different rates, causingthe glass to break.

Some reflective films are remov-able, allowing for seasonal opera-tion, while others are permanent.A reflective film or "sun screen"shade that is operable may bemore practical than purchasingpermanent reflective film or tintedglass.

Replace the Windows orRetrofit Them?

A choice confronts the home-owner who is considering replac-ing existing windows with newwindows in order to save energy.The cost of new windows maymake further investments in win-dow insulation difficult, and theoverall energy savings could belower than retrofitting the existingwindows.

For example, the homeownerwho wants to replace single-glazed windows with new double-glazed windows may be able tosave both money and energy bychoosing instead to spend a simi-lar amount on weatherizing thewindows, adding storm windowsand opting for further window in-sulation (Figure 19).

As with all types of window in-sulation, the tastes and prefer-ences of the consumer will havemore impact on the economiceffectiveness of the various op-tions than any other single factor.Thus, the decision to purchasenew windows or some other wilt-

25

dow insulation option should bemade after taking all the factorsthat influence the use of the win-dows and window treatment intoaccount.

What About AutomatedControl cf Window Insulation?

Automated controls for conven-tional, non-insulating windowtreatments have been available foryears, though they tend to be tooexpensive for many households.High costs have also deterred theuse of automatic controls for resi-dential window insulation. At1983 prices, the cost of completely

FIGURE 19: Although movable insula-tion demands attention. many consumerswill still prefer a window covering to ahare, well-glazed window. This designwas fabricated for a public building bygrantees in West Virginia. This projectresulted in a small business, Shades ofWest Virginia Sewing Cooperative,which otters hand-quilted shade covers.Ow group plans to switch its emphasisto edwational workshops on windowinsulation

FIGURE 20: Automated window insulation controls can workwith either interior and exterior devices. With interior pro-ducts, a sun sensor is used, while exterior products usually de-mand both a sun and wind sensor, to protect the product fromwind damage.

automatic systems can run $450 ormore per window.

Yet, automated control canmake economic sense even atthese prices. If the house has largeexpanses of southfacing glass, forinstance, it may be worth it toautomate the system.

Most completely automated sys-tems employ a sun sensor whichactivates a motor that opens thewindow insulation when the sunis shining. Exterior automated sys-tems often feature both a windand sun sensor. If wind speeds aretoo great, the wind sensor willopen the window insulation toprevent damage (Figure 20).

It takes an expensive mechanismto sense sunlight, mechanicallyopen a product and then close it,while somehow ensuring that thesealing system is fully employed.In order to make sealing a reason-ably good prospect, these auto-mated systems generally workbest on devices that employ track-ing side seals.

26

At least one controls manufac-turer is conducting research intosome simpler controls, including aday-night control and a winter-summer control that would alterthe operation of the window insu-lation to prevent heat gains insummer and maximize solar gainsin winter. If prices are reasonable,these types of controls would eli-minate the problems associatedwith the need to operate movableinsulation devices.

One grantee explored the possi-bility of manufacturing a low-costautomated system for window in-sulation. This grantee attemptedto design a mechanical roller sys-tem for exterior sun-rejectionshades for large passive solar sys-tems. The grantee reported thatexterior products suffered fromdamage.

Yet, this grantee reasoned that adevice that could simply drop thewindow insulation without con-ceri t for sealing the product wouldstill be useful and possibly afford-able in cooling applications.

23

Several grantees discovered that not all "movableinsulation" devices are easy to operate. Some devel-oped exterior products that had to be opened fromthe outside, which was sometimes difficult or im-possible. Others noted that heavy insulating materi-als caused operational difficulties.

One grantee developed a sliding glazing productand tested it in several homes. The device consistedof a roll-up, twin-layered shade, made of low-cost,clear plastic. Problems arose over the s'=aling system;it was difficult to get the flexible plastic to track. upand down, despite the use of velvet-covered sidetracks. Users reported that simply pushing on theplastic would disengage the side seals. Users alsilfound the plastic virtually impossible to clean, a probtern common with many plastic glazings.

Other grantees pointed out that some of the rigidboards used for insulating panels may pose firehazards. Some suggested the use of flame-retardantpapers or fabrics with these boards, while otherssimply opted for insulating boards that were alreadytreated with flame retardant or were non-flammable.

In another project, two grantees in Iowa field testedinsulating board panels in ten houSeholds. KennethLillemo and Scott Holcomb of Huxley, Iowa, used anopaque, closed-cell insulating board. The sealingsystem consisted of a simple friction fit between thewindow jambs.

Although most of the participants in the ten house-holds said they enjoyed the benefits of window insu-lation (greater comfort and potential energy savings),they noted a wide range of problems.

Because the panels were not covered with fabric orany other protective material, they tended to shedsmall particles. Some people noted that these opaquepanels actually increased the need for extra lighting,since all natural light was blocked when the panelswere in place.

Because the panels were quite difficult t, remove(as are many friction-fit products), some participantstended not to remove them when appropriate. Heatbuilt up behind the panels on windows that receivedsunlight, and the heat was intense enough to warpthe panels in some cases.

When the panels were off the windows, other prob-lems arose. Storing the panels was the major prob-lem, and in one case, the panels were virtuallydestroyed by one participant's small children.

