Is Conservation Voltage Reduction truly energy efficiency?
This author no longer works for DNV GL.
Energy policy, codes and standards, and equipment technology upgrades—either self-directed or through a program—drive energy efficiency. The mechanics of each of these drivers that ultimately change how energy is used for different purposes in homes, businesses, and industrial facilities can be incredibly complex, as consumers are not always eager to adopt new energy efficient technologies and behaviors. But what if there was a way to reduce electricity consumption without any change in the electricity consuming equipment stock or behavior on the part of consumers?
Conservation Voltage Reduction (CVR) is a proven technology for reducing energy and peak demand. It is a measure implemented upstream of end service points in the distribution system so the efficiency benefits are realized by consumers and the distributor. This is done without any intervention on the part of consumers. CVR is implemented by controlling the voltage on a distribution circuit to the lower end of a tolerance band, either defined by ANSI C84.1 (114–126 volts) or another target range. Conservation then occurs on the circuit when certain end-use loads draw less power when voltage is lowered.
The reaction to lowered voltage varies significantly by end use. Space heaters, for example, will have a reduced load but are not expected to result in net energy conservation since it would simply take longer to condition a space to a desired temperature. For other end uses, both real power (watts) and corresponding energy (watt-hours) are reduced because of lowering the voltage. In addition, the reactive power consumption is reduced, at levels exceeding the reductions in the real power. Some end-uses have little to no reaction to moderate reductions in voltage as current draw picks up to maintain constant power. The net impact of CVR on a distribution circuit is therefore highly dependent on the mix of end-use loads. CVR has been estimated by Pacific Northwest National Laboratory to produce between 0.5–4% energy savings on circuits where it is implemented, with 80–90% of that occurring on the customer side of the meter.
So given that it can be broadly implemented—at least for circuits designed to accommodate CVR—with minimal customer recruitment, incentives, and inconvenience, why not combine CVR into traditional energy efficiency portfolios? This is a big question for regulators, especially in states with ambitious targets for efficiency and mature traditional Demand Side Management programs already in place. But is CVR truly energy efficiency? Some argue that reduced voltage does not constitute efficiency because reduced voltage means reduced performance in the end uses that are responsible for the savings. Others argue that it should be counted as conservation as long as end-of-line voltage is within the applicable tolerance, and if the reduced voltage is something that customers do not even notice.
And then there is the question of who should pay for CVR. If ratepayers stand to benefit the most in terms of savings, should state regulators approve cost recovery proportional to the savings on the customer side of the meter? Can established Evaluation, Measurement, and Verification methodologies be adapted to adequately differentiate the costs and benefits of CVR? What about separating savings achieved by a standard energy efficiency portfolio from CVR when they intersect? Many of these issues are currently being investigated by researchers. As research turns to information in the next couple of years, the ball will be placed more firmly in the regulators’ court to make a decision that many eyes will be on.
DNV GL consultants are deeply engaged in the regulatory support, system planning, implementation, and evaluation of CVR. For more information on our CVR services and recent experience, please contact Will Gifford or Jessica Harrison.