Page 35 - Green Builder Sept-Oct 2020 Issue
P. 35
DOE Annual Building Science Roundup A BETTER WAY
U.S. Department of Energy’s Zero Energy Climate changer. The home’s intense
Ready Home (ZERH) program. temperature control stems in part from a shell of
The company constructed its rst zero foam insulation, R-22 insulated concrete form
energy home in and has built zero (ICF) block walls, and open- and closed-cell spray
energy custom homes to date. Zero Net foam in the walls, ceiling and attic.
Now, a partner in the DOE ZERH program CREDIT: COURTESY OF ZERO NET NOW
since its inception in
, has committed to
certifying all of its homes to the DOE Zero-
Energy Home label.
The company routinely achieves among
the lowest Home Energy Rating System
(HERS) scores in the country. On the HERS
index, a typical new home built to code
would achieve roughly to
, while a
net zero energy home would score under
On-site power. A roof-mounted
photovoltaic system offsets
electricity usage and cuts energy bills
to nearly zero on most months, and
leads to a utility bill credit on others.
CREDIT: COURTESY OF ZERO NET NOW
. This is made possible by building a very a -inch concrete core, with about . inch
ecient home, and then adding solar panels of rigid EPS on each side, for a total wall
that will produce as much energy as the insulation value of R-.The solid walls are
home uses over the course of a year. Zero airtight and the continuous foam layers on
Net’s homes often score below before the either side limit thermal bridging or heat
addition of the photovoltaic panels. transfer through the walls.
With this home, Zero Net Now achieved a The ICF blocks were used in the below-
HERS score of without photovoltaic and grade basement walls and the above-grade
minus when the
. kW of solar panels walls, providing a continuous thermal barrier
were added. from the footing to the roof line. They also
provide R- of slab-edge insulation around
BUILDING BLOCKS the basement oor slab.
The homes start with the highly insulating Before pouring the oor slab, the builder
properties of insulated concrete forms sprayed . inches (R-) of closed-cell spray
(ICFs). The
.-inch-wide blocks enclose foam directly onto the gravel base, where the
www.greenbuildermedia.com September/October 2020 GREEN BUILDER 33
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