This project identified almost every potentialproblem associated with the use of low-cost, home-made, pop-in panels as "movable" insulation. Theonly difficulty not experienced was thermal shock. Ifthese panels had been used as seasonal devices,rather than movable insulation, many of these prob-blems would not have occurred.

Kits are available for the do-it-yourselfer that canhelp solve some operational troubles with rigid, pop-in panels. For example, one manufacturer hasdeveloped a soft-foam, sealing system for rigidpanels that makes them much easier to remove.

The lesson many of the grantees learned is that ifthe movable insulation product isn't very easy tooperate, it probably won't be used properly, may notlast very long and won't give much user satisfaction.

One grantee experimented with the concept ofsubstituting sealed window treatments for stormwindows in the moderate climate of Potomac,Maryland, a location with 3,800 heating degree days.

Robert Wehrli, an architect and former staffer at theNational Bureau of Standards, explored the possibili-ties and economics of sealing conventional windowtreatments to allow these treatments to function inlieu of storm windows, and sometimes at significantco,t savings over storm windows.

Wehrli noted that by employing a sealing systemwith tightly woven draperies, a total R-value ofR-1.77 could be a.hieved, while adding an extra layerof glazing would yield about R-1.8. Thus, the granteereported that his window treatments would cut hisheat losses nearly in half. Wehrli produced a numberof prototypes that employed zippers, hook-and-looptape, weighted hems, and other strategies. He chosestandard drapery lining fabrics that can be resistant tomoisture, although they probably would not serve as

vapor barrier.Wehrli employed the prototypes over 2,000 square

feet of single glazing (see photos) This amount ofglaring greatly exceeds the amount found in most

24

AEI

Asa

homes, but Wehrli's house was designed to take ad-vantage of solar gains through a large amount ofsouth-facing windows. His main goal was to stop"the waterfall effect," which describes the way coldair moves down a window pane, as part of the con-vection process. Wehrli's windows were so tall thatthis waterfall effect caused chilling drafts that made ituncomfortable to be near the windows. Addingstorm windows seemed less desirable in this casethan covering the windows with a tightly wovenfabric that could contain the cold air at the bottom ofthe window with the help of a sealing system.

The grantee carefully monitored his prototypes andfound that they performed as expected. He reportedthat the window coverings stop drafts from the con-vective loop and that operating the devices isn't dif-ficult despite their large size. Although moisturetends to condense on the windows in colder weather,he noted that no damage has resulted because themoisture quickly evaporates when warm room airmoves to the window when the curtains are opened.However, Wehrli acknowledged that excess moisturecondensation could be a problem in colder climateswith his design.

2

In a cost analysis, he noted that the materials costfor his prototypes could be as loW as 55¢ per squarefoot, and finished products with labor could run from814 to $5.83 per square foot. Based on a comparisonwith storm windows, he noted that his prototypeswould cost roughly one-third the cost of storm win-dows, with a similar final R-value.

Finally, he produced a manual for professionaldrapers, upholsterers and interior designers that ex-

4.

-;"

wehrli's sealed drapery is designed to stop the "waterfall" ef-fects of air moving down these tall windows, which can causechilling drafts. These sealed drapery liners effertively halt theseconvection currents.

Research is continuing in many directions towardreducing energy lost due to windows. Although heatmirrors have entered the marketplace at last, researchinto this new technology will continue, to find waysto improve manufacturing techniques and to discoverwhether the concept can be adapted to the retrofitmarket.

Further from commercialization is the idea of onegrantee, who explored the possibility of constructinga window unit that automatically adjusts to weatherconditions: when the sun shines, the window rejectssolar radiation to reduce cooling costs, and when thesun is gone, the window is insulated against the cold.

While this may seem to be a nearly impossibleideal, the concept of the "thermal shutter," which isbeing developed under the management of nationallaboratories with funding from the U.S. Department

plains the process of producing products similar tohis prototypes (Appendix B). Wehrli noted thatdrapery production shops are already in existenceacross the country, and if these businesses couldlearn how to turn their products into insulatingdevices, these products may be able to competefavorably with other window insulation options.

....,70".41,s'

On the inside, the tall drapes are closed with the help of along rod. The drapes are translucent, and they can be left dos-ed on a cold winter day without reducing light levels. (Photosby Robert Wehrli)

of Energy, comes close to it. The thermal shutter em-ploys a gel-like substance between two layers ofglass. When solar radiation is absent, the gel is trans-parent, but when the sun shines, the gel becomestranslucent and reflective to reject solar radiation.

Like the early stages of th' development of heatmirrors, which also was a research and developmentproject funded by DOE, the thermal shutter heat mir-rors overcame cost problems, and it is thus possiblethat the thermal shutter concept may be available inwindow units some time in the not-too-distantfuture.

One of the more promising concepts in window in-sulation is the notion of "microporous" transparentmaterial for windows, a material that offers excellentthermal performance while maintaining its transpar-ency. These materials consist of a rigid matrix of

2825

transparent silica with a pore size that is considerablyshorter than the wavelength of light. Like foamedplastic or rubber, this material would consist of tinypores, yet unlike these foams, which tend to diffuselight and hardly approach transparency, the micro-porous material's pores are so minute that light istransmitted directly, and the view isn't impeded.

