Environmental Engineering Reference
In-Depth Information
of situations [7-8]. The aim of benchmarking is to answer this question.
Benchmarking mainly consists of comparing the measured consumption
with reference consumption of other similar buildings, or it is generated
by simulation tools to identify excessive or unacceptable running costs.
As mentioned before, benchmarking is also necessary to identify build-
ings presenting interesting energy-saving potential. An important issue
in benchmarking is the use of performance indexes to characterise the
building.
These indexes can be
1. Comfort indexes, comparing the actual comfort conditions to the
comfort requirements
2. Energy indexes, consisting of energy demands divided by heated/
conditioned area, allowing comparison with reference values of
indexes coming from regulations or from similar buildings
3. Energy demands, directly compared to 'reference' energy demands
generated by means of simulation tools
9.4.2.1 Walk-Through or Preliminary Audit
The preliminary audit (alternatively called a simple audit, screening audit
or walk-through audit) is the simplest and quickest type of audit. It involves
minimal interviews with site operating personnel, a brief review of facility
utility bills and other operating data and a walk-through of the facility to
become familiar with the building operation and to identify any glaring
areas of energy waste or inefficiency.
Typically, only major problem areas will be covered during this type of
audit. Corrective measures are briefly described, and quick estimates of
implementation cost, potential operating cost savings and simple payback
periods are provided. A list of ECMs or ECOs requiring further consider-
ation is also provided. This level of detail, although not sufficient for reach-
ing a final decision on implementing a proposed measure, is adequate to
prioritise energy efficiency projects and to determine the need for a more
detailed audit.
9.4.2.2 General Audit
The general audit (alternatively called a mini-audit, site energy audit,
detailed energy audit or a complete site energy audit) expands on the pre-
liminary audit described earlier by collecting more detailed information
about facility operation and by performing a more detailed evaluation of
ECMs. Utility bills are collected for a 12- to 36-month period to allow the
auditor to evaluate the facility's energy demand rate structures and energy
usage profiles. If interval meter data are available, the detailed energy
