Measurement and verification (M&V) is critical to accurately assess energy savings from an energy conservation measure (ECM). Because energy savings reflect the absence of energy use or demand, determining accurate calculations requires an understanding of the baseline energy use as well as the pertinent factors that influence energy demand across the project scope.
In a nutshell, the energy savings equation is the following:
Energy Savings = Baseline Energy Use – Post-retrofit Energy Use +/- Adjustments
Under a well-structured M&V process, the conditions before and after ECM implementation are well understood and documented to ensure reliable comparisons that incorporate factors with significant influence on energy consumption.
Establishing a Baseline
The baseline represents the energy usage prior to ECM implementation and is compared against the post-retrofit energy usage to determine savings. To follow M&V best practices, the baseline period should cover a complete operational cycle— from minimum energy demand and consumption to the maximum— that immediately precedes the commissioning of the new ECM.
The length of the baseline period depends on the scope of the ECM project and the purpose of M&V reporting. Under the International Performance Measurement and Verification Protocol (IPMVP), M&V options range from an isolated equipment retrofit to integrated whole facility energy processes. Therefore, the various M&V options have different measurement boundaries to address the scope of the specific project. It is important that the baseline period be an appropriate timeframe to incorporate all of the significant factors that influence the M&V measurement boundary. For instance, whole facility energy consumption can be heavily influenced by weather, necessitating a baseline period of an entire year. On the other hand, a lighting retrofit that is more so dependent on hours of operation may only require a baseline period of a couple of weeks to capture all the parameters affecting its measurement boundary.
It is vitally important to document the baseline period conditions because they will likely differ from those during the reporting period that follows ECM installation. The collected data should encompass information on equipment impacted by the ECM as well as the independent variables and static factors involved in the M&V process. This should include specs on equipment and operational procedures as well as factors like ambient temperature and production volume. Documenting these baseline conditions enables reliable comparisons between baseline and reporting periods, and highlights areas where adjustments may need to be included in energy savings calculations.
Including adjustments in the energy savings calculation ensures consistency between the baseline period and the reporting period that follows ECM installation. Adjustments are divided into two categories: routine and non-routine adjustments.
Routine adjustments are factors impacting the measurement boundary that is expected to change routinely during the reporting period. To be included in the energy savings calculation, the factor should have a significant impact on energy consumption. Example factors include weather and production volume and should be evaluated to determine their influence on energy demand over the reporting period.
Non-routine adjustments involve factors expected to stay static. This includes adjustments such as facility size or building occupancy. When such changes occur, their statistical significance needs to be assessed to determine whether or not to include the factor in the energy savings calculation.
Energy savings can be classified into a couple of categories depending on the impact and incorporation of adjustments. The first category is Avoided Energy Consumption, evaluated as the savings in energy consumption compared to what would have been had the ECM not been implemented. For this approach, it is most common to make regular adjustments to the baseline period to reflect conditions throughout the reporting period. This is known as forecasting. Less common is to employ backcasting, where the reporting period is adjusted to mirror baseline conditions.
The second category is Normalized Energy Savings. This strategy utilizes standardized conditions other than those from the baseline or reporting periods as the basis for adjustment. This involves regular adjustment to both the baseline and reporting periods to an agreed-upon condition set, such as a typical meteorological year for weather data.
M&V Is Critical To Evaluate Savings
With all of the factors and variables involved in energy usage, it is pivotal that businesses incorporate a strong M&V process to accurately determine savings from their energy efficiency initiatives. A verified M&V process will require that a facility undergo thorough documentation of conditions before and after project installation in order to calculate accurate, reliable energy savings.
With each M&V process tailored to a specified project, businesses often feel more confident in their approach with the support of an expert. Northmore Gordon and our credentialed M&V team members are available to assess your energy needs and assist in the development and implementation of an effective M&V process.