2516 energy performance townhouses

8/14/2019 2516 Energy Performance Townhouses

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ADVANCED HOUSING TECHNOLOGY PROGRAM

MONITORING AND EVALUATION OF THE ENERGY PERFORMANCE OF THE

21ST

CENTURY TOWNHOUSE UNITS

Subcontract No. 86X-SC895C and 62X-SC895C

Prepared for:

Martin Marietta Energy Systems, Inc.Oak Ridge, TN 37831-6501

by:

NAHB Research Center, Inc.400 Prince Georges Boulevard

Upper Marlboro, MD 20774-8731

June 1997


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INTRODUCTION................................................................................................................... 1

STRUCTURAL CHARACTERISTICS OF TOWNHOUSE UNITS................................ 3

TOWNHOUSE UNIT 7STRUCTURAL INSULATED PANELS ......................................... 3

Foundation ....................................................................................................... 3

First and Second Levels .................................................................................. 3

Exterior Finish................................................................................................. 4

Attic/Roof......................................................................................................... 4

Mechanical/Plumbing ..................................................................................... 4

TOWNHOUSE UNIT 8INSULATING CONCRETE FORMS............................................. 5

Foundation ....................................................................................................... 5


Exterior Finish................................................................................................. 5Roof/Attic ......................................................................................................... 5


TOWNHOUSE UNIT 9STEEL FRAME.......................................................................... 6

Foundation ....................................................................................................... 6


Exterior Finish................................................................................................. 6

Attic/Roof......................................................................................................... 6

Mechanical\Plumbing ..................................................................................... 6

TOWNHOUSE UNIT 10AUTOCLAVED AERATED CONCRETE.................................... 7

Foundation ....................................................................................................... 7

First And Second Levels ................................................................................. 7

Exterior Finish................................................................................................. 8

Attic/Roof......................................................................................................... 8


MODEL CODE ENERGY ANALYSIS................................................................................ 8

DATA AND METHOD FOR THE ANALYSIS OF INDIVIDUAL TOWNHOUSE UNITS .......... 9

Townhouse Unit 7.......................................................................................... 12

MEC Analysis Results ......................................................................... 14Energy Consumption Estimates .......................................................... 15

Townhouse Unit 8.......................................................................................... 17

MEC Analysis Results ......................................................................... 19

Energy Consumption Estimates .......................................................... 20


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Townhouse Unit 9.......................................................................................... 22

MEC Analysis Results ......................................................................... 24

Energy Consumption Estimates .......................................................... 25

Townhouse Unit 10........................................................................................ 27

MEC Analysis Results ......................................................................... 29Energy Consumption Estimates .......................................................... 30

ENERGY SIMULATION ANALYSIS ............................................................................... 32

TOWNHOUSE ENERGY PERFORMANCE MONITORINGCOOLING SEASON ............... 35

Air Conditioning Energy Consumption ...................................................... 35

Performance of Individual Townhouse Units............................................. 36

Townhouse Unit 7Structural Insulated Panels ............................... 36

Townhouse Unit 8Insulating Concrete Forms................................ 41

Townhouse Unit 9Steel Frame with Spray Foam Insulation .......... 45

Townhouse Unit 10Light Weight Autoclaved Aerated

Concrete .................................................................................. 50

Building Temperature Profile ...................................................................... 55

Temperature Response ................................................................................. 57

TOWNHOUSE ENERGY PERFORMANCE MONITORINGHEATING SEASON ............... 62

Performance of Individual Townhouse Units............................................. 63

Townhouse unit 7Structural Insulated Panels ................................ 63

Townhouse Unit.................................................................................. 65

8Insulating Concrete Foam Forms ................................................. 65

Townhouse Unit 9Steel Frame with Spray Foam Insulation .......... 69

Townhouse Unit 10Lightweight Aerated Autoclaved

Concrete .................................................................................. 73

Summary........................................................................................................ 76

VISITOR SURVEYS....................................................................................................... 77

Likelihood of Adoption ................................................................................. 78

Attributes Influencing Adoption of Innovations ........................................ 81


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NAHB Research Center, Inc. 1 June 1997

INTRODUCTION

The NAHB Research Center (Research Center) built four 21st

Century Townhouses in itsResearch Home Park as part of the Research Centers research home program. The principalobjective of the program is to:

Test, demonstrate, and gain experience with innovative home buildingproducts, systems, and technologies to aid the movement of innovativeproducts and systems into the mainstream of home construction.

Products incorporated in the 21st

Century Townhouses feature two themes:

innovative structural systems in home building and

approaches to achieving advanced residential energy efficiency.

The objective of Task 2 of the U.S. Department of Energys (DOE) Advanced Housing

Technology Program (AHTP); is to initiate the monitoring and evaluation of theperformance of selected energy-related technologies included in the townhouses. This taskbegins with the selection of technologies or attributes of units to be studied. It then proceedswith the development and initiation of an overall analytical approach to the technical analysisand monitoring protocols. In this report, the Research Center evaluates the results to date andsynthesizes the findings.

This report focuses on the second theme, the analysis and evaluation of energy-relatedtechnologies as they affect residential energy efficiency. A comprehensive survey of visitorsreactions to the Photovoltaic (PV) solar system in one of the townhouses was initiated inOctober 1997 and completed in March 1997. Subsequently, another more general survey

pertaining to the other energy-related technologies was implemented in March 1997. Theinitial results of the survey of PV technology will be included in a separate report devoted tobuilding integrated photovoltaics (BIPV). The initial results of the general survey to-date isincluded as part of this report.

The NAHB Research Centers 21st

Century Townhouse project consists of four townhouses.In keeping with the objective of demonstrating innovative products, a minimal amount ofdimensional lumber framing was used in the construction of the townhouses. Theconstruction materials include high and low density foams, oriented strand board (OSB),structural insulated panels with insulating foam, high and low density concrete, and steelframing.

According to Prince Georges Countys original lot number designations, individualtownhouse units in this report are referenced as units 7, 8, 9, and 10. Their significantfeatures are as follows:

Townhouse unit 7 walls and roof are constructed of Structural InsulatedPanels (SIPs) consisting of two panels of OSB sheathing enclosing an


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expanded polystyrene (EPS) core. This unit uses a gas fueled heat pumpfor both heating and cooling.

The foundation walls of units 7, 8, and 9 are constructed using insulatingconcrete forms (ICFs) provided by ICE, which uses forms made of EPSthat are stacked, reinforced with metal rebars, and filled with concrete.

The main feature of unit 8 is its construction using ICFs, from foundationto gable. This townhouse uses an integrated hot water/furnace unit forheating and an electric outdoor unit for cooling.

Unit 9 is characterized by its steel frame construction with Icynene sprayfoam insulation in the wall and ceiling. This townhouse unit uses a groundsource heat pump for both heating and cooling and includes a hot waterdesuperheater.

Unit 10 features walls that are constructed using Hebels lightweightautoclaved aerated concrete (AAC) blocks. The roof is wood trussframing insulated with spray foam and blown fiberglass. The foundationwalls are constructed using Superior Walls pre-formed concrete panels.

A PV solar system, with inverter and battery storage, supplements theutility electric supply. The home uses an integrated hot/water furnace unitfor heating and an electric outdoor unit for cooling, similar to townhouseunit 8.

In summary, units can be identified either by their numbers or their most significant structuralfeature:

unit number 7SIP construction

unit number 8ICF construction

unit number 9Steel Frame construction

unit number 10AAC construction

Townhouse units are designed with common walls between the units. Units 8 and 9, have anICF common interior wall with each other; units 7 and 10, share a common wall with anunconditioned garage as an adjoining unit. In this respect, units 7 and 10 have more incommon with detached housing units than attached units typical in townhouse construction.

Unit 7 was occupied during the period of performance. Unit 8 was occupied for a portion ofthe period of performance, and units 9 and 10 were unoccupied during the entire period ofperformance. Each of the units were available for numerous tours and each containsappliances and lighting which may have been operational throughout the period of

performance.


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STRUCTURAL CHARACTERISTICS OF TOWNHOUSE UNITS

This section contains the detailed structural characteristics of each of the townhouse unitswhich is useful in interpreting the results of the energy analyses.

TOWNHOUSE

UNIT

7STRUCTURAL

INSULATED

PANELS

Foundation

The foundation wall consists of the ICE Block stay-in-place concrete wall forming system toform an 8' basement. The ICE Block walls have a stated R-value of 26. The forms consist ofexpanded polystyrene (EPS) foam with a light-gauge steel web connecting interior and exteriorform walls. The total wall thickness measures 11-1/8" with the concrete core a structuralequivalent of an 8" conventional reinforced concrete wall. Window and door block-outs consistof 2 x 12 pressure-treated lumber left in place after concrete placement to serve as a means forattaching doors and windows. A 2 x 12 pressure-treated sill plate was fastened to the top of the

foundation wall with anchor bolts.

