MCS launched a four-week consultation on 4 July 2025 on a new MCS Standard covering an air-to-air heat pump system performance estimate standard and calculator tool1. The consultation closes at 5.00pm on 6 August 20251.
The proposed document is titled "Air to Air Heat Pump Pre-sale information and Performance Calculation" and is tailored specifically for air-to-air heat pump systems1. MCS states that, presented in a narrative format, it sets out the methodology and formulae used to provide estimate performance figures1. Alongside it, MCS has released an updated Excel-based calculator tool, which it says enables installers to carry out compliant performance estimates efficiently and provides the ability to estimate performance for air-to-air heat pump installations1.
MCS describes the focus of the consultation as the inclusion of air-to-air heat pumps, which it calls an important development in response to growing government interest in broadening the scope of low-carbon heating technologies1. The consultation documents comprise the draft standard, the draft system performance calculator tool and a consultation response form1.
"MCS has launched a four-week consultation on a new MCS Standard to include an air to air heat pump system performance estimate standard and calculator tool."
Responses are invited from stakeholders on the proposed updates and should be submitted to consultations@mcscertified.com before the deadline1.
Why it matters for households
Air-to-air heat pumps, which heat rooms by moving heat into the air rather than into water for radiators or a cylinder, sit outside the technology list that most UK grant and certification schemes have been built around. A performance estimate standard matters to a household because it governs the figures an installer can put in a pre-sale quote: how much heat a proposed system is expected to deliver and what that implies for running costs. MCS says the draft sets out the methodology and formulae behind those estimate figures, and the calculator is intended to let installers produce them on a consistent basis1. For a home weighing up an air-to-air system, that is the difference between a number produced to a published method and a number produced ad hoc. The performance estimates and savings claims that appear in installer quotes are the practical output of this kind of standard, and the wider framework of heat pump standards, testing and certification determines how such claims are checked. Nothing in the consultation documents as published sets out how air-to-air systems would be treated under government support schemes, and no such change has been reported1.
What happens next
The consultation runs until 5.00pm on 6 August 2025, with responses submitted by email to consultations@mcscertified.com1. MCS has not stated in the announcement when, or whether, the standard will be finalised, and no date for publication of a final version has been reported1.