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Passive House and High Performance Housing: A Report to the UMORE Park Management Team

Submitted byJohn CarmodyDan Handeen

Center for Sustainable Building ResearchCollege of Design

University of Minnesota

Mar. 8, 2012

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Passive House and High-Performance Housing

Contents1 Introduction3 Part 1: The Passive House Concept3 What is a Passive House? 4 History4 Origin of Performance Requirements6 Critiques of the PassiveHouse Software7 PassiveHouseCertificationStrategiesinMinnesota11 Advantages of Passive House12 ChallengestoBuildingPassiveHousesinMinnesota19 Part 2: Results and Conclusions 19 Results24 Life Cycle Cost Comparison34 Conclusions37 Part 3: Building Survey and Case Studies38 CertifiedPassiveHouses38 Waldsee BioHaus38 The NewenHouse Prototype I39 Konkol Residence39 Isabella EcoHouse40 Non-CertifiedPassiveHouses40 Bagley Classroom40 Skyline House41 Esko Farmhouse41 Synergy, TE Studio42 The Holm Retreat42 The Erickson Home43 HighPerformanceHouses43 The Walker House43 Stemwell House44 CaseStudyI:KonkolResidence(TEStudio)46 CaseStudyII:Synergyhigh-performancehome(TEStudio)48 CaseStudyIII:NewenHousePrototypeI(CoulsonArchitect)50 CaseStudyIV:IsabellaEcoHomeExperimentStation(CompassRose)52 Web Resource List

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ACKNOWLEDGEMENTS

The authors are grateful for the opportunity to conduct this study on Passive House and other high perfor-mancehousingapproachesthatmightbeappropriateinmeetingthegoalsoftheUniversityofMinnesota’sUMOREdevelopment.Weappreciatethedirection,support,andfeedbackoftheUMOREManagementteamincludingCharlesMuscoplat,CarlaCarlson,LarryLaukka,TomLaSalle,KenLarson,StevenLott,JulieBoudurtha,LorriChapman,andAllieKlynderud.

The report has required the assistance of many people in collecting case study information and providing insightsintoenergyefficientconstructioninMinnesota.Wewouldliketothank:Tim Eian, TE StudioStephan Tanner, INTEPPhilipp Gross, TE StudioEdwin Dehler-Seter, Concordia Language VillagesMikeLeBeau,ConservationTechnologiesRachel Wagner, Wagner Zaun ArchitectsCarly Coulson, Coulson ArchitectSonyaNewenhouse,MadisonEnvironmentalGroupMaliniSrivastava,NDSUNancySchultz,CompassRose,Inc.Ray Pruban, Amaris HomesBrad Richardson, Christian HomesEd VonThoma, Building Knowledge

ThereportwasalsoenhancedbydiscussionswithotherbuildingresearchersattheUniversityofMinnesotaincludingPatHuelman,LouiseGoldberg,GarrettMosiman,andRolfJacobson.

Coverimages,clockwisefromtopleft:IsabellaEcoHomeResearchStation,CompassRoseDesign;NewenHouse Prototype, CoulsonArchitect;UofMDuluthBagleyClassroom,SalmelaArchitects;The KonkolHouse,TEStudio.


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IntroductionPurpose and scopeThis study grew out of a desire to explore innovative approaches to meeting the aspirational goals of theUMOREParkdevelopmentforalow-energy,low-impactsustainablecommunity.Duringastudytrip of sustainable community design in Europe, the Passive House concept was introduced to the UMOREmanagementteam.Thisreportisintendedto further explore the Passive House concept as itmightbeappliedtotheUMOREdevelopmentprojectinMinnesota.ThereportalsoexaminesexamplesofadvancedenergyefficientconstructionnowoccurringinMinnesotasothatthePassiveHouse concept can be put into a larger context of highperformancehousingoptions.Muchoftheinformation in the report is based on interviews and data collection from Passive House and other advancedenergyefficienthomesonMinnesota.

Thereportconsistsofthreesections.Part1providesan overview of the principles and issues inherent to Passive House construction, and investigates someofthecomplexities,challenges,andbenefitsofaPassiveHouseapproachtoconstruction.Thesecondpartincludestheresultsandconclusions.Part 3 comprises a survey of Passive House build-ingsinMinnesota,inadditiontosomeotherhigh-performancebuildingsforcomparisonpurposes.This is provided in order to establish a spectrum of constructiontypesrelatedtoenergyefficiencyandenergyperformance.Fourcasestudiesaredocu-mentedingreaterdepth.


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Part 1: The Passive House Concept

What is a Passive House? Initsmostbasicdefinition,aPassiveHouse(PH)isabuildingforwhichthermalcomfort(ISO7730)canbeachievedsolelybypost-heatingorpost-cooling the fresh air mass required to achieve sufficientindoorairqualityconditions–withouttheneedforadditionalrecirculationofair.

In execution, a Passive House is a very well-insulated, virtually air-tight building that is primarily heated by passive solar gain and internal heat sourcessuchasoccupantsandelectricalequipment.Energylossesareminimized.Anyremainingheatdemandisprovidedbyaverysmallsource.Avoid-ance of heat gain through shading and window orientationalsohelpstominimizeanycoolingload.

A certified Passive House refers to a building or structurethathasmetthecertificationcriteriasetforthbythePassiveHouseInstitute(PHI)inDarm-stadt,Germany.1)Thebuildingmustusenomorethan4.746kBtu/ft2 per year for heating or cooling, as calculated usingthePassiveHousesoftware.2)Thebuildingmustusenomorethan38.1kBtu/ft2peryearinprimary(source)energyforallenergyconsumed, including heating, cooling, and electric loads, as calculated using the Passive House soft-ware.

The Passive House Certification Criteria

For a building to be certified as a Passive House, it must meet the following criteria:

Heating energy consumption ≤ 4.7 kBtu/ft2/yr.Cooling energy consumption ≤ 4.7 kBtu/ft2/yr.Primary energy consumption ≤ 38.1 kBtu/ft2/yr.

Airtightness ≤ .6 ACH@50pa

Also recommended but not required:

Design heating load ≤ 10 W/m2

Window heat transfer coefficient ≤ U-0.14

3)Theairtightnessofthebuildingmustbenomorethan0.6airchangesperhourat50pascalspressure,asmeasuredbyablowerdoortest.

The Passive House standards also recommend, but donotrequire,thefollowing:1)Amaximumdesignedheatingloadforthebuild-ingof10W/m2 (3.4Btu/hr/ft2).* 2)WindowswithamaximumU-valueof0.14.

Passive House experts and practitioners add multiple aspectsofwhatthePassiveHouseapproachimplies.Simplicity, durability, low-maintenance, and com-fortable are all adjectives used to describe a Passive Housebuilding.“PassiveHouseiseconomically,environmentally, and socially responsible and per-manentlyfeasible.[Itprovides]qualityoflifeatlowcost and low impact to the planet,” says Tim Eian, a PassiveHousearchitectbasedinMinneapolis.*This is the estimated maximum amount of heat that can safely and effectivelybesuppliedviaventilationair.Heatingdemandsinexcessof10W/m2willrequireadditionalheatsources.


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HistoryThe Passive House concept originated in Darmstadt, Germany under the name PassivHaus.Dr.WolfgangFeist, a physics professor, was researching high-per-formancehomes.Drawingfromsuperinsulationandpassive solar design techniques that originated in the US and Canada, he and his colleagues proposed the idea that if the insulation levels were high enough, the need for a typical furnace and air distribution system(anditsassociatedcost)couldbeeliminated.The money that would have been spent on a furnace could instead be put toward greater insulation and airtightness measures, and thus be cost-competitive withconventionalconstruction.Thisinitialtheoryhas been proven over the course of about 30 years by the careful analysis of over 100 European Passive Houses by the PassivHaus Institut or PHI.

Origin of Performance RequirementsHeating/CoolingEnergyThe4.75kBtu/ft2/yr(15kWh/m2/yr)numberissetto be the optimum amount of energy for a German home to be able to heat itself without requiring a typicalfurnaceorheatingsystem.Thenumberisbased on analysis of economic data, and results in a roughly 80%-90% reduction in overall energy usage comparedtoatypicalhome.

PrimaryEnergyIt was quickly noticed that the heating needs of the buildingcouldbemetbyveryinefficientmeans,suchasincandescentlightbulbs.Thisdefeatedtheunderlying point of the heating standard, and did not address the greater systemic problems due to electri-calpowergeneration.Throughanalysisofglobalwarming projections and carbon emissions, the Pas-sivHaus Institut proposed that the optimal amount ofprimaryenergy(thatisenergygeneratedoff-site)consumed by all operations in the building, includ-ing heating, cooling, and electrical processes, should

ThefirstPassivHaus.ConstructednearDarmstadt,Germanyin1991.

AschematicdescriptionofPassiveHousedesignelements.


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belessthan120kWh/m2(31.8kBtu/ft2)peryear,ascalculatedusingthePassiveHousesoftware.ThisfigureisbasedonaCentralEuropeanenergymix.Becauseofinefficienciesinheatproductionandelectricaldistribution,itrequiresroughly2.7units of source energy to provide one unit of energy foruseatthebuilding.IntheUS,however,thereisevengreaterinefficiency,estimatedatafactorof3.1sourceunitstoonesiteunit.Electricalfuelsourcesandgridefficienciesvarywidely,butifthePHprimary energy standard was adjusted to account for average US electrical grid distribution, it would be closerto105kWh/m2(27.7kBtu/ft2)peryear.

AirtightnessTo meet the heating or cooling energy requirement of the Passive House, control of the indoor environ-ment is necessary and an airtight structure ensures thiscontrol.Anairtightnesslevelof0.3ACH50is about as low as economically reasonable for a timber structure, while humidity levels and building durability are adversely affected at airtightness lev-elsabove1.0ACH50.ThePassiveHousestandardof0.6ACH50strikesabalancebetweeneconomicfeasibilityandadequatehygrothermalcontrol.

ClearBenchmarksforRatingandComparisonThe Passive House standards are unique in that they setspecific,predictableandmeasurableenergyper-formancetargets.Thissetsastandardagainstwhichanybuildingcanbemeasured.ThisisincontrasttoprogramssuchastheUSDepartmentofEnergy’sEnergy Star program or the US Green Building Council’sLEED for Homes program, which mea-

sureperformanceinrelationtoareferencebuilding.

Calculation and SoftwareTo aid in the design of such a high-performance building,Dr.FeistandPHIdevelopedatoolcalledthe Passive House Planning Package,orPHPP.Itis essentially an intricate Excel spreadsheet that calculatestheenergyflowsofaparticularbuildingbasedontheuser’sentries.Thespreadsheetrequiresentriesrelatingtoveryspecificaspectsofthebuild-ing, such as window frame U-values and appliance efficiencyratings.ThePHPPcalculationsincludethe effects of occupancy, solar orientation, shad-ing,andlocation-specificclimatevariationsbasedonclimatedatasets.Additionally,itcalculatestheenergy lost through thermal bridging in the user-definedassemblies.BycomparingtheresultsofthePHPP with actual measured data from constructed Passive Houses, the developers have been able to adjust and verify the accuracy of the PHPP to a very closepercentage.

One of the strengths of the PHPP is that it places particular emphasis on the heat losses created by thethermalbridgingofstructuralcomponents.Theeffectiveness of different types of thermal envelope assemblieshasbeenwellresearched.Theweaknessliesintheconnectionswherematerialsmeet.“Thebigthingshavebeenfiguredout.Nowit’sdowntothe details,” according to Passive House designer andarchitectRachelWagner.

