Page 304 - Mechanical Engineers' Handbook (Volume 4)

5 Presenting the Results of an Energy Audit 293

the time. Additional lighting controls such as automatic dimmers can reduce energy con-
sumption by making better use of daylight. Attention should also be given to the efficiency
of the luminaire and (for indoor lighting) interior wall surfaces in directing light to the areas
where it is needed. Reference 1 provides data for estimating savings from more efficient
luminaires and more reflective wall and ceiling surfaces.

4 EVALUATING ENERGY CONSERVATION OPPORTUNITIES
The auditor’s evaluation of energy conservation opportunities should begin with a careful
consideration of the possible effects of energy conservation measures on safety, health, com-
fort, and productivity within a facility. A conscientious effort should be made to solicit
information from knowledgeable personnel and those who have experience with conservation
measures in similar facilities. For energy conservation measures that do not interfere with
the main business of a facility and the health and safety of its occupants, the determinant of
action is the financial merit of a given measure.
Most decisions regarding the implementation of an energy conservation measure are
based on the auditor’s evaluation of the annual dollar savings and the initial capital cost, if
any, associated with the measure. Estimation of the cost and savings from energy conser-
vation measures is thus a critically important part of the analytical work involved in energy
auditing.
When an energy conservation opportunity is first identified, the auditor should make a
rough estimate of costs and savings in order to assess the value of further investigation. A
rough estimate of the installed cost of a measure can often be obtained by consulting a local
contractor or vendor who has experience with the type of equipment that the measure would
involve. For commercial building energy conservation measures, a good guide to costs can
be obtained from one of the annually published building construction cost estimating guides.
The most valuable guides provide costs for individual mechanical, electrical, and structural
components in a range of sizes or capacities. Rough estimates of the annual dollar savings
from a measure can use simplified approaches to estimating energy savings such as assuming
that a motor operates at its full nameplate rating for a specified percentage of the time.
If further analysis of a measure is warranted, a more accurate estimate of installed cost
can be developed by preparing a clear and complete specification for the measure and ob-
taining quotations from experienced contractors or vendors. In estimating savings, one should
be careful to calculate the measure’s effect on energy use using accurate data for operating
schedules, temperatures, flow rates, and other parameters. One should also give careful con-
sideration to the measure’s effect on maintenance requirements and equipment lifetimes, and
include a dollar figure for the change in labor or depreciation costs in the savings estimate.

5 PRESENTING THE RESULTS OF AN ENERGY AUDIT
Effective presentation of the energy audit’s results is crucial to achieving energy savings.
The presentation may be an informal conversation with maintenance personnel, or it may be
a formal presentation to management with a detailed financial analysis. In some cases the
auditor may also need to make a written application to an outside funding source such as a
government agency.
The basic topics that should be covered in most presentations are the following:
1. The facility’s historical energy use, in physical and dollar amounts broken down by
end use.