Environmental Engineering Reference
In-Depth Information
2. Preliminary audit stage: Global monthly consumptions are generally
insufficient to allow an accurate understanding of the building's
behaviour. Even if the analysis of the energy bills does not allow
identifying with accuracy the different energy consumers present in
the facility, the consumption records can be used to calibrate build-
ing and system simulation models. To assess the existing system
and to simulate correctly the building's thermal behaviour, the
simulation model has to be calibrated on the studied installation.
The iterations needed to perform the calibration of the model can
also be fully integrated in the audit process and can help in identify-
ing required measurements and critical issues [7].
3. Detailed audit stage: At this stage, on-site measurements, sub-
metering and monitoring data are used to refine the calibration
of the Building Energy Systems (BES) tool. Extensive attention is
given to understanding not only the operating characteristics of
all energy-consuming systems but also situations that cause load
profile variations on short and longer term bases (e.g. daily, weekly,
monthly, annually). When the calibration criteria is satisfied, the sav-
ings related to the selected ECOs/ECMs can be quantified [7-9].
4. Investment-grade audit stage: At this stage, the results provided by
the calibrated BES tool can be used to assess the selected ECOs/
ECMs and to orient the detailed engineering study.
5. Infrared thermography audit: The advent of high-resolution ther-
mography has enabled inspectors to identify potential issues within
the building envelope by taking a thermal image of the various
surfaces of a building. For purposes of an energy audit, the ther-
mographer will analyse the patterns within the surface tempera-
tures to identify heat transfer through convection, radiation or
conduction. It is important to note that the thermography ONLY
identifies SURFACE temperatures, and analysis must be applied to
determine the reasons for the patterns within the surface tempera-
tures. Thermal analysis of a home generally costs between US$300
and US$600. For those who cannot afford a thermal inspection, it
is possible to get a general feel for the heat loss with a non-contact
infrared thermometer and several sheets of reflective insulation. The
method involves measuring the temperatures on the inside surfaces
of several exterior walls to establish baseline temperatures. After
this, reflective barrier insulation is taped securely to the walls in
8-foot (2.4 m) by 1.5-foot (0.46 m) strips, and the temperatures are
measured in the centre of the insulated areas at 1-hour intervals for
12 hours. (The reflective barrier is pulled away from the wall to mea-
sure the temperature in the centre of the area that it has covered.)
The best manner in which to do this is when the temperature dif-
ferential (Delta T) between the inside and outside of the structure