This concept has been under development forabout 50 years, with the greatest interest coming dur-ing the last ten years. Referred to as "aerogel," thematerial would work best sandwiched between twolayers of regular glass, to protect it from moisture andcompression, which will damage it. LawrenceBerkeley Laboratory (LBL) notes that the R-value of a3-inch thick window made with this material would

26

be R-15. This outstanding thermal potential has led toconsiderable interest in further development of thisconcept, yet much work remains. An aerogel prepar-ation facility is in the works at LBL, and bench-scaletesting is anticipated during the 1980's.

Another unusual concept was researched by onegrantee, who explored the possibility of using highlypolished half-cylinders of rock salt to both reject andtransmit heat. The "heat-shield" of rock salt trans-mits radiant heat from its concave side, while the con-vex side rejects solar radiation, and thus cools. Thisconcept is in the early development phase, and,while it may have applicability to window heat loss,no major research efforts have been directed towardusing this technology.

29

The following method providesa way to roughly calculate heatlost through your windows. Theanswer you get will likely under-estimate your heat losses, becauseit only takes into account heat lostthrough conduction, which is onlyone of several ways in which heatis lost through windows.

For example, if your windowsare very leaky, heat losses from in-filtration may easily exceed con-ductive heat losses. Also, manyexperts note that heat lost throughradiation may be the most signifi-cant single source of heat lossthrough windows. However, it isnot possible in a simple analysis tocalculate heat losses through thesemethods. Nor does this methodfactor in heat savings from solargains. Consult reference bookslisted in Appendix B if you wish toadd this information to your eco-nomic analysis.

Yet, this method can give you aconservative idea of how muchwindow heat loss is costing you.1nually. You can also use thismethod to compare savings fromdifferent window insulation op-ti3ns, and to calculate savingsfrom other energy conservationwork, such as wall or ceiling insu-lation.

In many cases, tax credits of-fered by states and the FederalGovernment could further reducethe cost of some window insula-tion items. Check with your stateor local energy office, your stateand federal revenue offices or yourtax preparer for information aboutthese tax incentives. In addition,remember that unlike many othertypes of investment, investmentsin energy conservation provide"tax free" returns.

To do the calculations, you willneed a calculator, a tape measure,and a few utility or fuel bills to find

out how much energy costs perunit. Follow the chart that followsfor a step-by-step approach.

1. MEASURE YOUR WINDOWSMeasure width and height of allwindows to calculate the numberof square feet of window space.[Example: Window A: 40 inchestimes 50 inches.2,000 inches,divide by 144 (inches in a squarefoot) - 14 square feet(SF)]

2. DETERMINE R-VALUE OFWINDOWSNote, for each window, whetherthe window has single, double ortriple glazing. For simplicity, usethe following R-values:Single glazing 0.9Double gl zing .R 1.8Triple glazing .R-2.7

3. CHOOSE A HEATING DEGREEDAY NUMBERConsult the heating degree daymap in Part II and select a heatingdegree day figure that is closest toyour location. If your location ismissing from the map or you wishto further refine your calculation,consult your local or state energyoffice or utility for an appropriateheating degree day estimate.

4. CALCULATE HEAT LOSS INMILLIONS OF BTU'S (MBTU'S)Plug your numbers front steps 1through 3 into this formula, whichwill tell you roughly how manymillions of British Thermal Units(Btu's are one way in whichheating energy is measured) arelost through your windows on anannual basis:

Window Area (SF)x Heating Degree Daysx 24 (Hours in a Day)

Existing R-Value of Window Area

30

Example:200 (SF) x 6,000 Degree Days x 24

(R) - 0.9

= ?8,800,000 = 32 MBtu's Lost

0.9 ThroughWindowsAnnually

5. CALCULATE THE DOLLARVALUE OF ONE MBTU'SA. Go to your utility or fuel bill,and note what type of fuel you usefor heating, and what type of unitsyour fuel is measured in. UseChart A: CONVERTING YOURUNIT OF ENERGY TO BTU'S todetermine the number of Btu's perunit of fuel.

B. Take your number of Btu's perunit and divide it into 1,000,000(Btu's). Example: You heat withnatural gas, and the utility sells itin therms. From CHART A, younote that one therm delivers100,000 Btu's. 1,000,000 dividedby 100,000 .. 10 thermslin onemillion Btu's (MBtu's).

C. Note from your fue: bills thecost of one unit. Expmple: Yourfuel bill tells you one therm costs$0.50.

D. Multiplyyour unit cost by thenumber of units in one MBtu's.Example: From Step 5.B youfound that there are 10 therms inone MBtu's. Thus, 10 times theunit cost of $0.50 a $5.00 perMBtu's. Thus, your raw cost perMBtu's is $5.00.

E. Your raw cost per MBtu's prob-ably doesn't reflect the cost of ac-tually heating your home, becausemost heating systems are not 100percent efficient. Thus, you needto make a rough estimate of howefficient your system is, and divideyour raw cost per MBtu's by thisefficiency factor to determine theactual cost of heat. Consult

27

CHART B: ESTIMATE OF HEAT-ING PLANT EFFICIENCY LEV-ELS to determine what your effici-ency divisor should be. Example:You heat with an older natural gasfurnace. From CHART B you findthat an older furnace may be 65percent efficient. Thus, your $5.00per MBtu's should be divided bythe efficiency divisor from Chart Bof 0.65: $5.00 divided by 0.65 =$8.00. Thus, $8.00 per MBtu's isyour real cost.

