Case Study

Vital Stats Location: Seattle - Beacon Hill Star Level: 5-Star Checklist: Single Family Size: approx. 1,700 square feet Section Points Site and Water 125 Energy Efficiency 112 Indoor Air Quality 133 Material Efficiency 136 Size Multiplier 1.10 Total Score 557

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Dwell Development – 1756, 1758, 1760, & 1762 18th Avenue S
Seattle, WA

This month’s featured projects are four, 5-Star single-family homes in the Beacon Hill neighborhood of Seattle. Dwell Development has created a community of single-family homes that balance sustainable building with modern design. During construction, Dwell achieved a 90 to 95 percent waste diversion rate and salvaged a high percentage of lumber that was reabsorbed into the surrounding neighborhood. In the energy field, two of the homes feature an 800 watt photovoltaic system and all four tested to be 32 percent more efficient than code. Additionally, the project incorporates a variety of locally produced and recycled materials in both the interior and exterior finishes.

Site and Water Protection

• Used rain barrels and green roof planters, rain barrels will provide 100 gallons of water storage per unit
• Limited plants in landscaping, instead used gravel and drought tolerant grasses
• Rainwater collection and extensive pervious surfaces will provide 100 percent of site’s irrigation needs
• Use of low-toxic outdoor materials for landscaping such as stone and lpe decking
• Limited turf grass to less than 25 percent of landscaped area
• Selected lower flow 1.7 gallon per minute (gpm) kitchen and 1.1/1.5 gpm bathroom faucets
• Used dual flush toilets in all bathrooms
• No garage used on two homes, the other two homes used small 1-car garages
• Overall design creates enhanced outdoor space that encourages community among residents

Energy-Efficiency

• Two homes feature 800 watt PV system, 2 homes pre-wired
• Envelope 10 percent more energy efficient than Washington energy code
• Blower door test demonstrated air leakage ranging from 0.15 - 0.22 ACH
• 32 percent reduction in space conditioning energy over IECC04
• Homes also certified through Energy Star Northwest
• Opted to use natural, updraft cooling instead of air conditioner
• Used high-efficiency hydronic heating system with separate zones for sleeping and living
• Installed on-demand hot water heating for space heating
• Energy Star front loading washers, gas clothes dryers, dishwashers, refrigerators, and heating equipment

Indoor Air Quality

• Chose wood floor, sealed concrete, and ceramic in lieu of carpet
• Used urea formaldehyde-free insulation, cabinets, and trim
• During construction, took measures to reduce moisture and construction dust
• Trained subcontractors on healthy jobsite plan and workplace safety
• Low-VOC/low-toxic paints used for all interior surfaces
• Used sealed combustion heating and hot water system
• Installed whole house radiant heating system
• Two units have no garages, others have garage sealed with exhaust fan
• Used Greenguard certified EcoBatt insulation
• Used sloped sill pan with end dams and back dams for windows, sills, and exterior doors
• Hose tested windows to ensure seals

Material Use

• Achieved 90 to 95 percent overall construction waste diversion rate
• Invited neighborhood to use salvaged siding, beams, and some framing lumber from site
• Chose locally produced cedar siding, framing lumber, and concrete
• Reduced interior walls through open living space design
• Used domestic birch panels for interior doors
• Chose Ceasarstone for countertops
• Used concrete subfloor as finish floor
• Used fiberglass windows as an alternative to vinyl
• Selected a 50-year warranted siding product

Still Images

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Photos courtesy of Tucker English

 

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