Unlike some other energy modeling software that calculatesresultsina“blackbox,”thePHPPis


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relativelytransparent.BecauseitisExcel-based,theuser is able to directly investigate the ways in which theresultsarecalculated.Althoughsomewhatdaunt-ingatfirst,thePHPPisrelativelyeasytouse.Themost intimidating aspects are the number and the specificityofinputsthatitrequiresforaccuratecal-culation.Regardlessofwhetherornotoneisseek-ingPassiveHousecertification,thePHPPprovidesa robust and thorough means of checking the energy balance of a high-performance building, and shows theimpactsofchangesindesignorcomponents.

RachelWagner,saysthatherofficewillinitiallymodelaclient’shometothe2006IECCstandard,whichisverysimilartoMinnesota’scurrentbuild-ingcode.Thentheyenterthespecificationsoftheenergyefficienthometheyactuallyplantobuild.Whentheenergycalculationsofthe“improved”housearesharedwiththeclients,“Theyneversay‘no’.”

Critiques of the PHPP SoftwareSome building scientists believe the software to be overlysimplistic.Unlikemostenergy-modelingprograms, the PHPP calculates the energy balance of the building as a whole, not as separate conditioned zones.Thiscouldpotentiallyaffectthethermalcom-fort of individual rooms as heat distribution may not beadequateorideal. Another critique is that the PHPP calculates monthly energy balances instead of performing time-resolved simulations.Whilenotaprobleminrelativelymildand stable climates such as central Europe, these

simplifiedcalculationtechniquesaretheoreticallyproblematicinextremeclimatessuchasMinnesota.However, the Passive House experts concluded that the insulation levels of a Passive House are so high that the temperatures and energy demands do not fluctuateasdrasticallyasinatypicalhome,sohour-by-hourcalculationsarenotnecessary.

CoolingEnergyRequirementsThe PHPP was validated by observing the behavior ofbuildingsinCentralEurope.BecausetheclimatethereismilderthantheUpperMidwestoftheUS,there is some concern over whether or not the PHPP adequatelyaddresseslatentheatinMinnesota’shot,humidsummer.

DataEntryBecause of the popularity of the Passive House movement in Europe, many companies provide data for their products that can be easily entered into the PHPP.Additionally,therearesomeproducts,suchas windows or heat recovery ventilators, that are certified“PassiveHouse”components.OnlyafewAmerican manufacturers currently provide the same typeofdataorreceivesuchcertification,soenter-ing component data in the PHPP can be somewhat difficult.ThedefaultperformancenumbersinthePHPP are particularly harsh against components that arenotPH-certified.Forinstance,theefficiencyofanon-PHHRVisenteredat12%lessthanitisrated.

NeedforUserAccuracyBecause of the intricacy and interrelated nature of thePHPP,eachentryfieldneedstobeunderstood


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andcorrectlyfilled.Omittedorincorrectnumberscanhavesignificanteffectsontheendresultsofthespreadsheet.

AreaCalculationAnother common issue with the PHPP is howfloorareasarecalculated.Whilethestandard area measurement in the US is basedonexteriorwallmeasurements(asperASHRAE),thePHPPusesTreatedFloorArea(TFA),whichissimilartotheFinished Floor Area or conditioned space area.TFAreferstotheareainsidetheex-terior walls, minus interior walls and stair-cases as well as columns over a certain size;and60%ofsecondaryspacessuchas storage, mechanical rooms and base-ments.Whilethismaynotbeadifficultconcept,theproblemariseswhenvaluesaregivenperunitarea.Cost per square foot or energy use per square foot could vary greatly depending on which type of area is used, with the ASHRAE technique giving a result withupto30%lowercostsandgreaterefficiency.

Passive House Certification Strategies in MinnesotaSince Passive House is a set of performance criteria, and not a prescriptive method, there are many ways toworktowardmeetingthespecificperformancecriteria.Thereareanumberofcommonstrategies,however.Thefirstone,andprobablythemostimportant, is to set the performance criteria as the goalatthebeginningoftheprocess.PassiveHouseenergyconsultantMikeLeBeauofConservation

Technologies in Duluth, says that it is much more efficientandcost-effectiveifyou“startwiththe[energyperformance]goalanddesigntothat,ratherthanstartwithadesignandforceittomeetagoal.”

SimpleShapesBecause of the relationship between surface area and volume,simplegeometrymakesforamoreefficientbuildingandisrewardedinthePHPP.Fewerbump-outs, dormers, and wings means less surface area perunitofconditionedfloorarea.Simplergeometryalso implies fewer structural connections and less possibilityforthermalbridging.Andbecausetheyhave fewer edges and joints, it is also easier to achieve the airtightness standard with simple-shaped buildings.

Floor area - 1200 ft2

Volume - 10800 ft3

Surface area - 3000 ft2 Floor area - 1200 ft2

Volume - 13800 ft3

Surface area - 5277 ft2

Impacts of Building Geometry on Volume and Surface Area


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Regardless of what type of insulation or wall as-sembly is utilized, it is important to make sure that moisturewillnotremaininthewall.

High-performanceWindowsBecause of the amount of sunlight that we receive in Minnesota,windowscanprovideanannualnetgaininheatingenergy.However,windowsdonotgener-allyinsulateaswellasopaquewalls.Forthisreason,high-performance triple- or quadruple-glazed win-dows with a low U-value and tightly-sealed frames areusedforPassiveHouseconstruction.Windowsarealso“tuned”basedontheirsolarorientation,with windows that have higher solar heat gain coef-ficientsplacedonthesouthsideofthebuilding.

InsulationTo meet the low levels of allowable heating energy, highamountsofinsulationarecrucialinMinnesota.InsulationvaluesforaMinnesotaPassiveHousewalls are typically about three times as much as is calledforbyMinnesotaBuildingCode.Highinsula-tion values can be achieved in many different ways andwithdifferentmaterials.Manydesignersprefera low-tech approach that uses double stud walls and densely-packedcelluloseinsulation.Thematerialsare relatively inert, and they have low environmental impactalongwithbeingrelativelyinexpensive.Other designers prefer insulated concrete forms for their ease of construction, durability, and waterproof construction.Ahigh-techrouteistousevacuumpanels.Thesepanelsinsulateverywellandenablethinner walls, but they are not forgiving in construc-tion.

Standard Energy Star WindowU-0.35

Typical Passive House WindowU-0.17

Window section comparison


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BackupHeatFor most of the year, passive solar heating is ad-equate.However,duringperiodsofextremecold,abackup heat source is required and it is unrealistic to distribute all necessary heat through the ventilation systeminMinnesota.Becauseoftheireaseand

simplicity, different types of electric heaters are fre-quently used, including baseboard, radiant panel, and radiantfloor.Air-to-airheatpumpsarealsofrequentlyused.Anotherbackupoptionisawoodstove,whichcanprovidesecurityifallotherutilitiesfail.

Typical MN Code Advanced Passive House

Wall

Roo

fSl

abComparison of Wall, Roof, and Slab Sections

for Three Building Energy Standards

Gra

phic

by

TE S

tudi

os

R-19R-35

R-58

R-38 R-60 R-77

R-10 R-10

R-44


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ExteriorShadingDevicesPassive Houses rely on solar heat gain through windows.Whilelargesouthfacingwindowsensurecomfort during the winter months, they can let in uncomfortable amounts of light and heat in the summerand“swingseasons”ofspringandfall.Tocounter unwanted solar gain, numerous types of exteriorshadingdevicesareused.Thesecanincludeactive devices, such as awnings and roll-up shades, and passive elements, such as balconies and roof overhangs.Dependingonwherethewindowisplaced,eventhewallthicknesscanprovideshading.

PassiveSolarDesignA fundamental Passive House strategy is to use thesuntoheatthebuilding.Thisisachievedbyorienting the building to maximize the opportunity for passive solar gain through windows into the conditionedspace.Minnesota’sclimateandamountof sunshine can provide a net heat gain with proper solar-orienteddesignandwindowplacement.

Heat-RecoveryVentilationTo achieve the energy performance and airtightness inaMinnesotaPassiveHouse,aheat recovery ventilator, or HRV, is an almost necessary compo-nent.Thesedevicesdrawinfreshairfromoutsideandexhauststaleairfrominside.Whiledoingso,they transfer the heat from the exhaust air to the incomingairandtherebysaveheatingenergy.Heatrecovery ventilation can provide greater occupant comfort and support occupant health via increased freshairlevelsoveratypically-ventilatedbuilding.

The Heat Recovery Ventilator

ExteriorshadingdeviceontheBiohausnearBemidji,MN


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PassiveHouseCertificationintheUnitedStatesThe Passive House Institute in the United States (PHIUS)hasbeguntrainingprofessionalsinPassiveHouse design and use of the PHPP, and certifying buildingsasofficialPassiveHouses.Theyareacutely aware of the challenges to achieving certi-ficationgiventherangeofclimatesintheUnitedStates(suchasMinnesota),andhavebeguninvesti-gation into creating an alternate set of performance criteriathataremorelocallyappropriate.Whilethishas been met with resistance by PHI in Germany, it seems to be the logical next step in spreading the standardtoothermoredemandingclimates.

Some other northern European countries have modifiedthetargetsordevisedtheirowntargetstobemoreattainable.Forexample,Swedenhasslightly more lenient targets for their northern projectscomparedtotheirsouthernprojects.Franceand Norway as well have devised their own sets of performancetargetstobemorelocation-specific.IfthePassiveHouseenergyusetargetsaremodifiedtoreflectthespecificclimatesinwhichtheprojectis built, it may increase the number of projects that attaincertification.

It should be noted that one can still design and certify a Passive House building without taking thetraining,andbuildingscanbecertifiedbyanyrecognizedPassiveHouseaffiliatearoundtheworld,not just those in the country where the building resides.

Advantages of Passive HouseDecreasedEnergyCostsThe Passive House performance criteria are primarilyconcernedwithlowenergyusage.Ifthisdecreased energy use is translated to dollars, a clear benefitofbuildingaPassiveHouseisdecreasedoperatingenergycosts.

EnergySecurityRequiring less energy to heat, cool, and enjoy your housemeanslessfuelneedbeconsumed.Althoughthe US has large reserves of coal and natural gas, andgoodaccesstooil,thefluctuationsandvolatil-ity of the fuel markets are unpredictable, and less relianceuponthemprovidesameasureofsecurity.

PassiveSurvivabilityPassive Houses can be designed to maintain oc-cupant comfort and building function if utilities are unavailableforsomereason.Wagnersaysaboutherprojects:“Ifthepropanerunsoutortheelectricalgrid is cut off, the health and well-being of the occupants and the systems within the building are notthreatened.”

OccupantHealthThe underlying premise of Passive House is that all heating can be distributed using only the ventilation air.Theventilationisintendedtobeanassuranceofgoodairqualityinsidethehome.Mostexistinghomes and many new ones simply recirculate air withinthebuilding,addinglittlefreshair.Olderhomes that use radiators often have no ventilation system,andthusnofreshairintake.PassiveHouses


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are designed to have higher indoor air quality than many existing homes because of increased ventilationlevels. It should be noted, however, that building a very airtight house in Europe has lower air quality risks since standards regarding VOC and other pollutant emissions from materials are more stringentthanintheUS.IfaPassiveHouseisbuiltis the US without these standards, care should be taken to select materials with low-VOC emissions to ensureanon-toxicindoorenvironment.

