How the Home Cooling Checker works

The overheating score is a 0-100 factor-scored model. It adds up the physical drivers that make a specific home run hot in summer: whether it is a top-floor flat (which takes roof heat gain with no buffer above and scores highest), which way the main rooms face (south and west get the most solar gain), how good the fabric is (poor insulation or a low EPC band traps heat), the construction era and thermal mass, single-aspect layouts that cannot cross-ventilate, loft conversions, and whether the postcode sits in an urban heat island. Homes at or above 70 are high risk, 40-69 moderate, and below 40 lower risk.

These drivers are the ones identified by the Climate Change Committee and Arup's 2022 analysis, which found that around 55% of UK homes already fail the bedroom overheating criterion in CIBSE TM59 - the design methodology for assessing overheating risk in homes - which in turn underpins Building Regulations Part O, the mandatory overheating requirement for new residential buildings in England since June 2022.

Honesty note. Our score is informed by the TM59 and Part O drivers; it is an indicative, explainable risk score, not a certified TM59 dynamic thermal simulation and not a Part O compliance assessment. It tells you whether cooling is justified and why - it does not certify a building. For a formal assessment, a Part O calculation by a qualified assessor is the right instrument.

The recommendation is a single, honest decision: air-to-air heat pump, or air conditioning. It turns on two things you tell us - your current heating type and whether you are willing to replace it - plus how many rooms you want to cool. If you have a fossil-fuel or electric system (mains gas, oil, LPG or direct electric) and you are willing to replace it, we recommend an air-to-air heat pump, which cools in summer, heats in winter, and opens the grant path. If you want to keep your existing heating, or it is not a system the grant can replace, we size a cooling-only air-conditioning system to your room count instead - a single-split for one or two rooms, multi-split for a few, ducted for whole-home - with a portable unit flagged as an interim option for renters or tight budgets.

We publish the inputs, not the internal weighting. What matters for trust is that the same property always produces the same recommendation, and that the recommendation, the grant position and the required accreditation are all derived from that one decision - they cannot disagree with each other.

The £2,500 figure is the air-to-air pathway of the government's Boiler Upgrade Scheme. It is genuinely useful, but it only pays in one of two situations - so the model always shows you both, and never states it as a blanket promise:

• Eligible - you replace your heating. If you replace a fossil-fuel or electric heating system with an air-to-air heat pump, installed by an MCS-certified installer, the £2,500 applies. The old system has to be decommissioned, not run alongside the new one.
• Not eligible - you keep your boiler. If you keep your existing heating and add cooling as a standalone unit, that cooling-only add-on does not qualify for the grant - however it is marketed. Adding air conditioning while keeping your gas boiler is a private-pay job, not a grant job.

Grant rules and the £2,500 amount can change. Every result records the date the rules were checked - currently 14 August 2026 - and you should always confirm the current terms on gov.uk before applying.

Two different accreditations apply, and the checker routes your enquiry by system type to the pool that holds the right one - we never send a grant-eligible air-to-air job to a refrigerant-only installer, or a pure air-conditioning job to a heat-pump-only one:

• Air-to-air heat pump (the grant path): must be installed by an MCS-certified installer. MCS certification is a condition of the Boiler Upgrade Scheme, not an optional badge.
• Air conditioning (split, multi-split, ducted or portable): involves handling refrigerant, which UK law restricts to F-Gas-certified engineers, typically registered through REFCOM.

To be clear about what GetComfort is: we do not employ, and do not claim to be, an MCS or F-Gas accredited installer. The installer matched to your enquiry is independently accredited and vetted separately. Our job is the property model and the routing - theirs is the regulated installation work.

An external condenser unit is often permitted development for an ordinary house within size, siting and noise limits - but three things change that answer, and we cannot read any of them reliably from property data: whether the home is in a conservation area, whether it is a listed building, and its exact floor level and aspect. So the checker asks you, rather than inferring them.

When one of those unknowns would materially change the verdict, the model returns an honest “confirm with your Local Planning Authority” result instead of guessing the more permissive outcome. A false “likely permitted development” is the risky direction to be wrong in, so unknowns never resolve toward it. Flats and maisonettes are treated as likely to need permission regardless, and listed buildings always need both planning permission and listed-building consent.

The property details we pre-fill come from public records, keyed to your home's Unique Property Reference Number (UPRN) - not from anything we observe about you. The sources are the official Energy Performance Certificate register, HM Land Registry price-paid data, and local-authority planning records, brought together on HomePortfolio, a UK property-intelligence platform of 30 million-plus records. Where a home has no full EPC on file - many do not - the affected fields come back blank and we ask you to confirm them, rather than inventing a value.

The property-intelligence model behind the checker was built by Solomon Amos, GetComfort's founder and technical architect. He built HomePortfolio, the 29.5 million-property UK platform this checker runs on, holds a PhD in Engineering (research in machine learning and cybersecurity), lectured in Applied AI and Machine Learning on the University of York's Online MSc Computer Science programme, and holds seven AWS certifications and SC security clearance. So the data the checker reasons over is data he designed and built - a specific, checkable credential, not a generic “engineering background” line.

His authority is engineering and data rigour, not a heating trade credential: he is not an MCS or F-Gas accredited installer and does not claim to be. That is exactly why this page exists. Rather than asking you to trust a reviewer's badge, every regulated figure on the site is sourced to the primary authority - CIBSE TM59, Building Regulations Part O, gov.uk's Boiler Upgrade Scheme guidance and MCS - so you can check the working yourself. Views and figures here are independent of his employer.

The grant amount, scheme name and rules on this page are read from the same single source of truth as every checker result, so they stay in step automatically. They were last confirmed against gov.uk as of 14 August 2026. If the Boiler Upgrade Scheme changes, that date moves and the figures move with it - the grant is an acquisition detail we keep honest, never the headline of what GetComfort does.