Environmental Engineering Reference
In-Depth Information
rate or infiltration of air through the building envelope is of concern; both
of which are strongly affected by window construction and quality of door
seals such as weather stripping. The goal of this exercise is to quantify the
building's overall thermal performance. The audit may also assess the effi-
ciency, physical condition and programming of mechanical systems such as
the heating, ventilation, air-conditioning equipment and thermostat.
A home energy audit may include a written report estimating energy use
given local climate criteria, thermostat settings, roof overhang and solar ori-
entation. This could show energy use for a given time period, say a year, and
the impact of any suggested improvements per year. The accuracy of energy
estimates are greatly improved when the homeowner's billing history is avail-
able showing the quantities of electricity, natural gas, fuel oil or other energy
sources consumed over a one- or two-year period. Some of the greatest effects
on energy use are user behaviour, climate and age of the home. An energy
audit may therefore include an interview of the homeowners to understand
their patterns of use over time. The energy billing history from the local util-
ity company can be calibrated using heating degree day and cooling degree
day data obtained from recent, local weather data in combination with the
thermal energy model of the building. Advances in computer-based thermal
modelling can take into account many variables affecting energy use.
A home energy audit is often used to identify cost-effective ways to improve
the comfort and efficiency of buildings. In addition, homes may qualify for
energy efficiency grants from the central government.
Recently, improvements in smartphone technology have enabled home-
owners to perform relatively sophisticated energy audits of their own
homes. This technique has been identified as a method to accelerate energy
efficiency improvements.
The term energy audit is commonly used to describe a broad spectrum of
energy studies ranging from a quick walk-through of a facility to identify
major problem areas to a comprehensive analysis of the implications of alter-
native energy efficiency measures sufficient to satisfy the financial criteria of
sophisticated investors. Numerous audit procedures have been developed for
non-residential (tertiary) buildings (ASHRAE [1-5]). An audit is required to
identify the most efficient and cost-effective energy conservation opportuni-
ties (ECOs) or measures (ECMs). ECOs (or ECMs) can consist of more efficient
use of energy or of partial or global replacement of the existing installation.
When looking at existing audit methodologies, the main issues of an audit
process are
1. The analysis of building and utility data, including study of the
installed equipment and analysis of energy bills
2. The survey of the real operating conditions
3. The understanding of the building behaviour and of the interactions
with weather, occupancy and operating schedules