The floor of the walk-out basement is an uninsulated concrete slab reinforced with wire mesh.The slab is stepped 6" to divide the one-car garage and family room. A double 18 gauge steelframe wall separates the garage and living areas. Inner and outer walls consist of 3.5" 18 gaugesteel studs with a 5/8" type-X fire-rated gypsum wallboard between the inner and outer steelstud wall. A 1" void separates the wallboard surface from the outer wall. The outer wall studbays and space between walls are insulated with the Icynene Insulation System, a modifiedurethane spray-on foam.

Windows and a single patio door in the basement are low-E glazed, argon-filled Andersen units

with a U-value of 0.32 (R-3). The door between the garage and living area is a steel Therma-Tru unit with an R-9 foam filled core and steel frame, carrying a 90 minute fire rating. The 8' x7' garage door is supplied by Masonite.

The below-grade exterior walls are treated with EPRO water-based foundation waterproofingsystem in lieu of a petroleum based coat that would cause the foam to melt. Both sides of theinterior wall separating garage and living area were clad with 5/8" type-X gypsum wallboard,completing the fire-rating required by code. All other interior walls were 1/2" gypsumwallboard attached by screwing directly into a light gauge steel flange embedded in the ICEBlock form.

First and Second Levels

The floor decks consists of 16" 125 series TrusJoist I-beams (TJIs) set on the foundation sillplate, running front to back. Joists are spaced 24" on-center with a 3/4" plywood rim joists.The flooring consists of 3/4" Weyerhaeuser Structurboard oriented strand board (OSB) withtongue and groove edges. Floor sheathing is fastened to joists with construction adhesive andnails. To decrease air infiltration, the rim joist area is sealed with Amoco's Infi Seal, a gasketedair barrier that is set under the sill plate and wraps over the joist onto the floor deck. The


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interior overlap is then attached to the wall surface under the wallboard. The rim joist area isinsulated with the Icynene Insulation System spray-in foam to an R-19 value. The joist baysabove the unconditioned garage are also insulated with the Icynene Insulation System.

The exterior wall is constructed of stress skin insulated panels. Wall panels consists of a 3-5/8"

(EPS) foam core sandwiched by layers of 7/16" OSB. Typically, stress-skin panels have nointerior wall studs or headers. Some do recess the foam between OSB faces at the top, bottom,and sides, and window and door openings sufficient to place a nominal 2 x 4 stud that facilitatesattachment. However, the local fire code required the panels to be manufactured with 2 x 4studs at least every 8 feet vertically and horizontally as draft/fire stops. Wall height for bothfloors is 8'.

Interior partition walls are framed with 25 gauge metal studs. Windows and patio door areAndersen low-E, argon-filled units with a U-value ranging from 0.33 to 0.35 (R-3). The frontdoor is an R-9 Therma-Tru fiberglass insulated door. The single patio door opens onto apotential deck/balcony at the rear of the unit. Interior walls and ceilings are clad with 1/2"

gypsum wallboard except the party wall separating interior living area with the garage ofanother unit, which is two layers of 5/8" type-X fire-rated gypsum wallboard.

Intermediate load bearing capacity for the second level floor is provided by a pair of beams. Aflush Micro=lam laminated veneer lumber (LVL) 1-3/4" x 16" beam supports half the floor.The other half is supported by a dropped beam consisting of a single of 3-1/2" x 12" Parallamwhich has been incorporated into the kitchen bulkhead.

Exterior Finish

A United States Gypsum (USG) exterior insulation and finish system (EIFS) was used on theexterior walls. A 1" layer of expanded polystyrene (EPS) foam was attached with mastic andWindlock fasteners to all wall surfaces. The foam serves as a base for the USG base coat andmesh. A pre-colored finish was trowel-applied over all base coat areas.

Attic/Roof

The roof is constructed with 8" sandwich insulated panels with an R-value of 30, making theunfinished attic conditioned space. It is covered with 30 pound asphalt roofing felt and anATAS standing seam metal roof system. The gable ends are constructed of the same sandwichpanels as the walls.

Mechanical/Plumbing

Heating and air conditioning will be provided by York Triathlon gas-engine heat pump. Thewater heater will also be a gas unit. Basement and second level supply registers are located inthe ceiling and the first level supply registers are in the floors.

A combined sprinkler system with all ceiling heads was also installed.


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TOWNHOUSE UNIT 8INSULATING CONCRETE FORMS

Foundation

The foundation of unit 8 uses the same ICE Block system described for townhouse unit 7 toform a walk out basement. The floor consists of a concrete slab and the finished ceiling

height is 9' 4". EPRO waterproofing is applied on below grade exterior walls. The interior isclad with 1/2" gypsum drywall. Windows and the patio door are Andersen argon-filled withlow-E glazing. The majority of the basement is devoted to a single recreation room with acloset and a utility room completing the balance. All but 12' of the east-facing basement wallis shared with unit 9. The 12 foot segment has an exterior exposure.


All exterior walls are constructed of 9 1/4" ICE Block (6" equivalent core). The east-facingwall of the first and second level is shared with unit 9. Interior partitions are framed with 25gauge steel studs. Interior walls and ceilings are covered with 1/2" gypsum wallboard. The

first floor deck is framed side to side with 135 Series 16" deep TJIs spanning the 22' 6" widthof the unit spaced 24" on center. The joists are hung on Micro=lam ledges that are attachedto the exterior walls with two 1/2" x 8" j-bolts every two feet. The floor sheathing is 3/4"Weyerhaeuser Structurboard OSB. The front door is an R-9 Therma-Tru fiberglass door.Windows and rear patio door is are Andersen argon-filled, low-E glazed units.

Exterior Finish

The same USG EIFS system used on unit 7 was applied on exterior walls.

Roof/Attic

The roof is framed using wood trusses with raised heels, often referred to as an energy truss.This design allows an even distribution of insulation to its full height to the edge of the atticspace. The insulation will be 15" of blown-in Certainteed InsulSafe Fiberglass providing anR-value of 38. The roof is sheathed with 7/16" Weyerhaeuser OSB and covered with 30pound roofing felt and a ATAS standing seam metal roofing.

Mechanical/Plumbing

The heating plant is a Lennox Complete Heat gas furnace system which also providesdomestic hot water. Air conditioning is a Lennox high-efficiency 12 SEER electric unit.Basement registers are in the ceiling, first level registers are in the floor, and second levelregisters are located in the floor and ceiling and are selectable so that either system or bothare being used.

A GFX drainwater heat recovery system was installed in the drains of the two upstairsshowers. The warm shower drain water tempers the incoming cold water, which feeds thecold side of the shower diverter valve.

Also, a combined sprinkler system using blazemaster orange and copper pipes with centralsupply heads was installed in this townhouse.


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TOWNHOUSE UNIT 9STEEL FRAME

Foundation

The foundation of unit 9 is identical to unit 8, sharing the west-facing wall except for a 12'section, which has a below-grade exposure.


The first floor is supported by Mitek Posi-Strut steel floor trusses. The trusses span 22' 6" andare top chord bearing on one end and supported by hangers on the other. Floor sheathingconsisted of 3/4" Weyerhaeuser Structurboard OSB.

Exterior walls are constructed with 2 x 6 light-gauge steel framing members with an actual walldepth of 5-1/2". Walls are sheathed with Durock cement board except for the west-facing wallshared with unit 8. Exterior frame walls are insulated with the Icynene Insulation Systemdescribed in the section on unit 7, with wall stud bays filled with a 5-1/2" (R-19) layer ofsprayed-in foam.

Interior walls consist of 25 gauge steel framing covered with 1/2" gypsum wallboard. Exteriorwindow and door openings were lined with pressure-treated 2 x 6 lumber to facilitateattachment. Windows and patio doors are Andersen argon-filled, low-E glazed units with a U-value of 0.32 to 0.35, or about R-3. The front door is a Therma-Tru fiberglass unit, and thedoor leading to the garage is a Therma-Tru steel door, both with R-9 foam cores.

Exterior Finish

The exterior walls feature the USG EIFS textured finish identical to the system used on unit 7except for its use of USG Durock sheathing on first and second level steel frame walls. The 1"

EPS foam layer served as the EIFS base and provided the 1" thermal break recommended forsteel stud walls.

Attic/Roof

The roof trusses are Mitek Ultra-Span light gauge steel with a raised-heel design. The roof issheathed with 7/16" Weyerhaeuser OSB and attached with Enrico pins, which arepneumatically driven nails. The ATAS standing seam metal roof is placed on a base of 30pound roofing felt. The attic is insulated with a 3-1/2" layer of Icynene foam with an additionallayer of Certainteed InsulSafe blown-in fiberglass insulation.