SimplicityBy replacing the typical furnace and its associated ductwork with simpler systems such as an HRV with electric backup, the complexity of the heating systemcanbereduced.Anumberofhomeownershavebeenabletoinstalltheirownheatingsystems:Instead of bending metal for ductwork, running gas lines, and installing a large furnace, the HVAC systemsconsistedofasingleboxwith“plug-and-play” distribution ductwork, similar to vacuum cleanerhose.Itrequiresdrillingholes,runningtheductstotheregisters,andpluggingthemin.

A simpler system also implies less noise, less energy consumption, and fewer components to replace over time.

DurabilityIn keeping with a basic tenet of sustainability, Passive Houses are intended to be long-lasting structures.Becauseofthecarefulanalysisofenve-lopeprofilestypicallyundertakeninPassiveHousedesign, the structures should last more than one

hundredyears.Theuseofhigher-qualitycompo-nents implies less maintenance or replacement over time,resultinginreducedmaintenanceexpenditures.

BrandRecognitionDespite the skepticism, confusion, and excitement over the Passive House concept, it has quickly become the standard by which high-performance buildingismeasured.TheE.U.hasmandatedthatall new single-family homes shall be Passive House compliantby2020.ThetermPassiveHousewasrelatively unheard of three years ago, but has gained popularity and recognition -- and it is regarded as a challengingstandardtomeet.IfonebuildsaPassiveHouseinMinnesota,itisaremarkableachievement.

AccountabilityandEaseofUseThe Passive House approach provides a proven tool andprovenmethod.Ifprojectsarecertifiedaccord-ing to the Passive House standard, the designers and builders are held accountable to meeting the stringentcriteria.ThePHPPprovidesacoherentand comprehensive means of guiding and testing throughoutthedesignprocess.

Challenges to Building Passive Houses in MinnesotaPassive House sets a standard for energy use - a very aggressivestandard.PassiveHouseshavebeenbuiltinMinnesota,andareperformingbeyondexpecta-tions.Theconcepthasbeenprovenanditisknownto be feasible, but it does not come without some challenges.



InitialConstructionCostsWhile the costs associated with the construction ofPassiveHousesinMinnesotavaryfromprojectto project, there will always be increased cost comparedtoconventionalconstruction.Thehigher-performing components, such as windows, doors, and appliances, coupled with the increase in enve-lope materials and the labor needed to install them, willgenerallyleadtoagreaterfirstcost.“Youdon’thave to bring the windows from Germany,” says Wagner,“butthewindowsaregoingtobeexpensivewhereveryougo.Yourestrictoptionswhenyouneed such high performance - but you do need that levelofperformance.”

Some estimates for building a single-family Passive House come in as low as 3% over a comparable “code”home,butaremoregenerallyassumedtobeintherangeof10-20%higher.Evenwhenmeasured against the anticipated lower utility costs over the life of the building, the up-front costs are a significantdecidingfactor,andgenerallythemostinfluentialone.However,itshouldbenotedthatmanyconstructioncostsareassociatedwithfinishes,andnotrelatedtoenergyperformance.Thus,esti-matesandfinalconstructioncostsarehighlyrelatedtoclientorownerpreferencesandcanvarywidely.

The Passive House performance standard is based on Central European cost effectiveness studies, and the cost of increased insulation and higher-performingcomponentsisjustifiedusingEuropeanconstructionandutilitycostestimates.Thisreason-ing may not be applicable or relevant to other areas of the world depending on local resources, climate,

utility rates, construction methods, and access to high-performancebuildingcomponents.

AvailabilityofComponentsOne obstacle to the construction of Passive House buildingsinMinnesotaisthelackofaccesstocrucialhigh-performancebuildingcomponents.While European manufacturers and consumers have embracedhigh-efficiencyproducts,theAmericanmarket is in the early phases of developing high-performancecomponents.However,accordingtoRachelWagner,thelackoftechnologiesis“notasbiganobstacleasitisbeingmadeouttobe.”LeB-eauaddsthat“Wehavegoodwindows,andwehavethebeginningofgoodmechanicalsystems.”Whilethere are a handful of American manufacturers building high-performance windows, for example, certified Passive House windows are currently only availablefromEurope.However,oneWisconsin-based manufacturer and a Colorado-based manu-facturerareslatedtostartproducingPH-certifiedwindows in the near future, and Optiwin, a German PH-certifiedwindowcompany,isconsideringUS-basedfabrication.

Other high-technology approaches such as vacuum panels and phase change materials have very little market presence in the United States, although one Minnesotamanufacturerisproducingphasechangematerialsforintegrationintomultipleapplications.Product integration and market acceptance of these technologiesremainstobeseen.


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Finely-tunedDesignAnother challenge to building Passive House in Minnesotaisfindingbuildingprofessionalsthatunderstand the subtleties and particularities of build-ingaPassiveHouse.AccordingtoNorbertKlebl,aPassiveHousedeveloperinColorado,“Thebiggestchallenge for high performance affordable home buildersistofindcompetentandimaginativesub-contractors.“Theideathatheatingcanbedistributedsolely by the ventilation system is not common and requires a deep understanding of the interactions be-tween the heating, ventilation, and energy systems in abuilding.Manyengineerswillover-designsystemstoavoidriskofinsufficientperformance.Whilethisapproach generally guarantees the desired thermal outcomes, it can also result in energy consumption thatfarexceedsthePassiveHousestandards.Ontheotherhand,anoversimplificationofthemechanicalsystemcanleadtothermalcomfortissues.

Seeminglyinsignificantloadssuchaspumpsandcompressorscanrequirelargeamountsofelectricity.These types of loads are not typically considered in an HVAC design, but can have detrimental effects againstthepursuitofPHcertification.

To be successful, a Passive House design requires afinely-tunedsystemthatrespondsuniquelytothe needs of the house within the limited amount ofenergyavailable.HVACprofessionalsneedtodesignspecificallytothetaskathand,andworkwith precision and creativity to match the systems to thebuildingandthePHenergyusetargets.

When the building energy use is so low, reducing any heat loss becomes increasingly important, and commonly overlooked weaknesses such as thermal bridgingneedtobeaddressed.SuccessfulPassiveHouse design requires structural engineers who understand how certain structural conditions can compromise thermal integrity and will instead designdetailstoavoidthem.

Finally, the actual construction of the building is themostimportantaspectofperformance.Eventhebest-designed structure will fail if the builder does notunderstandtheplans.Theairtightnessrequire-ment in Passive House creates the need for excep-tionalattentiontodetailonthepartofthebuilder.Passive House designer Rachel Wagner commented that one of her projects did not attain Passive House certificationonlybecausetheblowerdoortestcamein0.1ACH50abovetheallowablelimit.Thehomebuilder learned from that experience and the next PH house they built came in 30% underthelimit.

Beside the airtightness consideration, there is the simplematterofqualityconstruction.Inanironictwist regarding high-performance buildings, energy consultantMikeLeBeausayshehasseenmanymore building failures due to rainwater intrusion thanduetoairtightnessissues:“Peopleworrywaymoreaboutpermratings...thantheydo[about]windowflashing.”



ArchitecturalDifferencesThe architectural implications that result from Pas-sive House design could potentially dissuade buyers orclientsfromwantingtopursueit.Theneedforsolar heat gain makes it necessary to have larger windowsonthesouthsideofthehouse.Incontrast,the north side of the house will ideally have very few,ifany,windowsinordertominimizeheatloss.This may be incompatible with certain architectural styles, and may be different in appearance than a “normal”Midwesternhome.However,anydistribu-tion of windows is theoretically possible if their compromised thermal performance is mitigated by othermeans.

According to Duluth-based Architect Carly Coulson, a Passive House typically has more glass than a traditional-lookinghome.Sheusesdifferentclad-ding treatments and architectural elements such as pergolastobreakuptheappearance.Thewindowunits themselves are an additional consideration since the windows in a Passive House are usually casement type, rather than double hung, because ofimprovedairsealingcapabilities.Themullionsoften seen in traditional windows can also decrease thermalperformance.

Because of the relationships of surface to volume, PassiveHousecertificationiseasiertoattainwithsimplergeometry.Ataminimum,thisoptimizationof surface area can lead to simple gabled house formswithnoarticulationsoftheexteriorwalls.At its geometric extreme, this could mean a cube-shapedbuilding.Additionally,theinsulationlevels

that permit such low energy consumption are gener-ally quite thick, which results in walls from 16 to 24 inchesthick.Thisisconsiderablydifferentthanthestandard 8-inch-thick residential wall with which mostMinnesotansarefamiliar.

DesignConflictsOccasionally,thereareconflictsbetweendesiredoutcomes.Oneexamplecouldbethedesirefortreesin the nearby landscape versus the need to optimize solargain.Dependingonthelocalconditions,itmaybenecessaryforthetreestobetrimmedorremoved.Similarly, a desired view from inside the house may suggest that the main windows should look to the north, rather than the south, where they would be mostsuitablefromanenergyperspective.However,carefullyconsidereddesignbyqualifiedandknowl-edgableprofessionalscanresolvethesechallenges.

MoistureandDurabilityEven though the Passive House concept has proven effectiveinanumberofMinnesotabuildings,thelong-term health impacts and durability of some of thesestructuresisunknown.TheconcernlieswithMinnesota’shot,humidsummers.Typicalconstruc-tionhasenoughairandheatflowthroughthewallto“dryout”anyhumiditythatmayhaveentered.Ina Passive House wall, there is very little heat energy tocarrymoistureout.TheeffectmaybethataPassiveHouse’shighinsulationlevelsareverysafeand effective in the cold, dry winter, but could retain harmfullevelsofmoistureinthesummer.Furtherresearch and long term monitoring is required to adequatelyaddressthisissue.


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With regard to the effect of humidity on the wall structure,thequalityofconstructioniscrucial.The danger of harmful moisture accumulation is much greater from poor airsealing rather than from diffusevaporflowthroughtheassembly.BecausePassive Houses are generally more airtight, they arepotentiallylesspronetomoistureproblems.LeBeau is concerned that there could be a high degree of failure in US Passive Houses if basic building science and quality construction principles arenotheeded:“Optimismandexcitement[aboutthePassiveHouseconcept]makeitseemlikethesebuildingsareimmunetoforcesofnature.”

One way to address this issue is the application of hygrothermically symmetric building assemblies suchasInsulatedConcreteForms(ICF’s)andStructuralInsulatedPanels(SIP’s).Thesewalltypeshave the vapor barrier in the thermal middle of the wall and allow any moisture to dry toward both the insideandoutsideofthewall.Anadditionalsecurityof ICF walls is that they contain biologically inert materials like foam and concrete, which do not promotebacterialorfungalgrowth.

PublicPerceptionsThe energy use limits put forth by Passive House are quiteaggressive.An80-90%reductioninhomeen-ergy use can be seen as nearly impossible to achieve withoutsacrificingcomfort,style,andfamiliarity.Itis also viewed as prohibitively expensive, especially inanextremeclimatesuchasMinnesota’s.

ManyAmericansaredisinclinedtowardhavinglimits imposed on their living spaces, and although they may be concerned about how much money they spend,theydonotwanttobetoldhowtospendit.Passive House sets a limit on energy use that some peoplemayfindarbitraryorunnecessary.Equivalentto living in a typical house or driving a vehicle, per-sonalhabitsandprioritieshaveasignificantimpacton energy use and whether or not the performance criteriaaremet.