6. DETERMINE THE DOLLARVALUE OF HEAT LOSTTHROUGH YOUR WINDOWSReturn to Step 4 and note thenumber of MBtu's that are _lostthrough your windows annually.In our example in this step, wefound that 200 square feet of sin-gle-glazd windows loses 32MBtu's per year in a climate with6,000 heating degree days. Takethe real cost per MBtu's from Step5.E and multiply this cost by thenumber of MBtu's lost per year:Example 32 ( MBtu's) x $8.00(cost per MBtu's) = $256.i)0 peryear. Remember that this estimaterepresents only a part of the heatlosses through your windows; itcan be considered to be the mini-mum your windows are losing,considering only losses throughconduction.

Comparing Savings AfterAdding Window Insulation

After you have roughly deter-mined how much heat is being lostthrough your windows and howmuch this heat costs, you areready to estimate how much youcould save by adding window in-sulation. There are two methods:one for fix2d or seasonal devicesand one for movable insulation.Again, use the step-by-step ap-proach to estimate savings.ESTIMATING SAVINGS FROM FIXED

OR SEASONAL INSULATION

1. CALCULATE HEAT LOSSAFTER ADDING INSULATIONFirst, estimate the R-value of thefixed or seasonal movable insula-tion. Use square-foot area mea-surements and degree day num-ber from your initial calculationsthat estimated heat loss in our firststep-by-step method. Plug yournumbers into the followingformula:

28

*If your type of fuel or unit isn't listed, consult yhur utility or fuel sup-plier for Btu content per unit.

*Efficiency levels listed in this table are meant only to be estimates, forsimplified use in your calculations.**Add .05 extra efficiency for radiant-type stoves (rather than fanpowered stoves), add .05 for heat exchangers and add .20 for stoveswith effective catalytic afterburners.

Arta (Square Feet)Degree Days

24 (Hours in a Day)

New R-Value ts.ih Window Insulation

Heat Lo, in Mfitn'sAtter Adding Window In,lilat,on

Example; Assume the homeownerin the 6,000-degree-day climatewith 200 square feet of sin-gle-glazed windows wants to i-ddstorm windows. The R-value afteradding the second layer of glazingwould be R-1.8. The calculationlooks like this:

31

200 x 6000 x 24 16 MBtu's Lost Annually(R-) 1.8 After Adding Storm

Windows.

2. CALCULATE DOLLAR VALUEOF HEAT LOST AFTER ADDINGINSULATIONUsing the cost per MBtu's deter-mined in our heat losi example,multiply the number of MBtu's bythe cost of heat per MBtu's. [Ex-ample: 16 x $8.00 (cost perMBtu's)$128. Thus, $128 is thevalue of heat lost after addingstorm windows.

3. COMPARE VALUE OF HEATLOST BEFORE AND AFTER ADD-ING INSULATIONCompare before and after costs,using answers calculated in theheat loss method, to determine es-timated annual savings. [Example:Using our heat loss estimates fromearlier examples, note that thehomeowner in our example waslosing roughly $256 annuallythrough 200 SF of single-glazing ina 6,000-degree-day climate. Afteradding storm windows, the loss isreduced to $128 (from Step 2above):$256 minus $128.$128 annual sav-ings after adding storm windows.

4. DETERMINE COST OF ADD-ING INSULATION AND SIMPLEPAYBACK (OPTIONAL)If you wish to determine simplepayback times on your window in-sulation investments, first youmust get estimates on how muchthe window insulation will cost.Once you have these costs, youcan divide costs by the annual sav-ings to determine simple payback.Example: Say 200 square feet ofstorm windows costs $3 persquare foot, for a total cost of $600of doing this storm window job. Ifannual savings are $128, then thecalculation would look like this:$600 divided by $128=4.69 yearssimple payback time.Note that with many window in-sulation jobs, a simple payback ap-proach, as defined here, may over-estimate the actual payback timebecause only one type of heat lossis being considered. Your simplepayback estimate could well be theabsolute longest time such an in-vestment may take to pay for it-self.

ESTIMATING SAVINGS WITHMOVABLE INSULATION

.1. ESTIMATE R-VALUES ANDU-VALUES FOR THE MOVABLEINSULATIONBecause movable insulation is notin place 24 hours a day, a slightlydifferent approach is needed tocalculate savings. First estimate R-values for the existing windowand for the movable insulation.Then convert these values to U,which is the reciprocal of R, in or-der to do this calculation. U des-,tribes the rate at which heat istransferred, while R describes theresistance to heat transfer. Exam-ple: Assume window is double-glazed (R-1.8) and that a movableinsulation device with an R-valueof 5 will be used over the window.Because U= 1/R, divide your R-values into 1:1 divided by 1.8=U 0.551 divided by 5.0=U-0.20

2. ESTIMATE NUMBER OFHOURS PER DAY THAT MOVA-BLE INSULATION WILL BE USEDDecide, for your calculation, howmany hours per day your movableinsulation will be in place over thewindow. Example: The windowinsulation will be in place 14 hoursa day, while the single-glazed win-dow will be the only insulation for10 hours a day. Thus, for 14 hoursa day, the 4-value will be 0.25,while for 10 hours a day it will be1.1.

