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When an organization makes a commitment giving higher priority
to reducing energy costs and protecting the environment, it is important
to measure the results of these efforts. Senior managers need this
information to justify budgets for capital improvements to produce
long-term benefits and to determine the benefits received from these
investments. These measurements can provide feedback on whether
investments are producing the anticipated benefits. If they are
not, monitoring may identify reasons for the shortfalls and help
facility managers improve performance with other projects.
Some of these measurements are relatively easy to quantify. For
example, energy and water quantities and associated costs are provided
monthly to the facility manager, and the cost-benefit of some energy
and water reduction measures can be readily determined from those
bills. Levels of specific indoor air pollutants can be measured,
but the cost-benefit determination is less straightforward. Many
issues are not so readily quantified, for example: durability, maintenance,
drought-tolerant landscaping, and indoor environmental quality.
For projects financed by Energy Savings Performance Contracts, or
ESPCs, an annual verification of cost savings should be provided.
Instrumentation and measurement plays a role throughout the process,
from measuring baseline energy use, to commissioning new systems,
to optimizing long-term performance and serving as the basis of
performance metrics and contractor payments.
The International Performance Measurement and Verification Protocol
(IPMVP) provides a wide range of measurement and verification (M&V)
alternatives, including stipulation based on engineering calculations,
metering, and using the results of a short-term test to calibrate
computer models. In general, more detailed and labor-intensive efforts
yield more information, but the value of the information must be
weighed against the cost of the M&V program. Simple, low-cost
measurements are often adequate and cost effective. Energy management
system tracking features are an effective way to collect consumption
and demand information.
Two documents have been published by IPMVP: Volume I - Concepts
and Options for Determining Energy Savings, and Volume II - Concepts
and Practices for Improved Indoor Environmental Quality. They are
available to download from the IPMVP
Web site.
Factors affecting the costs of measurement and verification include
these:
- Number of energy measures implemented
- Size and complexity of energy conservation measures
- Interactions between energy conservation measures
- How risk is allocated between the owner and the contractor in
a performance contract.
The appropriate M&V strategy can be determined by assessing
the project's complexity and the way risk is allocated between an
energy service company and its customer. Risk allocation refers
to whether the contractor (a) is responsible only for equipment
performance (efficiency), or (b) also bears some risk related to
operational factors, such as uncertainty in the load.
In an ESPC, the M&V program would evaluate all measures of
performance in the contract. For example, a lighting contract might
include measurements of both electric power consumption and lighting
levels.
Electrical Energy
Determining electrical energy consumption is relatively straightforward,
and an ordinary electrical meter is adequate for simple daily, weekly,
or other longer electrical energy determinations. If consumption versus
time is required, either the manual method of taking frequent meter
readings or automated data collection is necessary. For the collection
of time-based information, split-core current transducers and power
transducers can be installed without disconnecting power. Data loggers
can be used to collect data, which can then be downloaded as needed.
Electrical Demand
Time-based information is essential if electrical demand is to be
determined. For this purpose, it is essential to have the appropriate
software to determine the "peak" value. The peak can be a time-averaged
value over a sliding 15- or 30-minute time frame in which single or
multiple spikes are not indicative of the peak as measured by the
local utility. Others simply measure the highest demand in a month
and base demand charges on that value.
Chilled Water and Hot Water
Btu meters can be installed to determine the energy consumption of
HVAC equipment lines: chilled water, hot water, and steam. Simple,
reasonably accurate meters can be installed "hot," that is, without
needing to turn off the system.
Indoor Environmental Quality (IEQ)
Measuring the benefits of IEQ is difficult but not impossible. IEQ
is an aggregate of the environment created by air quality, light,
noise, temperature, and humidity conditions. Indoor air quality has
received the most attention recently, but the other factors are also
important contributors to the sense of well being of facility occupants.
There are methods and instrumentation for measuring pollution levels
(including carbon dioxide, carbon monoxide, volatile organics, ozone,
particulates, and other air emissions), light levels, noise levels,
and indices of comfort, such as mean radiant temperature. Employees
can be surveyed to determine their reactions to their indoor environment
and their perceptions of its effects on their performance and sense
of satisfaction.
It is also important to assess objectively the impacts on employees'
performance of measures designed to improve IEQ. Although these
measures are more indirect, some of the statistics that may be examined
include absenteeism, sick days, and drops in productivity. To make
sense of this information, the data must be collected for a significant
period of time, both before and after the changes. The Rocky Mountain
Institute and Pacific Gas and Electric have conducted several studies
linking improvements in IEQ to improvements in productivity. In
most federal facilities, for example, the cost-per-square-foot of
the workforce is 20 times greater than the cost-per-square-foot
of the building. This huge difference readily demonstrates that
investments in IEQ that improve productivity are likely to be rapidly
recovered.
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