It is commonly perceived that occupants of energy-efficientbuildingswillbesubjecttouncomfortabletemperaturesandunabletouse“regular”appliances.However, Passive Houses address these issues with appropriatetechnologiestoensureusercomfort.The default indoor design temperature for the PHPP is 20ºC, or 68ºF, and can be adjusted by the user if desired.Itisthenuptothedesignertoassembleathermal envelope and HVAC system that meets the designcriteria.Similarly,theelectricaluseiscappedatacertainfiguredependingonthesizeofthehome.Itisuptothedesignerandhomeownerstooutfitthebuildingwithenergyefficientappliancesthatmeettheirlifestyleneedswithinthatenergybudget.

In the end, a Passive House is simply a building that has been designed to perform to certain set of criteria--How the occupants decide to live in it is entirelyuptothem.Iftheydecidetoexceedthemodeled electrical use or turn up the thermostat, the buildingdoesnotprohibitthemfromdoingso.



IntegrationwithOtherBuildingProgramsandRegulationsThe Passive House standard focuses on reducing energy use, and thus indirectly addresses greenhouse gasemissions.Itdoesnotaddresssite,water,materials,andothersustainabilityissues.However,by combining Passive House with other criteria such as LEED or the Living Building Challenge, one canaddressabroaderscopeofsustainabledesign.Conflictsmayarisebetweendifferentbuildingprograms,however.

Salmela Architect designed the high-performance Bagley Classroom Building on the Duluth campus oftheUniversityofMinnesota.CarlyCoulsonwas the project architect for the building, which iscertifiedLEEDPlatinumandisseekingPassiveHousecertification.AsCoulsonappliedthosetwostandards to the building, she noticed occasional incompatibilities.Forinstance,LEEDofferscreditsforreflectiveorhigh-albedoroofmaterialstoavoidurbanheatislandeffects.However,anoptimizedPassive House design would suggest a solar absorp-tive material in order to reduce the heating load ofthebuilding.AnotherexampleisthatLEEDrecommends ventilation rates at 30% beyond the coderequirement.Heatingandcoolingthisextraventilation air requires energy that could make PH compliancedifficult.

Passive House architect Tim Eian also notes a few specificcodeissuesrelatedtoradonmitigationandplumbingventingthatconflictwiththePassiveHousedesignapproach.WhilePHcertificationcan

still be achieved while meeting the code require-ments, the issues that these particular codes are meant to address are not relevant when one builds PassiveHousetypeconstruction.


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TheBioHausattheConcordiaGermanLanguageVillagenearBemidji,MN.DesignedbyStephanTanner,theBioHauswasthefirstcertifiedPassiveHousebuildingintheUS.

Part 2: Results and Conclusions

The purpose of this study is to determine the current status and viability of the Passive House concept in Minnesotaandtoanswerquestionsaboutitsap-plicabilityatUMOREPark.Casestudiesandinter-views with designers and other experts are the main sourcesofinformationtoanswerthesequestions.This section includes the cost and performance results that were compiled on case study houses as well as a discussion of some key topics such as the impact of Passive House design on planning,

examples of community scale Passive House devel-opments,marketissues,andconclusions.

ResultsOverallViabilityandPerformanceofPassiveHousesinMinnesotaIfUMOREistomeetOnePlanetgoalsforcarbonand energy, Passive House design is one viable approach that is being successfully applied in Minnesota.Severalexamplesofcertifiedandnon-


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certifiedbuthighlyefficienthouseshavebeenbuiltinMinnesotaandWisconsin.Manyofthesehousesare designed to use 70%-80% less energy than a typicalhousebuilttocode.ThiswouldbeequivalenttoaHERSratingof20-30(where0isnoenergyuseand100isatypicalcodebuilding).

The Passive House concept has been proven in MinnesotaforoverfiveyearsattheBioHausattheConcordia German Language Village near Bemidji, and it is currently exceeding the PH performance criteriaby10%-15%inclimatezone7.PassiveHouse seeks the same sort of reduced environmental impacts as programs such as the 2000-Watt society, and the Swiss Minergie standard, but also provides a designtooltoachieveit.

The Passive House movement is still at an early stageinMinnesota.Asdocumentedintheprevioussection, there are many potential advantages as well assomeknownchallengesthathaveappeared.Ourresearchhasrevealedfivecertified Passive House projectsinMinnesotaandwesternWisconsinatthis time—three single-family houses and two smallinstitutionalbuildings(aclassroomontheUniversityofDuluthcampusandaclassroom/dormitoryatConcordiaLanguageVillage).Thereare also three projects that have been designed and willundoubtedlymeetthecertificationrequirementswhenbuilt.OneoftheseisaprototypePassiveHouse and the other two are designed for clients innorthernMinnesota.Inaddition,thereareanumber of high performance houses that are close

tothePassiveHousestandard.Examplesoftheseare included in the analysis for comparison of costs andperformance.InPart3ofthereport,asurveyofseveralPassiveHouseandhighlyefficientprojectsinMinnesotaandWisconsinaredescribed.Datafrom four of the case study houses are presented indetail.Forsomeoftheprojectsinthesurvey,costswerenotavailable.TheresultsinthissectionaredrawnfromthiscollectionofcertifiedPassiveHouseandhighlyefficientprojects.

InitialCostsforPassiveHouseandOtherHighPerformanceProjectsTable1showsnineprojects—fivewithactualcon-struction costs and three with estimates for projects designedbutnotyetbuilt(costswerenotavailableforoneoftheprojects).Basedondatacollectedso far, Passive House costs range widely, from a custom home at $342 per square foot to a simple single-familyhomeat$100persquarefoot.Twoexamples of more conventional high performance houses by Amaris Homes and Christian Builders inMinnesotaareinthe$90-$140persquarefootrange.NotethatTable1showscostpersquarefootinformationintwoways—TFA(treatedfloorarea)andtheASHRAEmethodforcalculatingfloorarea.The ASHRAE method is the more common way that costs per square foot are calculated in the US build-ingindustry.Floorareasaremeasuredtooutsidewallsandincludeallpartitionsandstairs.TheTFAmethod is used in the Passive House software and does not include wall thicknesses and unconditioned spaces.Itshouldbenotedthattherecanbequite



Project Location HDD(ft2) TFA

(ft2) ASHRAE Cost

$/ft2 TFA

$/ft2 ASHRAE

Certified Isabella Isabella, MN 9818 2134 53842 $1,841,328.00 $862.85 $342.002 Passive House Konkol Hudson, WI 7876 1973 2757 N/A N/A N/A(all include PV) Newenhouse Viroqua, WI 7795 833 1233 $254,000.00 $304.92 $206.00

Skyline Duluth, MN 9900 2660 2950 $775,000.00 $291.35 $262.71 Non-certified Synergy* Minneapolis, MN 7876 1692 2300 $321,805.00 $190.19 $139.92

Passive House Synergy (no PV)* Minneapolis, MN 7876 1692 2300 $299,000.00 $176.89 $130.00 Holm* Biwabik, MN 9818 1531 2200 $230,000.00 $150.23 $104.55

Erickson* Ely, MN 9818 1060 1500 $150,000.00 $141.51 $100.00

High-performance Stemwell House Plymouth, MN 7882 43061 4306 $388,721.04 $90.271 $90.27Walker House Rogers, MN 7981 33561 3795 $367,122.00 $109.39 $96.74

Table 1: Construction Costs of Case Studies

*Not yet constructed or not yet completed (estimates only).1Calculated conditioned floor area, not true TFA.2Figure includes ALL enclosed space, including unconditioned areas.

MN Code Passive House Cost IncreaseBuilding Envelope $54,291.00 $66,315.00 22%Fenestration $18,800.00 $51,632.00 175%Mechanicals $17,700.00 $23,300.00 32%Other $108,058.00 $108,058.00 0%Site $50,000.00 $50,000.00 0%Total $248,849.00 $299,305.00 20%PV for Zero Energy $125,000.00 $22,500.00 -82%Total Zero Energy $373,849.00 $321,805.00 -14%

Calculations performed by TE Studios based on a two-story, 1,667 single-family home.

Table 2: Passive House Initial Construction Cost Comparison

significantdifferencesbetweenthetwofigures.Compounding this issue is that professional apprais-ers cannot legally count any below grade space, regardlessofgrade,finish,orspaceconditioning.

The cost differences shown in Table 1 cannot be attributedsolelytoenergy-efficiencyimprovementsbecauseofthedifferenceinfinishmaterialsandotherdesignfeatures.ThePassiveHouseprofes-sionals interviewed for this report estimate a 3% to 20% cost increase to build a Passive House over

acodebuildinginMinnesota.Inaddition,fourofthehousesincludephotovoltaic(PV)solarsystemsinthecost.WhilethePVsystemsarepartoftheoverall strategy to attain net zero energy in these houses, they are a costly way to reach that goal and tendtoobscurethecostofthehouseitself.

The case studies typically do not clearly identify theaddedcostsforPassiveHouseconstruction.In the process of developing the Synergy Passive House prototype home, TE Studios performed some


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Location HDDTFA (ft2)

Annual Heating

(Btu)

Heating (kBtu/ft2

TFA/yr)

(Btu/ft2)/yr/(HDD/

yr)

Total Annual Energy

(Btu-site)

Total Energy per ft2/yr.

(Btu)Isabella Isabella, MN 9818 2134 9600000 4.50 0.45820 0 0.00

Isabella no PV Isabella, MN 9818 2134 9600001 4.50 0.45820 13000000 6.09Certified PH Konkol Hudson, WI 7876 1973 6208168 3.15 0.39951 -9153037 -4.64

Konkol no PV Hudson, WI 7876 1973 6208169 3.15 0.39951 13867353 7.03Newenhouse Viroqua, WI 7795 833 3915100 4.70 0.60295 0 0.00

Newenhouse no PV Viroqua, WI 7795 833 3915101 4.70 0.60295 9245000 11.10

Skyline Duluth, MN 9900 2660 19410000 7.30 0.73707 39900000 15.00Synergy* Minneapolis, MN 7876 1692 7464135 4.41 0.56011 0 0.00

Non-certified PH Synergy no PV* Minneapolis, MN 7876 1692 7464136 4.41 0.56011 18923000 11.18Holm* Biwabik, MN 9818 1531 1837200 1.20 0.12222 15310000 10.00

Erickson* Ely, MN 9818 1060 1166000 1.10 0.11204 10494000 9.90

High-performance Stemwell House Plymouth, MN 7882 4306 38100000 8.85 1.12257 103000000 23.92Walker House Rogers, MN 7981 3356 62900000 18.74 2.34840 129600000 38.62

Table 4: Predicted Energy Performance of Case Studies

*Not yet constructed or not yet completed

Code Code Upgraded Upgraded CostR-value Cost R-value Cost Difference

Above GradeSheathing/framing $2,592.89 $3,636.60 $1,043.71 Wall insulation R-19 $938.40 R-26.5 $5,278.50 $4,340.10 Ceiling insulation R-38 $983.84 R-60 $2,649.66 $1,665.82

Below GradeWall insulation R-10 $1,159.20 R-24 $4,567.20 $3,408.00 Underslab insulation R-0 $- R-10 $1,173.90 $1,173.90

HVAC system upgradesUpgrade to Variable Speed Furnace $700.00 $700.00 RenewAire ERV System $1,500.00 $1,500.00 Upgrade to 14 SEER A/C $500.00 $500.00 Upgrade from 14 SEER to 15 SEER Heat Pump $800.00 $800.00 Zone Controls $2,100.00 $2,100.00

Totals $5,674.33 $22,905.86 $17,231.53 Cost per square foot $2.54 $10.24 $7.71

Table 3: Energy-Efficient Home Initial Construction Cost Comparison

Based on 2,236ft2 home.Source: Amaris Custom Homes



detailed cost analyses and arrived at a number of relevantconclusions.Theircalculationsarebasedon two versions of a two-story 1,667 square-foot single-familyhome(Table2).ThefirstmodelisbuilttomeettheMinnesotacode,andthesecondmodelmeetsPassiveHouseperformancecriteria.They estimate a 20% increase in initial construc-tion costs to build a Passive House instead of a Minnesotacodeminimumhouse.Iftheexpensesare included for a net-zero photovoltaic system, the MinnesotaCodehomerequiressuchalargearraytomeet its energy needs that it winds up costing more thanthePassiveHousewithPV.

