Comparing Two Homes by Rating

Comparing two homes by rating works only if the comparison is fair: same method, similar dates, scores as well as bands, feature ratings, and context such as size, type and location. A band alone is too coarse, a score alone ignores features, and a rating alone ignores condition, size and price. Fair comparison uses all of those together, and acknowledges where comparison stops and personal judgement begins.

A useful comparison starts with scores, then features, then context. Scores show modelled energy closeness, features show why scores differ, and context shows whether the difference matters for this buyer or tenant: a larger home will use more total energy even with a better per-square-metre score, and a home in a colder region will face higher heating demand than an identical home in a milder region.

Start with the underlying score, not the band. Two homes both in band C may differ by many score points, and two homes in adjacent bands may differ by one point. Score closeness is a better guide to modelled energy similarity than band equality, and it prevents a one-point band gap being treated as a large quality gap.

Then compare features. A home with poor walls but good heating differs from a home with good walls but poor heating, even if their scores match, because their improvement paths, costs and comfort profiles differ. Feature comparison reveals which home needs fabric work, which needs system work, and which needs both, and that revelation matters more for budgeting than the headline score.

Check dates and methods. Certificates issued years apart, or under different method versions, may not be directly comparable, because method updates change scores without physical change. Check assessment dates on both certificates, and if dates differ greatly, treat the comparison as approximate and seek updated assessments or audit information where the decision is important.

Check size and type. Compare per-square-metre figures for building quality, and total figures for bills and carbon, and do not confuse the two. A detached house and a mid-terrace flat should not be compared on total energy alone, because built form alone creates large differences, and a comparison that ignores built form will mislead.

In the UK, comparing homes within the same nation, using the same register and method, is relatively straightforward, though method version and date still matter. Comparing a Scottish home with an English home requires care, because formats and some calculation details differ, and underlying scores and features should be compared rather than bands alone.

Across EU borders, direct rating comparison is not valid without adjustment, because national methods, climate data, class boundaries and carbon factors differ. A home in one country and a home in another should be compared on physical features, construction and system quality, with local professional advice, rather than on certificate classes, which are national constructs.

One comparison mistake is choosing a home on band alone, then discovering condition, size or location problems that outweigh energy differences. Energy is one factor in a home choice, alongside price, location, size, condition and tenure, and a band gap of one letter rarely outweighs a major difference in any of those other factors.

Another mistake is ignoring the potential rating and recommendations in comparison. Two homes with the same current rating may have very different potentials: one may be close to its maximum, the other may have large, cheap improvement scope. Comparing current ratings without potentials hides that difference, and a buyer who ignores it may pay the same for a home with far less improvement headroom.

Keep both certificates side by side, with notes on scores, features, dates, sizes, types and potentials, plus viewing notes on condition and comfort. That comparison sheet supports a decision that can be explained later, and it prevents a band impression from overriding a fuller picture.

Ask agents or assessors to explain any score or feature difference you do not understand, and ask surveyors about condition differences that ratings cannot show. Ask yourself which difference matters most for your use: running cost, comfort, improvement scope, or resilience, and weight the comparison accordingly, rather than letting a letter decide.