GRAND PRIZE WINNER. ZeroEnergy Design. Phone: Website: Sponsors:

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1 GRAND PRIZE WINNER ZeroEnergy Design Phone: Website: Sponsors:

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3 Entry P122 The Little Green Rhody Narrative We are pleased to submit a net-zero possible design for the competition. Our multidisciplinary team includes both a Rhode Island licensed architect and a residential mechanical designer, who is also a specialist in energy modeling and a certified HERs rater. The requested drawings and visualization capture our proposed design. We ve adapted the same footprint for the both the three and four bedroom plans. Our intent was to create a simple, aesthetically pleasing form that reflects the local vernacular of the neighborhood, and will be economical to construct and operate. Life-Cycle Assessment Global Warming Potential The Little Green Rhody relies on traditional wood frame construction paired with a modified concrete foundation system. For the wood frame, we elected for 2x4 studs at sixteen inches on center. The 2x4s have a minor savings relative to 2x6s at twenty-four inches on center, but the sixteen inch spacing is preferable for the siding attachment the strapping for the rainscreen needs to align with the stud spacing, attaching the siding at twenty-four inches on center over strapping can lead to wavy siding, so sixteen inch spacing is preferred. When comparing 2x4s vs. 2x6 both at sixteen inches on center, we find that the savings of 2-3% (a result of less wood and insulation) is preferable to the minor savings in operational energy, when paired with our exterior insulation detail. There will be a savings in the material cost of the insulation and lumber. Care has been taken to minimize the framing factor (the amount of wood in the stud wall) by setting the overall dimensions of the home on a sixteen inch grid, setting the typical windows within the grid and aligning one side of each door to the grid. The modified concrete foundation system we have used is engineered and manufactured by Superior Walls of America, though there may be comparable systems. When compared to a two foot by one foot spread footing and eight inch cast in place concrete wall, the Superior Walls uses twenty-five less cubic yards of concrete. This is a result of less concrete in the walls system, as well as a rubble footing in place of a poured concrete footing. The system has an ICC Code Approval Report, number ESR The minor modification is that we ve proposed to use expanded polystyrene (EPS) in place of extruded polystyrene (XPS) for reasons indicated above. As the insulation in non-structural, we do not feel the substitution should be problematic. This results in a savings of about three metric tons, or an 18% reduction in the overall foot print of the home. (Note we have accounted for the steel reinforcement that is required by this system see the Calculations page section at the end of this PDF.) The system is structurally sounds and offers a continuous layer of concrete on the exterior of the system that will be beneficial in creating a long-term waterproof foundation, relative to a discontinuous system like concrete blocks. The proposed roof will be constructed of trusses at twenty-four inches on center. The use of a truss constructed of 2x4 and 2x6 material will use less wood than a roof framed with traditional rafters and ENTRY P122

4 ceiling joists. The truss also allows for a raised heel at the top of wall so that the ceiling insulation is not diminished at the pinch point where the roof meets the wall. The insulation materials both above and below grade have been selected for their low global warming potential. We have excluded use of extruded polystyrene (XPS) from the project due to it s high global warming potential. For below slab and the interior of the foundation wall, we ve relied on Expanded polystyrene (EPS.) Below the slab, we ve used Type 9 EPS it has a high compressive strength and is suitable for below grade applications. It s also extruded in Smithfield, RI, a mere 7 miles from the site. Operational Energy Use The Little Green Rhody uses less than half the energy of an equivalent code-built home. The chart below compares operational cost for the four bedroom Little Green Rhody to a code-built baseline, as defined by the User Defined Reference Home (UDRH.) (Note this comparison does not account for PV.) The raw data for this comparison can be found in the REM/Rate export included in this PDF. $4, $3, $3, $2, $2, $1, $1, $ $0.00 Operational Energy Cost Comparison $3, Code-Build Baseline $1, Little Green Rhody (#P122) - 4 BR $4, $3, $3, $2, $2, $1, $1, $ $0.00 Appliances Lighting Hot Water Cooling Heating Total In further support of the operational energy use of the Little Green Rhody, please reference the following included in this PDF: - a Home Energy Rating (HERs) Certificate for the Four Bedroom version of our design with a 7.5kW PV array completed by our certified HERs rater - REM/Rate Performance Factors for the Three Bedroom unit - REM/Rate Performance Factors for the Four Bedroom unit The low operational energy use of the Little Green Rhody is largely attributed to it s air tight and well insulated building envelope. Beyond minimizing heat loss, the heating load is further offset by placing a majority of the well-insulated, high solar heat gain windows on the south side of the home to capture the sun s free heat. Shading from the roof overhang and the wood trellis over the south-facing sliding ENTRY P122

