Common Issues

Question 1

Non-routine adjustments

Answer 1

Non-routine adjustments are needed where a change occurs in equipment or operations that affect the energy use within the measurement boundary. Such change occurs to a static factor, not to independent variables. These types of changes or non-routine events may occur during any M&V period, and changes may include facility size, equipment efficiency, capacity, operating sequence, or any other element that results in changes in energy use within the measurement boundary.

For example, an EEM improved the efficiency of a large number of light fixtures. When additional light fixtures were installed after the EEM installation period, a non-routine adjustment was made. The energy of the extra fixtures was determined and added to the baseline energy so that the EEM’s savings were still reported.

Question 2

Examples of Changes in Static Factors Requiring Non-Routine Adjustments

Answer 2

Significant equipment problems or outages, facility shutdowns, or atypical operations

Amount of space being heated or air conditioned

Type of products being produced or number of production shifts per day

Building envelope characteristics (new insulation, windows, doors, air tightness)

Amount, type, or use of the facility’s and the users’ equipment
Indoor environmental standards (e.g., light levels, temperature, ventilation rate)

Occupancy type, or operating schedule

Question 3

Demand savings

Answer 3

Demand savings at a facility can provide capacity savings for the providing utility and cost savings to the facility. Demand savings are determined and valued differently under different circumstances, and details must be defined in the M&V Plan. Demand savings are typically realized when EEM’s reduce the facility’s overall demand during specific periods defined by the providing utility but can be based on other criteria such as site-level demand management goals.

Question 4

Electricity Measurements

Answer 4

To measure electricity accurately, measure the voltage, amperage, and power factor, or true Root Mean Squared (RMS) wattage with a single instrument. RMS power meters and data loggers should be used wherever possible. RMS measurements account for normally occurring distortions in alternating current as well as changes in power factor.

Question 5

Data issues

Answer 5

Missing or lost data

Use of monitoring and control systems for data collection

Question 6

Statistics for M&V

Answer 6

Using Confidence Levels & Confidence Intervals
Expressing Savings Uncertainty:
The uncertainty in any reported savings value is properly expressed as the range within which we expect the true value to fall, with some level of confidence.
For example, a savings calculation may result in savings of 5,000 units with an uncertainty of
±200 units, with a confidence of 95%. Such a statement means that we are 95% confident that the true value of savings is between 4,800 and 5,200 units or are 5,000 units +/- 4%. The confidence interval is 5,200 – 4,800 = 400 units, and the savings uncertainty is 200 units.

Evaluating Results

Significant Digits & Rounding
An example of an exact number could be a utility rate. If a local power company’s rate was $0.06 per kWh and Company X used 725,691.0 kWh one month, the utility bill would be $43,541.46, not $40,000 per rounding rule. This is because the utility rate is exact; it can be represented as $0.06000̅ per kWh.

Question 7

What is an ESPC

Answer 7

An energy services performance contract (ESPC) is a contractual agreement between an energy services company (ESCO) and a facility owner. The ESCO installs EEMs at the facility, and the owner pays the ESCO back for their investment over a period of years from the energy cost savings generated from the project. The ESCO typically monitors the performance of the project for the life of the contract and reports verified energy savings periodically.

Question 8

Persistence of Savings

Answer 8

Persistence of energy savings can be achieved beyond the M&V reporting period by performing follow-on efforts that build on M&V. One approach is “Monitoring, Targeting, and Reporting” (MT&R), which can seamlessly follow the M&V process. If Options B and C have been used for verifying savings, the project will have metering in place for the routine measurement of consumption. More importantly, models will

also have been developed that correlate energy use with driving factors such as weather. These same models can be “re-tuned” to estimate energy consumption that accounts for EEM installation. This enables a periodic comparison of actual and expected consumption, which will readily reveal and quantify any loss of EEM effect (or unrelated waste), enabling prompt remedial action to be taken in cases where the unexpected avoidable cost is deemed significant.