How to do a home energy audit yourself

An energy audit doesn't have to be a professional exercise. A careful, room-by-room inspection tells you most of what you need to know — which gaps are letting in cold air, whether your insulation is doing its job, and which habits or appliances are costing the most. The audit itself is free; what you choose to act on is up to you.

Why bother with an audit?

Most households waste a significant portion of the energy they pay for — through gaps, poor insulation, inefficient appliances, or heating and hot water that's set higher than needed. The problem is that you can't see energy leaving. An audit makes the invisible visible: you find the cold spot behind the bookcase, the loft hatch with no insulation, the boiler timer that's been set wrong for years.

Once you know where the losses are, you can target fixes where they'll have the biggest effect rather than guessing. Draught-proofing a leaky door is far cheaper than upgrading windows, but you only know it's the priority if you've actually checked.

What you need to prepare

Nothing is strictly essential, but the following helps:

• Your recent energy bills (or access to your account online) — ideally twelve months' worth so you can see seasonal patterns.
• A notepad or your phone to record what you find as you go.
• A cold or windy day to do the draught check — draughts are easy to feel in cold weather and almost undetectable in a warm spell.
• A thermometer (even a cheap one) is useful for spotting colder rooms or surfaces, but not essential.
• A smart meter or in-home display (if you have one) shows real-time energy use, which helps identify which appliances draw the most power.
• Your boiler or heating system manual — useful when you check settings.

Step-by-step walk-through

Work through each of these steps in order. Take notes as you go — a simple list of what you found and roughly where is enough.

1. Review your bills and usage

   Before you start the physical inspection, look at your energy bills for the past year. Note your total consumption in kilowatt-hours (kWh) for both electricity and gas (or oil, or whatever fuels you use). Look for months when usage jumped unexpectedly — that sometimes reveals a specific problem. If you have a smart meter, check whether there's a baseline usage overnight (when everything should be off) that seems high; that can point to appliances left running or on standby.

2. Hunt draughts room by room

   On a cold or windy day, move through every room and check the following systematically:

   • External doors — around the frame, under the door, through the letterbox and keyhole.
   • Window frames — run your hand slowly around the inside edge. Older single-glazed windows often have gaps between the frame and the wall.
   • Where pipes, cables or wires enter through walls — these gaps are often left unsealed.
   • Floorboards on ground floors, especially near walls and skirting boards.
   • The loft hatch — one of the most commonly overlooked draught sources.
   • Unused fireplaces and chimneys — these are major draughts even with no fire lit.

   Mark down anything that felt cold or draughty. These are cheap to fix and often have an immediate effect on comfort.

3. Check insulation in loft and walls

   Go up into the loft or attic if you have one. Is insulation present between and over the joists? Is it at least 270 mm (about 10 inches) deep? Is it in reasonable condition, not compacted or wet? If it's thin, patchy or absent, adding insulation is usually one of the cheapest improvements with the fastest payback. While you're there, check whether the loft hatch itself is insulated and sealed around the edges.

   For walls, find out whether your home has solid walls or cavity walls (cavity walls were common from roughly the early twentieth century onwards in many countries; older homes tend to be solid brick or stone). If cavity, check whether the cavity has been filled — your energy supplier, a previous survey, or a building control record may have this information. Solid walls are harder and more expensive to insulate.

   Check accessible floor insulation if you have a suspended timber ground floor — cold air from beneath is a significant source of heat loss in older homes.

4. Inspect heating and hot water settings

   Check your boiler, heat pump or other heating system:

   • What temperature is the thermostat set to, and is the timer programme correct for your current routine?
   • Are thermostatic radiator valves (TRVs) set sensibly — turned down in rooms you rarely use?
   • Are there any radiators that feel cold at the top (trapped air) or cold in patches (sludge build-up)?
   • What is the hot water temperature set to? Is water stored at the right temperature for safety?
   • Is the hot water cylinder insulated with a jacket? Are hot pipes insulated in the first metre from the cylinder?
   • When was the boiler or heat pump last serviced?