5 door limit overheating during the warmer months. The following sub-sections further describes the attributes of the building envelope and mechanical systems. Building Envelope Foundation: The basement is continuously insulated both on the foundation walls and below slab. This insulation keeps the basement within the conditioned space making it a similar temperature as the rest of the house, with controlled humidity. These attributes, paired with the access from both the first floor and the back yard, will make it a great place for storage, mechanical equipment, and even play space for the children. Above Grade Walls: We ve employed an external insulation strategy to allow for continuous insulation of the walls system. This wall system with perform significantly better than a wall that relies on cavity insulation as the wood studs have great structural capacity but are a poor insulator when compared to insulation. There are a couple of different types of rigid insulation that are suitable for an exterior insulation detail. We ve proposed to use 3 of mineral wool insulation it has a low global warming potential, is not a petroleum based product, and does not expand and contract like foam-based insulation products. This last point is particularly important because we ve proposed just one layer of three inch thick mineral wool. If polyisocyanurate were to be substituted, for example, it would be important to install two layers with staggered seams as each panel is prone to expand and contract with temperature creating small gaps between the panels, reducing overall performance and creating a potential for condensation on the sheathing. The images below, created in Therm, show a typical wall with a post compared to the same wall with exterior insulation. Not only is the interior surface temperature of the exterior insulated wall warmer, but it s condensing surface, the sheathing, is warmed such that it will not reach the dew point and cause condensation. This will increase the durability and longevity of the wall. ENTRY P122

6 Roof: We ve proposed a vented roof assembly with a truss structure and fourteen inches of loose filled cellulose at the attic ceiling. The vented assembly allows for the use of economical yet effective insulation at the attic ceiling. The raised heal at the edge of the truss avoids the typical thermal bridge that occurs at the roof wall intersection. Though the attic space will not be suitable for storage or mechanical equipment, we feel this is not an issue as the basement if fully insulated and conditioned. Window & Doors: Our design calls for triple glazed windows and doors. The triple glazing not only reduces heat loss in a cold climate, but also significantly improves thermal comfort for the occupants as the interior surface temperature of the windows will be a few degrees warmer than a double paned window. Though there are many manufacturers in the US who are making triple and even simulated triple pane (through using a film in place of the center pane of glass) windows, our experience is that the triple pane windows being manufactured in Europe are actually more economical and higher performing. The imported windows have lower U-frame values, better performing glass spacers, and higher solar heat gain glass an important quality for a cold climate as the glass will admit more of the sun s free heat. Luckily, many of the manufacturing facilities are near ports as is the site. Shipping the windows across the sea can actually have a smaller carbon footprint than trucking them across the country or for Canada, where some of the best performing windows in North America are currently made. Shipping from manufacturing facilities in to ports in Europe is often a short distance by truck or rail. Shipments can be received in Port of Providence. Using the transportation carbon calculator found at log-net.com, we compared the carbon foot print of windows fabricated by a supplier we ve used in Germany vs. another in Ontario, Canada. The result was over 5% more metric tons of carbon for the windows fabricated in Canada. With both a better price point and performance, the imported windows are a great option. Air Barrier: A continuous air barrier is detailed from the foundation up to the roof and back down again. An effective air barrier will significantly decrease operational energy, make the envelope more durable as the majority of moisture is carried through air movement, and improve the thermal comfort for the occupants. The air barrier is called out in one of our building sections. Of note is the use of both the ZIP wall sheathing and building paper. The ZIP system is a great air barrier it s more economical than plywood and it s continuity can be visually verified. Though the coating on the ZIP system does double as a code approved weather barrier, we ve included a layer of building paper in order to allow traditional flashing details throughout the wall assembly. Heating, Cooling, Ventilation & Hot Water We ve designed the house to be all electric so that the electricity can be offset in part or in full by PV or solar panels atop the roof. The heating and cooling is provided via an air-source heat pump. It s simple and economical to install. The small size of the system is well suited to a low energy home such as this one where the heating and cooling loads have been significantly decreased. National Grid, the local electricity provider, offers a rebate up to $500 of this piece of equipment. There is also a Heat Recovery Ventilator (HRV) that will provide dedicated ventilation with heat recover, an important addition to an air tight home. ENTRY P122