Mechanical\Plumbing

The forced air heating and cooling system features a Waterfurnace ground-source heat pumpwith three 180' vertical wells. Domestic hot water is also provided by this unit. The basementand second floor registers are located in the ceiling, and the first floor registers are located in thefloor. Individual air returns are located on the second level.

A GFX drainwater heat recovery system pre-heats water to the cold water side of the showersand the water heater intake. A combined fire sprinkler system was installed with side wallheads.


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TOWNHOUSE UNIT 10AUTOCLAVED AERATED CONCRETE

Foundation

Unit 10 has a Superior Wall pre-cast concrete foundation wall set on a gravel footing. Thedesign of the Superior Wall foundation is based on the principles of optimum valueengineering, conserving concrete, and steel reinforcement by strategically placing it in load-bearing vertical studs, reinforced top and bottom plate, and a 1-1/2" concrete exterior surface.A 1" layer of extruded polystyrene is cast between the exterior wall surface and vertical "studs"and serves as a thermal break between exterior and interior walls. The resultant wall hascavities that can be insulated additionally with fiberglass batt insulation. Window and doorblock-outs consist of 2 x 8 lumber and serve as a nailing surface for easy attachment.

The foundation forms a walk-out basement. The concrete slab floor is stepped between garageand living areas identical to unit 7. The doubled steel frame wall between interior living andgarage areas is configured, insulated, and finished identically to unit 7 steel basement wall.Interior walls are framed with 25 gauge steel studs and interior walls are finished with 1/2"gypsum wallboard. Windows and the patio door were Andersen argon-filled, low-E glazedunits. The garage has an 8' x 7' Masonite door and the door separating the living area from thegarage is a Therma-Tru R-9 steel unit with steel frame.

First And Second Levels

The entire first and second level exterior walls were built with the Hebel Wall System,consisting of a lightweight AAC block that contains a load bearing structure, insulation, andinterior and exterior wall substrates in a single material. A reinforced concrete bond beam wascast between the first and second level and at the top of the Hebel wall using a hollowed HebelAAC unit form that corresponds to a U-block in conventional masonry construction. Load-

bearing lintels were constructed over all openings from the same materials. The width of theHebel wall is 8". Wall openings were lined with 2 x 8 pressure-treated lumber, a traditionalmechanism for attaching doors and windows.

The first and second level floor systems used TrusJoist International engineered wooden I-beams for floor support. Each joist has a 3" fire cut at the end bearing on the exterior walls. Alayer of roofing felt was placed between joist and concrete beam to protect the joist againstwater absorption. The Hebel material extended to the top of the foundation, so cut-outs weremade in the Hebel material 24" on center to accommodate the joist. The floor sheathing isWeyerhaeuser 3/4" OSB. The joist bays over the unconditioned garage were filled with theIcynene Insulation system (R-19). As with unit 7, Micro=lam and Parallam LVL beams were

used as intermediate load-bearing support for the second level floor.

Windows and patio doors are identical to unit 7. The front door is an R-9 Therma-Tru insulatedfiberglass model. Interior walls are framed with 25 gauge steel studs and doors are lined with 2x 4 lumber to facilitate attachment.

The interior Hebel wall surface was finished with the Litewall interior plaster supplied by EliteCement Products, Inc. Interior walls were clad with 1/2" gypsum wallboard.


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Exterior Finish

The exterior finish system consists of the Litewall one-coat stucco system supplied by EliteCement Products, Inc. The Portland cement-based stucco contains fibrous reinforcement andpolymers to inhibit cracking and to ensure proper adhesion. The mix, designed for use onAAC, also contains lightweight aggregates to insure the same thermal expansion coefficient asAAC. The stucco mix was spray-applied as a 3/8" base coat troweled to a smooth surface. Thesame mix, which contains texturing aggregates, was hand applied and floated to a textured 1/8"finish.

Attic/Roof

The roof was framed with raised heel lumber trusses, sheathed with 7/16" OSB, and coveredwith 30 pound roofing felt and an ATAS standing seam metal roof. The attic was also insulatedwith Certainteed InsulSafe blown-in fiberglass insulation. The east-facing gable is composed ofHebel building material and finished with the same exterior finish system. The east-facinggables are clad with OSB, a 1" foam substrate, and USG fiberglass mesh and base coat. Thefinish coat was supplied by Elite Cement Products, Inc.

Mechanical/Plumbing

The mechanical system features the Lennox Complete Heat gas furnace and domestic hot watersystem. Air conditioning is a Lennox high-efficiency electric unit. Basement and second levelregisters are located in the ceiling, and first level registers are located in the floor.

This townhouse is fitted with the electronics for supplying the home with solar-generatedelectricity pending the delivery and installation of a roof-mounted photovoltaic module array.

MODEL CODE ENERGY ANALYSIS

In the construction of the townhouse units, a major focus on increased energy efficiency isrealized. The increased efficiency is attributed primarily to the building envelope and spaceconditioning equipment. One evaluation which seeks to quantify the increased energyefficiency is a comparison of the townhouse construction with the minimum requirements ofthe Model Energy Code (MEC)1. This particular analysis highlights the benefits of specificbuilding materials. A short-coming of the basic MEC analysis is that certain aspects of energyefficiency such as HVAC efficiency, infiltration, and duct losses are not specifically accountedfor in the analysis.

Each of the four units is considered individually. A set of basic thermal transmittance (U) orthermal resistance (R) requirements are established for each unit

2. These basic requirements

are derived directly from the 1993 MEC. An analysis of each townhouse unit has beenperformed to develop specific U-and R-values for the wall, floor, and ceiling/roofsubsystems. The results of this analysis are then used to compare to the requirements on asubsystem by subsystem basis. The results of the comparison are shown in tabular andgraphical form.

1

The analysis uses the 1993 MEC with the notable exception that each planar basement wall is considered separately. This approach isconsistent with recent changes in the MEC.

2The higher the U value, the greater the heat transfer across the particular subsystem.


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Compliance with the MEC is established when each of the subsystems meet the requirementsestablished for a standard MEC compliant building. The primary influence on the basic UA

3

requirements is the location of the building and the associated heating degree days (HDD) forthe locality. In a MEC analysis, compliance of individual subsystems helps assurecompliance of the building as a whole. In the event that one subsystem is not in compliance,

a method is available for "trading off" a better performing subsystem for a lesser performingsubsystem, but it is limited.

A computer software package, MECcheck4, developed at the Pacific Northwest Laboratory,

establishes a base UA requirement for the building according to the wall areas; other featuresare included in the design. A whole building performance UA is thus established for thetownhouse unit and compared to the required UA. When the townhouse unit UA is less thanthe minimum required UA, the building is in compliance with the 1993 MEC. The softwarealso includes an option to derive the benefits for a more efficient HVAC plant, a feature notpart of the 1993 MEC.

DATA AND

METHOD FOR THE

ANALYSIS OF

INDIVIDUAL

TOWNHOUSE

UNITS

Using the BOCA5

terminology, the four townhouse units are analyzed as Group R(residential), Type A-1 (detached), and Type A-2 (attached). As noted above, the two endunits are separated from the attached two center units by an unconditioned garage. Theenergy analysis is most accurately reflected by considering the units as two detachedsingle-family homes and one two-family home. However, according to building officialswith Prince Georges County (the local jurisdiction), the units are technically consideredtownhouses.

Weather data used in the analysis is based on ASHRAE 1989 (except for the HeatingDegree Days [HDD] ), for Andrews Air Force Base and includes the following data:

winter dry-bulb temperature = 14Fsummer dry-bulb temperature = 90Fdesign wet-bulb temperature = 76FHeating Degree Days (ASHRAE 1981, 65F base) = 4224Heating Degree Days used in analysis = 4459

6

The geographic coordinates are 38 5' Latitude and 76 5' Longitude.

