Page 21 - Green Builder Magazine Sept-Oct 2021

DOE Annual Building Science Roundup
SILVER LININGS
Hybrid Performer

At Walnut Farm, mixed insulation types and optional solar
arrays promise near net-zero living.

UILDER JAY EPSTEIN, owner one of the homes at Walnut Farm, a Options for homes at Walnut Farm
of Healthy Communities in Wil- 2,227-square-foot, two-story, three-bed- include a storage battery. The inverter
Bliamsburg, Virginia, has been room, 2.5-bath dwelling, for a 2020 DOE is upgraded to allow for a plug-in elec-
interested in energy-efficient homes for Housing Innovation Grand Award in the tric vehicle (EV) and an inverter transfer
several years. He sees Walnut Farm, the Production Home category. module can be added to allow for battery
state’s first Zero Energy Ready Home Of the eight Healthy Communities or generator backup.
(ZERH) community, as the culmination homes completed to date, five homeown-
of a lifetime of improving his craft. The ers have chosen to install solar panels at ENERGY EFFICIENCY
75 single-family production homes are construction. This includes the award- TIMES TWO
one- and two-story midwestern crafts- winning model, which has a 5.94-kilo- To achieve zero energy, power production
man designs that are loaded with big watt (kW) array of 18 solar panels on the is half of the equation; an energy-efficient
front porches and wood trim details out- roof that should cover most of the home’s home is the other half.
side, and energy efficiency, durability and electric needs. With the photovoltaic (PV) Healthy Communities starts with a
indoor air quality details inside. system installed, the dwelling achieves a highly insulated thermal building enve-
“Walnut Farm is unlike any commu- Home Energy Rating System (HERS) score lope. Epstein uses a combination of
nity Healthy Communities has built in of 9. Even without the PV, the home scores insulation types in the home’s 2-by-6
the last 40 years,” he says. “Each previ- a 46, far lower than typical new homes. advanced framed exterior walls. The wall
ous community has been a building block With PV the home should save its owners cavities are filled with sprayed cellulose,
and learning lesson that has brought us to an estimated $2,100 annually compared or a “flash and batt” technique is used.
today’s ‘product.’” to a home built to the state’s energy code, The latter consists of spraying one inch
The judges must have agreed with which is equivalent to the 2015 Interna- of open-cell spray foam into the cavities to
this assessment, because they selected tional Energy Conservation Code (IECC). seal the framing to the exterior sheathing,

Average Monthly Energy Bill
$30 Climate IECC,4A, mixed-humid

Calculated
Dry (B) Moist (A)
Marine (C)
7
6
Annual Savings 4 6
$2,100 5 5

Calculated versus typical new homes 4

3
2 3
2 2
Saved in the first 30 Years
$87,500 1

Includes fuel escalation rates,
2019 EIA Energy Outlook

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