7 For domestic hot water, we ve proposed a heat pump hot water heater. Though a solar thermal system can be an efficient means of creating hot water, it still requires a backup system. It also adds an additional system to the house and competes for roof space with the PV panels. The energy consumed by the heat pump hot water heater can be offset by the production from the PV panels. National Grid also offers a $750 rebate of heat pump hot water heaters. Renewable Energy We ve sized a 7.5 kw PV or solar electric system for the four bedroom home and a 7.3 kw for the three bedroom home. Both array sizes will easily fit on the south-facing roof surface and will result in net-zero energy meaning the home will produce as much energy as it uses over the course of a year. There are currently two sources to offset the cost of the proposed PV array. The current installed cost of PV is about $4.00 / watt. At this rate, the 7.5 kw array will have an installed cost of about $30,000. It may be possible to further decrease this up front cost with in-kind donations. Though neighboring states, like Massachusetts, offer PV leasing programs, they are not currently available in Rhode Island. If the project does move forward to construction, this option should be reinvestigated. There is currently a grant available from the Rhode Island Renewable Energy Fund (RIREF) that will offset 25% of the system cost. There is also a federal 30% tax credit available for the installed cost. If the homeowner does not use the entire tax credit in the year the house is purchased, the credit can be rolled over until Affordability and Constructability The proposed construction system by Superior Walls should be cost competitive with a poured foundation with comparable insulation. Because it is a manufactured and marketing system, there may also be a greater potential for sponsorship relative to a traditional poured foundation. The framed above grade walls should be easy and economical to construct with volunteer labor. If the project is constructed, our team would be happy to provide framing plans that will minimize the use of wasted wood, showing how the window and door placement, as well as the overall dimensions, conform to a sixteen inch on center grid. The ZIP wall sheathing is less expensive than plywood. It is installed like conventional sheathing. Volunteers can tape the seams to create the air barrier, and a supervisor can easily verify with a visual inspection that the system is continuous prior to the application of the building paper. The wood roof trusses can be pre-manufactured or assembled by volunteers. The rigid insulation can also be installed by volunteers. Though the product is available in 3 x 48 x 96 boards, it will be easier to install in the 3 x 36 x 48 size as it can be carried and handled by one person. The proposed use of furring strips to strap the siding back to the structure is a code approved and tested installation detail. It should be noted, however, that we feel the installation of the strapping should be executed by trained professionals and not volunteer labor. In addition to connecting the siding back to the structure, the furring strips also create a drainage space behind the siding, which will improve the life of the finish. This detail, typically called a rainscreen, is a best practice for siding installation. After the furring strips are installed, volunteer labor can install the siding if this is common practice for Habitat projects. ENTRY P122

8 This home, even without PV, will significantly exceed the basic requirements of the Energy Star program. Our experience working in Rhode Island is that homes of similar performance have received a $4,000 rebate which helps to offset the upfront premium for additional insulation. Aesthetics and Livability Site & Exterior look The exterior of the Little Green Rhody fits well with neighborhood vernacular of gabled homes with either clapboard, brick veneer, or shingle siding. The majority of homes in the area do not conform with the current zoning code they are located too close to the street. The proposed design respects the building setbacks and includes a front porch that will help to activate the street space. Parking, on a two- or double-track driveway will limit paved area and increase the permeability of the site. The parking is located along the north side of the site where there are few windows on the lower level. This leaves the south side of the house open to the side yard. For the time being, the view out the south side also enjoys the view to the undeveloped neighboring lot. Rain barrels located on the bottom of the down spouts collect rainwater for use in landscaping. Storage for garbage bins, typically an eye sore, is conveniently located close to the street, between the front and side doors. Shading from summer heat gain for the south facing second floor windows is provided by the two foot long overhangs. A wood shade trellis over the south facing sliding door will shade the door and the small patio. Additional covered outdoor space is provided at the front porch. The front door serves as both the everyday and guest entrance for the home. The covered porch shield the entrant from the elements. To the right of the entry is a bench with storage below for taking off shoes and a coat closet sized to accommodate a large family. The open kitchen, living and dining space is flexible to allow the family to furnish it to their liking. There is even space for a work space (not shown on plans) if the family would like to include one. The nine foot ceilings on the first floor will work well with the scale of the space. A full bathroom on the first floor will be important for a large family. The three bedroom plan creates acoustical privacy between each bedroom by using the closets as a buffer space. All of the bedrooms are generously sized with ample closet space. Bedroom 2 has two closets and a larger size than Bedroom 3, allowing to be shared by two children. The four bedroom plan fits three modest sized children s bedrooms in addition to a more generously sized master bedroom. The large linen closet provides ample storage space for the family. Each bedroom contains one south facing window. ENTRY P122