5. Audit appliances and standby

   Walk through every room and make a note of:

   • Appliances that are always plugged in and drawing power — older appliances are often much less efficient than current ones.
   • Devices left on standby: TVs, set-top boxes, games consoles, phone chargers, desktop computers.
   • The age of your fridge, freezer, washing machine and dishwasher — anything over fifteen years old is likely significantly less efficient than a modern equivalent, though replacing working appliances before they fail is rarely cost-effective on energy savings alone.
   • The fridge temperature setting (3–5°C / 37–41°F for a fridge; around -18°C / 0°F for a freezer is typical).

   A plug-in energy monitor (an inexpensive device available in hardware shops) can measure exactly how much any appliance draws; useful if you suspect a particular device is a heavy user.

6. Check lighting

   Go through every light fitting in the house and note which use LED bulbs and which still use older halogen or incandescent bulbs. LEDs use significantly less energy and last far longer. Make a list of the fittings to replace — prioritise rooms that are lit for many hours each day.

7. Inspect windows and doors

   Are the windows single, double or triple glazed? Single glazing loses heat very rapidly. For double or triple glazing, look for condensation forming between the panes (a sign that the seal has failed and the insulating gas has escaped, reducing their effectiveness). Check whether external doors are solid or have a lot of glazing, and how well they seal when closed.

Make a prioritised fix list

Once you have your notes, sort the issues you found into three rough groups:

• Free or near-free: adjusting the thermostat and timer, turning off standby, turning down TRVs in unused rooms, draught-proofing with a door snake or cheap weatherstrip. Do these first — they cost almost nothing and can start saving immediately.
• Low-cost fixes: draught-proofing gaps around pipes and floorboards (sealant costs very little), fitting a hot water cylinder jacket, replacing remaining halogen bulbs with LEDs, fitting radiator reflector panels. These typically pay back within one to three heating seasons.
• Bigger investments: loft or wall insulation, replacing old windows, a new or upgraded heating system. These have larger upfront costs but often the biggest long-term impact. Many countries and regions offer grants, rebates or subsidised loans for insulation and efficient heating — check what's available before spending your own money.

Don't try to do everything at once. Fix one thing, see the effect on your bill, then tackle the next.

When a professional assessment is worth it

A DIY audit is a great starting point, but a certified professional assessor brings equipment — thermal cameras, blower door tests that pressurise the house to find leaks — that reveal problems invisible to the naked eye. It's worth considering if:

• You're planning significant renovations or a retrofit and want to get the specification right.
• Your energy bills are unusually high and you can't identify why.
• You want to access a grant or scheme that requires an official assessment or energy performance rating.
• You're buying or selling a property (in many countries an official energy performance certificate is legally required).

Professional assessment requirements and certification schemes vary by country. In the UK, look for a registered energy assessor or a Trustmark-accredited retrofit coordinator. In the US, the RESNET HERS rater scheme covers professional home energy ratings. Other countries have their own equivalent bodies.

Track results after changes

Once you've made changes, track whether they work. Note your meter reading or monthly kWh figure before and after each change. Energy use varies with weather, so compare like with like — the same month in different years, or adjust for how cold the period was. A smart meter display makes this easier by showing daily and monthly usage at a glance. Even rough tracking helps you see which changes had the most impact and keeps you motivated to tackle the next one.

Audit checklist

• Gather twelve months of energy bills before you start.
• Do the draught check on a cold, windy day.
• Check every external door, window frame, pipe entry and the loft hatch for draughts.
• Inspect the loft — is insulation present, deep enough and in good condition?
• Find out whether your walls are solid or cavity, and whether cavity walls are filled.
• Check the thermostat setting, timer programme and TRV settings.
• Look for radiators with cold patches (bleed if at the top; investigate if elsewhere).
• Check whether the hot water cylinder has a jacket and pipes are insulated.
• Note which appliances are left on standby or always plugged in.
• Identify any remaining halogen or incandescent bulbs to replace with LEDs.
• Check window glazing type and condition.
• Make a fix list sorted by cost and likely impact.
• Note a baseline meter reading before making changes so you can track results.