Adding a new bedroom suite above the garage at this home provided a great opportunity to upgrade this existing house to make both more sustainable and comfortable.

One of the upgrades done to the original home was the insulation and sealing of the crawl space underneath it. This is referred to as a “conditioned crawl space". The vapor barrier and spray foam work together to seal off the crawl space from the dusty, moist and buggy soil.

And when we say buggy, we mean it! Look what was in the space when the retrofit began!

A sub-soil radon pipe was run under the vapor barrier and connected to this riser. The plumbing is not set up to have a radon mitigation system, as radon is not known to be high in the area, but this outlet is ready to be connected to a complete system if needed.

The old induced draft gas furnace (80%) was replaced with a much smaller sealed combustion 95% gas furnace. The fuel for the old furnace had become disconnected and was pumping exhaust air into a semi-conditioned crawl space (circa 1978). DANGEROUS!!!

The mechanicals under the floor and their duct work are now inside the thermal boundary, reducing heat loss, air leakage, and improving the operating efficiency and longevity of the equipment.

The new gas furnace is a back-up system for the more efficient electric heat pump that both heats and cools the home. The design intent is that the electric unit works from the solar system and when it can't keep up due to winter temperatures being too low, the gas is there to pick up the slack. Ideally, the furnace will run very little.

The owners have the goal of net zero energy and have been gradually transitioning their home from natural gas to electricity. They recently had this solar PV system installed.

This Navien tankless water heater serves both the existing house and the new ADU. It replaced a 40 gallon natural gas atmospheric draft water heater. The location of the old unit was such that it could have back-drafted into a space adjacent to the master bedroom, introducing hazardous gases.

A dual zone, 21.5 SEER (seasonal energy efficiency ratio), Lennox mini split was added during the remodel to service the Zoom Room and the existing master suite. This saved money, as two separate systems would have been about $7,500 more. In addition, the existing master bedroom was unconditioned and comfort was impacted because of it.

Spray foam insulation both seals and insulates the floor, walls and roof.

A vapor diffusion port was installed at the roof ridge of the Zoom Room addition. This air-tight, but vapor-open, vent allows any moisture that accumulates in the attic spray foam to escape. Building scientists are finding that moisture gets into attic foam and accumulates at the ridge. Now the vapor will migrate to and through the Tyvek and escape, improving durability.

A blower door test was done on the Zoom Room when the building envelope was complete. This is a test of building air-tightness and this ADU came in at 0.8 ACH-50 (air changes per hour at a vacuum of 50 pascals of pressure). This shows more than three times less air infiltration than the Energy Code requirement of 3 ACH50.

The Zoom Room was built above a garage and garages are not the healthiest source of air. In our heating climate, as the warmed air rises it produces the stack effect, which creates suction on the floor of the ADU. The same concept applies in the crawl space. Both the air tightness of the ADU, and the sealing of the crawl space stop unwanted air infiltration from not-so-clean sources.

An Energy Recovery Ventilator provides fresh air to the Zoom Room, which is so air-tight (0.8 ACH50) that ventilation for the occupants is a concern. The ERV can operate 24/7, ensuring the space is always getting fresh, filtered air while stale indoor air is exhausted from the space.

This device is also able to extract energy (heat) and moisture from one air stream and put it in to the other air stream. This stabilizes indoor air conditions (both temperature and humidity), preconditions the fresh air, and reduces the load on the mini-split, in both the summer and the winter.

All surfaces inside the space are cleanable (no carpet - tile, wood, quartz).

New cabinets in the Zoom Room are KCMA-certified.KCMA certification is an Environmental Stewardship Program certification that involves 22 different criteria around these 5 categories: air quality, product resource management, process resource management, environmental stewardship and community relations. Of the 110 possible points, a certified manufacturer must reach 80.

Reclaimed barn wood was used for accents at the window sills.

The decks were finished with Moistureshield composite decking with a total pre- and post- recycling content of 95%.

The beams for the stairs and landing above were made from salvaged materials. The garage door header was reused for the stair platform beams.