It is possible to achieve very good energy perfor-mance with more conventional construction using advanced practices such as greater amounts of insulation,airsealing,andmoreefficientmechanicalsystems.Table3showsthecostincreasesinthe$10per square foot range for these items provided by one contractor based on a 2,236 ft2home.

EnergyPerformanceAs shown in Table 4, predicted total energy use for all Passive House projects is quite low—below 20 kBtu/sf-yr.InthefourcasesusingPVsolarsystems,netenergyuseiszero(orinonecaseanegativenumberbecauseitproducesmorethanituses).The

Total energy use per square foot per year

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two more conventional high performance houses use 24and30kBtu/sf-yrbycomparison,andachievedHomeEnergyRatingSystems(HERS)** ratings of 40and57,respectively(where0isnoenergyuseand 100 is a typical code building meeting the 2006 IECC).AHERSratingof85orbelowqualifiesforthe US EPA Energy Star program and a rating below 60isconsideredverygood.

In one interview, Ray Pruban of Amaris Custom Homes also noted very good performance at little to no additional construction cost in two other projects.OnewasaLEEDforHomesprojectinHugo,MinnesotathatachievedaHERSratingof47thatwasbuiltfor$229,000excludinglot(1,624ft2 of conditioned space and 800 ft2unconditioned).Another was a 3400 ft2 LEED for Homes project inNorthfield,Minnesotathatwasbuiltforap-proximately$400,000($117/ft2)excludinglotandachievedaHERSratingof20.AmarisHomesapply

** The software used to calculate HERS ratings does not adequately calculatecertainaspectsofPassiveHousedesign.Thisisaknownissue and is currently being resolved between the Passive House InstituteoftheUS,andtheResidentialEnergyServicesNetwork.

best practices such as a well-insulated, airtight envelopeandhighlyefficientmechanicalsystems.

Life Cycle Cost ComparisonConsidering the limited number of Passive Houses builtsofarinMinnesotaandthewiderangeofconstructioncosts,itistooearlytodrawdefinitiveconclusionsaboutcostversusperformance.Usually,there is no clear side-by-side calculation available of thecostsandbenefitsofaPassiveHousecomparedtoamoreconventionalalternative.However,thereisoneexamplethatillustratessomeofthetradeoffs.In their case study of the Synergy prototype Pas-sive House, TE Studios provided a side-by-side comparison of cost and energy for three scenarios showninTable5.Theseare1)AbasecasehousemeetingtheMinnesotacode,2)TheSynergyPas-siveHouseprototype,and3)TheSynergyPassiveHousewithenoughphotovoltaics(PV)tomeetthenetzeroenergygoal.Constructionestimatesrangefrom $248,849 for the base case to $299,305 for thecomparablePassiveHouse.TheadditionofPVtomeetnetzeroenergycosts$22,500.Costsper

Base Synergy PH Synergy PH with PVkWh/yr (site) 30880 5546 0kWh/sf/yr 18.5 3.3 0.0annual energy cost $1,456 $554 $0.00 annual maintenance cost $2,488 $1,244 $1,244 savings over base $2,146 $2,700

cost $248,849 $299,305 $321,805 cost/sf $149 $180 $193 cost above base $50,456 $72,956

Table 5: Passive House Cost and Energy Comparison

Energy costs are extrapolated from Synergy report as follows: $488.84 per year natural gas (44,440 kBtu per year @ $1.10/therm) $432.00 per year electricity (4,320 kWh per year @ $0.10/kWh)Source: TE Studio



square foot range from $149 to $193 across the three scenarios.Projectedannualenergyandmaintenancecosts appear in Table 5, and show an annual cost savings over the base case for the two Passive House scenarios.

In their case study report, TE Studio performed a life cycle cost analysis for the three scenarios shown inTable6.Assuminga6.5%energyinflationrate,the Synergy Passive House costs less to own and operateafterapproximately19years.TheSynergyNet Zero Passive House costs less to operate after 21years.Asthegraphshows,therearesignificant

cost savings over the lifetime of both Passive Houses compared to the conventional code house going into the future once the breakeven point has beencrossed.

UnderstandingLifeCycleCostsThere are many ways to analyze the costs and benefitsofamoreenergyefficienthouse.Eachmethod has its advantages and disadvantages and they are based on several assumptions that may changeinthefuture.Theconclusionsdrawnfromany such life cycle cost analysis do not necessarily take into account all of the relevant factors in the

Base Synergy Synergy Net

ZeroYear 1 $252,294 $300,854 $330,299 Year 10 $288,395 $316,731 $339,247 Year 20 $345,187 $340,722 $349,190 Year 30 $434,351 $377,036 $359,132 Year 40 $584,282 $436,480 $369,075 Year 50 $848,281 $539,345 $379,017

Table 6: TE Studio Life Cycle Cost Comparison

Includes estimated maintenance expenses and 6.5% annual energy inflation rate.Source: TE Studio

$-

$100,000

$200,000

$300,000

$400,000

$500,000

$600,000

$700,000

$800,000

$900,000

Year 1 Year 10 Year 20 Year 30 Year 40 Year 50

Base

Synergy

Synergy Net Zero

TE Studio Life Cycle Cost Comparison Chart


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decisionmakingprocess.Tables7and8showthe results of several ways of looking at life cycle costs based on the basic data from the TE Studio comparisonpresentedintheprevioussection.Theanalysis in Table 7 is based on energy cost savings only while the analysis in Table 8 includes savings in both energy and maintenance costs for the Passive Houses.

SimplePayback1(withnoenergyinflationrate).The most basic payback calculation is to divide the investment(addedconstructioncost)bytheannualcost savings to obtain the number of years it takes forthecumulativecashflowtoreachzero.InTable7, this number is 56 years for the Passive House and 50 years for the Net Zero Passive House based on energycostsavingsalone.InTable8,thepaybackperiod is 25 years for both the Passive House and

Base Synergy Synergy Net ZeroInitial construction cost1 $248,849.00 $299,305.00 $321,805.00 Construction cost increase over base case house $50,456.00 $72,956.00 Annual energy cost savings1 $902.10 $1,456.70 Simple payback 1 (assumes no energy cost inflation) 56 years 50 yearsSimple payback 2 (assumes energy cost inflation2) 25 years 25 yearsNet present value 1 (2% discount rate)2,3 $1,792.00 $402.00 Net present value 2 (4% discount rate)2,3 $(13,533.87) $(20,575.82)Year 1 net monthly cash flow4 $(180.48) $(248.27)30 year lifetime cost2,4 (mortgage + energy costs) $560,236.83 $575,801.74 $586,993.92

Table 7: Life Cycle Cost Comparison (Energy costs only)

Notes:1TE Studio estimate.2Energy inflation rate of 6.23% natural gas and 3.75% electricity. Figures based on annual cost averages 1970-2009 from www.eia.gov.330 year NPV.4Based on 30 year mortgage of initial construction cost at 4.5% interest rate with no down payment.

Base Synergy Synergy Net ZeroInitial construction cost1 $248,849.00 $299,305.00 $321,805.00 Construction cost increase over base case house $50,456.00 $72,956.00 Annual energy cost and reduced maintenance savings1 $2,146.35 $2,700.95 Simple payback 1 (assumes no energy cost inflation) 24 years 27 yearsSimple payback 2 (assumes energy cost inflation2) 18 years 15 yearsNet present value 1 (2% discount rate)2,3 $29,658.99 $28,268.94 Net present value 2 (4% discount rate)2,3 $7,981.66 $939.71 Year 1 net monthly cash flow4 $(76.79) $(144.58)30 year lifetime cost2,4 (mortgage + energy + maint. costs) $634,891.53 $613,129.09 $624,321.27

Table 8: Life Cycle Cost Comparison (Energy and Maintenance costs)

Notes:1TE Studio estimate.2Energy inflation rate of 6.23% natural gas and 3.75% electricity. Figures based on annual cost averages 1970-2009 from www.eia.gov.330 year NPV.4Based on 30 year mortgage of initial construction cost at 4.5% interest rate with no down payment.



the Net Zero Passive House when energy and maintenancecostsavingsareincluded.

SimplePayback2(withenergyinflationrate)The Simple Payback 1 approach described above does not account for the fact that energy costs are likelytoincreaseovertime.SimplePayback2inTables 7 and 8 shows the number of years it takes forthecumulativecashflowtoreachzerowithanenergyinflationrateof6.23%fornaturalgasand3.75%forelectricity(basedon30yearaveragesinMinnesota).InTable7,thisnumberis24yearsforthe Passive House and 27 years for the Net Zero PassiveHousebasedonenergycostsavingsalone.In Table 8, the payback periods are 18 and 15 years respectively when energy and maintenance cost savingsareincluded.Theinflationrateisappliedtotheenergycostonly,notmaintenance.TheSimple Payback 2 method including energy and maintenance cost savings was used by TE Studio in theirlifecycleanalysiswitha6.5%overallenergyinflationrate.

NetPresentValueSimplepaybackanalysishasitsshortcomings.Itdoesnotaccountforcashflowthatoccursafterpayback has been achieved and does not measure thelong-termvalueofaninvestment.Italsoignoresthe time value of money—the principle that money received in the future is not as valuable as money re-ceivedtoday.NetPresentValue(NPV)isananalysistool that accounts for the time value of money by discountingcashflowsthatoccurinthefuture.Ifthe

result of an NPV calculation is a positive number overthetimeperiodspecified,itisconsideredagood investment, if it is a negative number it is not agoodinvestment.NetPresentValue1inTables7and 8 shows the results of NPV calculations with a2%discountrate.NetPresentValue2showstheresultsofNPVcalculationswitha4%discountrate.The discount rate represents the cost of borrowing money or earning interest on money and must be establishedbytheindividual.NetPresentValue1(2%discountrate)isapositivenumberover30years in Table 7 for both the Passive House and Net Zero Passive House meaning they are good investmentsoverthetimeperiodoftheanalysis.Net Present Value 2 is a negative number in Table 7(energysavingsonly)forbothPassiveHousesmeaning that it is not a good investment when the discountrateis4%.HoweverinTable8wherebothenergy and maintenance costs are included, both Passive Houses are a good investment with a posi-tiveNPVata4%discountrate.

