Page 31 - Green Builder Magazine Sept-Oct 2021

DOE Annual Building Science Roundup
SILVER LININGS

loft-level bedrooms to supplement the pump. Testing of the cutting-edge $1,000
100 percent LED light fixtures. The light- HRV coil has been so successful that the
ing is controlled by the same internet- and two backup systems (the fan coils and the
voice-activated system that controls the hydronic floor heating and cooling) may
window blinds, the HVAC and the ventila- not be needed.
tion systems, which are also controlled by The air-to-water heat pump also warms
humidity and CO2 sensors. an 80-gallon tank for domestic hot water.
The system includes a 40-gallon buffer
IT’S ALL ABOUT THE AIR tank to prevent heat pump short-cycling.
One of the most unique aspects of the home The HRV unit provides ventilation
is its HVAC systems. The home’s primary throughout the house by drawing stale
space conditioning system is a highly effi- and moist air from the bathrooms and
cient (COP 3.92 heating, 6.75 cooling) air- laundry, and supplying fresh conditioned
to-water-source heat pump that provides air to the living and sleeping rooms. The
space heating and cooling in three ways. It air is filtered through MERV 13 filters.
supplies hot or chilled water to a coil within The HRV has wireless controls and can
the supply side duct of the heat recovery be operated remotely through the home’s
ventilator (HRV). The HRV distributes the automation system. It has humidity-trig-
heated or chilled air via ventilation ducts. gered sensors in the shower rooms and
The air-to-water heat pump also provides CO2-triggered sensors in the living room.
hot and chilled water to fan coil units It can also be set for timed or continuous
located in the first-floor master bedroom operation. The air intake damper can be
and the second-floor library, which is open closed in the event of smoke or bad out-
to the first-floor living space. door air quality. The boost setting can be
There is also a third heating system, activated to remove forest-fire smoke or
an in-floor hydronic system, which also other contaminants that might come in
uses water heated by the air-to-water heat when doors are opened.

NO GLASS NEEDED.
Vinyl-framed windows have
U-Factors of 0.14 to 0.16.

PHOTOVOLTAIC POSITIVE.
A 12.4-kilowatt (kW) solar system
gives the home a -19 HERS rating.

COURTESY OF ZIGZAG MOUNTAIN ART
THICK THINKING. The home’s
6.5-inch walls include two layers
of oriented strand board (OSB).

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