The type A-1 Maximum Wall Uo7 = .2188-(4459*.00001555) = .149

The type A-2Maximum Wall Uo= .215

The type A-1 and A-2Maximum Roof/Ceiling Uo = .036-[(4459-3900)*.00000476] =.033

3 the thermal transmittance (U) times the area (A)4

Version 2.05

The regional model building code.6

the heating degree day value is consistent with that used in the MEC checkprogram7 based on the 1993 MEC chapter 8 requirements


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The type A-1 and A-2Maximum Floor Over Unheated Space Uo= .050

The type A-1 and A-2Maximum Basement U= .205-(4459*.0000233) = .101

The type A-1 and A-2Minimum Unheated Slab On Grade R= 4.0

The MEC permits an increase in the Wall thermal transmittance (Uo) requirement if the wallsystem exhibits as thermal mass characteristics. The basis of the qualification is a calculationof the heat capacity (HC) of the wall exceeding 6 Btu/ft

2-F. The heat capacity is found by

the following formula from the MEC:Heat Capacity = Weight * Specific Heat

Two of the townhouse units are constructed using wall materials which may qualify asthermal mass. Unit 10 is constructed using lightweight AAC by Hebel Southeast, and unit 8is constructed using the ICE foam concrete forms filled with high density concrete. Bothsystems are analyzed below for qualification as thermal mass:

Hebel Light Weight AAC8 8" block characteristics are as follows:

Density 32.0 lb/ft3

Conductivity 0.9 Btu-in/ h-ft2-F

R-value 9.0 (static)9

Weight 26.0 lb/ft2

Specific Heat 0.250 Btu/lb-FMEC HC value 6.5 Btu/ft

2-F

Since the AAC HC value is greater than 6.0, it satisfies the criterion forthermal mass using MEC Table 502.1.2c

10:

Uo for non-mass wall 0.149Uw non-mass wall 0.127

11

Uw from table (interpolated) 0.167Maximum Uo for ICE Block Mass Wall 0.177

ICE Foam Form Concrete Block12

characteristics are as follows:

Density of concrete 150 lb/ft3Specific Heat of concrete 0.200 Btu/lb-FWeight of 6" form 56.4 lb/ft2MEC HC value (6" form) 11.28 Btu/ft2-FWeight of 8" form 76.1 lb/ft2MEC HC value (8" form) 15.22 Btu/ft2-F

8

Hebel Block9 From Hebel literature, an effective R-value of 30 is also included in the literature10

the lightweight AAC is considered a mass wall with mixed insulation and mass11

using formula in note 6, table 12)12 manufactured by ICE Block


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Since the ICE Block foam form HC value is greater than 6.0, it satisfies thethermal mass criterion in regard to thermal mass for both the 6 and 8" forms.MEC Tables 502.1.2a and b were used in the calculation since the insulation ison both sides of the mass:

Uo for non-mass wall 0.149Uw non-mass wall 0.12213

Uw from table (interpolated) 0.15214

Maximum Uo for ICE Block Mass Wall 0.174

The level of duct insulation required for ducts on the inside of the buildingenvelope (not necessarily in conditioned spaces), with a temperature difference(TD)

15greater than 40 is an R 5.0 ft2-F-hr/Btu. The ducts in the townhouses are

insulated with a minimum R 6.0.

The HVAC equipment for each townhouse unit must meet the minimum

equipment efficiencies specified. A comparison of the heating and AC equipmentwith the basic requirements are shown in Table 1:

Table 1

HVAC Equipment Installed

HVAC Equipment Unit Heating Cooling

Water Furnace Ground Source HeatPump

9 COP = 3.501

EER = 14.72

York Triathlon Natural Gas Heat Pump 7 COP = 1.263

SEER = 15.64

Lennox Complete Heat 8,10 AFUE = 90%3 SEER = 12.03

1estimate based on 50 kBtu/hr load and 60F temperature difference

2estimate based on 27 kBtu/hr load and 20F temperature difference

3manufacturer's data

4based on proposed method to calculate SEER using fuel cost for gas & electricity

Gas water heaters installed must comply with MEC section 504.

The following analyses for each townhouse unit are based on:

Calculation of the Uo-and R-values necessary for compliance with MEC

requirements given the unique material characteristics and local climatic data. Performance of a MEC analysis of each townhouse using MECCheck software.

Completion of a MEC analysis of the house as built, using REM Designsestimation software to derive annual heating and cooling energy use estimates andcosts.

13

using formula in note 6, table 6)14

average of MEC Table 502.1.2a, Uw = 0.162 and MEC Table 502.1.2b, Uw = 0.14215 refer to chapter 5 of the MEC


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As noted earlier, the units are technically considered townhouses from a building codestandpoint and must comply with MEC requirements for multifamily townhouses, butactually the two end units, separated from the rest of the units by an unconditionedgarage, can be considered one-family detached units and the two middle units thatshare a common wall can be considered two-family units or duplexes. Consequently,

in computing compliance with MEC requirements in the tables that follow, the morestrict MEC requirements for one- and two-family houses were also derived forcomparison purposes.

Townhouse Unit 7

The MEC minimum requirements for each subsystem in unit 7 are shown in Table 2.

Table 216

Subsystem U and R Requirements

Building SubsystemSpace Conditioning

Mode

One- and Two-

Family

Multifamily/

Townhouses

Uo Uo

Walls Heating or cooling 0.149 0.215

Roof/Ceiling Heating or cooling 0.033 0.033

Floors over unheatedspace

Heating or cooling 0.050 0.050

R-value R-value

Heated slab on grade Heating NA NAR-value R-value

Unheated slab ongrade

Heating 4.0 4.0

U-value U-value

Basement wall Heating or cooling 0.101 0.101

Crawl wall Heating or cooling NA NA

U-values in BTU/hrft2F; R-values = 1/U

Unit 7 is constructed with ICE Block foundation system enclosing the basement. The SIPs,manufactured by Insulspan Co., enclose the first and second floors. One-inch expandedpolystyrene (EPS) board is added as insulation to the outside of the SIPs for application of thewall finishing system. Also, SIPs eight inches thick are used for the roof system.

16 Adapted from Table 502.2.1 1993 MEC


16/144


Table 3 describes the physical dimensions of unit 7. Wall sections representing differentconstruction materials are included separately.

Table 3

Construction Features of Unit 7

Wall/Ceiling Surface Area U-value UA-Value SubscriptICE Block

1182.85 0.068 12.39 w1

Top Plate2

17.54 0.081 1.42 w2

SIP Wall 1703.03 0.046 77.84 w3

Wood wall framing members3

245.04 0.112 27.40 w4

Framed Gable Sections 331.62 0.055 18.38 w5

Garage/Basement Wall (Steel)4

217.09 0.069 14.87 w6

Windows (U=0.32) 197.97 0.320 63.35 g1

Windows (U=0.35) 144.00 0.350 50.40 g2

Windows (U=0.31) 24.00 0.310 7.44 g3

Fireplace Opening5

14.33 0.855 12.25 fp

Door (U=0.16) 21.07 0.160 3.37 d1

Door (U=0.14) 21.64 0.140 3.03 d2

Sliding Door (U=0.32) 20.00 0.320 6.40 d3

Total Gross Wall Area (Ao) 3375.30 o

Overall U-value6

(Uo) 0.092 o

Roof (8" SIP) 1049.00 0.029

Floor Over Unheated Space 356.83 0.046

Basement Walls7

349.50 0.068

R-value

Slab Edge8

(24" insulation depth) 14.76

Note: All U-values in Btu/hr-ft2-F

1

basement wall sections less than 50 percent below grade2pressure treated wood (nominal 2" x 10.75")3nominal 2x4 typical4double 3 1/2" steel wall with Icynene thermal break

5use steel insert, fully enclosed flue box (U-value = steel + air space)

6

ow w w w w w g g g fp d d d

o

U=[(UA) 1+(UA) 2+(UA) 3+(UA) +(UA) +(UA) +(UA) +(UA) +(UA) +(UA) +(UA) (UA) (UA) ]

A

4 5 6 1 2 3 1 2 3) + +

7basement wall sections more than 50 percent below grade8slab edge of basement walls considered in Gross Wall Area


17/144


The data on unit 7 in Table 2, are compared with the MEC requirements for multifamilytownhouses and single- and two-family units in Table 4, showing the difference in the Uo-and R-values of various components of the building as built and as required by MEC.

Table 4

Townhouse unit 7 MEC Compliance Record

Building Element As Built One- and Two-FamilyMultifamily /

Townhouses

Uo Uo%

differenceUo

%

difference

Walls 0.092 0.149 39 0.215 57

Roof/Ceiling 0.029 .033 12 .033 12


0.046 .05 8 .05 8

R-value R-value R-value

Heated slab on grade NA NA NA


Unheated slab on grade 14.76 4.0 73 4.0 73

U-value U-value U-value

Basement wall 0.068 0.101 33 0.101 33

Crawl wall NA NA NA

U-values in BTU/hr*ft2*F

*Percent reduction in Uo from MEC requirement

MEC Analysis Results

The MEC analyses results in Table 4 indicate that each component of unit 7, not only fullycomply with the 1993 MEC, but has substantially lower U-values than required by MEC,which could contribute to significant increases in energy performance. The exact contributionto the whole house energy usage depends on the relative importance of each building elementin the total structure. See Appendix A for results of the analysis performed using MECChecksoftware.


18/144


Energy Consumption Estimates

Energy simulation analysis software was used to evaluate the thermal and energyperformance of the whole townhouse. The software package, REM/Design

17, provides

energy consumption data and an estimate of the annual energy cost for the unit. The energyanalysis calculates the energy performance attributable to the efficiency of the buildingenvelope components, the HVAC plant, and includes infiltration losses, and ductperformance. A comparison of the estimated energy consumption is also made based on the1993 MEC. The software analysis for unit 7 shows:

A MEC minimum required overall Uo of 0.113 compared to an overall Uoof 0.072 as built.

