Energy Audit Procedure
An energy audit consists of several steps (the process can vary according
to the type of building or facility being audited):
When the CET auditor arrives at your site, he will first give you an overview of the audit process. He
will answer any questions you have, and address any concerns or potential
problems up front. We want you to understand the entire process – only with
your participation can the audit be as effective as possible. With the goal
of achieving the best possible understanding of your situation, the auditor
will ask you questions about the building, any particular problems or concerns
you may have about it, and how you use it.
To get a residential audit underway, the auditor will usually ask your permission to connect your refrigerator
to a power-consumption meter. This device will monitor your appliance’s
power consumption for the duration of the audit – the longer the monitoring
time, the more accurate our estimate of monthly energy consumption.
The auditor will survey the building from attic to basement. He
will be measuring exterior surfaces and windows, noting insulation levels,
potential air leakage sites, light fixtures, hot water fixtures, and any
other energy-related features. All windows will be closed and locked, and
all other openings in the building closed, in order to leave the house in
a “winter-like” condition – as tightly buttoned up as it would be on a cold
winter night. All of the information noted during this tour will serve as
input for computer modeling of the building’s energy consumption, and will
guide energy-efficiency improvement suggestions.
The
blower door is a powerful tool for measuring a building’s air leakage rate and for locating many leakage sites. After
putting the building in a closed-up, “winter-like” condition, the auditor
will install the blower door in an exterior doorway. An expandable aluminum
frame is fitted to the doorway, with a nylon panel mounted over the opening
to seal it. A sleeve in the panel holds the blower –a large, variable-speed
exhaust fan with several calibrated pressure-measuring ports. A sensitive
digital pressure gauge is connected to the fan. In a typical test, the fan
is turned on, and its speed is increased until the building has been very
slightly depressurized with respect to the outdoors. By exhausting air from
the building, the fan creates a lower-pressure zone inside, which causes
outside air to leak in at an accelerated rate. This situation yields two
types of information. By measuring how fast the fan must be set create a
precise pressure drop within the building, the auditor can calculate the
amount of outside air that would leak in under normal conditions – very useful
for modeling the building’s energy consumption. In addition, the low pressure
created by the fan serves to exaggerate the building’s normal leaks. Take
a quick tour of the building with the auditor while the fan is running – chances
are you’ll find previously hidden air leaks just by holding out your hand
to feel the draft! The blower door is an invaluable guide to airsealing
efforts.