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11 PROPOSED WOOD FENCE HATCH TO BASEMENT RAIN BARREL BUILDING SETBACK CAR 2 PV ARRAY CAR 1 STORAGE FOR GARBAGE BINS RAIN BARREL 2 TRACK DRIVEWAY N PROPOSED 10' CURB CUT SCALE: 1"= 20' ENTRY P122 - SITE PLAN

12 P REF 7.5' x 5' BDRM 3 9' x 9' 7.5' x 5' DN BDRM 2 9' x 11' TRELLIS ABOVE UP LINEN BDRM ' x 12.5' BENCH COVERED FRONT PORCH N SCALE: 1/8" 1"= = 81' ' - 0" ENTRY P122-3 BEDROOM PLANS

13 P REF 7.5' x 5' BDRM 4 9' x 9' 7.5' x 5' DN BDRM 3 9' x 9' TRELLIS ABOVE UP BDRM 2 9' x 9' LINEN BENCH BDRM ' x 10' COVERED FRONT PORCH N SCALE: 1/8" 1"= = 81' ' - 0" ENTRY P122-4 BEDROOM PLANS

14 SCALE: 1/4" 1"= = 41' ' - 0" ENTRY P122 - EAST ELEVATION

15 SCALE: 1/4" 1"= = 41' ' - 0" ENTRY P122 - WEST ELEVATION

16 NORTH SOUTH SCALE: 1"= 1/8" = 81' ' - 0" ENTRY P122 - ELEVATIONS

17 LAP NON PERFORATED HOUSEWRAP OVER TOP OF WALL PRIOR TO INSTALLING ROOF TRUSS TO CONNECT WALL AND CEILING AIR BARRIERS BEDROOM HALLWAY LINEN GYPSUM WALL BOARD CEILING TAPED AS AIR BARRIER ZIP WALL SHEATHING TAPED AS AIR BARRIER LIVING SPACE WINDOW HEADER AND SILL PROFILE TAPED TO AIR BARRIER TAPE SHEATHING TO FOUNDATION W/ ZIP TAPE INSULATED BASEMENT TAPE AND SEAL INTERSECTION OF SLAB, POLYETHELENE AND FOUNDATION TO CREATE AIR SEAL ENTRY P122 - BUILDING SECTION

18 PV ARRAY ROOF ASSEMBLY (OUTSIDE IN): - ASPHALT SHINGLES - ROOFING PAPER - SHEATHING 2' OVERHANG SHADES SOUTH-FACING SECOND STORY WINDOWS RAISED HEEL TRUSS 14" LOOSE FILL CELLULOSE TRIPLE GLAZED HIGH SOLAR GAIN WINDOWS WOOD TRELLIS TO SHADE SOUTH FACING SLIDING DOOR TRIPLE GLAZED HIGH SOLAR GAIN SLIDING DOOR 9' - 0" 8' - 0" BEDROOM LIVING SPACE HALLWAY GUTTERS TO DOWNSPOUTS TO RAIN WATER BARRELS WALL ASSEMBLY (OUTSIDE IN): - FIBER CEMENT CLAPBOARD SIDING - 1x4 16" O.C. - 3" MINERAL WOOL INSULATION - BUILDING PAPER - ZIP WALL SHEATHING - 16" O.C., CAVITY FILLED W. MINERAL WOOL OR COTTON BATT - 1/2" GYPSUM WALLBOARD - NO VOC PAINT & PRIMER INSULATED BASEMENT FOUNDATION WALL BY SUPERIOR WALL OR EQUIVALENT (OUTSIDE IN): - 1 3/4" CONCRETE - 4 1/2" EPS INSULATION - 1/2" POLYISOCYANURATE INSULATION - 2 1/4" x 7 1/2" REINFORCED CONCRETE 24" O.C. - 1" EPS INSULATION WRAPPING STUDS 4" CRUSHED STONE CONCRETE BASE TO FOUNDATION SYSTEM DRAINAGE PIPE TO SUMP PUMP OR DAYLIGHT SLAB ASSEMBLY (TOP DOWN): - 4" CONCRETE SLAB - 6 MIL. POLYETHELENE VAPOR BARRIER - 3" TYP IX EPS INSULATION ENTRY P122 - BUILDING SECTION & AIR BARRIER DIAGRAM