NetMonthlyCashFlowNetMonthlyCashFlowanalysisisanotherwaytoevaluateaninvestmentinenergyefficiency.Themonthly mortgage payment is calculated for the additionalmoneyspentfortheenergyefficiencyimprovement.Thisiscomparedtothemonthlyenergysavings.Anyinvestmentwithapositivenetmonthlycashflowisattractivetothehomeowner.NetmonthlycashflowisnegativeforbothPassiveHouse scenarios in Table 7 when only the energy savingsareconsidered.InTable8whereenergy


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and maintenance savings are considered, the net monthlycashflowisstillnegativeinbothcasesbuttheamountissmaller.Inbothcases,themortgageinterestrateis4.5%.

30-YearLifetimeCostAfinalmethodofcomparingalternativescenariosis30-yearlifetimecost.Thisrepresentsthetotaloftheinitial construction cost, the energy costs, and the cost of the mortgage payment on borrowed money over30years.Inthiscalculation,thepresentvalueof money spent or saved in the future is not taken intoaccount.InTable7wheremaintenancecostsare not included, the 30-year Lifetime Cost for the Passive House is $575, 802 versus $560, 237 for the basecase(a3%increase).ThelifetimecostfortheNetZeroPassiveHouseis$586,994(a5%increaseoverthebase).InTable8whereenergyplusmainte-nance costs are included, the 30-year Lifetime Cost is$613,129versus$634,892forthebasecase(a4%decrease).ThelifetimecostfortheNetZeroPassiveHouseis$624,321(a2%decreasefromthebase).

LifeCycleCostSummaryThe preceding life cycle cost analysis discussion isnotintendedtoprovidedefinitiveanswersabouttheeconomicviabilityofPassiveHouses.Instead,it serves as a means to illustrate the many issues and variables that might be considered in such a decision.Therearetwowaystoconsidercost-effectiveness.Thefirstistoaskwhatisthemostcost-effective way to reach carbon-neutral or zero-net-energytargets.PassiveHouseisaverycost-ef-

fectivewaytomeetthesegoals.Thesecondistoaskwhat is a cost-effective level of investment in energy efficiencymeasuredbypayback,netpresentvalue,andotherconventionaleconomicanalysistools.Simple payback periods based on no energy cost inflationover30yearsmightbeconsideredtoolong.However,withtheinclusionofenergycostinflationestimates and maintenance cost savings, the payback periodcanbesignificantlyless(aslowas15years).The Net Present Value method of cost analysis producesarangeofresultsaswell.Theinvestmentispositive(worthinvesting)whenthediscountrateis2%butitisnegative(notworthinvesting)whenthediscountrateis4%.Othermethodsshownegativemonthlycashflowforenergysavingsaloneas well as when both energy and maintenance cost savingsareincluded.Similarly,the30-yearlifetimecost is slightly higher for the Passive House options versus the base case when energy costs alone are considered but are lower when maintenance cost savingsareincludedaswell.

There is one key factor in considering long term investments in homes that is not recognized by any oftheselifecyclecostanalysismethods:Thatisthatenergyefficiencyimprovementsactuallyincreasethevalueofthehome.Thebenefitsoftheinvest-ment are not only monthly energy and maintenance savings but also the additional money gained on resaleofthehouseduetotheimprovements.

It is important to remember that all of this analysis is based on one hypothetical set of data prepared



by TE Studio to provide information on the af-fordabilityofthePassiveHouseconcept.Changesinkeyassumptionscansignificantlychangetheresultsandconclusions.Forexample,the20%costpremium that TE Studios attributes to Passive House construction is higher than some other designers havenoted.Asthecostdifferenceisreduced,thelife cycle costs are more attractive for the Passive House.Similarly,energypriceincreasesorcarbontaxes designed to increase fossil fuel energy prices would make the analysis more favorable for investinginthePassiveHouse.Ontheotherhand,the maintenance cost savings in the TE Studio projectionshaveyettobeverifiedovertime.Finally,any life cycle cost analysis does not include other qualitativebenefitsthatarenotaccountedforsuchascomfort,health,andsecurity.

Multi-FamilyStructuresBecause of the relationship of surface area to volume mentioned previously, it is generally easier for larger and multi-family buildings to meet the performancecriteria.WhiletheUMOREprojectis primarily focused on single-family homes, some medium-density multifamily housing is likely to be included,aswell.Costpremiumsmayalsodecreasewith larger buildings as a result of purchasing efficiencies.Manymulti-familyPassiveHouseprojectsarefoundinEurope.

PassiveHouseMarketAcceptanceandDevelop-mentThere is not enough information at this point on themarketforPassiveHousedesigns.However,a rapidly growing movement of Passive House developments implies that developers see a potential market for energy- and environmentally-conscious homebuyers.

The Nestwerk Passive House multifamily residential project in Dresden, Germany.

AmultifamilyresidentialPassiveHouseprojectinGermany.


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There will be an important regional test of the marketforPassiveHousesatJacksonMeadowsinStillwater,Minnesotawhere14homeswillbebuilttothePHstandardasPhase2ofthedevelopment.Implementation has been slow because of the gen-eral downturn in the housing market, but developer Harold Teasdale remains committed to sustainable communitydesign.“JacksonMeadowisallaboutpushingupstream,”saysTeasdale.“There’sthiswholesysteminplace.Youjusthavetobewilling

togetawholeseriesof‘No’s,’andkeep asking the question, and ask-ing the question, ask ‘why not, why not,whynot?’untilyoucanfinallybust through and get someone to say, ‘well maybe if this is done this way,’thensuddenly,‘yeah,Iguessit would work if you did it that way.’Andallyou’relookingforisthatopening.”

Phase three at the Ecovillage in Ithaca,NewYorkwillbeanothertest of the Passive House concept at adevelopmentscaleintheUS.The

Third Residential Ecovillage Experience, or TREE, is a development designed around the most cutting-edge concepts in neighborhood design, including rainwater management, district solar energy, and PassiveHouseenergyperformance.TheTREEproject has secured thirty of the forty Joint Venture Partners they need to start the project, and they plan tobreakgroundinearlyspringof2012.

JacksonMeadowssustainabledevelopmentnearMarineonSt.Croix,MN

JacksonMeadowssustainabledevelopmentnearMarineonSt.Croix,MN



LayouttooptimizesolaraccessalongaNorth-SouthaccessinDenmark.

The layout of multiple Passive House buildings at the Third Residential EcoVillage Experience (TREE)inIthaca,NY.

In Arvada, Colorado, the GEOS development is planning for zero net energy use by combining PassiveHouseenergyefficiencymeasures with solar electric and geothermalsystems.Geothermalsystems were integrated largely because of the roofspace limita-tionsinthedensitytheydesired.Three hundred housing units are planned in a mixed-use neighbor-hood with traditional street layout that balances solar access with NewUrbanistdensities.DeveloperNorbert Klebl estimates that home-owners will be able to purchase the homes at no additional cost, because the increase in mortgage payments will be morethanoffsetbytheenergycostsavings.*** There are currently 12 interested homeowners, but the project remainsidleuntilmorefundingissecured.

LayouttoOptimizeSolarGainPassive House takes much of its inspiration from the solarandenergyefficienthousingmovementof1970’sAmerica.Oneofthemostbasicconceptsishowtodesign the building and the neighborhood to maximize useofsolarenergy.Thesolar-optimizedlayoutmaybedifferentthanthatofatypicaldevelopment.Thefirstprinciple is that buildings should not shade each other in the winter months, when the need for solar gain is highest.Properorientationandspacingofbuildings,along with careful tree selection and placement, will ensure adequate solar gain to meet the energy perfor-*** Boulder Green Building Journal,Spring2007.


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An example of spacing and layout for optimal solargainonaclusterofone-storyhouses.Theshadowsrepresentthesun’sangleat2pmonDec.21stinRosemount,MN.

An example of spacing and layout for optimal solargainonaclusteroftwo-storyhouses.Theshadowsrepresentthesun’sangleat2pmonDec.21stinRosemount,MN.



mancetargets.Thefiguresonthepreviouspageillustrate the spacing required for one- and two-story developmentsinMinnesota.Itisunlikelythatthisconstraint will limit density up to 5-6 units per acre but could result in some unconventional layouts withrespecttohowunitsareorientedtostreets.Oneexample of a single-family Passive House develop-ment in Denmark has houses spaced apart and angledtofaceSouthalongaNorth-Southstreet.

Planners for the GEOS development partnered with the National Renewable Energy Lab to analyze optimal solar layouts for a medium-density develop-ment.Thestudyresultedinastaggeredbuildingplacement,or“checkerboard”plan,whichprovidessolaraccesstoeachbuilding.

PassiveHouseDesignandDistrictEnergyAs the need for energy diminishes in individual houses, the economics of district energy systems are affected.DuringtheEuropeantour,commentsweremade that the energy demand for Passive Houses was so low that it was not cost effective to develop districtenergysystems.AstudyinMontreal,however, concluded that it was more cost effective to achieve 50-75% of the Passive House standard and use a district system to provide the remaining energy.Thiswillhavetobeanalyzedonacase-by-case basis to determine whether it is more cost effectivetoinvestinenergyefficiencyinindividualhousesversusinvestinginefficientdistrictenergysystems.

The GEOS development is taking a hybrid ap-proach,planningtobuild“minidistricts”of3to6homes sharing one water-to-water heat pump with a verticalgeothermalloop.Thehomesaveragearound1500ft2 and will meet PassiveHouse standards so the heat loads including domestic hot water will be less than10kBtuperunit.Heatpumpsof3to4tonswillsufficeforeachdistrict.Energyrecoveryventilatorswill be assisted by earth tubes from REHAU primar-ilyforcoolingbutalsoforpreheatingofwinterair.The ERV delivery ducts will distribute the base heat-ingloadofabout5kBtu.Thepeakswillbecoveredbysmallelectricbaseboardheaters.

The“checkerboard”layouttooptimizethesolargainoftheGEOSdevelopmentinArvada,CO.


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Another project under development in Colorado is moving farther away from district energy, by reli-ance on newly-available smaller ground-source heat pumps that make unit-based geothermal systems morefeasible.However,thelowercostofdistrictsystemsperunitstillmakesthemfinanciallyappeal-ingforthetimebeing.

Conclusions•IfUMOREistomeetOnePlanetgoalsforcarbonand energy, Passive House design is one viable approachthatisbeingsuccessfullyappliedinMin-nesotaandWisconsin.Severalexamplesofcertifiedandnon-certifiedbuthighlyefficienthouseshavebeenbuiltintheregion.Predictedtotalenergyusefor several Passive House projects is quite low—below20kBtu/sf-yr.FourPassiveHousedesignsusePVsolarsystemstoachievenetzeroenergy(orin one case a negative number because it produces morethanituses).Thetwomoreconventionalhighperformancehousesinthestudyuse24and39kBtu/sf-yrbycomparison.

•CostpremiumsforPassiveHouseconstructionareestimatedinthe3-20%range.Basedondatacollected so far, Passive House costs range widely, from a completed custom home at $342 per square foot to a simple single-family home estimated at$100persquarefoot.Becauseoftherangeofprojectsanddifferencesinfinish,thereisnoclearside-by-side calculation available of the costs and benefitsofaPassiveHousecomparedtoamoreconventionalalternative.Itisalsopossibletoachieve very good energy performance with more

conventional construction using advanced practices such as greater amounts of insulation, air sealing and moreefficientmechanicalsystems.Twoexamplesofmore conventional high performance houses in the studyareinthe$90-$140persquarefootrange.

