ABSTRACT
This ten-townhome project was initiated and led by the City of Issaquah in collaboration with county, utility, and university partners to demonstrate what is possible for production housing. “All the zero energy projects prior to this were of unlimited budget. I wanted to prove it was available to everyone,” said Aaron Adelstein, Director of partner organization Built Green of King & Snohomish Counties. The project was completed in 2011 for a construction cost of $2.4 million. The homes sold for 25 to 30 percent above market rate. (See Box 17.1 for a summary of project details.) Box 17.1: Project overview https://www.niso.org/standards/z39-96/ns/oasis-exchange/table">
IECC climate zone
4C
Latitude
47.54°N
Context
Urban, 18 miles southeast of Seattle
Size
10 townhomes, 13,401 ft2 (1,245 m2)
Unit size 800 ft2–1,750 ft2 (74 m2–163 m2)
1-, 2-, and 3-bedroom units
Height
2–3 stories
Program
Single-family residential (attached)
HERS Score with PV
0 to –12
ACH at 50 pascal
1.8 to 2.5
Occupants
About 20
Energy use intensity in 1 unit (February 1, 2012 to January 31, 2013)
EUI: 21 kBtu/ft2/year (66.3 kWh/m2/year)
Net EUI: –1 kBtu/ft2/year (–3.2 kWh/m2/year)
Certifications
ILFI Net Zero Energy; Built Green Emerald-Star; Salmon-Safe; WaterSense
Note: See Table 17.1 for net zero energy performance of eight units over a two-year period.
Energy performance for the trellis and eight of the nine occupied units https://www.niso.org/standards/z39-96/ns/oasis-exchange/table">
Annual Averages (kWh)
Unit size
Consumption
Production
Net Energy
1 BR
3,920.5
5,606.5
–3,666
1 BR
5,170.5
6,250.5
–2,414
2 BR
7,923.5
7,626
354
2 BR
9,065.6
7,953.5
2,947.1
3 BR
9,308
8,514
1,543
3 BR
9,222.5
8,509.5
1,298
3 BR
9,115
9,493
2,407
3 BR
7,096.3
8,275.3
–2,358
Trellis
5,825.6
513.6
–673.9
TOTAL:
–562.8
Source: Office of Sustainability / City of Issaquah
Note: Data is the one-year average for April 2013 to April 2015. The data for the ninth unit was not available at press time
