Start with the fabric of the building, not the boiler

Older Welsh properties are wonderful places to live, but they were built in an age when coal was cheap and nobody worried about heat loss. Solid stone or brick walls, slate roofs, timber sash windows and exposed hillside or coastal sites all mean warmth escapes quickly. In a typical unimproved stone cottage or valley terrace, roughly a third of heat leaves through the walls, a quarter through the roof, and a good chunk through draughts and windows.

The temptation is to begin with a new boiler or a heat pump. Resist that for now. Insulation and draught proofing are usually cheaper, they cut bills immediately, and they make any later heating upgrade work far better. Work from the top down and from the simple to the complex.

Draught proofing: the cheapest wins come first

Draughts are the fastest way to feel cold and the easiest problem to fix. Spend a weekend with a tube of sealant, a roll of self-adhesive brush strip and a few spare hours.

• Chimneys: an unused flue pulls warm air out all winter. A chimney balloon or sheep's wool draught excluder costs very little and makes an instant difference.
• Doors: fit brush or rubber seals around the frame, a letterbox flap, a keyhole cover, and a fabric draught excluder at the base. A heavy curtain over a front door in an exposed porch area helps enormously.
• Windows: foam or brush seals on sash windows, plus silicone strips on casements. If the sashes rattle, a simple sash-lift or screw-in stop tightens them.
• Floors and skirting: gaps between floorboards and at the skirting line are common in older terraces. Paper-backed insulation pushed between joists, or a plain sealant bead, deals with many of them.
• Service pipes and cables: seal the holes where pipes enter from outside.

One caution: rooms with an open fire, a gas boiler or a solid fuel stove need a permanent air supply. Never seal up ventilation openings, trickle vents or air bricks that feed a combustion appliance.

Loft insulation: top it up properly

If your loft has 100mm of old mineral wool, you are well below the modern standard of around 270mm. Topping up with a second layer laid crossways over the joists is a job most people can do themselves, and the material is inexpensive.

Welsh weather makes the details matter. Keep a 50mm gap at the eaves so air can still move through the roof space, using rafter trays or proprietary eaves vents. Blocking ventilation in a damp climate invites condensation and timber rot. Insulate and draught-seal the loft hatch, lag any exposed pipework, and fit an 80mm jacket on a cold water tank. Do not insulate directly beneath a cold water tank, as a little warmth from below helps prevent freezing in a hard snap.

If you have a flat roof or a room-in-the-roof conversion, get specialist advice before adding insulation, as ventilation and fire safety need care.

Windows, doors and curtains

Original timber windows in a conservation area or listed building should generally be repaired rather than replaced, and secondary glazing is often the sensible answer. A well-fitted secondary pane can perform nearly as well as double glazing at a fraction of the cost, and it keeps the character of the property.

• Fit thermal linings or heavy interlined curtains, and close them at dusk.
• Tuck curtains behind radiators rather than over them, or fit a shelf above the radiator to push warm air into the room.
• Consider reflective foil panels behind radiators on solid external walls.
• Check whether you need consent before changing windows or doors in a conservation area.

Run your heating system better

How you use the heating often matters as much as the equipment. A few adjustments cost nothing at all:

• Set room thermostats to 18–21°C. Each degree above that adds roughly 6–10% to the heating portion of your bill.
• Time the heating to come on about half an hour before you get up and to go off half an hour before bed, rather than leaving it running low all day.
• Fit thermostatic radiator valves and use them. Turn down bedrooms and spare rooms, keep the main living space comfortable.
• If you have a condensing boiler, try a flow temperature of around 55–60°C for radiators. It runs more efficiently and still heats the house, though it takes longer to warm up.
• Lag hot water pipes, fit an 80mm cylinder jacket and keep hot water stored at 60°C.
• Bleed radiators annually and have the boiler serviced. A balanced system heats more evenly.

Portable electric heaters are rarely a saving. Per unit of heat they usually cost more than gas, so use them only to take the chill off a single room for short periods.

Bigger upgrades, in the right order

Once draughts, the loft and your heating controls are sorted, larger measures start to pay. Solid wall insulation, whether internal or external, is the big one for stone and solid brick homes, but it must be done with breathable materials. Traditional Welsh stone walls need to manage moisture; cement render and impermeable finishes trap damp and cause problems. Lime-based systems and vapour-open insulation boards are usually the right choice.

Think about a whole-house plan rather than piecemeal work, so insulation, ventilation and heating are designed together. If you are considering a heat pump, the property needs to be reasonably airtight and well insulated first, with adequately sized radiators. Before committing to anything expensive, speak to your local authority's energy advice team or a Welsh Government-backed warmth scheme, and check what grant funding is available in your area. A well-planned sequence of small, sensible improvements will keep an older Welsh home warmer for years to come.