19 APA 4BR Net Zero, Registry ID: Rating Number: Certified Energy Rater: Rating Date: Rating Ordered For: 4 Bedroom Entry P122 Estimated Annual Energy Cost 5 Stars Plus Uniform Energy Rating System Energy Efficient 1 Star 1 Star Plus 2 Stars 2 Stars Plus 3 Stars 3 Stars Plus 4 Stars 4 Stars Plus 5 Stars 5 Stars Plus or Less HERS Index: -0 Efficient Home Comparison: 100% Better General Information Conditioned Area: 2039 sq. ft. HouseType: Single-family detached Conditioned Volume: cubic ft. Foundation: Conditioned basement Bedrooms: 4 Mechanical Systems Features Air-source heat pump: Electric, Htg: 10.5 HSPF. Clg: 17.5 SEER. Water Heating: Heat pump, Electric, 2.40 EF, 66.0 Gal. Use MMBtu Cost Percent Heating 6.3 $ % Cooling 2.0 $83-535% Hot Water 6.2 $ % Lights/Appliances 18.1 $ % Photovoltaics $ % Service Charges $0-0% Total $ % This home meets or exceeds the minimum criteria for all of the following: 2009 International Energy Conservation Code Duct Leakage to Outside: 1.00 CFM. Ventilation System: Balanced: HRV, 60 cfm, 30.0 watts. Programmable Thermostat: Heating: Yes Cooling: Yes Building Shell Features Ceiling Flat: R-52 Exposed Floor: NA Vaulted Ceiling: NA Window Type: Schuco Si82 Above Grade Walls: R-27 Infiltration: Foundation Walls: R-10.7 Rate: Htg: 1.00 Clg: 1.00 ACH50 Slab: R-13.2 Edge, R-13.5 Under Method: Blower door test Lights and Appliance Features Percent Interior Lighting: Range/Oven Fuel: Electric Percent Garage Lighting: Clothes Dryer Fuel: Electric Refrigerator (kwh/yr): Clothes Dryer EF: 3.01 Dishwasher Energy Factor: 0.75 Ceiling Fan (cfm/watt): 0.00 The Home Energy Rating Standard Disclosure for this home is available from the rating provider. REM/Rate - Residential Energy Analysis and Rating Software v13.0 This information does not constitute any warranty of energy cost or savings Architectural Energy Corporation, Boulder, Colorado. ZeroEnergy Design 156 Milk Street, Suite 3 Boston, MA Certified Energy Rater

20 PERFORMANCE FACTORS - C:\...\JMC 2011 UDRH v2 for REM 12.9.udr Date: March 01, 2013 Rating No.: Building Name: APA 3BR No PV Rating Org.: Owner's Name: Phone No.: Property: Rater's Name: Address:, Rater's No.: Builder's Name: Weather Site: Providence, RI Rating Type: File Name: APA_REM_3BR NoPV.blg Rating Date: 3 Bedroom #P122 UDRH APA 3BR No PV DIFF % DIFF Normalized Loads (Btu/sf shell area/dd) Heating: % Cooling: % Normalized Consumption (kbtu/sf floor area/yr) Heating: 22.6 a % Cooling: % Water Heating: % Lighting: Appliances: Photovoltaics: Total w/o PV: % Total: % Normalized Consumption (Btu/sf floor area/dd) Heating: % Cooling: % Normalized Costs ($/sf floor area/yr) Heating: $ $ $ % Cooling: $ $ $ % Water Heating: $ $ $ % Lighting: $ $ $ % Appliances $ $ $ % Photovoltaics $ $ $ Total: $ $ $ % Normalized Design Loads (Btuh/sf shell area/dd) Heating: % Cooling: % Normalization Factors Floor Area: Shell Area: Heating Degree Days (B65): Cooling Degree Days (B74): a Duct loss exceeds 50% of equipment capacity. Verify duct and equipment sizing inputs. REM/Rate - Residential Energy Analysis and Rating Software v13.0 This information does not constitute any warranty of energy cost or savings Architectural Energy Corporation, Boulder, Colorado.