3. CALCULATE HEAT LOSSESWITH MOVABLE INSULATIONUsing your degree day numberand your window area in squarefeet, use the following formula:

Area x Degree Daysx (Hours with Insulation x Ul)

+ (Hours without x U2) =Heat Losses in MBtu's Annually

with Movable Insulation.

(Iristead of simply multiplying by24 hours, we break 24 hours downinto the time with movable insula-tion and time without.)

Example.50 SF x 6000 DD x 1(10 hours) x U .55)

+ (14 hours) x (U .20)1 =

2.49 MBtu's lost per year.

4. CALCULATE SAVINGS, COSTOF JOB AND PAYBACKGo to Steps 3 and 4 in the previous

32

example to calculate savings, andif desired, simple payback.

Comparing Your Options

Let's work through some op-tions with dollar values added in.This example concludes with asimple payback analysis. Ourmythical family, the Smiths, livein a 7,000 degree-day climate,where heating costs them $9.50per MBtu, after furnace efficiencyis taken into account. The familywants to explore the minimumsavings they could expect from awindow insulation program thatlooks like this:

Option 1: Add storms to 50square feet of south-facing, sin-gle-pane windows, with thelowest bid at $3 per square foot.Option 2: Add R -8, non-mova-ble seasonal panels with tightseals to 40 square. feet of north-facing, single-paned windows,with the cost being $2.25 asquare foot.Option 3: Add an R-2 doublestorm window to the same 40square feet of north-facing,single-pane glass for a total ofR-.7, instead of the panels, withthe cost being $5.50 a squarefoot.Option 4: Add R-5 movable in-sulation to east- and west-facingwindows that total 70 squarefeet of single glazing, at a cost of$7 a square foot, assuming themovable insulation is open tenhours a day.With Option 1: Savings wouldlook like this:Before: 9.3 MBtu's a year lost,worth $88.35After: 4.65 MBtu's a year lost,worth $44.17Cost of job: $150.Annual savings (at 1983 fuelcosts) are $44.17.Simple (longest) payback: 3.4years.

(Note, in that these are south-fac-ing windows, they would actuallyexperience no heat loss, but a netgain on an annual basis it they areunobstructed, after the new stormwindows are installed. This couldsignificantly shorten paybacktime.)

With Option 2: Before: 7.4MBtu's a year lost, worth$70.87.

29

After .84 MBtu's a year lost,worth $7.90.

Cost of job: $90.Annual savinr,s (at 1983 fuel

costs) are $62.97Simple payback: 1.42 years.With Option 3: Before: 7.4

MBtu's a year lost, worth$70.87.

After: 2.7 MBtu's a year lost,worth $25.65.

Cost of job: $220.Annual savings (at 1983 fuel

costs) are $45.22.Simple payback: 4.8 years.

(Note the difference between thechoices for the same windows.The low-cost high-R panels havean exceptionally short payback.Yet, if the occupants prefer theview from these north-facing win-dows, they still would get a goodreturn on triple glazing.)

30

With Option 4: Before: 13 MBtu'sa year lost, worth $123.50.

After. 8.5 MBtu's a year lost,worth $80.75.

Cost of Job: $490.Annual savings (at 1983 fuel costs)

are $44.75.Simple payback: 10.9 years.

If the Smiths do Options 1, 2and 4, the annual savings wouldwork out to be $151. Overall costof these fhree options would be$730, with a total payback for thepackage of 4.8 years.

Note that this analysis doesn'ttake into account the expectedlifespan of the product or anymaintenance costs that may beassociated with them. Durabilityshould be an important criterionfor deciding betWeen variousoptions.

33

GeneralMovable Insulation, WilliamLangdon, Rodale Press,Emmaus, PA, 1980.Thermal Shutters andShades, William A.Shurcliff, Brick HousePublishing Co, Andover,MA, 1980.Solarizing Your PresentHome, Joe Carter, ed.,Rodale Press, Emmaus,PA, 1980.Insulating Window Shades,Ray Wolf, Rodale Press,Emmaus, PA, 1980.Preservation Briefs: 9, TheRepair of Historic WoodenWindows, Technical Preser-vation Services Division,.; S. Department of the In-ter:or, Washington, DC.Usually available throughstate historic preservationoffices.

Energy Conservation andSolar Energy for HistoricBuildings: Guidelines for Ap-propriate Designs, TechnicalPreservation Services Divi-sion, U.S. Department ofthe Interior, Washington,DC. This publication isavailable for $6.95 a copyfrom the National Centerfor Architecture and Ur-banism, 1927 S Street,NW, Suite 300,Washington, DC, 20009.A comprehensive windowinsulation product direc-tory can be found in theFebruary 1982 and theJune 1983 issues of SolarAge. The magazine can becontacted by writing toSolar Age, Harrisville, NH03450 or by calling603/827-3347.The following two periodicalsregularly feature articles onthe latest developments inwindow insulation:New Shelter, 33 E. MinorSt., Emmaus, PA 18049,Popular Science, 380Madison Avenue, NewYork, NY, 10017.

