MCS published an updated version of MCS 031: The Heat Pump Pre-Sale Information and Performance Calculation on 18 December 2024, taking the standard to Issue 4.01. Compliance with the update is mandatory from 18 March 20251. MCS has also developed an Excel tool to simplify the calculation and present the information in the required format1.
The previous method used Seasonal Coefficient of Performance (SCoP), based on a presumed flow temperature, to estimate the Seasonal Performance Factor (SPF) and calculate the amount of electricity required to deliver the annual heat demand1. MCS states that recent studies have shown SCoP overestimates the likely SPF and takes little account of the emitters being used: whether radiators, underfloor heating or a combination of both1. The new method uses the type of system, the specific heat loss of the property, and a lookup table of SPFs drawn from the Heat Emitter Guide1. It also flags particular warnings where existing radiators are being used and could be undersized1.
"MCS has published an updated version of MCS 031: The Heat Pump Pre-Sale Information and Performance Calculation"
MCS later set out the purpose of the standard for installers. MCS 031 seeks to give consumers a reasonable and impartial assessment of heat pump performance by estimating the annual energy consumption of the proposed heat pump system during a typical year, and it is a requirement under MCS that this estimate is provided to the customer at the quoting stage2. The methodology relies on fixed data points, including the energy usage figures retrieved from a property's EPC, which MCS says means customers can directly compare estimates obtained from different MCS certified installers2. MCS states that MCS 031 is not a design or specification tool to calculate a property's heat load or to size a heat pump; design requirements sit within The Heat Pump Design Standard (MIS 3005-D), where it is mandatory to select a heat pump based on the property's heat load as defined by a heat load calculation in accordance with BS EN 12831-1:20172.
The Heat Pump Association said it had been working with the MCS Heat Pump technical working group to update MCS 031, which it described as released the day before its own statement of 19 December 20243. The HPA statement also covered the Electrification of Heat Demonstration report, funded by the Department for Energy Security and Net Zero, which monitored 742 heat pump systems installed across a range of dwelling types and ages3. The HPA reported that the median SPF for air source heat pumps improved by over 10% compared to previous installations, and that the report highlights an average of 293% efficiency for the sampled ASHPs, compared to a typical fossil fuel heating system efficiency of 84%3. The HPA said the number of ground source heat pumps installed in the trial was not statistically sufficient to draw any conclusions, but cited an additional DESNZ funded study of 1,717 installations in 2017 to 2022 which found the average GSHP SPF had improved by 10% from 2017 to 2022, and that exactly one third (33%) of GSHPs and 8% of ASHPs were performing at SPF 3.5 or above3. The HPA also said the report noted a gap between average design SCOPs and average in-situ SPFs3.
| Item | Detail |
|---|---|
| Standard | MCS 031, Issue 4.0 |
| Published | 18 December 20241 |
| Mandatory compliance from | 18 March 20251 |
| New method inputs | System type, specific heat loss, Heat Emitter Guide SPF lookup table1 |
| Accompanying tool | Excel tool1 |
Why it matters for households
The estimate a householder sees at the quoting stage is the number used to compare one installer's proposal with another's. Under the previous method, that figure was derived from a presumed flow temperature and, in MCS's own words, took little account of the emitters being used1. The revised method ties the estimate to the type of system, the property's specific heat loss and a lookup table of SPFs from the Heat Emitter Guide, and warns where existing radiators may be undersized1. For a household weighing up a heat pump, the practical effect is that the projected running cost rests on a narrower set of assumptions about the property and the heat distribution system already in place, rather than on a single presumed flow temperature. MCS states the standard is not a sizing or design tool, and that heat load calculation and heat pump selection sit under MIS 3005-D2. The HPA's account of the Electrification of Heat report points to variation in real performance attributable to the type of heat pump installed, consumer behaviour and installation design3, which is the gap the revised estimate is intended to narrow.
What happens next
Compliance with MCS 031 Issue 4.0 is mandatory from 18 March 20251. MCS published an installer guide to the changes on 19 February 2025, ahead of that date2. No further dated steps are set out in the published material.