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Measuring and verifying energy savings

Does your organisation hesitate to invest in energy efficiency because it fears that the projected cost savings will not be achieved – or that it will have no way of knowing whether or not the savings are made?

To avoid this common problem, savings measurement and verification needs to be an essential part of your implementation plan and an integral part of business case to justify it.

Advances in metering and monitoring hardware and software make it technically possible to measure energy consumption against a baseline; however this still leaves the problem of how to go about the task in a robust, transparent and credible manner.

This article explains what measurement and verification is and introduces the international protocol which stipulates how it should be carried out.

It covers the following topics:

  • Obstacles to realising energy efficiency
  • International Performance Measurement and Verification Protocol (IPMVP)
  • Analytical methodology
  • Measurement and verification plan
  • IPMVP training

You might also like to read this related article:

The Power of Energy Data

Obstacles to realising energy efficiency

It is widely held that the take-up of energy efficiency projects is not what it ought to be. One reason is managerial perception of risk, which is fed by the lack of credible precedents and suspicions about implausible-sounding products and extravagant energy savings claims. In its recent energy strategy, the government explicitly identifies this as an obstacle to progress.

A powerful way of addressing this is simply to expose projects to rigorous measurement and verification (M&V). The mere threat of such evaluation will tend to eliminate questionable propositions at the outset, and some suppliers operating on the right side of the ethical divide may even agree to accept payment contingent on a contracted level of savings being achieved (Energy Performance Contracting). This approach not only helps to reduce the perceived riskiness of energy-saving investments, but also delivers well documented case histories to act as precedents for future projects.

International Performance Measurement and Verification Protocol (IPMVP)

There are various published protocols and standards that lay down the ground rules for evaluating the impact of energy efficiency initiatives. They typically cover the following two aspects:

  • The analytical methods to be employed and
  • The framework or operational principles within which the analyses are carried out.

The most highly-developed protocol, and arguably the de facto global standard, is Volume I of the International Performance Measurement and Verification Protocol (IPMVP), which is issued by the Efficiency Valuation Organisation (EVO).

The protocol can be summarised as follows:

1.    Evaluations should be as accurate as possible
It does not stipulate any particular degree of accuracy, but merely requires the parties (solution provider and customer) to decide each case on its own merits, keeping the cost of M&V in proportion to the savings anticipated in each case. Incidentally, IPMVP includes a useful Appendix dealing with the statistics of uncertainty and error in estimates.

2.    Interactive effects should be taken into account
For example if a project to save fuel by heat recovery incurs additional electricity costs for fans and pumps (an adverse effect), or if a reduction in electricity consumption in offices decreases the need for air conditioning (beneficial effect), then these secondary impacts should be taken into account.

3.    Analysis should be conservative
Where there is uncertainty, pessimistic assumptions should be made.

4.    All significant and relevant factors are measured
For example, if daylight availability is important in determining electricity consumption it needs to be recorded.

5.    Data is recorded and analysed in an open manner
If necessary a third party should be able to repeat the analysis, using data provided in or with the M&V report.

Analytical methodology

Under IPMVP, energy savings (or what it calls “avoided energy use”) are calculated by comparing actual consumption after an energy-saving project with what it would otherwise have been if no such project had been carried out. The procedure calls for a mathematical model of energy performance, linking energy consumption to variations in driving factors such as the weather, production outputs, daylight availability, and so on - whatever is relevant in the particular circumstances.

M&V can be applied in a number of ways, most commonly either to a single submetered system or to a whole building undergoing a series of energy saving projects simultaneously. In general, the process is as follows:

1    During an appropriate baseline period, measurements of energy consumption are made at regular intervals along with all its relevant driving factors.

2    A mathematical relationship between them is established. This may be done by statistical methods (notably regression analysis) but other techniques can be used to create the baseline performance model.

3    During a post-project reporting period, ongoing measurements of the driving factors are plugged into the baseline model to get an estimate of what energy consumption would have been expected, if the system was still behaving as it did during the baseline period. IPMVP calls this result the “adjusted baseline consumption” and the difference between this and actual consumption is a clean estimate of energy savings that has allowed for variations in all the relevant factors.

Measurement and verification plan

Many energy managers will recognise this as highly analogous to energy monitoring and targeting, and some will have been using exactly this methodology to estimate energy savings, hopefully following the five operational principles described earlier. What few of us have had in the past - and this is one of IPMVP’s most important contributions to the art of M&V - is a measurement and verification plan.

The idea of an M&V plan is to put an end to the practice of analysts making it up as they go along after the event. Numerous times I have been asked to verify a project retrospectively, and found that not all the necessary data were available. Or that the supplier understood the principles of weather-correction but the customer did not. Or that there had been an unrelated one-off change like part of a building being demolished or a new product line being introduced.

The M&V plan exposes all these issues before the project is carried out and allows the parties to agree beforehand how they will be dealt with. The lack of a plan could so easily prove fatal -suppose for example that nobody is explicitly assigned the job of collecting the required data.

CMVP training

Anyone can download IPMVP from EVO and apply it but in sensitive cases it makes sense to have the evaluation carried out, or at least vetted by, someone who holds the Certified Measurement and Verification Professional (CMVP) qualification.

CMVP status is gained by taking a four-hour examination administered by the Association of Energy Engineers after a mandatory two-and-a-half day training course presented by an accredited trainer.

Your Independent RISK FREE Solutions

The Green Consultancy help you with Energy savings verification in line with IPMVP or with Energy metering, monitoring and control.

Put us to the test NOW! To discuss your requirements please call John Treble on 01761 419081 or email John@GreenConsultancy.com

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The Green Consultancy and International Performance Measurement and Verification Protocol (IPMVP)

The Green Consultancy is one of the very few UK energy consultancies to employ independent energy measurement and verification professionals, working to IPMVP which is the de facto global standard for the conduct of energy savings verification.

It is published by the Efficiency Valuation Organisation (EVO) and is designed to promote transparency, completeness, objectivity, and conservativeness.  The Association of Energy Engineers (AEE) and EVO award the CMVP® (Certified Measurement and Verification Professional) qualification to those who attend the training course, subsequently pass the examination, and remain active in the field of measurement and verification.

John Treble

Put us to the test NOW!

For over twenty five years we have been delivering superior outcomes for thousands of commercial, industrial and public-sector clients.

You need not take our word for it – hundreds of their comments are at the foot of these pages.

To discuss your requirements please call John Treble on 01761 419081 or email


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