Start With the Draughts You Can Feel

Before you start pricing up new windows or thinking about external wall insulation, spend a breezy afternoon walking around your home with a damp hand or a lit incense stick. Run it along skirting boards, window frames, loft hatches and any pipe that disappears through a wall. You will almost certainly find more gaps than you expect, and most of them cost very little to fix.

Draught-proofing is the cheapest energy measure on the list and it works immediately. A basic kit for a whole house — brush strips for doors, self-adhesive foam for windows, silicone sealant for gaps around frames — usually comes in under £50 and takes a weekend to fit. Do it properly and you can knock a noticeable chunk off your heating bill, because you are no longer paying to warm the street.

A few places people consistently miss:

• Chimneys. An open flue is basically a permanent hole in your ceiling. A chimney balloon or draught excluder costs £15–£30 and is one of the best-value fixes in any period property. Just remember to remove it before you light a fire.
• Letterboxes and keyholes. Brush seals and a keyhole cover cost a few pounds and take ten minutes to fit.
• Skirting boards. Where floorboards meet the wall, a bead of sealant or a thin strip of wood closes a surprising amount of leakage.
• Loft hatches. If you can see daylight around it, you are losing heat all winter.

One word of caution: don't seal rooms containing a gas boiler, open fire, wood burner or any other fuel-burning appliance without checking ventilation requirements. In those spaces you need a permanent air brick or vent, and blocking it is a safety issue, not a saving.

Loft Insulation: The Best-Value Upgrade There Is

If your loft is bare between the joists, or has a thin layer that looks older than you are, this is where your money works hardest. Current guidance suggests around 270mm of mineral wool — roughly 100mm between the joists plus a cross-laid layer of 170mm on top. That depth feels enormous when you see it, but it is what actually delivers the performance.

For a typical gas-heated semi-detached house, topping up from very little insulation to the recommended depth can save in the region of £180–£250 a year, and the materials for a DIY job on a straightforward loft often cost £200–£400. That is a payback of two to three years, which almost nothing else in home improvement can match.

Practical points worth knowing before you start:

• Never insulate directly over recessed downlights or the tops of cables that run warm — leave a gap and check manufacturer guidance.
• Keep the eaves clear for ventilation. Push insulation right into the corner and you risk trapping damp, which is a far more expensive problem than a cold loft.
• Lag any pipes and the cold water tank while you are up there. Lagging costs pennies and prevents burst pipes in a hard frost.
• If you have a loft conversion or a flat roof, this route isn't open to you, so consider rigid insulation boards between and under rafters instead.

If you would rather not crawl around in fibreglass, professional installation is often subsidised through government-backed schemes, and the cost can be lower than you'd guess. Get a couple of quotes and ask specifically what depth they will achieve.

Windows, Curtains and the Evening Routine

Replacing windows is a major renovation with a payback measured in decades, so leave it unless yours are genuinely single-glazed and rotten. There is a lot you can do with what you already have.

Thick, floor-length curtains with a thermal lining make a real difference, especially in older homes. Fit them on a track that overlaps in the middle, and let them hang below the sill rather than stopping at it — you want to trap a layer of still air against the glass. A simple pelmet or a curtain track mounted close to the ceiling stops warm air pouring down behind the fabric.

Habits matter too. Open curtains during the day to let sun in, close them at dusk before the temperature drops. In rooms you use in the evening, a well-fitted roman blind plus curtains is more effective than either alone. And if you have radiators under windows, a reflective foil panel behind the radiator pushes heat back into the room rather than into the wall.

Small Gaps That Add Up

Draughts are rarely dramatic. They are dozens of small, unglamorous leaks that together behave like an open window. Suspended timber floors are a classic culprit — cold air moves freely beneath them and rises through every gap between boards.

You can often deal with this from above. Lifting a few boards and sealing the gaps with a flexible sealant, or simply running a bead along the visible joints, makes a measurable difference. If you have access from a cellar or crawl space, insulating between the joists is even better, though it is muckier work.

Don't forget internal doors to unheated spaces — a garage, a conservatory, a utility room that never quite warms up. A decent brush or rubber seal on these doors keeps the rest of the house from subsidising them.

Working Out the Payback Before You Commit

The sensible order of operations is simple: draught-proof first, insulate the loft second, then reassess. Those two steps together cost a few hundred pounds and can transform how a house feels, without a single skip in the driveway.

Once those are done, sit down with your energy bills and do some rough arithmetic. Divide the cost of any further measure by the annual saving you expect, and you get your payback in years. Anything under five years is usually worth doing. Anything over fifteen needs to be justified by comfort, appearance or the fact that you plan to stay put for a very long time.

Larger work — cavity wall insulation, solid wall insulation, floor insulation, new glazing — has its place, but it should be a deliberate decision rather than a default. Most homes have an easy 20–30% of heat loss sitting in cheap, unglamorous fixes that nobody photographs for Instagram. Do those well, and you may find the bigger jobs can wait a while longer.