Other ReferencesMovable Window Insulation,John Pierre Stephens andBarbara Wezelman, Sun-wise Co-op, 2535Westemesse St., Davis, Ca95616, 1982. Copies areavailable for $2 each bywriting to the above ad-dress and including a self-addressed, stampedenvelope.How To Make Low-costEnergy-Saving Zip-Up Cur-tains for ProfessionalDrapers, Upholsterers and In-terior Designers, RobertWehrli and Rita Molyneau,Potomac, MD, 1981.Energy Efficient Interior Win-dow Treatments, LeonaWindley, Cooperative Ex-tension Service, Utah StateUniversity, Logan, UT,1982.

Proceedings of the AmericanSection of the InternationalSolar Energy Society; AnnualMeetings 1978-82, PassiveSolar Conference, 1979-82.

34

Optimal Weatherization ofLow-Income Housing in theU.S.: A Research Demonstra-tion Project, Richard Cren-shaw and Roy E. Clark,National Bureau of Stand-ards, U.S. GovernmentPrinting Office, NBS-BSS -144, Washington, DC,1982.

Window Design Strategies toConserve Energy, RobertHastings and RichardCrenshaw, NationalBureau of Standards, U.S.Government Printing Of-fice, no. 003-003-01794-9,Washington, DC.Moisture and Home EnergyConservation: How to Detect,Solve and Avoid RelatedProblems, prepared by theNational Center for Ap-propriate Technology forthe U.S. Department ofEnergy, Government Print-ing Office, Washington,DC, 1983.GPO 061-000-00615-0

31

The following grants were amongthose reviewed in the course ofresearching and preparing thisdocument.

Benard Domning, Jr.Mobile, ALDOE Contract No. DE-FG44-F1R410446ATMIS ID: AL-81-006

The grantee designed, constructedand installed insulated, decorativeshutters for a residence. The shuttershad an R-value of 7.2 and cost $2.16per square foot.

Environment Research,Tempe, AZDOE Contract No. DE- FGO3- 78R90199CATMIS ID: AZ-78-003

The grantee tested glazings for thepatented "Solar Heat Exchanger Win-dow Wall." Heat-absorbing reflectiveglass was used for collection on the in-side surface during the heating seasonwith efficiencies comparable to thoseof active air collector systems. Duringthe summer a pivotal sash is rotated180 degrees to position the heat-absorbing reflective glass with thereflective surface to the exterior.Theoretical analysis and experimentaltests have confirmed that 65 percent ofthe solar and thermal gain can be re-jected in the summer mode. Venting isalso provided to dissipate absorbedsolar energy to the outsideatmosphere.

lohn Pierre StephensDavis, CADOE Contract No. DE-EG03-80R950028/1170/S ID: CA-80-001

The grantee performed a literaturesearch on state-of-the-art movablewindow insulation. This research ledto the consideration of a number ofpossible designs that were thenfabricated and installed in ademonstration house. The results ofthis research were documented in aninformational pamphlet for the public.

.12

Nyle Robert WerthmannSan Francisco, CADOE Contract No. DE-FG03-78R901987ATMIS ID: CA-78-025The grantee reviewed natural lightingconcepts and the use of in-sulating/refleaing shutters. The plan-ning, asser-1,1y, installation, and con-trol techniques for insulating shuttersare addressed. Model studies of il-lumination distribution are alsodescribed in the final report.

Raymond AugerAspen, CODOE Contract No. DE-FG48-81R801070ATMIS ID: CO-81-010The grantee designed and tested amotorized roller system for exteriorwindow insulation and sunscreens.The commercialization of the sysiemwas interrupted by several problems.An exterior system like this is subjectto extrerws in weather conditions(high winds) affecting the mechanicaloperation of the roller system. Fulfill-ing terms of the system warranty wasexpensive with the first installation,due to unknowns. The system needsrefinement through continued fieldtesting and the grantee needs addi-tional financing to promote and sellthe product.Laurence RasmussenBoulder, CODOE Contract No. DE-FG48-79R800437-ATMIS ID: CO-79-008The final report describes the benefitsof using foam for insulating glazingsystems; it provides testing methodsand results, a list of materials tested,and problems encountered.

Stephen AndrewsDenver, CODOE Contract No. DE-FG48-80R801401ATMIS ID: CO-80-001

The grantee proposed a passivesolar retrofit of an existing house to in-clude the installation of exterior win-dow blinds (lowered shades) to reducesolar gain during the cooling seasonand movable exterior window insula-tion for the heating season.

Wilbert MinorNewark, DEDOE Contract No. PE-FG43-79R306053ATMIS ID: DE-79-009

The grantee mounted two insulatingwindow treatments between two roll-down shades and tested the thermalperformance of each against conven-tional blinds. Also, an insulatingdrapery liner (R-3.8) was mounted ona standard traverse rod behind pinch-pleated drapery. Both were tested inan independent laboratory. Effects ofdetails, materials and edge seals arediscussed in the final report.

Frederick TyrellPort Richey, FLDOE Contract No. DE-FG44-80R410301ATMIS ID: FL-80-012

The grantee implemented a newtechnique for attaching storm win-dows to awning windows, while stillallowing for their opertion. Thedesign was tested and demonstratedincreased thermal efficiency whileallowing for adequate ventilation.

Robert HendersonJerome KaplanIndianapolis, INDOE Contract No. DE-FG02-79R510116ATMIS ID: IN-79-004

The grantee designed, built, install-ed, and evaluated a double-layerMylar, inside storm window system.Fifty units were produced as an initialstep toward cony ercializing the prod-uct. Thermal j rformance of thedesign has been reported successful,but installation and operational prob-lems require some design changesprior to any serious commercializationeffort.