•ConsideringthelimitednumberofPassiveHousesbuiltsofarinMinnesotaandthewiderangeofconstructioncosts,itistooearlytodrawdefini-tiveconclusionsaboutcostversusperformance.However, if carbon-neutrality or net-zero-energy is the desired goal, Passive House is very likely a cost-effectivewaytoreachthosetargets.

Fromastrictlyfinancialperspective,onecanusemore conventional economic analysis tools such as payback and net present value to determine cost-effectivelevelsofinvestmentinenergyefficiency.ComparingthePassiveHousetoaMinnesotahousebuilt to meet code, simple payback periods based onnoenergycostinflationover30yearsmightbeconsideredtoolong(over50years).However,withtheinclusionofenergycostinflationestimatesandmaintenance cost savings, the payback period can besignificantlyless(aslowas15years).TheNetPresent Value method of life cycle analysis produces arangeofresultsaswell.Lookingatenergycostsalone,theinvestmentispositive(worthinvesting)whenthediscountrateis2%,butitisnegative(notworthinvesting)whenthediscountrateis4%.Theinvestment is always positive when both energy and maintenancecostsareincluded.Similarly,the30-year lifetime cost is slightly higher for the Passive House options versus the base case when energy



costs alone are considered but are lower when maintenancecostsavingsareincluded.

•Inadditiontodecreased energy and maintenance costs, the Passive House concept has advantages including, durability, energy security, passive surviv-ability,andoccupanthealth.ThePassiveHousehasgrowing brand recognition, is easy to use, and holds designersaccountable.

•The Passive House Concept has challenges such as higher initial costs, availability of some high per-formance components and materials, lack of profes-sionalengineerscapableofdevelopingfinely-tuneddesigns, lack of experienced contractors, potential architectural limitations, and concern over possible moistureproblemsifnotbuiltcorrectly.Manyofthese challenges are likely to be addressed as the Passive House movement matures and experience is gainedintheregion.

•PassiveHouseisnottheonlycertificationpro-gramthatwillresultinsignificantenergysavings(althoughithasanemergingbrandrecognitionasaveryhighstandard).PassiveHouseissuccessfulbecause it uses a simple performance standard and providesthetoolstoachieveit.TomaintainthegoalsofUMORE,asimilartypeofstandardwithaccountabilityisdesirable.Itmaybebeneficialtouse Passive House in combination with systems such asMinnesotaGreenStar,LEED,ortheLivingBuild-ingChallenge,forexample.PerhapsmultiplelevelsofperformancewouldbeappropriateatUMOREwith the high end marked by carbon-neutral struc-

tures, followed by net-zero energy structures, and thenPassiveHouse.

•Because of common walls and more compact configuration,itiseasiertomeetthePassiveHousestandardwithmulti-familybuildings.

•PassiveHouseandotherlowenergydesignsmaybeusedwithdistrictenergysystems.Astheneedfor energy diminishes in individual houses, the economicsofdistrictenergysystemsareaffected.This will have to be analyzed on a case-by-case basis to determine whether it is more cost effective toinvestinenergyefficiencyinindividualhousesversusinvestinginefficientdistrictenergysystems.Decisions regarding district systems should be analyzed against multiple factors, including fuel type, long-term fuel availability, and greenhouse gas emissions.

•Ideally,neighborhoods with Passive House con-struction should be designed to permit solar access foreachhome.Thisisunlikelytoaffectdensitybut may require some unconventional layout with respecttohowunitsareorientedtothestreet.Onthe other hand, the Passive House concept can be carriedoutwithlessthanidealsolaraccess.

•UMOREParkcouldsponsorsometypeofcompe-tition inviting innovative high performance housing demonstrationprojects.PassiveHousewouldbeoneof these and could be monitored and compared side bysidewithotheroptions.Suchacompetitioncould


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capture the excitement and enthusiasm surrounding PassiveHouseconstruction.



Part 3: Building Survey and Case Studies

The third part of this report comprises a survey of PassiveHousebuildingsinMinnesotainadditiontoanumberofotherhigh-performancebuildings.Thebuildingsfallintothreecategories:1.CertifiedPassiveHousesThesehouseshavereceivedofficialcertificationfromthePassiveHouseInstitute.OnlyafewexistintheMinnesota-Wisconsinregion.

2.Non-certifiedPassiveHouseThese buildings are designed to meet Passive House standards but either did not pass certi-ficationorarestillintheprocessofreceivingcertification.

3.High-performanceHousesThese houses are not necessarily designed to meet Passive House standards but are examples of energyefficienthousedesign.

These three groups of houses provide a spectrum of construction types related to strategies, costs and energyperformance.

At the end of this section, four more extensive case studies are documented to explore performance, cost anddesignstrategiesingreaterdepth.Theseare:•PassiveHouseintheWoods,TEStudio•SynergyHouse,TEStudio•Newenhouse,CoulsonArchitect•IsabellaEcoHouse,CompassRose,Inc.


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Waldsee BioHausStephan Tanner, Intep LLCThe Waldsee BioHaus is a 5,000ft2, two story classroom and dorm complex completed in 2006 outsideofBemidji,Minnesota.ItwasthefirstbuildingtobeCertifiedPassiveHouseintheUS.It is extensively monitored, and incorporates in-teractive feedback displays that show visitors how thehouseisperforminginrealtime.Ithasbeenexceeding the Passive House performance criteria by10%-15%.Totalprojectcostwas$1,100,000($220/ft2gross).photo by John Carmody

The NewenHouse Prototype ICoulson ArchitectThe NewenHouse Prototype 1 is a two-story, 1250ft2

single-family home completed in 2011 near Viroqua, Wisconsin.Itusesasolarhotwatersystem,hasPV installed to achieve net-zero, and a rainwater collectionsystem.ItisseekingLEED-HPlatinumcertificationandhasthehighestHERSratingonrecordforWisconsin.Totalconstructioncostwasapproximately$254,000($206/ft2gross).

Certified Passive Houses

photo by Sonya Newenhouse



Certified Passive Houses

Isabella EcoHouseCompass Rose DesignsThe Isabella EcoHouse is a 5,245ft2 single-family residence completed in 2009 near the Canadian borderwithMinnesota.Constructedasalive-inresearch project, the $1,800,000 house incorpo-rates extensively monitored assemblies including electrical storage, rainwater catchment, and liquid andsolidseasonalheatstorage.Itisdesignedtobenet-zeroandiscertifiedLEEDPlatinum.

photocourtesyCompassRose,Inc.

Konkol ResidenceTE StudioThe Konkol Residence is a 2,757ft2, three story single-family home completed in 2010 outside ofHudson,Wisconsin.Ituseselectricresistancein-floorheatingwithaPVarraytogenerateelec-tricity,andasolararrayforhotwaterheating.Itisdesigned to operate CO2-neutral.Projectcostsareunavailable.Allelectricaluseisbeingmonitored.

photo by Chad Holder


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Skyline HouseWagner/Zaun ArchitectsThe Skyline House is a two-story, 2900ft2 single family home, completed in 2008 near Duluth, Minnesota.Itusesahydronicradiantslabandawood stove for space heating, and a tankless hot water heater paired with evacuated tube solar col-lectors.Theconstructioncostwasapproximately$775,000($220/ft2)

Non-Certified Passive Houses

image courtesy Wagner Zaun Architects

Bagley ClassroomSalmela Architects The Bagley Classroom building is a 1995ft2, one-story classroom completed in 2010 on the UniversityofMinnesotaDuluthcampus.ItusesaVenmarpreheaterandahydronicradiantfloor.ItisalsoLEEDPlatinumcertified.Totalconstructioncostswere$700,000($350/ft2).Monitoringsystemstrack occupant comfort, interior temperature and humidity,PVgeneration,andallelectricaluse.

photo by Paul Crosby



Esko FarmhouseWagner/Zaun ArchitectsThe Esko Farmhouse is a two-story, 1800ft2 single family home completed in 2009 near Cloquet, Minnesota.Itusesaradiantslab,hotwaterradia-tors, and a wood stove for space heating, and is built“solar-ready.”Itisexceptionallyairtight,at0.4ACH50.Actualcostsforall utilities was approximately$100permonthfortheyear2009.Constructioncostsareunavailable.

photo by Gail Olson


Synergy PrototypeTE StudioSynergy is a 2300ft2, two-story single-family home that has been developed as a low-energy prototype.Asyetunbuilt,itisdesignedtousean air-to-air heat pump with electric resistance backupheating.Waterisheatedbyasolarar-ray.Estimatedannualheatingcostis$218,andestimatedtotalenergycostis$544peryear.Construction costs are estimated to be approxi-mately$300,000($130/ft2).image by TE Studio


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The Holm RetreatCoulson ArchitectTheHolmRetreatisa1-1/2story,2200ft2 single-familyhomethatwillbebuiltinBiwabik,Min-nesota.ThewallsareR-57.Totalconstructioncostisestimatedtobe$230,000($106/ft2).

The Erickson HomeCoulson Architect The Erickson Home is a one-story, 1500ft2 single-familyhomethatwillbebuiltinEly,Minnesota.Total construction cost is estimated to be $150,000 ($100/ft2).


image by Coulson Architect

image by Coulson Architect



High Performance Houses

The Walker HouseChristian BuildersThe Walker House is a two-story, 3795ft2 single-familyhomecompletedin2011inRogers,Min-nesota.ItusesanHRVandadvancedair-sealingtechniques,anditexceedsMNenergycodestan-dards.Constructioncostswere$367,122.

Stemwell HouseAmaris Custom HomesThe Stemwell House is a 4306 ft2 single-family homecompletedin2011inPlymouth,Minnesota.Ituseshighperformancewindows,ahigh-efficiencyfurnace,andadvancedair-sealingtechniques.Italsousesahigh-efficiencyboilerforspaceheatingandwaterheating.Constructioncostwas$388,721.IthasaHERSratingof40.

photo by Christian Builders

image by Amaris Custom Homes


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Case Study I: Konkol Residence (TE Studio)

photos by Chad Holder



General Building InfoProject name KonkolResidence“PassiveHousein

the Woods”Yearcompleted 2010PHcertified? YesLocation Town of Hudson, WIArchitect/designer TimDelheyEian,TEStudio,Ltd.Builder MorrConstructionMechanicaleng. TimDelheyEian,TEStudio,Ltd.&

Thomas Brandmeier, Lüfta GmbHEnergy consultants CraigTarr,EnergyConcepts,Inc.

Site and Climate InfoClimate zone US 6Elevation 886.75ft.Avg.outdoortemps:Jan 11.84ºFApril 46.4ºFJuly 73.58ºFOctober 48.74ºFHeating degree days 7876Cooling degree days 699BuildingDesigntemps:Jan -20ºFJuly 95ºFAvg.dailyhorizontalinsolation 3.9kWh/m2/dayAvg.dailyverticalinsolation 3.3kWh/m2/dayClearness index 0.5Avg.annualprecipitation 29.41in.Avg.annualwindspeed 10.6mph

Utility infrastructureSpace heating Electricresistancein-floorheating

matsElectrical generation and storage Photovoltaic, grid-tiedThermal generation and storage Solarthermal,tank;Geothermal,heat

exchangetoventilation;23,020,390BTU designed PV generation

Ventilation Balanced HRVWater heating Solar thermal with electric on-demand

backupWater consumption WellData and performance tracking e-MonitorOthercertifications MNGreenStargold(pending)

Additional NotesDesigned to operate CO2neutral.Designedtogeneratemoreenergythanituses.

