Ratings and Energy Labels, Compared

Building energy ratings and product energy labels both use A to G scales, but they rate different things by different methods, and they should never be compared directly. A building rating models a whole home's heating, hot water and lighting under standard occupancy, using construction, systems and climate data. A product label rates a single appliance, such as a fridge, washing machine or television, under laboratory test conditions for that product type. The shared letters are a coincidence of presentation, not a shared scale.

That distinction matters because a home rated C and a fridge rated C have nothing in common except the letter. The home's C reflects modelled energy per square metre, fuel and system factors, while the fridge's C reflects its energy use relative to other fridges of its type, under test cycles.

Building ratings are whole-system models. They combine fabric losses, heating efficiency, controls, hot water and lighting into a single score, with standard assumptions that allow homes to be compared. Product labels are product-specific tests: a washing machine label reflects wash cycles and load sizes defined for washing machines, a television label reflects screen size and viewing patterns, and a heat pump product label, where it exists, reflects heating performance under test conditions that differ from installed performance in a real home.

Scales also rescale differently. Product labels have been rescaled in the EU in recent years, removing plus classes and resetting A to G so that A is initially rare, to encourage future improvement, while building rating scales are set by national assessment methods and change with method updates. A product label from before a rescale cannot be compared with one after it without noting the rescale, just as a building rating from an older method cannot be compared with one from a newer method without noting the method change.

Check what is rated before comparing any two labels or ratings. Note the rated object, a home or a product, the method, the test or model conditions, and the date and scale version. If any of those differ, the comparison needs adjustment or should not be made at all, and a seller or advertiser who compares a building rating with a product label, or an old label with a new label, should be asked to explain the basis.

Check scope: does a product label cover only energy, or also water, noise, capacity or other performance? Does a building rating cover only modelled energy and carbon, or also condition, comfort or running costs? Scope differences mean a good label in one dimension does not guarantee good performance in another, and a building rating does not guarantee a comfortable home, just as a product label does not guarantee a quiet or durable appliance.

In the EU, product energy labelling is governed by EU labelling regulations, with a common label format across member states for products sold in the EU, while building certificates are national under the EPBD framework. A consumer in the EU therefore encounters a common product label system alongside national building certificates, and should not assume that commonality extends to buildings, where national methods and classes still differ.

In the UK, product labelling follows UK labelling regulations, retained and adapted from EU law, with a similar A to G format, while building EPCs follow UK national assessment methods. A UK consumer should therefore treat product labels and EPCs as separate systems with separate regulators and methods, even though both use familiar letters and colours, and should check each system's guidance separately.

One comparison mistake is choosing a home or a product on letter alone, without checking score, test conditions, or date. A product at the top of one label class and a product at the bottom of the next class may differ negligibly, just as homes in adjacent bands may differ by a single score point, and letter-only shopping overpays for negligible differences in both cases.

Another mistake is assuming a high product label guarantees low installed energy. A heat pump, boiler or appliance labelled efficient in a laboratory may perform differently when installed in a real home, with real pipework, controls, sizing and use patterns. Installed performance, commissioning, and household use matter as much as label rating, and a label should be treated as a starting comparison, not as a performance promise.

Keep building certificates and product labels separately, with their dates, methods and scores noted, so future comparisons do not confuse them. For a home purchase, keep the EPC with viewing and survey notes; for a product purchase, keep the label, manual and warranty, so installed performance can be compared with label claims if a dispute arises.

Ask a retailer or assessor to explain what a label or rating actually measures, under what conditions, and what it leaves out. Ask also whether the scale has been rescaled since the label or rating was issued, and whether installed performance is expected to match label performance for your use. Those questions keep letters in their proper, separate places.