How to Prove Energy Savings: A Simple M&V Plan

Part 4 of 10 in Cobler's Energy Management: The Economics of Saving Energy course. New here? See the course page.

A year after the project, someone from finance pulls up the office tower's April bill. In April 2026, before the measures, the tower used 530,000 kWh. In April 2027, after them, it used 532,000 kWh. Read on its own, the bill says the project failed, because consumption went up. So did it?

Well, the bill alone can't answer that, because weather, working days, tenants and the monthly fuel adjustment all change it too. To prove energy savings, we compare the energy metered after the project with the energy the building would have used without it. We get that second number from the baseline that Part 3 built, adjusted for those changes. And we write the rules for all of this down before the project starts, in a measurement and verification (M&V) plan.

The tower is our made-up building on the MV (medium voltage) non-domestic General tariff. Part 2 valued its three measures at about RM158,065 and 112.5 tonnes of CO₂e a year. So the plan we write here is what will show whether those savings really happen.

The adjusted baseline

Let's start with those two Aprils, because April 2027 was hotter. Part 3 measured how hot a month is in cooling degree days (CDD). That's the degrees by which each day's average outdoor temperature was above 24 °C, added up over the month. April 2026 had 135 CDD, and April 2027 had 160. Part 3 also found that each extra CDD adds about 600 kWh to the tower's month. Both Aprils had 22 working days, so only the weather needs an adjustment:

• Extra cooling expected from the hotter weather: 25 CDD × 600 kWh = 15,000 kWh.
• What the tower would have used in April 2027 without the measures: 530,000 + 15,000 = 545,000 kWh. We call this figure the adjusted baseline.
• What it actually used: 532,000 kWh.
• Avoided energy: 545,000 − 532,000 = 13,000 kWh.

That's close to the 12,700 kWh a month that Part 3 expected. So the project worked, even though the bill went up.

The saving is the gap between what the building would have used and what it did use, not the difference between two bills.

The same problem works in reverse, because a cooler month can make a failed project look successful. The ringgit on the bill also move for reasons outside the project, because the AFA (Automatic Fuel Adjustment) rate changes every month. So M&V compares kWh and kW first, and only then turns the verified savings into ringgit.

Three periods

For that comparison to be fair, the plan fixes three periods before the project starts:

• Baseline period: the "before". For the tower, that's October 2025 to September 2026, the twelve months of bills and meter data from Part 3.
• Installation period: while the measures are fitted and tested, October to December 2026. We don't count savings in this period, because the building is neither "before" nor "after".
• Reporting period: the "after", January to December 2027. This is where we measure the savings.

Both measured periods are a full year, so each includes every season and holiday once.

Both measured periods cover a full year for the reason Part 3 gave, which is that consumption changes with the seasons and the holidays. A baseline picked from a quiet quarter would make every later month look like a saving.

The measurement boundary

Next, the plan decides what the meter should see. The part of the building whose energy we measure is what we call the measurement boundary, and there are two broad choices:

• The whole building, using the main meter or the TNB (Tenaga Nasional Berhad) bill. This captures every effect of the project, including side effects, but also every unrelated change.
• One system, using a sub-meter on the equipment that the measure changes, such as the chiller plant. This isolates the measure from the rest of the building.

The international reference for M&V is the International Performance Measurement and Verification Protocol (IPMVP), maintained by the Efficiency Valuation Organization. It describes four options:

• Option A: one system, with the key parameter measured (for example, the running hours of new lights) and the rest estimated.
• Option B: one system, with all its energy measured by a sub-meter.
• Option C: the whole building, using the main meter and a model of the drivers. It works best when the savings are large compared with the building's normal swing, more than about 10% of the whole-building bill.
• Option D: a calibrated computer simulation, used when there's no usable baseline, such as in a new building.

So which fits the tower? Its measures save about 2.5% of its electricity, much smaller than the 14% difference between its May and December bills. A whole-building comparison couldn't separate a saving that small from the weather. So the plan measures each measure where it happens:

• M1 (plant stops at 6pm): the chiller plant sub-meter, looking at the hours from 6pm to 8pm on working days.
• M2 (VSDs on the condenser pumps): new meters on the two pump feeders, fitted with the variable speed drives (VSDs).
• M3 (demand limiting): the maximum demand (MD) on the TNB bill, together with the BMS (building management system) log of the loads it held off.

The whole-building April comparison from the start stays in the plan as a cross-check, not as the proof.

Routine adjustments

Now, some drivers change every period in a way everyone expects, such as the weather, the number of working days and the running hours. Allowing for them is what we call a routine adjustment. The plan writes down the rule for each one before the reporting period, so nobody can choose a convenient method afterwards.

