Doug Parker wanted to insulate his Boulder,
Colo., home from rising energy prices as he looks
toward retirement. His e;ciency retro;t maintains amenity at a fraction of the energy cost.
Audit programs nationwide have shown how di;cult it is for homeowners to move beyond the audit
to implementation. Some local entities have responded. Home Performance with Energy Star, for
instance, is working with utilities to connect homeowners with certi;ed contractors.
auditor can let you know which of your appliances is using more than its share of energy.
3) ;e building envelope comprises several key components.
Air sealing is usually one of the ;rst recommendations for older homes. ;e thermal
pressure boundary is generally located at the
level of the ;nishes ; drywall, trim and ;ooring ; with the insulation and moisture barriers behind. Old homes o;en leak at a rate of
1.0 natural air changes per hour, meaning that
you pay for inside heating or cooling to o;set
outside temperatures once every hour. Much
of the leakage may be occurring around a;ic
hatches, bath fans, recessed lights and top plates
at the ceiling. ;ese should be sealed in the a;ic
before more insulation is piled on top of them.
Insulation is o;en performed in tandem
with air sealing. ;ere is a law of diminishing
returns with greater insulation (“R-value”), so
identify the least-insulated parts of the house
and improve them ;rst. Blown cellulose or
;berglass ;lls gaps and, if installed at high
enough density, as in a wall cavity, reduces the
air in;ltration that occurs between the ba;s of
conventional insulation. You can blow insulation in a;ics, or into walls through “drill and ;ll”
from outside or inside, depending on what kind
of holes you want to patch. Rigid insulation,
applied to the wall sheathing, reduces heat loss
through studs and headers. Evaluate your ;oor
or your crawlspace/basement to make sure
insulation is continuous around your thermal
boundary in a heating-dominated climate.
Use as much insulation as you can ;t;
space will be the limiting factor in many of
Windows, doors and skylights are where
the cost-e;ectiveness of greater insulation
generally comes into dispute, as a high-tech window replacement is expensive and
can have a payback as long as your mortgage. Consider moveable insulation that ;ts
tightly against the window frame. If heat loss
from windows is causing you to crank your
thermostat, comfort alone might justify the
expense. Skylights have traditionally been
energy losers, but the new tubular skylights
A deep energy retro;t that moves beyond quick ;xes
Copyright © 2009 by the American Solar Energy Society Inc. All rights reserved.
provide daylighting with minimal energy loss.
4) Heating and cooling systems are typically oversized in older houses. If you are tightening and insulating your house, you may get
away with a signi;cantly smaller system or a
di;erent type of system altogether.
Parker subjected his system to a “
duct-blaster” test and found that it leaked almost
as fast as the test fan could blow. A;er sealing all his accessible ductwork, he divided his
house into four zones, each controlled by a
programmable thermostat. He replaced his
80 percent-e;cient furnace with a 95 percent-e;cient one “right-sized” for his home through
calculations in the Air Conditioning Contractors of America Manual J ( acca.org).
He addressed his cooling problem with a
14 SEER air conditioner. It was not the most
e;cient one available, but he had his utility
install a “savers’ switch,” allowing the utility to
turn o; the compressor for 15-minute intervals
during peak hours. It saves him as much energy
as a more expensive air conditioner, and he
says he doesn’t notice when it goes o;.
If you already have a baseboard electric
system or if your furnace is ine;cient and
your ducts are outside the thermal envelope,
look into air-source or ground-source electric heat pump options. ;ey can be ductless,
and they pair well with PV. ;ey increase the
e;ciency of electric heating to the point at
which it competes with natural gas in terms
to fundamental load reduction and renewable energy supply
has paybacks that go beyond dollars.