Home Energy Audits: What to Expect During a Visit

What a home energy audit actually involves

A home energy audit is a structured, room-by-room look at how your property uses, loses and — increasingly — generates energy. It is not the same as a quick online EPC calculator. An assessor walks the building with you, opens loft hatches, checks boiler settings, notes window types and asks how the house actually feels through the year. Expect the visit to take between one and three hours for a typical UK semi or terrace, longer for older or larger properties with extensions and multiple heating zones.

The aim is simple: to work out where your money is going and which improvements will make the biggest difference for the least disruption. You should finish the visit knowing what to do first, what can wait, and roughly what each step involves.

Before the assessor arrives

You do not need to tidy the whole house, but a little preparation makes the visit far more useful. Have your most recent energy bills to hand, ideally covering a full twelve months, plus any EPC certificate, boiler service records and details of work done by previous owners.

• Clear access to the loft hatch, boiler, hot water cylinder, fuse board and any smart meters or thermostats.
• Make a note of rooms that are always cold, draughty or damp, and when the problem is worst.
• Jot down how you use the heating: what time it comes on, what temperature you set, and whether any rooms are switched off.
• Mention any planned work — a new kitchen, a loft conversion, an extension — so the recommendations fit your plans.

If you have a dog that objects to strangers, or a loft full of boxes, say so in advance. Assessors are used to real homes, not show houses.

Insulation, heating and glazing: the core checks

Insulation is usually the first thing examined. The assessor will measure what is in the loft — modern standards suggest around 270mm of mineral wool — and check whether it has been laid evenly, with no gaps around pipes, downlights or the eaves. They will look for cavity wall insulation, check whether it is present and whether there are any signs of damp that might suggest it has failed or was installed badly. Solid walls will be noted as harder and more expensive to treat, but not impossible.

Heating gets close attention. A condensing boiler running at 80°C is working harder than it needs to; turning the flow temperature down to 60°C or lower can cut gas use noticeably, provided the radiators are correctly sized. The assessor will check radiator valves, whether thermostatic heads are fitted and working, and whether the hot water cylinder has a well-fitted jacket. Older properties with a conventional cylinder and an immersion heater often have easy savings hiding in plain sight.

Glazing is assessed honestly. Single glazing loses heat quickly, but replacing every window is rarely the cheapest first step. Secondary glazing, heavy curtains and draught-proofing around frames can perform surprisingly well for a fraction of the cost. The assessor will also check for trickle vents and whether windows have been sealed shut — a common mistake that traps moisture indoors.

Ventilation and airtightness: the balance people forget

A house needs to breathe. Too much draught and you lose heat; too little and you get condensation, mould and poor air quality. The audit looks at both sides of that equation. Expect a check of extractor fans in the kitchen and bathrooms, whether they actually shift air, and whether windows have working background ventilation.

If your home is very airtight — common in newer builds — the assessor may discuss mechanical ventilation with heat recovery, which brings in fresh air while recovering warmth from the stale air it expels. In older properties, the emphasis is usually on controlled ventilation rather than sealing everything up. This matters if you are planning insulation work, because tightening a leaky house without addressing ventilation can create damp problems later.

Where renewables fit in

Only once the fabric and heating are understood does it make sense to talk about on-site generation. The assessor will assess roof orientation, pitch and shading for solar panels, and whether your electricity use pattern suits battery storage. For many homes, a well-insulated property with a heat pump and a modest solar array will outperform a poorly insulated one with a large array bolted on.

• Solar PV works best on a south-facing roof with minimal shading; east-west roofs still generate useful output across the day.
• Heat pumps suit well-insulated homes with larger radiators or underfloor heating, and work most efficiently at lower flow temperatures.
• Solar thermal can pre-heat domestic hot water, though it competes for roof space with PV.
• Battery storage makes most sense if you are home in the evening or on a time-of-use tariff.

Reading your report and deciding what to do first

The written report should arrive within a few days. Look for a clear priority order rather than a long wish list. Typically the sequence runs: draught-proofing and loft insulation first, then heating controls and flow temperature, then glazing and wall insulation where cost-effective, then renewables.

Check whether each recommendation includes an approximate cost, an expected saving and a note on disruption. Anything involving scaffolding, planning permission or a qualified installer should be flagged. If two recommendations conflict — for example, sealing a chimney breast when you want an open fire — the report should say so.

Finally, treat the audit as a starting point, not a verdict. Ask questions, get two or three quotes for anything significant, and remember that a warm, efficient home is usually built up in stages rather than in one expensive weekend.