Standards & methodology
IPMVP
IPMVP
The global protocol for verifying energy savings — four calculation options, the savings equation, and why Option C whole-facility regression depends on accurate degree day data.
What IPMVP is
IPMVP (International Performance Measurement and Verification Protocol) is published by the Efficiency Valuation Organization (EVO) and is freely available to download.
Energy savings cannot be metered directly — they are the absence of energy that would otherwise have been consumed. Without a structured methodology, two engineers reviewing the same utility bills can reach different conclusions. IPMVP defines how to calculate, document, and verify savings so ESCOs, clients, lenders, and auditors can agree on one defensible number.
IPMVP is referenced in ISO 50015, ISO 50047, EU energy efficiency policy, and performance contracts worldwide. There is no “IPMVP certified” designation — compliance is demonstrated through the M&V plan and reviewed by counterparties.
The savings equation
Energy savings = Baseline energy − Reporting period energy ± Adjustments
Adjustments correct for differences in operating conditions — primarily weather, but also occupancy, production throughput, and other factors outside the building owner’s control.
Weather is the most common independent variable in those adjustments. It must be documented, sourced reliably, and matched precisely to billing periods — not calendar months.
The four options
| Option | Approach | Typical use |
|---|---|---|
| A | Retrofit isolation — key parameters measured, others stipulated | Simple measures with predictable performance (lighting, VSDs) |
| B | Retrofit isolation — all parameters measured | Higher-value measures where sub-metering is justified (HVAC, compressed air) |
| C | Whole facility — regression on utility meter vs. weather and other variables | Multiple simultaneous measures; ISO 50001 verification; limited sub-metering |
| D | Calibrated simulation — model calibrated to measured data | New construction; no reliable pre-retrofit data |
Option C in more detail
Twelve months of baseline utility bills are regressed against heating and cooling degree days (and other relevant variables if needed). The model predicts what the building would have consumed in the reporting period without improvements. The difference is the verified saving.
Option C is the approach most aligned with Ed and the degree day API — but “IPMVP compliant” is not a claim we make. No such software certification exists. We support Option C workflows based on the principles of the protocol.
Why Option C lives or dies on degree day data
The regression is only as good as its independent variables. Three common failures:
- Calendar-month degree days against billing-cycle bills — bills do not follow calendar months; the mismatch introduces systematic error
- Wrong base temperature — default 18°C / 65°F is rarely correct for a specific building
- Distant weather station — a station kilometres away in different terrain can diverge significantly from the building’s microclimate
The API delivers degree days matched to exact billing dates at the building location, with documented coordinates, base temperature, and method — the source metadata an M&V plan requires.
How IPMVP connects to other standards
| Layer | Standard |
|---|---|
| Governance | ISO 50015 |
| Calculation | IPMVP |
| Model quality | ASHRAE Guideline 14 |
| Savings reporting | ISO 50047 |
| EnMS context | ISO 50001 |