35

Linda NicholsonDes Moines, lADOE Contract No. DE-FG47-81R701204ATMIS ID: IA-81-006

The Energy Research and Informa-tion Foundation collaborated with twoother local and state energy groups todevelop a model demonstration housethat shows how the insulation of in-terior walls, application of vapor-barrier paint, contructior of a bread-box solar water heater, weatherstrip-ping and caulking, and the installationof basement insulation can saveenergy in a conventional house.Kenneth LillemoHuxley, IADOE Contract No. DE-FG47-80R701112ATMIS ID: IA-80-013

A rigid foam product made fromPVC resins was employed in a ten-household study k the use in movablenighttime insulation. The study fo-cused on acceptance of the productand its use. The thermal effectivenessof the product was not oetermined;the study focused on a user evaluationof the product, which was made into"T' )p-in" panels.

Charles and D.L. PariseauMt. Lake Pike, MDDOE Contract No. DE-FG43-80R302406ATMIS ID: MD-80-008

The grantee installed a mechanicaldown draft duct system in a south-facing, solar A-frame house. Thiswork was coupled with the installationof window quilts and crawlspace in-sulation. These measures reportedlyincreased the comfort level in thehouse as well as reducing fuel con-sumption. A $180-200 reduction inelectric bills and a 3-to-4 cord drop inwood consumption during the heatingseason was noted in the final report.

Robert WehrliPotomac, MDDOE Contract No. DE- F G43-81R308083ATMIS ID MD-81-(X)8

The grantee developed an instruc-tion guide for professional draperl,upholsterers and interior designers ohhow to fabricate low-cost, energy-saving, sealed-edge, zip-up curtains.Performance data from the final reportindicates that use of the sealed fabriccurtains increased the R-value ofsingle-glazed windows from 0.9 to1 77, cutting energy losses from win-dows in half.

Barbara AllenBozeman, MTDOE Contract No. DE-FG48-79R800445ATMIS ID: FT-79-005

The grantee researched the historicuses of daylighting for purposes ofeducating designers on how to usenatural light to conserve electricity.

Richard ThompsonCharlestown, NHDOE Contract No. DE-FG41-81R124257ATMIS ID: NH-81-001

The grantee tested and monitoredan insulated solar shutter in order todocument actual energy savings dur-ing both the heating and coolingseason. Testing identified severalproblems; the panels started todelaminate due to the temp ..:ature ex-tremes within the shutter, and snowaccumulating between the shutter andthe window made operation difficult.The edge seal (3M Z-stripn") providedan effective seal around the edge ofthe laminated, rigid insulation shutter.

Todd BrownDover, NJDOE Contract No. DE-FG42-81R205263ATMIS ID: NJ-81-002

The grantee constructed and testedthe performance of a solar win-dow/collector. The collector consists ofthree panes of glass; the inner pane istinted and the space between thetinted layer and the. next layer isvented to allow movement of heatedair up and out of the collector into aseries of ducts which distribute theheated air throughout the house. Thispassiveiactive system is designed toheat and cool an existing house. Thegrantee is still working to refine thesystem.

Ted Dunn and Tom HoranJersey City, NJDOE Contract No. DE-FG42-80R205174ATMIS ID: NJ-80-006

The grantees retrofitted a woodframe house with thermal curtains andpassive solar air collectors. Publicoutreach activities such as tours,newspaper articles, and slide showswere developed to help disseminateinformation to Hudson Countyresidents.

Sunshine Insulation ConsultantsAlbuquerque, NMDOE Contract No. DE-FG46-79R610970ATMIS ID: NM-79-006

The grantee built and installed 12 in-sulat,ing window shutters. The shut-ters Cost $12 a square foot, too costly tocompete with storm windows anddraperies.

3 6

cummulipPorirlipessimilnprolliplirorm

Peter GrandePhoenixville, PADOE Contract No. DE-FG43-79R306074ATMIS ID: PA-79-015

The grantee built a 64-square-footwindow collectors with a V-groove,foam-glass and plastic glazing. At amaterials cost of $258.27 the collectorcut heating demands by about 7 per-cent and a 3.7-year payback ispredicted, assuming that the labor isfree.

Laura DuncanAustin, TXDOE Contract No. DE-FG46-79R610960ATMIS ID: TX-79-016

The grantee constructed a one-wayheat shield from highly polished, half-hollow cylinders of rock salt. Theshield predominately transmits radia-tion in one direction. Most radiationattempting to pass through the shieldin the other direction is reflected. Theconcave side that receives thetransmitted and reflected radiationheats, while the convex side cools.

James BriggsKerrville, TXDOE Contract No. DE-FG46-79R610956ATMIS ID: TX-79-003

The grantee developed a device thatwill insulate a window, shade it orreflect light towards the window. Itcan be retrofitted to existing windowsor used in new construction.Mechanical and structural problemsencountered during the project arepresented in the final report.

Leona WindleyLogan, UTDOE Contract No. DE-FG48-81R807312ATMIS ID: UT-81-004

The grantee produced anddisseminated a booklet and fourslide/tape presentations coveringenergy-conserving interior windowtreatments suitable for educatingothers to teach how to construct,mount and select interior windowtreatments. The report covers theprocess for development, evaluation,accomplishments and impact of tht'project.

