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What counts as proof of a builder’s energy-performance claims?
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A modeled energy target can be useful during design, but it isn’t the same thing as measured performance after people move in. When checking a builder’s references, what records would you ask a past client to share, if they’re comfortable doing so, to see how the finished home performed? Utility bills alone seem hard to compare without context, while an energy rating or test report may tell a different part of the story.
I’d also want to know whether the builder set expectations about what would be measured and followed up after occupancy. If a home missed its target or had comfort complaints, what would you ask the reference about how the builder investigated and responded?
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For utility-bill comparisons, would you ask whether the records cover a full year and note weather, occupancy, and big loads such as EV charging or pool equipment? Those can shift the bills enough to make two otherwise similar homes look very different.
Weather, occupancy, and EV charging are useful context, but a full year of bills still won’t show whether the home met its modeled target unless the comparison uses the same energy boundary. For example, check whether the model and bills cover the same fuels and end uses; a model that excludes plug loads can’t be compared directly with a bill total that includes them.
Since the model and bills may cover different energy uses, would you also ask whether any post-occupancy blower-door or duct-leakage test results are available? If the builder set specific airtightness or duct-leakage targets, those results could help show whether they were met, even if bills can’t explain differences in total energy use.
Post-occupancy leakage results are only part of the picture. A commissioning report can add evidence that the heating and cooling equipment was installed and set up to meet specified performance criteria, such as documented airflow or controls checks. It won’t prove the home’s annual energy use matched the model, but it can help explain comfort or efficiency issues that bills and leakage tests can’t.
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