Technical Description: Konkol Residence (Passive House in the Woods)

Building descriptionBuilding type Single family detachedBldg axis or orientation E-W, broad side faces perfectly southFootprint 919.03ft2Grossfloorarea(ASHRAE) 2,757.09ft2Heated living area 1,973.12ft2Heated volume 16,570.66ft3Externalwallarea(toambient) 2,924.23ft2Externalwallarea(toground) 674.04ft2WindowareaS.wall 309.79ft2WindowareaN.wall 0.00ft2WindowareaE.wall 37.35ft2WindowareaW.wall 193.64ft2Total window area 540.78ft2Wall construction ICF with EIFSWall R-value 68.4Roof construction FlatroofontopofI-Joists(hotroof)Roof R-value 94.6Basement construction ICF with EIFSBasement R-value 68.4Slab construction Slab on top of insulationSlab R-value 58.5Window type Aluminum-cladwoodtilt&turnWindow U 0.14

Energy DataModeledpeakload 10,201Btu(heating)Modeledannualload 6,208,167Btu(heating)Est.annualenergyuse 13,867,353Btu(total)Est.heatingcost $162.25(beforeon-sitegeneration)Est.totalenergycost $362.43(beforeon-sitegeneration)Air tightness 0.25ACH50(68CFM50)HERS index notfinalized

Cost DataTotal Project cost withheld at client requestConstruction cost withheld at client requestCost/sf withheld at client requestEstimated additional cost for PH construction

withheld at client request

30-yr Life Cycle cost withheld at client request


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Case Study II: Synergy high-performance home (TE Studio)

images by TE Studio



Technical Description: Synergy high-performance home

General Building InfoProject name Synergy HouseYearcompleted unbuiltPHcertified? certifiableLocation Minneapolis,MNArchitect/designer TimDelheyEian,TEStudio,Ltd.Builder unbuiltMechanicaleng. TimDelheyEian&PhilippGross,TE

Studio,Ltd.Energy consultants n/a

Site and Climate InfoClimate zone US 6Elevation ~800ft.Avg.outdoortemps:Jan 11.84ºFApril 46.4ºFJuly 73.58ºFOctober 48.74ºFHeating degree days 7876Cooling degree days 699BuildingDesigntemps:Jan -20ºFJuly 95ºFAvg.dailyhorizontalinsolation 3.9kWh/m2/dayAvg.dailyverticalinsolation 3.3kWh/m2/dayClearness index 0.5Avg.annualprecipitation 29.41in.Avg.annualwindspeed 10.6mph

Utility infrastructureSpace heating Airtoairheatpump(electricity)with

electric resistance backupElectrical generation and storage Photovoltaic, grid-tiedThermal generation and storage Solar thermal DHW, tankVentilation Balanced HRVWater heating Solar thermal with electric backupWater consumption MunicipalData and performance tracking n/aOthercertifications n/a

Building descriptionBuilding type Single family detachedBldg axis or orientation E-W, broad side faces perfectly southFootprint 1,149 ft2

Grossfloorarea(ASHRAE) 2,299 ft2

Heated living area 1,693 ft2

Heated volume 12,819 ft3

Externalwallarea(toambient) 2,384 ft2

Externalwallarea(toground) 0 ft2

WindowareaS.wall 223 ft2

WindowareaN.wall 27 ft2

WindowareaE.wall 103 ft2

WindowareaW.wall 40 ft2

Total window area 392 ft2

wall construction Double-studw/cellulosewall R-value 58.5Roof construction FlatroofontopofI-joists(hotroof)Roof R-value 94.6Basement construction n/a(slab-on-grade)Basement R-value n/aSlab construction Slabo.t.o.insulationSlab R-value 44.35Window type Aluminum-cladwoodtilt&turnWindow U 0.13

Energy DataModeledpeakload 9,410Btu(heating)Modeledannualload 7,464,136Btu(heating)Est.annualenergyuse 18,583,547Btu(total)Est.heatingcost $218.70(beforeon-sitegeneration)Est.totalenergycost $544.50(beforeon-sitegeneration)Air tightness ≤0.6ACH50HERS index n/a

Cost DataTotal Project costConstruction cost $250,000(estimated)Cost/sf $150(estimated)Estimated additional cost for PH construction

$50,000(estimated)


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Case Study III: NewenHouse Prototype I (Coulson Architect)

photo by Sonya Newenhouse

photo by Jim Klousia photo by Jim Klousia



Technical Description: NewenHouse Prototype I

General Building InfoProject name NewenHouse Yearcompleted estimated completion October 2011PHcertified? PendingLocation Viroqua, Wisconsin 54665Architect/designer SonyaNewenhousew/Dina

Corigliano&CarlyCoulsonBuilder MidwestEarthBuilders;Hearthand

Sol ConstructionMechanicaleng. CarlyCoulson,MichaelLeBeauEnergy consultants Carly Coulson

Site and Climate InfoClimate zone US 6Elevation 1250 ftAvg.outdoortemps:Jan 20ºFApril 49ºFJuly 73ºFOctober 52ºFHeating degree days 7673Cooling degree days 485BuildingDesigntemps:Jan 68 FJuly 68 - 77 F maxAvg.dailyhorizontalinsolation 3.9kWh/m2/dayAvg.dailyverticalinsolation 3.2kWh/m2/dayClearness indexAvg.annualprecipitation 33”Avg.annualwindspeed 10mph

Utility infrastructureSpace heating radiant panel backupElectrical generation and storage grid-connected, roof mounted,

photovoltaic systemThermal generation and storage n/aVentilation 92% HRVWater heating roof mounted solar DHW system

with central tank with electric heating element

Water consumption 9500gallons/yr4occupantsData and performance tracking YesOthercertifications EnergyStarCertifiedandRegistered

LEEDforHomes(applyingforPlatinum)

Additional NotesUtilitiesexpectedtobe<$50/moforwaterandelectricity

Building descriptionBuilding type Singlefamilydetached(4occupants)Bldg axis or orientation Broad side faces 30º east of due southFootprint 1,475 ft2

Grossfloorarea(ASHRAE) 2,950 ft2

Heated living area 2,660 ft2

Heated volume 53,200 ft3

Externalwallarea(toambient) 3,311 ft2

Externalwallarea(toground) 663 ft2

WindowareaS.wall 333 ft2

WindowareaN.wall 30 ft2

WindowareaE.wall 114 ft2

WindowareaW.wall 60 ft2

Total window area 537 ft2

wall construction 14”double-studw/cellulosewall R-value 54Roof construction Parallelchordtrussesw/celluloseRoof R-value 88Basement construction ICF + 4”XPSBasement R-value 43Slab construction 4” concrete over 12”XPSSlab R-value 60Window type Insulatedfiberglassframe,tri-pane,Ar

fill,low-EWindow U Southfacing0.19,Allother0.17

Energy DataModeledpeakload 16,000Btu(heating)Modeledannualload 19,400,000Btu(heating)Est.annualenergyuse 39,900,000Btu(total)Est.heatingcost $300(includeson-sitegeneration)Est.totalenergycost $1000Air tightness 0.7ACH50HERS index n/a

Cost DataTotal Project cost n/aConstruction cost $775,000.00Cost/sf $220(includesgarageandexterior

appendages)Estimated additional cost for PH construction

$72,625.00(includessolarthermalsystem)


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Case Study IV: Isabella EcoHome Experiment Station (Compass Rose)

imagescourtesyofCompassRoseInc.



Technical Description: Isabella EcoHome Experiment Station

General Building InfoProject name Isabella EcoHouseYearcompleted 2007PHcertified? YLocation Isabella,MNArchitect/designer Nancy SchultzBuilder BradHolmes,Rod&SonscarpentryMechanicaleng. Bill Gausman, System One ControlEnergy consultants MikeLeBeau,ConservationTechnolo-

gies

Site and Climate InfoClimate zone US 7Elevation 1987Avg.outdoortemps:Jan 14ºFApril 49ºFJuly 78ºFOctober 52ºFHeating degree days 9700Cooling degree days 189BuildingDesigntemps:Jan n/aJuly n/aAvg.dailyhorizontalinsolation 3.8kWh/m2/dayAvg.dailyverticalinsolation 3.2kWh/m2/dayClearness index n/aAvg.annualprecipitation 21.5in.Avg.annualwindspeed 10mph

Utility infrastructureSpace heating hydronic radiant slabElectrical generation and storage 8.4kWPVgrid-tiew/Pb-acidbackupThermal generation and storage Solarheated500gwatertank;taconite

heatstoragebed;woodstovebackupVentilation HRVWater heating Solarw/10kWbackupboilerWater consumptionData and performance tracking pretty much everything Othercertifications LEED Platinum

Additional NotesRainwatercollection;greenroof;seasonalheatstorage;

Building descriptionBuilding type Single-familyBldg axis or orientation E-WFootprint n/aGrossfloorarea(ASHRAE) 5384Heated living area 2134Heated volume n/aExternalwallarea(toambient) n/aExternalwallarea(toground) n/aWindowareaS.wall n/aWindowareaN.wall n/aWindowareaE.wall n/aWindowareaW.wall n/aTotal window area n/awall construction CCSF + densepack cellulosewall R-value R-55Roof construction n/aRoof R-value R-90Basement construction (Usedforheatstorage)16"EPSBasement R-value n/aSlab construction n/aSlab R-value n/aWindow type German quad-pane wood frameWindow U SU-0.088;NWEU-0.07

Energy DataModeledpeakload 10W/m2Modeledannualload 9.6mmBtuEst.annualenergyuse 66kWh/m2/yrEst.heatingcost $0.00Est.totalenergycost $0.00Air tightness .5ACH50HERS index 3

Cost DataTotal Project cost $1,841,328.00Construction costCost/sf $342 GSFEstimated additional cost for PH construction

n/a


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Web Resource ListPassive House InformationPassive House Institute http://www.passiv.de/07_eng/index_e.htmlPassive House Alliance, US http://phaus.org/home-pagePassive House Institute US http://www.passivehouse.us/passiveHouse/PHIUSHome.htmlDr.WolfgangFeist’sPassiveHouseinformationpage http://www.passivhaustagung.de/Passive_House_E/passivehouse.htmlPassipedia, the Passive House wiki site http://passipedia.passiv.de/passipedia_en/startPassiveHouseAllianceMinnesota http://www.phmn.org/Minnesota Passive House PractitionersTE Studio http://testudio.com/Wagner Zaun Architecture http://www.wagnerzaun.com/Coulson Architect http://www.carlycoulson.com/Projects and DevelopersGEOSDevelopmentinArvada,Colorado. http://discovergeos.com/TREEEcovillageinIthaca,NewYork. http://ecovillageithaca.org/treenew/NewenHousedeveloperstheMadisonEnvironmentalGroup,Inc. http://www.madisonenvironmental.com/IsabellaEcoHouseResearchStationdevelopersCompassRose,Inc. http://www.compassrose-inc.com/Home/Welcome.htmlJacksonMeadownearStillwater,Minnesota http://www.jacksonmeadow.com/Amaris Custom Homes http://www.minnesotagreenhomebuilder.com/index.phpChristian Builders http://www.christianbulders.comThe Walsdee Biohaus at Concordia German Language Village http://www.waldseebiohaus.typepad.com/

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