Built Green Net Zero Group Entry

West Seattle Emerald Star

Project Details

Builder: TC Legend Homes
GSF: 3,160 sq ft
Completion: October 2017
Location: Seattle, WA

Energy Performance: Home Energy Rating System (HERS) score of zero with solar PV (41 without PV)

This West Seattle home is a three-story, 3,160 square foot net-zero energy home located on an urban infill lot. It features a ground floor one-bedroom mother-in-law apartment with three additional bedrooms on the main two floors. Flexibility was key in the design to allow the house to continue to be functional as the homeowners' young family grows. With that in mind, there are "flex" spaces on each floor, right-sized bedrooms, a generously sized utility room, and ample outdoor spaces.

The builder, homeowners, and Built Green verifier met early in the process to plan out how the home would meet the many stringent Emerald Star requirements. TC Legend Homes dedicated one of its team members to track documentation, source materials, and act as the liaison between the builder, homeowner, and verifier during the construction process. This project is only the second home in Seattle to meet the stringent requirements of the Emerald Star checklist!

Energy Efficiency

  • Home Energy Rating System (HERS) score of zero with solar PV (41 without PV)

  • Walls: R-29, 6" Graphite SIPs taped at all interior and exterior joints

  • Roof: R-49, 10" Graphite SIPs taped at all interior and exterior joints

  • Foundation: R-23 ICF stem walls, R-20 rigid foam under slab

  • Windows: triple-pane, wood-framed, low-e windows, U=0.14

  • Air sealing: 0.48 ACH 50

  • Ventilation: Zehnder HRV

  • HVAC: Chiltrix air-to-water heat pump w/ 4.5 COP for in-floor radiant hydronic heat on ground floor and ceiling-mounted air distribution heads on second and third floors

  • Hot water: Chiltrix air-to-water heat pump with tank storage

  • Lighting: 100% LED

  • Appliances: ENERGY STAR refrigerator, clothes washer, range hood; induction cooktop

  • Solar: 9.9-kW PV

  • Two electric vehicle charging stations (one in garage and one outside)

  • Energy Star v. 3.1 Certified

  • DOE Zero Energy Ready Home Certified

Health and Indoor Air Quality

  • Low- and no-VOC paints and finishes

  • Low- and no-VOC adhesives and sealants

  • PVC alternatives used throughout home

  • EPA Indoor airPLUS certified

  • Fully insulated garage air-sealed from house with automatic exhaust fan

  • No added urea formaldehyde wood products

  • No combustion appliances in house

  • Fresh air supply to all bedrooms