The 1993 MEC maximum energy consumption requirements for heatingand cooling of 46.1 million Btu. As compares to an estimated 36.2 millionBtu consumed by the unit as built, a 22 percent reduction.

Figures 1 and 2 graphically summarize the annual component energy consumption estimatesresulting from the software analysis. Figure 3 shows the MEC comparison of heating andcooling energy consumption and estimated annual cost between the townhouse as constructedand a similar house constructed to code minimums as analyzed by the software.

Figure 1

Infiltration

Above Grade Walls

Glazing

Foundation Walls

Slab Floors

Ceilings/Roofs

Doors

Other

-6.00 -4.00 -2.00 0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00

Annual Consumption (Millon Btu)

Infiltration

Above Grade Walls

Glazing

Foundation Walls

Slab Floors

Ceilings/Roofs

Doors

Other

Su

bsys

tem

Structural insulated Panels

Subsystem Heating Consumption Estimate

17 Version 6.05 by Architectural Energy Corporation


19/144


Figure 2

Glazing

Internal Gains

Ducts

Ceilings/Roofs

Above Grade Walls

Infiltration

Other

-0.50 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50

Annual Consumption (Million Btu)

Glazing

Internal Gains

Ducts

Ceilings/Roofs

Above Grade Walls

Infiltration

Other

su

bsys

tem

Structural Insulated Panels

Subsystem Cooling Consumption Estimate

Figure 3


0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

Heating,

MEC

BaseCase

Heating,

MEC As

Designed

Cooling,

MEC

BaseCase

Cooling,

MEC As

Designed

Cost,

MEC

BaseCase

Cost,

MEC As

Designed

Annua

lFue

lConsump

tion

(MMBtu/yr)

$0

$50

$100

$150

$200

$250

$300

$350

$400

$450

$500


20/144


Townhouse Unit 8

The MEC requirements for each subsystem, included in Table 5, include any benefits as aresult of the use of thermal mass in the above grade wall systems.

Table 518



Mode

One- and Two-

Family

Multifamily /

Townhouses

Uo Uo

Walls Heating or cooling 0.174* 0.215**




R-value R-value

Heated slab on grade Heating NA NA

R-value R-value

Unheated slab on grade Heating 4.0 4.0

U-value U-value


Crawl wall Heating or cooling NA NAU-values in BTU/hr*ft2*F, R-values = 1/U

* Increase in Uo requirement from 0.149 due to thermal mass credit** No increase in Uo-value for A-2 residential construction

Unit 8 is constructed with ICE Block foundation system enclosing the basement, first andsecond floors. A nominal 8" block is used for the basement and a nominal 6" block is usedfor the first and second floors. Raised heel roof trusses are used for the roof system.



21/144



Table 6

Construction Features of Townhouse Unit 8

Wall/Ceiling Surface Area U-value UA-Value Subscript

ICE Block1

319.33 0.068 42.73 w1

ICE Block2

1377.93 0.071 98.46 w2

Wood Window/Door Jambs3

RoughFraming

40.65 0.120 7.87 w3

Windows (U=0.32) 8.83 0.320 2.83 g1

Windows (U=0.35) 105.00 0.350 36.75 g2

Windows (U=0.31) 72.00 0.310 22.32 g3

Windows (U=0.30) 25.00 0.300 7.50 g4

Door (U=0.16) 21.07 0.160 3.37 d1

Door (U=0.14) 21.64 0.140 3.03 d2

Sliding Door (U=0.32) 53.89 0.320 17.25 d3


Overall U-value4

(Uo) 0.117 o

Ceiling Area 807.20 0.026

Floor Over Unheated Space NA NA

Basement Walls5

630.54 0.068

R-value

Slab Edge6



1basement wall sections less than 50 percent below grade, 8" ICE Block26" ICE Block32 x 8 wood typical

4

o

w w w g g g g fp d d d

o

U =[(UA ) 1+(UA ) 2+(UA ) 3)+(UA ) 1+(UA ) 2+(UA ) 3+(UA ) 4+(UA ) +(UA ) 1+(UA ) 2+(UA ) 3]

A

5base

ment wall sections more than 50 percent below grade6slab edge of basement walls considered in Gross Wall Area


22/144


The data on unit 8 in Table 6, are compared with the MEC requirements for multifamilytownhouses and single- and two-family units in Table 7, showing the difference in Uo and R-Values of various components of the building as built and as required by MEC.

Table 7

Townhouse Unit 8 MEC Compliance Record

Building Subsystem Space

Conditioning

Mode

One- and Two-

Family

Multifamily /

Townhouses

Uo Uo%

DifferenceUo

%

Difference

Walls 0.117 0.174 33 0.215* 46

Roof/Ceiling 0.026 .033 21 .033 21

Floors over unheated

space

NA .05 .05






Basement wall 0.068 0.101 33 0.101 33

Crawl wall NA NA NAU-values in BTU/hr*ft2*F* No increase in Uo-value for A-2 residential construction due to thermal mass** Percent reduction from MEC requirement


The MEC analysis results in Table 7 indicate that each component of unit 8 fully comply withthe 1993 MEC, but has substantially lower Uo-values than required by MEC, which couldcontribute to significant increases in energy performance. The exact contribution to wholehouse energy performance depends on the relative importance of each building element in thetotal structure. See Appendix A for results of the analysis performed using MECCheck

software.


23/144



Energy simulation analysis software was used to evaluate the thermal and energyperformance of the townhouse. The software package, REM/Design,

19provides energy

consumption data and an estimate of the annual energy cost for the unit, and compares resultswith MEC minimum requirements (see Appendix A). The software analysis calculates theenergy performance attributable to the energy efficiency of the building envelopecomponents, the HVAC plant, and includes infiltration and duct losses. The softwareanalysis for unit 8 shows:

A MEC required minimum overall Uo of 0.110 compared to an overall Uoof 0.083 as built.

A 1993 MEC maximum energy consumption required for heating andcooling of 80.6 million Btu compares to an estimated 33.9 million Btuconsumed by the unit as built, a 58 percent reduction.

Figures 4 and 5 summarize the annual energy consumption estimates resulting from thesoftware analysis. Figure 6 shows the MEC comparison of heating and cooling energyconsumption between the townhouse as constructed and a similar house constructed to codeminimums as analyzed by the software.

Figure 4

Infiltration

Above Grade Walls

Glazing

Foundation Walls

Slab Floors

Ceilings/Roofs

Doors

Other

-15.00 -10.00 -5.00 0.00 5.00 10.00 15.00


Infiltration

Above Grade Walls

Glazing

Foundation Walls

Slab Floors

Ceilings/Roofs

Doors

Other

Su

bsys

tem

Insulated Concrete Forms


19 version 6.05 by Architectural Energy Corporation


24/144


Figure 5

Glazing

Internal Gains

Ducts

Ceilings/Roofs

Above Grade Walls

Infiltration

Other

-0.50 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50


Glazing

Internal Gains

Ducts

Ceilings/Roofs

Above Grade Walls

Infiltration

Other

su

bsys

tem

Insulated Concrete Form


Figure 6


0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

Heating,

MEC

BaseCase

Heating,

MEC As

Designed

Cooling,

MEC

BaseCase

Cooling,

MEC As

Designed

Cost,

MEC

BaseCase

Cost,

MEC As

Designed

Annua

lFue

lConsump

tion

(MMBtu/yr)

$0

$100

$200

$300

$400

$500

$600

$700

$800

$900


25/144


Townhouse Unit 9

The MEC requirements for each subsystem in unit 9 are shown in Table 8.

Table 820


Building SubsystemSpace

Conditioning

Mode

One- and Two-

Family

Multifamily /

Townhouses

Uo Uo

Walls Heating or cooling 0.149 0.215


Floors over unheatedspace Heating or cooling 0.050 0.050

R-value R-value


R-value R-value

Unheated slab on grade Heating 4.0 4.0

U-value U-value


Crawl wall Heating or cooling NA NAU-values in BTU/hr*ft2*F, R-values = 1/U

Unit 9 is constructed with ICE Block foundation system enclosing the basement. The firstand second floors are framed using steel construction insulated with Icynene spray insulation.Additional insulating 1" EPS board is used for the finishing system. Raised heel roof trussesare used for the roof system.



26/144


Table 9 describes the physical dimensions of 9. Wall sections representing differentconstruction materials are included separately.

