by Tom Eckman, Northwest Power and Conservation Council, and Mark Sylvia, Massachusetts Department of Energy Resources, on behalf of the State and Local Energy Efficiency Action Network (SEE Action) Evaluation, Measurement, and Verification (EM&V) Working Group
The future for determining energy savings from efficiency programs has the potential to be dramatically different than the current paradigm. Investments in the smart grid, combined with other technological advances in residential interval meter data, nonintrusive load monitoring, and equipment-embedded sensors and controls are paving the way for a transformed future in the United States.
Applied to energy efficiency evaluation, these changes will give evaluators new tools that will have the potential to reduce the cost of EM&V, produce more timely results and increase the acceptance of the savings calculations. These advances are EM&V 2.0.
Current EM&V Practice
During the past few decades, ratepayer-funded energy efficiency has been an important resource to meet U.S. electricity demand. In 2010, investment in ratepayer-funded efficiency programs was roughly $4.8 billion, and indications suggest funding will rise to potentially $9.5 billion and greater by 2025.
This investment translates to roughly 18.4 Terrawatt-hours saved in 2010 – or about 0.5 percent of total retail electricity sales. Nationally, most future load growth likely will be met with energy efficiency.
Today, most ratepayer-funded programs go through an EM&V process to document that the expected savings are being realized. This evaluation usually happens every year or as part of a program cycle for a portfolio of programs. Because of the cost and time to evaluate energy savings using available approaches, not all programs may undergo detailed evaluation for any given program year.
Today, EM&V approaches that use deemed savings to help reduce costs and expedite results are becoming more prevalent; these approaches calculate savings based on the number of measures installed and the historic or calculated savings from those types of measures.
For additional verification, some programs incorporate contractor assessments of premises in which energy efficiency measures were installed, either through a physical inspection or through an off-site survey. Evaluators also might install spot metering devices when a measurement and verification (M&V) approach is used.
This M&V process can be time-consuming and expensive and requires the additional expense of the metering equipment. Furthermore, program participants sometimes view M&V as intrusive, and it can disrupt the normal operation of homes or businesses. Remote data collection, such as phone or mail surveys, produces less dependable information and does not necessarily remove the inconvenience or burden to those being surveyed.
Although a range of approaches have met historic needs for determining energy efficiency program savings, issues have arisen around the cost, timeliness and confidence in the results. Fortunately, many technological developments open the possibility of surmounting these issues. Among them are:
“- Nonintrusive Load Monitoring
Nonintrusive load monitoring (NILM) has the potential to dramatically reduce the cost of metering individual pieces of equipment and devices. This new monitoring technology, combined with software, can disaggregate loads using nothing more than the characteristics of the electricity that flows to the meter.
Generally, a device still must be installed at the meter, but it is much less time-consuming and intrusive than installing a meter on sample equipment inside a building. The Electric Power Research Institute is testing monitoring products with this capability. At this early stage, testing equipment metering and meter devices will be necessary to validate that the NILM can identify end-use loads within a building. It is also likely that NILM devices will at first only identify significant loads, but not every end use.
As the technology evolves, it seems reasonable to expect that more end uses will be distinguishable. Reducing or eliminating the need to enter a premise will reduce the cost and burden of EM&V; modern communication technology promises to quicken that availability dramatically.
“- Large-scale Data Analysis
Utilities are aggregating their customer, usage and program data as inputs for data analytics similar to those used in e-commerce. This allows testing of program designs, messaging and delivery mechanisms in customer uptake and energy usage changes with advanced statistical techniques, including randomized test and control groups.
Large-scale data analysis that uses interval data might be able to replace other methods that are more labor-intensive and intrusive to customers. By combining large-scale data analysis with experimental design and the use of randomized controlled trials, the availability of interval data might not only reduce the cost of EM&V but also could provide the program implementer and administrator near instantaneous feedback on program performance. This will help the implementer make adjustments to the program sooner and increase its effectiveness.
