|Location: Issaquah Highlands|
|Star Level: 5-Star|
|Checklist: Single Family New Construction|
|Verifier: Tom Balderston|
|Site and Water||183|
|Indoor Air Quality||162|
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Case Study written by Tom Balderston
Built Green 5-star has returned to Issaquah highlands this year with the completion of the model home at Sun Ridge, a neighborhood development that will consist of 35 new homes. The model home contains many Built Green features, and is one of the first market rate projects in Puget Sound to include 3.2 kW Solar PV systems as standard equipment. Judging by sales from the first two weeks, buyers are responding enthusiastically to the solar home concept.
Site and Water
This project includes 35 detached single-family homes less than ½ mile from the very walkable Issaquah Highlands village featuring excellent transit and all kinds of fun and exciting services. The landscaping emphasizes drought tolerant and native plants. There are small lawns in some of the rear yards which utilize drought tolerant grass species, as well. Select areas contain impervious driveways and sidewalks, and the entire site drains to in-street bioswales integrated into the parking strips. These are designed for 95% infiltration. Overflow in wet periods goes to the large DOT pond at the base of the hill below, which then re-used for irrigating public and street planting areas every year.
Extensive efforts were taken by the developer to preserve and protect nearby habitats. The forest buffer along the east and south sides of the development is all native vegetation, and a mitigation and development agreement created larger permanent green space in another part of the city. It is the intent of the builder to also certify these homes under the EPA WaterSense New Homes program. Faucets and showerheads were tested at 1.0 and 1.75 gallons/min, creating excellent hot water and water savings. In addition, the piping layout is set up with short runs to conserve water and improve the performance of the system.
The model home was evaluated from the planes with a REM RATE energy model, which predicts a 43% energy savings overall compared to the same house built to 2012 WA State Energy Code standards. The home is heated by high efficiency condensing tankless boilers, with radiant floors using a warm board product that responds quickly to changes in temperature and spreads the heat out. Approximately half of the homes in the development will have this system, with the other half having a 95% efficient furnace and forced air duct system.
The homes are insulated to meet the 2012 Washington Code levels, with the exception that the vaulted ceilings use an R42 hybrid spray foam and batt insulation that exceeds the code. Each home is provided with a 3.2 KW solar PV system, which provides approximately 20% of the energy used by the home annually. The roof design easily accommodates expansion, so the homes are net zero energy ready. The new SMA inverters have an "off grid' switch, so that if there is a power outage, the owners can turn a switch to disconnect from the grid and employ their own power.
The interior cabinets, doors, custom shelving, and windows are manufactured by Ichijo and meet the stringent JAS standards in Japan for low formaldehyde and VOC emissions. They have a high recycled content with composite wood and mdf cores. The whole house ventilation system includes fresh air inlet ports in the bedrooms and Panasonic whisper line fans. These were tested and commissioned for air flow and proper ducting. The garages include exhaust fans that are tied to the door opener. The garages were also pressure tested for good sealing and separation from the house. The exterior includes a weather resistive barrier inspected by the third party verifier.
The project documented a 75% recycling diversion rate for construction site waste. The interior trim detailing is very simple in order to reduce material. The home also uses a new CertainTeed fiber cement siding product with a high recycled content.
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