21 PERFORMANCE FACTORS - C:\...\JMC 2011 UDRH v2 for REM 12.9.udr Date: March 01, 2013 Rating No.: Building Name: APA 4BR Net Zero Rating Org.: Owner's Name: Phone No.: Property: Rater's Name: Address:, Rater's No.: Builder's Name: Weather Site: Providence, RI Rating Type: File Name: APA_REM_4BR wpv.blg Rating Date: 4 Bedroom #P122 UDRH APA 4BR Net Zero DIFF % DIFF Normalized Loads (Btu/sf shell area/dd) Heating: % Cooling: % Normalized Consumption (kbtu/sf floor area/yr) Heating: 22.0 a % Cooling: % Water Heating: % Lighting: Appliances: Photovoltaics: Total w/o PV: % Total: % Normalized Consumption (Btu/sf floor area/dd) Heating: % Cooling: % Normalized Costs ($/sf floor area/yr) Heating: $ $ $ % Cooling: $ $ $ % Water Heating: $ $ $ % Lighting: $ $ $ Appliances $ $ $ Photovoltaics $ $ $ Total: $ $ $ % Normalized Design Loads (Btuh/sf shell area/dd) Heating: % Cooling: % Normalization Factors Floor Area: Shell Area: Heating Degree Days (B65): Cooling Degree Days (B74): a Duct loss exceeds 50% of equipment capacity. Verify duct and equipment sizing inputs. REM/Rate - Residential Energy Analysis and Rating Software v13.0 This information does not constitute any warranty of energy cost or savings Architectural Energy Corporation, Boulder, Colorado.

22 Calculations Concrete Volume at Superior Wall Foundation System: Walls & Cast Concrete Columns Walls= 163 cf Column= 34 cf Total= 197 cf (1cf = yd3) = 197cf x yd3 = 7.29 yd^3 of Concrete, 4 Slab= 7.22 yd3 Slab + Superior Wall System: = 14.5 yd^3 of Concrete Comparison: Typical Concrete Foundation (Basement) Based on Same design. Walls= cf Footing= cf Slab= cf Total = cf (1cf = yd3) = cf x yd3 = 40yd^3 of Concrete Potential CO2: Calculations Include Whole Assemblies, with matching insulation specifications. Superior Wall System: Walls= 9.87 Tonnes, Slab 2.93 Tonnes; Total= 12.8 Tonnes Typical Foundation: Walls= 10.1 Tonnes, Footing 2.98 Tonnes, Slab 3.33 Tonnes; Total= Tonnes Overall Project Totals: Superior Wall System Model= Tonnes ; Typical Foundation Tonnes Extra Base Materials: Rebar at Superior Wall=.6 cf (Density of Steel=0.283 lb/in^3) (1lb=.0005 t (short tons) ( 1cf = 1728 in^3) 1728 in^3 x lb/in^3 = lb lb x 0.6= lb 294 lb x t (tons) = (.147t ) x 1.10 =.1617t Metal Studs at Superior Wall= 4cf (Density of Steel=0.283 lb/in^3) (1lb=.0005 t (short tons) ( 1cf = 1728 in^3) Attic Insulation= 638 sf x 14 = 8932 sf (1 ) Insulation Measured From Inside face of framing lb x 4 = lb lb x t (tons)= t (short tons) Trellis & Deck/ Porch lumber= Trellis= 20cf, Columns= 15.68cf; Total= 35.68cf Strapping, Interior & Exterior= 279 bf (1 Mbfm= 1000 bf) 35.68cf x 12bf= bf bf / 1000 bf=.428 Mbfm Deck/ Porch Concrete footings= 4cf 279bf / 1000 bf=.279 Mbfm 4cf x yd^3= 0.15 yd^3 ENTRY P122