Table 9


Wall/Ceiling Surface Area U-value UA-Value SubscriptICE Block

1227.13 0.068 15.39 w1

ICE Block2

210.75 0.071 15.06 w2

Exterior Steel Framed Walls 1202.20 0.087 104.03 w3

Bulk Head Area 10.66 0.022 0.24 w4


50.54 0.096 4.83 w5

Windows (U=0.32) 12.00 0.320 3.84 g1

Windows (U=0.35) 135.00 0.350 47.25 g2

Windows (U=0.31) 48.00 0.310 14.88 g3

Windows (U=0.30) 25.00 0.300 7.50 g4

Windows (U=0.29) 6.00 0.290 1.74 g5

Door (U=0.16) 21.07 0.160 3.37 d1

Door (U=0.14) 21.64 0.140 3.03 d2

Sliding Door (U=0.32) 36.67 0.320 11.73 d3


Overall U-value4

(Uo) 0.116 o

Ceiling Area 804.00 0.026

Floor Over Unheated Space NA NA

Basement Walls5

721.96 0.068

R-value

Slab Edge6


Note: All U-values in Btu/hr-ft2-F1

basement wall sections less than 50 percent below grade, 8" ICE Block26" ICE Block32 x 6 wood typical4

o

w w w w w g g g g g fp d d d

o

U=[(UA) 1+(UA) 2+(UA) 3+(UA) (UA) (UA) 1+(UA) 2+(UA) 3+(UA) 4+(UA) (UA) +(UA) 1+(UA) 2+(UA) 3]

A

4 5 5+ + +)

5basement wall sections more than 50 percent below grade

6slab edge of basement walls considered in Gross Wall Area


27/144


The data on unit 9 in Table 8, are compared with the MEC requirements for multifamilytownhouses and single- and two-family units in Table 10, showing the difference in Uo- andR-values of various components of the building as built and as required by MEC.

Table 10

Unit 9 MEC Compliance Record

Building Subsystem As Built One- and Two-FamilyMultifamily /

Townhouses

Uo Uo%

DifferenceUo

%

Difference

Walls 0.116 0.149 22 0.215 46

Roof/Ceiling 0.026 .033 21 .033 21


NA .05 .05





14.76 4.0 73 4.0 73


Basement wall 0.068 0.101 33 0.101 33

Crawl wall NA NA NAU-values in BTU/hr*ft2*F

* Percent reduction from MEC requirement


The MEC analysis results in Table 10 indicate each component of unit 9 not only fullycomply with the 1993 MEC, but has substantially lower Uo-values than required by MEC,which could contribute to significant increases in energy performance. The exact contributionto whole house energy performance depends on the relative performance of each buildingelement in the total structure. See Appendix A for results of the analysis performed usingMECChecksoftware.


28/144



Energy simulation analysis software was used to evaluate the thermal and energyperformance of the townhouse unit. The software package, REM/Design

21, provides energy

consumption data and an estimate of the annual energy cost for the unit comparing results

with MEC requirements (see Appendix B). The energy analysis calculates the energyperformance attributable to the energy efficiency of the building envelope components, theHVAC plant, and includes infiltration and duct losses. The software analysis for unit 9shows:

A MEC required minimum overall Uo of 0.111 compared to an overall Uoof 0.084 as built.

A 1993 MEC maximum energy consumption requirement for heating andcooling of 24.9 million Btu compared to an estimated 11.0 million Btuconsumed by the unit as built, a 56 percent reduction.

Figures 7 and 8 summarize annual energy consumption estimates resulting from the softwareanalysis. Figure 9 shows the MEC comparison of heating and cooling energy consumptionbetween the townhouse as constructed and a similar house constructed to code minimums asanalyzed by the software.

Figure 7

Infiltration

Above Grade Walls

Glazing

Foundation Walls

Slab Floors

Ceilings/Roofs

Doors

Other

-1.50 -1.00 -0.50 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50

Annual Consumption (million Btu)

Infiltration

Above Grade Walls

Glazing

Foundation Walls

Slab Floors

Ceilings/Roofs

Doors

Other

Su

bsys

tem

Steel, Spray Foam Insulation




29/144


Figure 8

Glazing

Internal Gains

Ducts

Ceilings/Roofs

Above Grade Walls

Infiltration

Other

-0.50 0.00 0.50 1.00 1.50 2.00 2.50 3.00


Glazing

Internal Gains

Ducts

Ceilings/Roofs

Above Grade Walls

Infiltration

Other

su

bsys

tem



Figure 9


0.0

5.0

10.0

15.0

20.0

25.0

Heating,MEC

Base

Case

Heating,MEC As

Designed

Cooling,MEC

Base

Case

Cooling,MEC As

Designed

Cost,MEC

Base

Case

Cost,MEC As

Designed

Annua

lFue

lConsump

tion

(MMBtu/yr)

$0

$50

$100

$150

$200

$250

$300

$350

$400

$450

$500


30/144


Townhouse Unit 10

The MEC requirements for each subsystem in unit 10 are shown in Table 11, taking intoaccount benefits from thermal mass in the above grade wall systems, calculated according toprocedures explained above.

Table 1122



Mode

One- and Two-

Family

Multifamily /

Townhouses

Uo Uo

Walls Heating or cooling 0.177* 0.215**




R-value R-value


R-value R-value


Heating 4.0 4.0

U-value U-value


Crawl wall Heating or cooling NA NA

U-values in BTU/hr*ft2*F, R-values = 1/U

* Increase in Uo requirement from 0.149 due to thermal mass credit

** No increase in Uo-value for A-2 residential construction

Unit 10 is constructed with a Superior Wall foundation system for the basement wall. Alightweight AAC system, manufactured by Hebel Southeast, forms the walls of the first andsecond floors. Additional wall insulation is not installed. Raised heel roof trusses are usedfor the roof system.



31/144



Table 12


Wall/Ceiling Surface Area U-value UA-Value Subscript

Superior Wall Sections1

170.27 0.071 12.16 w1

Concrete Bond Beam2

45.28 0.106 4.78 w2

Hebel AAC 2073.51 0.098 203.89 w3


77.17 0.115 8.90 w4

Garage/Basement Wall (Steel)4

184.11 0.069 12.61 w5

Windows (U=0.32) 197.97 0.320 63.35 g1

Windows (U=0.35) 120.00 0.350 42.00 g2

Windows (U=0.31) 48.00 0.310 14.88 g3

Fireplace Opening5

14.33 0.855 12.25 fpDoor (U=0.16) 18.56 0.160 2.97 d1

Door (U=0.14) 21.63 0.140 3.03 d2

Sliding Door (U=0.32) 20.00 0.320 6.40 d3


Overall U-value6

(Uo) 0.129 o

Ceiling (flat and cathedral) 870.60 0.026

Floor Over Unheated Space 350.14 0.046

Basement Walls7

329.42 0.071

R-value

Slab Edge8



1basement wall sections less than 50 percent below grade, excluding 1 3/4" top bond beam

2including Superior Wall top bond

32 x 8 pressure treated wood typical4double 3 1/2" steel wall with Icynene thermal break5use steel insert, fully enclosed flue box (U-value = steel + air space)

6

o

w w w w w g g g fp d d d

U =[(UA ) 1+(UA ) 2+(UA ) 3+(UA ) 4+(UA ) 5)+(UA ) 1+(UA ) 2+(UA ) 3+(UA ) +(UA ) 1+(UA ) 2+(UA ) 3]

7baseme

nt wall sections more than 50 percent below grade8slab edge of basement walls considered in Gross Wall Area


32/144


The data on unit 10 in Table 11, are compared with the MEC requirements for multifamilytownhouses and single- and two-family units in Table 13, showing the difference in Uo- andR-values of various components of the building as built and as required by MEC.

Table 13

Townhouse Unit 10 MEC Compliance Record

Building Subsystem As Built One- and Two-FamilyMultifamily /

Townhouses

Uo Uo%

DifferenceUo

%

Difference

Walls 0.129 0.177 27 0.215* 40

Roof/Ceiling 0.026 .033 21 .033 21


0.046 .05 8 .05 8






Basement wall 0.071 0.101 29 0.101 29

Crawl wall NA NA NA

U-values in BTU/hr*ft2*F* No increase in Uo-value for A-2 residential construction due to thermal mass

** Percent reduction from MEC requirement


The MEC analysis results in Table 13 indicate each component of unit 10 fully complies withthe 1993 MEC with respect to the total house, but has substantially lower Uo and R-valuesthan required by MEC, which could contribute to significant increases in energyperformance. The exact contribution to whole house energy performance depends on therelative performance of each building element in the total structure. See Appendix A forresults of the analysis performed using MECChecksoftware.


33/144



Energy simulation analysis software was used to evaluate the thermal and energyperformance of the townhouse unit. The software package, REM/Design

23, provided energy

consumption data and an estimate of the annual energy cost for the unit comparing resultswith MEC requirements (see Appendix B). The energy analysis calculates the energyperformance attributable to the energy efficiency of the building envelope components, theHVAC plant, and includes infiltration and duct losses. The software analysis for unit 10shows:

A MEC required overall Uo of 0.113 compared to an overall Uo of 0.091 asbuilt.