William BriggsRichmond, VADOE Contract No DE-FG43-80R302445ATMIS ID: VA-80-010

The grantee produced and tested apassive solar device similar to a vene-tian blind for cooling and increasinginterior lighting. The exterior-mounted device was monitored fortemperature and lighting levels over aone-year period and the results wereanalyzed.

33

Ellen StarrBellingham, WADOE Contract No. DE-FG51-80R000480ATMIS ID: WA-80-035

The grantee expects to start a smallcottage industry by constructing anddemonstrating a low-cost, easy-to-make, insulating curtain forgreenhouses and sunspaces.

34

James GaitorHinton, WVDOE Contract No. DE-FG43-80R302446ATMIS ID: WV-80-001

Seventeen roll-down, solid-core,roman and drapery-type windowcoverings were installed in sevenpublic buildings. The quilts, whichmeasured 760 square feet, were madein workshops attended by local crafts-men. The grantee expects the systemsto be cost-effective over the lifetime ofthe quilts. The project helped promotecommunity awareness, lowered fuelbills, refined window quilt movementmechanisms, and developed a co-opcottage industry according to thegra:!fee.

3

Eugene EccliWashington, DCDOE Contract No. DE-FG43-80R302391ATMIS ID: DC-80-.001

The grantee conducted a usersurvey, workshops, developed a train-ing manual, and a slide show on howto construct insulating curtains. Thecost of constructing curtains was. ap-proximately one-third that of iactory-made insulated curtains.

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Their experiences have been ex-amined and presented in a series ofthirteen informative publicatlorw.Your State energy offices have alimited number of these publicationsavailable without charge. Addi-tional copies are on sale at U.S.Government Printing OfficeBookstores near you.

A. riOPRIATE TECHNOLOGYA I WORK: Outstanding ProjectsFunded by the U.S. Department ofEnergy Appropriate TechnologySmall Grants Program(1978-1981).H'hfi8hs. twenty of the many uccvu e'ork,that are found in the DO jranhs prom4GPO IQOO.00Ci.7

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DRYING WOOD WiTH ThE : MAJOR ENERGY CONSERVA-HOW TO BUILD A SOLAR ";':. TNRETROF1Th A PLANNING.HEATED FIREWOOD DRYER GUIDE FOR NORThERNShows the over 14 million firewood users in CLIMATE5:: 1'

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America how- to build an efficient. lowcostins itati.o'-thl'S't ,trât,1vie f0 flu

firewood dryer and contains suue.etioIis for buld., . JkI(led iuner Inmore efficient burning of th. dry wood. deéidink the mOt pro . .din'rs . -.

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GPO 062400006134 . for Insulating roofs and walls. Thu dscLilon-

r.irncrv br APIfl U&flAV ThJDfV i'k1ng manual aUos uscr n northern.:LV*#W I l' II" I's#$VI I climat to d.Iannms the mt cost effective . 4

CONSERVATION mn for increasing the thermal sfflcienc.y of: -: -: --

Focuses on detecting moisture problems in their epacijc building envelope

the home and how to correct them and hi-.trautlng ?lement on how to con

HOME MADE ELECTRICITY: A1' /GPO ioiso INTRODUCTION -TO SMALL. ".

PHOTOVOLTAIC5 11' THE. .

PACIFIC ISLANDS: AN .- . .-..: . -.--. -./.

Introduces * use a . wuid, y'zter, and the

Y S expi,iences of tranteas, helps the readci

HElps teachers, mdült. educators and corn-. mike rnrmliuti appraisal of these systems.

munity leaders in tlt Pacific Islands explain D3O4 - :- '.

the bask parts of a PVsyst.m.

GPO t.000.t001e4- VVUUJ.Ffl IL JI.fl EIJA'. ZWWV.. .-. :

TO SORT THROUGH ThE. :

USING THE EARTH TO HEAT ØpwrJpJ5 .-. -.- :--, -:-

AND COOL HOMES gtg major de ion and problemProvides a guide so using the earth as a readi- areas wilts the Mchnoloy Including choosing. .;

ly available, kW-cosr rt,ource for space she ight design for -the windw,. how toheating and cooling with a focus on Inatalia- clwos. a workable nls;alLt1on n.fked a,sd .

Slots, economics, reliability and perfOnnasc.. how to sIze up yow wmdow-tnndatlon cullof siitanu saauhsg low'.grade geothermal given clintøt., cast, and home oivntatlon

energy anti tarih-ternpiiid 1r cystems

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INTRODUCiNG SUPPLEMENTAL ØIOGAS PRODUCTION ON ThE

FIRED HOME APPLIANCES .ina (aimsise ogas production. idShnwe conasaturs mid building trades peojrfr kwls4e. a brief dkcussion ci, how to evaluate

hOw to Increase heat Ing iy*in efficiency by Ike biogas prOduct son potential o' specific

r.elng u Ma orsppkswntal combustion air ranch orfgrni.

anti alsO Includes a uS- of basic ho ui4o be- 06&4000Ci6334struølmts to allow conasaness to build.wcdsusrj, ducts and van Is. Code md safatj, -

Imulkaf Ions of these actions are thoroughly

he available by March, 1NI) -

38 - -:.-* U&Iuftó.aM1P n*a 1$ £554,i L1AØ.

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