examine windows • • •
percent effi cient. Older building codes at the local level how you operate your HVAC
If you don’t have windows with
systems—those more than and enforced by the authority- system is most important.
good thermal transmittance
20-years old—are often 65 having jurisdiction, so there There are dozens of examples
(U-Factor) and solar-heat-gain
percent effi cient or less. will be different minimum EERs of things that can be done to
coeffi cient (SHGC), then you
High-effi cient furnaces, boilers depending on location and operate your existing system
should retrofi t them. Again,
and heaters are often 88 to sizes of equipment. For smaller using less energy without
follow ASHRAE’s AEDG recom-
95 percent effi cient. equipment, 15.2 EER is the best sacrifi cing comfort. The
mendations. U-Factor measures
Electric equipment is always on the market today. Larger basic premise is: Do not use
the heat transfer through a
rated by coeffi cient of perfor- equipment, such as chillers, are more energy than you
window, door or skylight and
mance, or COP, with electric rated in kW/ton Integrated Part absolutely must.
tells you how well the assem-
resistance heat being equal to Load Value. Air-cooled machines Implement setback sched-
bly insulates. The lower the
1.0. Air- or water-source heat are typically 1.2 kW/ton or lower, ules in your controls system
U-Factor, the greater resistance
pumps are typically 3.5 COP and water-cooled machines are to automatically change the
to heat fl ow and the better
(+/- 1.5 COP depending on many often 0.72 or lower. These are heating and cooling settings
the window’s insulation value.
factors, such as heat sink/ average ratings. For air-cooled when the building is not in use.
SHGC is the fraction of solar
source, compressor technol- systems 1.04 is more effi cient, Bring in only the code-required
radiation admitted through a
ogy and outdoor temperature), and 0.33 is best for water-cooled amount of outside air. Use
window, door or skylight. This
which means they are three systems. waste exhaust air to pre-heat
tells you how well the assembly
and half times more effi cient or -cool the ventilation air. Much
blocks heat caused by the sun.
than electric-resistance heat.
ENHANCE
can be done very inexpensively
The lower SHGC, the less solar
Air conditioners are rated to improve your equipment’s
heat it transmits.
many different ways, often OPERATIONS effi ciency—sometimes with
depending on the size and Tight buildings are great, as is the equipment and controls
improve equipment • • •
type of equipment. Residential highly effi cient equipment, but you already own.
After you have improved your
A/C units are rated in seasonal
insulation and windows to
energy effi ciency ratio, or SEER.
reduce your heating and
The legal minimum set by U.S.
cooling needs, the next step
law and regulated by the U.S.
is to invest in more effi cient
Department of Energy is now
HVAC equipment. Different
13 SEER. Most older units—those
types of HVAC systems are
more than 20-years old—are 6
rated using different methods
to 10 SEER. The best residential
by different authorities.
units on the market today are
Gas heating is typically rated
19 to 21 SEER.
in terms of percent effi ciency,
Commercial A/C equipment
meaning how much energy
is rated in energy-effi ciency
comes in versus how much heat
ratio, or EER, and 9.5 to 13 EER
is output. Today, most gas-
is common. Unlike the residen-
heating equipment is 80
tial marketplace, EER is set by
Circle No. 17
RETROFIT MAGAZINE // FALL 2009 63
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