A 1993 MEC maximum energy consumption requirement for heating andcooling of 97.4 million Btu, compares to 61.0 million Btu consumed asbuilt, a 37 percent reduction.

Figures 10 and 11 summarize the annual energy consumption estimates resulting from thesoftware analysis. Figure 12 shows the MEC comparison of heating and cooling energyconsumption between the townhouse as constructed and a similar house constructed to codeminimums as analyzed by the software.

Figure 10

Infiltration

Above Grade Walls

Glazing

Foundation Walls

Slab Floors

Ceilings/Roofs

Doors

Other

-10.00 -5.00 0.00 5.00 10.00 15.00 20.00 25.00 30.00

Annual Consumption (million Btu)

Infiltration

Above Grade Walls

Glazing

Foundation Walls

Slab Floors

Ceilings/Roofs

Doors

Other

Su

bsys

tem

Lightweight Concrete




34/144


Figure 11

Glazing

Internal Gains

Ducts

Ceilings/Roofs

Above Grade Walls

Infiltration

Other

-1.00 0.00 1.00 2.00 3.00 4.00 5.00 6.00


Glazing

Internal Gains

Ducts

Ceilings/Roofs

Above Grade Walls

Infiltration

Other

subsystem



Figure 12


0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

Heating,MEC

BaseCase

Heating,MEC As

Designed

Cooling,MEC

BaseCase

Cooling,MEC As

Designed

Cost,MEC

BaseCase

Cost,MEC As

Designed

Annua

lFue

lConsump

tion

(MMBtu/yr)

$0

$100

$200

$300

$400

$500

$600

$700

$800

$900

$1,000


35/144


ENERGY SIMULATION ANALYSIS

A simulation using REM/Design Software was performed for each unit to determine R-values for non-standard wall sections. The structural and material characteristics of each unitwere explicitly detailed, using either manufacture's data such as glazing U-values or actualmeasured envelope dimensions. Blower door tests provided infiltration data and the resultsfor each unit are shown in Table 14.

Table 14

Infiltration Testing Results

Unit ACH50*

ACHwinter**

ACHsummer***

7 4.8 0.41 0.27

8 3.8 0.23 0.14

9 2.3 0.15 0.09

10 5.0 0.42 0.28

* Air Changes per Hour @ 50 pascals

** Air Changes per Hour (natural) for Winter months (Dec.-Feb.)

*** Air changes per Hour (natural) for Summer months (Jun.-Aug.)

Note: the estimated ACH (natural) for summer and winter months determined from a model developed at the Lawrence Berkeley

Laboratory.

The REM/Design software simulation estimates building annual energy consumption.Building wall materials and R-values were used as inputs into the simulation. The existingdatabase of standard wall sections does not always contain information on the innovative wall

systems used in the construction of the townhouses. In such cases, the program had thecapability of estimating the wall R-value. A parallel path estimate was used to develop theoverall R-value for the wall section using the above inputs. Table 15 indicates the areas ofsome of the wall and floor sections used in the analysis. Units 7 and 10 are mirror images ofeach other as are units 8 and 9, but some differences still exists. For example, the slab floorareas are larger for units 8 and 9 since they do not include an unconditioned garage as part ofthe house structure. The differences in roof areas between units 7 and 10 are accounted forby the use of additional sloped ceilings in unit 7.


36/144


Table 15

Townhouse Comparative Statistics

Feature Unit 7 Unit 8 Unit 9 Unit 10

Above Grade Wall Area (ft

2

) 2938.8 1679.7 1733.3 2713.3Window/Door Opaque Area (ft

2) 428.6 307.5 305.4 426.1

Slab Floor Area (ft2) 529 875 804 529

Roof Area (ft2) 1049 807 804 871

Rim/Band Joist Area (ft2) 252.7 0 0 45.3

Foundation Wall Length (ft) 74.6 95.6 95.6 75.0

Frame Floor Area (ft2) 357 0 0 350

The software estimates the annual energy consumption of the building. An estimate of the

lights and appliance use is include in the energy consumption analysis. The program makesuse of fuel rates supplied by the user to estimate the annual cost of energy. All energycalculations are based on Btu energy use.

Table 16 shows the results of the simulation for the four townhouses. Caution is advised indrawing conclusions from a direct comparison of the townhouses since the nature of theorientation, connecting walls, duct location, infiltration rates, and other variables can result insignificant variations in any analysis. For example, units 7 and 10 have much larger glazingareas than units 8 and 9 resulting in greater energy losses and higher energy consumption.


37/144


Table 16

Compiled Results of Simulation Runs

Description Unit 7 Unit 8 Unit 9 Unit 10

Area of Conditioned Space ft2

2102 2293 2352 2193

Annual Heating Load million Btu/yr. 47.1 31.7 32.4 56.4Annual Heating Consumption million Btu/yr. 36.3 35.2 9.8 62.6

Annual Heating Cost $/yr. 278.29 271.51 175.49 471.95

Annual Cooling Load million Btu/yr. 35.8 23.5 20.1 37.7

Annual Cooling Consumption million Btu/yr. 7.8 6.7 4.7 10.7

Annual Cooling Cost $/yr. 196.20 167.04 116.76 268.59

Annual Water Heating Load million Btu/yr. 19.7 18.7 16.8 18.7

Annual Water Heating Con. Million Btu/yr. 25.9 19.1 8.3 19.1

Annual Water Heating Cost $/yr. 205.59 152.30 172.11 150.42

Annual Lights and Appliance Consumption million Btu/yr. 25.24 25.3 25.3 25.3

Annual Lights and Appliance Cost $/yr. 406.51 408.14 410.20 406.62

Peak Heating Load thousand Btu/hr 30.2 22.7 21.1 37.0

Peak Cooling Load thousand Btu/hr 40.5 25.2 23.0 44.0

Area Normalized Heating Consumption thousand Btu/ft2/yr. 17.3 15.4 4.2 28.5

Area Normalized Cooling Consumption thousand Btu/ft2/yr. 3.7 2.9 2.0 4.9

Area Normalized Heating Cost $/ft2/yr. 0.13 0.12 0.07 0.22

Area Normalized Cooling Cost $/ft2/yr. 0.09 0.07 0.05 0.12

Annual Space Conditioning Costs $/million Btu 7.75 10.47 20.16 10.10

Figures 1 through 12 above, compare the estimated losses attributed to each component. Inthe heating estimates, the above grade walls and infiltration losses make up the largestpercentage of losses. In cooling energy requirements, glazing and internal gains account formost of the cooling energy requirements.

The comparative value of the results in Table 16 of the simulation analysis are affected by thefollowing utility, operation, and construction factors and result in substantial differences inenergy consumption among the units:

The cost of electricity is slightly more than $0.08/kwh while the cost ofnatural gas is about $0.82/therm.

The HVAC set point is kept constant at 72F.

Units 8 and 9 have a common wall decreasing the wall area exposed to theoutdoors by over 1000 ft

2compare to the other two units.

The opaque openings are over 125ft2

larger for units 7 and 10.

The infiltration rates for units 8 and 9 are at least half of the other units.


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Cooling fuel consumption cost estimates for townhouse unit 7 are based on an electriccompressor unit operating at an estimated SEER-value of 15.6.

TOWNHOUSE

ENERGY

PERFORMANCE

MONITORING

COOLING

SEASON

Each of the townhouse units were monitored for heating and air conditioning energyconsumption, indoor temperature, and north and south wall surface temperatures. Theoutdoor ambient air temperature was also recorded. The data is gathered in ten minuteintervals, averaged, and logged.

In the three units which had gas fuel for heating and/or air conditioning, consumption waslogged by recording the number of pulses from the meter every ten minutes. Each pulserepresented one cubic foot of natural gas. This value was then converted to therms using thegas companys conversion factor, listed on the monthly billing. The energy used by thegeothermal heat pump is recorded by a watt meter on the unit power supply.

The amount of time the compressor was running was recorded for the two townhouses withoutdoor air conditioning compressors. Manufacturers data were then used to determine theenergy consumed by the air conditioning system, including the blower motor.

Operational data was logged for each unit at ten minute intervals and averaged. The analogoutput of the transducer was recorded at ten minute intervals and averaged to obtain realpower measurements. For compressor operating time, the sum of all the minutes during theten minute period in which the compressor operated was recorded. For gas consumption, apulse was recorded per cubic foot rotation of the two-cubic foot dial on the gas meter.Periodically, the utility electric meter data was recorded.

Air Conditioning Energy Consumption

The air conditioning equipment was activated in the beginning of June 1996, since prior tothis date, little, if any, air conditioning use was required; moreover, building construction wascompleted at this time and operation of each unit was more stable without interference fromcontractor use. Three of the four units were unoccupied; unit 7 was occupied by two people.