For M2, the routine adjustment is simple, because the old pumps ran at one fixed speed. Before the VSDs, the two pumps together drew 54.0 kW whenever they ran. So the adjusted baseline for any month is 54.0 kW × that month's actual running hours. Take a reporting month with 22 working days and the usual 11 hours a day:

• Running hours: 22 × 11 = 242 hours.
• Adjusted baseline: 54.0 kW × 242 h = 13,068 kWh.
• Metered on the two pump feeders: 9,300 kWh.
• Verified saving: 13,068 − 9,300 = 3,768 kWh.

Part 2 expected 16 kW × 242 h = 3,872 kWh for a month like that. The verified figure is about 3% lower, which is well within the range Part 3 gave, and the monthly report records both numbers.

M1 works the same way. Before the change, the plant drew about 220 kW from 6pm to 8pm. After it, the plant sub-meter should show almost nothing in those hours, apart from the evenings a tenant asked for cooling. The BMS logs each request, so the report can show the hours saved and the hours used on request.

One-off changes

But some changes aren't part of the normal pattern. A tenant adds a server room, a floor stands empty for six months, or office hours change. Allowing for these is a non-routine adjustment. The plan can't predict them, but it can say how we'll handle them.

For the tower, the plan says this. When a load is added or removed for reasons unrelated to the project, the facility manager records the date and meters the load. Then the baseline is adjusted by that metered energy. Say a tenant installs a server room, and its own meter shows it using 21,600 kWh in a 30-day month (a steady 30 kW). That month's adjusted baseline for the whole-building check rises by 21,600 kWh, so nobody mistakes the new load for a failed project.

Deciding the rule before the reporting period is what makes the result credible. If we chose the rules after we knew the numbers, every adjustment would look like a change made to get the answer we wanted.

Demand savings month by month

M3 needs a different check, because it saves no kWh, so kWh comparisons can't show it. What it saves is kW off the month's highest half hour, and Part 2 counted that only if the peak really falls. So the plan checks it every month with two records:

• the MD on the TNB bill, which is the highest half hour of the month
• the BMS log of how many kW the demand limiting was holding off during that half hour

The demand saving for the month is the kW held off in the highest half hour. Say the July 2027 bill shows an MD of 1,510 kW, and the BMS log shows 95 kW held off during that half hour. Without the limiting, the MD would have been about 1,605 kW, which is in line with July 2026's 1,610 kW. So the verified demand saving is 95 kW, worth 95 × RM89.27 = RM8,480.65 that month.

If a month is cool and the demand limiting never needs to act, that month's demand saving is zero, and the report says so. That's why Part 2 pointed out that M3 carries most of the value and most of the uncertainty.

The one-page plan

A saving only counts if someone can document it, so the plan also names who does what:

• The evidence owner is the tower's facility manager. They collect the meter data, the BMS logs and the bills each month, and they record any non-routine changes as they happen.
• The monthly report is due by the 10th of the following month. For each measure, it shows the adjusted baseline, the metered value, the verified saving and any adjustments made.
• Finance signs off the annual savings figure at the end of the reporting period.
• Meters and data get checked too. The new pump meters are commissioned before the reporting period starts. Any data gap is recorded and filled by the method in the plan, the same way Part 3 filled the missing March days.

M&V has a cost as well, in meters, staff time and reports. For the tower, the plan budgets RM8,000 a year, and the cash-flow model in Part 8 includes it.

And that's the whole plan. It all fits on one page, so here it is for the tower:

For more on the IPMVP options and continuous M&V, see measurement and verification: proving energy savings are real.

Worth the money?

So now we have a value for each measure, a baseline, and a plan to prove the savings. But the finance director's first question will be simpler than any of this. Are the savings worth what the measures cost? The quickest checks are payback and return on investment. We'll start the investment tools with them in Part 5, Simple Payback and ROI: The Quick Screening Tools.

Check your understanding

1. In May 2027 the tower used 540,000 kWh, against 535,000 kWh in May 2026. Both months had 22 working days, but May 2027 had 10 more cooling degree days. Using about 600 kWh per CDD, how much energy did the measures avoid, and what should the facility manager do?

2. In a cool month the BMS demand limiting never had to act. Why does the M&V report count no demand saving that month?

Recap

• A bill that goes down, or up, doesn't prove a saving, because weather, working days, tenants and AFA change it too.
• An M&V plan, written before the project, fixes a baseline period, an installation period and a reporting period.
• It chooses a measurement boundary for each measure.
• It sets rules for routine adjustments (such as weather and running hours) and non-routine ones (such as a new server room).
• The saving is the adjusted baseline minus the metered energy.
• Demand savings are checked month by month against the highest half hour.
• A named evidence owner collects the records, and finance signs off the result.

This is Part 4 of 10 in Cobler's Energy Management: The Economics of Saving Energy course. Previous: Before You Claim Savings: Baseline and Load Profile. Next: Simple Payback and ROI: The Quick Screening Tools.

Cobler builds CobiNeural, a platform that shows a facility team its building's energy, water and indoor air data as live numbers across the whole site. To see how your building performs, talk to us.