“- Current Uses of Interval Meter Data
Interval data from smart meters is affecting the solar and demand response business models dramatically. Solar and demand response companies are using interval data to gain insight on the load profiles of buildings, which helps them understand the economics of a given location.
Similarly, interval data is beginning to be used in evaluating large-scale, behavior-based energy efficiency programs to help understand the source of the energy savings.
Another component of EM&V 2.0 is the detailed data and analytics that exploit it, which smart meters or other smart grid components (providing local grid conditions) can provide. Smart meters can provide very short-term interval data (e.g., quarter-hour or even a few seconds) that did not previously exist for residential buildings and smaller commercial facilities not on special time-of-use rates.
When combined with low-cost sensors and controls that may be embedded in a wide array of appliances and equipment, there will be a rich set of data from which to work. This granularity of data – and the ability to see the data in real time – benefits evaluators and particularly building operators and managers who can make informed adjustments to building energy use throughout the day.
“- Sensors Embedded in Equipment and Appliances
Where interval data and NILM leave a gap, new, inexpensive sensors placed in individual pieces of equipment or in a building may complete the puzzle. Sensors will give evaluators and others a never-ending warehouse of equipment-specific energy usage and end-use load shapes. This will increase the accuracy of energy savings estimates greatly. It will allow operators to know if equipment is operating according to manufacturer specifications and allow evaluators to compare the expected energy consumption of a piece of equipment to its actual energy consumption.
When combined with the ability to communicate with a central platform, sensors replace much of the need for field measurement and verification of energy savings and will move the energy efficiency industry toward nearly instant knowledge of equipment energy performance and savings.
The plethora of available data combined with the ability to communicate it has the potential to produce multiple advantages for EM&V, particularly in the residential sector, including:
1) Richer information sources to inform deemed savings values;
2) Lower cost of EM&V by moving toward NILM or large-scale data analysis to identify performance and energy consumption;
3) Real-time energy performance of new equipment;
4) The ability to evaluate measures and whole programs within a shorter time than annually (large data sets need only relatively short time periods for defining regression analyses and/or control and test groups);
5) More uniform methods of determining energy savings in certain areas; and
6) The ability to identify at the end-use level when energy efficiency actions are taken and to help understand persistence.
These developments will help us improve the reliability and credibility of energy savings, which will give decision-makers the confidence to invest more in energy efficiency. They also may bring new capital into the efficiency market and create new investment channels.
Technological advances point to a future that will support EM&V that is less expensive, more timely and more accurate. With this information, we will have even more information to support greater investment in energy efficiency. Those interested in energy efficiency should look beyond the traditional EM&V practices toward the development and adoption of new practices.
To stay informed about the evolution of EM&V, get connected with the State and Local Energy Efficiency Action Network’s (SEE Action) EM&V Working Group, which continues to actively explore this rapidly evolving area. SEE Action is led by state and local officials and supported by the Department of Energy (DOE) and Environmental Protection Agency (EPA).
Tom Eckman is the manager of conservation resources for the Northwest Power and Conservation Council, which he joined in 1982. His primary responsibilities include the assessment of the energy efficiency potential in the Pacific Northwest region, the integration of conservation resources into the resource portfolio for the region’s electric utility system, and the development of a regional plan for the deployment of energy efficiency.
Mark Sylvia was appointed commissioner of the Massachusetts Department of Energy Resources (DOER) in 2011, having served previously as the first director of DOER’s Green Communities Division. He represents Massachusetts on several boards including the Regional Greenhouse Gas Initiative Inc,. National Association of State Energy Officials, Northeast Region, and Massachusetts Clean Energy Center.
SEE Action is a state- and local-led effort facilitated by DOE and EPA to take energy efficiency to scale and achieve all cost-effective energy efficiency by 2020. SEE Action offers publications, events, and technical assistance to state and local decision makers as they provide low-cost, reliable energy to their communities through energy efficiency.