The energy consumption of the air conditioning equipment was derived by either directlylogging data or from calculations based on compressor "on-time" data. The air conditioningenergy consumption data was totaled for each day and plotted against the average daily

difference between the indoor and outdoor temperature readings. The plot indicates indoortemperature range for various performance indicators such as hourly daily use.


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Performance of Individual Townhouse Units

Townhouse Unit 7Structural Insulated Panels

The space conditioning equipment consisted of a gas engine powered air-source heat pumpunit with a manufacturer's SEER rating of 15.60. The SEER rating is developed by themanufacturer using the proposed ANSI standard Z-21 which relates an equivalent SEER forthe gas engine heat pump to a comparable electric-powered unit. The comparison is based onfuel costs in a given geographic area. The rated capacity is 36,000 Btuh. A dedicated gasmeter was installed to record the gas supplied to the gas engine separate from other gasappliances. The gas meter was located downstream of a pressure reducing valve.

A plot of the data provided during four months of operation is shown in Figures 13 and 14.This data indicates the energy consumption trend based on the temperature difference

between the indoor and outdoor daily average temperatures. This townhouse was occupiedand the thermostat operation included a night setback of about four degrees Fahrenheit(2.2C), from 74F to 70F. The measured indoor temperature range over the full period wasbetween 67.4F and 77.0F. For the narrow cooling period under analysis, the trend in energyconsumption indicates approximately 0.1 therms per degree temperature difference betweenthe outdoor and indoor average temperature. The balance point is that outdoor temperature atwhich no space conditioning is required. It differs from the thermostat set-point, which isinfluenced by internal gains. Note the cooling season balance point for this particulartownhouse occurs when the average outdoor temperature is 10.5F below the average indooraverage temperature. (see Figure 13)


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Figure 13


Cooling Season Performance

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

-18.0 -16.0 -14.0 -12.0 -10.0 -8.0 -6.0 -4.0 -2.0 0.0 2.0 4.0

degree F Temperature Difference (Outdoor - Indoor)

therms

(exc

luding

blower

fanopera

tion

)

112 Day Period

Indoor temperature Range 67.4 - 77.0 F

Figure 14


Cooling System Performance

0.0

0.5

1.0

1.5

2.0

2.5

3.0

-10.0 -8.0 -6.0 -4.0 -2.0 0.0 2.0 4.0


therms

(exc

luding

blower

fanopera

tion

)

26 Day PeriodIndoor temperature Range 71.8 - 75.0 F


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Figures 15 and 16 respectively show a five- and two-day period of operation. The effect oftemperature setback is evident in the indoor temperature and the cooling system operation inthat the bulk of air conditioning operation follows the daytime peak temperature. The peakcooling load for the period was approximately 30,000 Btuh. At an interior set point of 72F,the estimated peak cooling load was 40,500 Btuh for the software analysis.

Figure 15


50.0

55.0

60.0

65.0

70.0

75.0

80.0

85.0

90.0

234

235

236

237

238

5 Day per iod by hour average

degreeF

0.00

0.05

0.10

0.15

0.20

0.25

0.30

CoolingSystemO

peration

therm s Am bient Indoor A ir


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Figure 16

Structural Insulated Panel

days 237-238, 1996

50.0

55.0

60.0

65.0

70.0

75.0

80.0

85.0

12:10AM

1:40AM

3:10AM

4:40AM

6:10AM

7:40AM

9:10AM

10:40AM

12:10PM

1:40PM

3:10PM

4:40PM

6:10PM

7:40PM

9:10PM

10:40PM

12:10AM

1:40AM

3:10AM

4:40AM

6:10AM

7:40AM

9:10AM

10:40AM

12:10PM

1:40PM

3:10PM

4:40PM

6:10PM

7:40PM

9:10PM

10:40PM

hour (by 10 minute averages)

degree

F

0.0000

0.0100

0.0200

0.0300

0.0400

0.0500

0.0600

aircon

ditioneropera

tion

(therms

)

Ambient Inside Air therms

Figure 15 shows the relationship between air conditioning demand and the outdoor andindoor temperatures. Since the townhouse is operated with thermostat setback, a largerdemand occurs in the evening at the setback period and little demand occurs following thesetback period. The operation of the air conditioning unit coincides closely with the outdoor

temperature and solar gains. Townhouse unit 7 has the largest amount of west facing glazingof all the units which will result in increased heat-gains penalties not evident in other units.


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Figure 17 shows the hourly average temperatures for two days during the summer coolingperiod. The peak south wall exterior temperature precedes the peak interior south walltemperature by two to three hours. Since exterior air temperatures remain relatively highduring the night, the wall surface and air temperatures tend to converge during the night time.Due to the incident solar gains at the peak period, the surface temperature of the south facing

wall rises 31.7F above the ambient air temperature.

Figure 17

Structural Insualted Panels

Days 236-237

55.0

65.0

75.0

85.0

95.0

105.0

115.0

125.0

1 3 5 7 911

13

15

17

19

21

23 1 3 5 7 9

11

13

15

17

19

21

23

hour averages

degree

F

Inside Air S Wall Ext S Wall Int Ambient

Actual consumption has exceeded the predicted consumption of the simulation software byabout 50 percent. To determine actual consumption, estimates of consumption were madefor missing data points. The difference in consumption is attributed to the complexity ofaccurately determining a SEER rating for a gas-powered air conditioner.


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Townhouse Unit 8Insulating Concrete Forms

The HVAC equipment in unit 8 consists of a gas forced-air furnace and an air conditioningoutdoor unit with a manufacturer's rating of SEER=12.0. The rated output capacity is 30,000Btuh. Data for the units operation was logged through monitoring of the time the airconditioning compressor was in operation. The time was then multiplied by themanufacturer's energy consumption rating, which included the blower fan, to obtain overallenergy consumption.

A plot of the data available during four months of operation is shown in Figures 18 and 19.These figures show energy consumption in relation to the temperature difference between theoutside and inside air temperatures. For the narrow 41-day period under analysis, the trend inenergy consumption indicates approximately .40 kWh per degree temperature differencebetween the outdoor and indoor average temperatures. The significant amount of data scatteris indicative of thermally massive walls. During the 41-day period, the indoor airtemperature was stable within a 2F range with an average indoor temperature of about74.3F.

Figure 18


Cooling Season Performance

0

2

4

6

8

10

12

14

16

18

20

-20.0 -15.0 -10.0 -5.0 0.0 5.0 10.0


kilowa

tthours

98 Day PeriodIndoor Temperature Range 61.0 - 78.2 F


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Figure 19


Cooling System Performance

0

1

2

3

4

5

6

7

8

9

10

-12.0 -10.0 -8.0 -6.0 -4.0 -2.0 0.0 2.0 4.0


kilowa

tthours

41 Day Period

Indoor Temperature Range 73.3 - 75.4 F

A five- and two-day period of operation is shown in Figures 20 and 21, respectively. Therelationship between the air conditioning unit operation and the outdoor and indoortemperatures is consistent for the period in that the air conditioning operation follows thedaytime peak temperature. The one exception is the rise in the indoor temperature on day

237. On this day, the rise in temperature is coincident with the air conditioning operationpossibly due to direct solar gains. Air conditioning operation appears to be dependent onwhat is assumed to be solar gains which is inferred by an indirect correlation between airconditioning operation and exterior temperature of the wall. (S Wall Ext" in Figure 22) Thistemperature is dependent on solar radiation falling on the wall surface.


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Figure 20


50.0

55.0

60.0

65.0

70.0

75.0

80.0

85.0

90.0

234

235

236

237

238

5 Day period by hour average

degree

F

0.00

0.20

0.40

0.60

0.80

1.00

1.20

Coo

ling

Sys

tem

Opera

tion

kWh Ambient Indoor Air

Figure 21


days 237-238, 1997

50.0

55.0

60.0

65.0

70.0

75.0

80.0

85.0

12:10AM

1:40AM

3:10AM

4:40AM

6:10AM

7:40AM

9:10AM

10:40AM

12:10PM

1:40PM

3:10PM

4:40PM

6:10PM

7:40PM

9:10PM

10:40PM

12:10AM

1:40AM

3:10AM

4:40AM

6:10AM

7:40AM

9:10AM

10:40AM

12:10PM

1:40PM

3:10PM

4:40PM

6:10PM

7:40PM

9:10PM

10:40PM

hour (by 10 minute averages)

degree

F

0

500

1000

1500

2000

2500

3000

A/Copera

tion

(wa

tts

)

Ambient Inside Air watts


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The air conditioning operation was less variable when the ambient temperature fell below theindoor temperature or when the direct solar gain was minimized. The thermal massiveness ofthe wall system was considered to be the primary controlling factor, mitigating the immediateimpact of the outdoor conditions. Operation of the compressor rarely approached a 50percent duty-cycle for one hour with most of its operation about 15 percent per hour.

Significant periods of compressor off time were also common.

The air cond

2516 energy performance townhouses

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