Draughts, insulation and keeping heat in

Reducing heat loss is the most reliable way to lower heating costs, and the order in which measures are worth doing is consistent.

The order of priority

Roughly by cost-effectiveness.

Draught-proofing, which is inexpensive, can be done by a householder, and addresses uncontrolled air movement — which in an older house can be a substantial share of heat loss.

Loft insulation, which is cheap per square metre and where topping up an inadequate existing layer is straightforward.

Heat rises, and an uninsulated or under-insulated loft loses a large proportion of a house's heat.

Hot water cylinder insulation, where one exists, which is very cheap and pays back quickly.

Cavity wall insulation, where the construction allows it, which is a professional job with a good return.

Floor insulation, particularly suspended timber floors, which lose more than people expect.

Improved glazing, which is expensive and where secondary glazing and heavy curtains provide much of the benefit at a fraction of the cost.

Solid wall insulation, which is the most expensive and which for solid-walled properties is where the largest remaining loss sits.

Draught-proofing, specifically

Where the most improvement is available for the least money.

Doors: brush or foam strips around the frame, and a brush or a draught excluder at the base.

Letterboxes and keyholes, which are surprisingly significant.

Windows: self-adhesive foam or brush strips, and sealant around fixed frames where gaps have opened.

Floorboards and skirting: filler or flexible sealant along the junction.

Loft hatches, which are frequently uninsulated and unsealed.

Redundant extractor fans and vents.

Chimneys in unused fireplaces, which draw a very large volume of air continuously and which an inflatable balloon or a removable plate addresses.

What must not be blocked

The critical safety point.

Ventilation for combustion appliances — gas fires, boilers, solid fuel — must never be blocked, since restricting it risks carbon monoxide accumulation.

Air bricks and underfloor ventilation, which prevent rot in timber floors.

Trickle vents in windows and background ventilation generally, since a house sealed completely produces the condensation and mould discussed elsewhere on this site.

The objective is eliminating uncontrolled draughts while retaining controlled ventilation, which is a different thing from sealing everything.

The heating controls

Frequently more consequential than insulation and generally ignored.

A room thermostat set appropriately, since each degree of reduction produces a measurable saving.

Thermostatic radiator valves, which allow unused rooms to be kept cooler.

A timer set to actual occupancy rather than running continuously.

And, for condensing boilers specifically, a lower flow temperature, which allows the boiler to condense and operate at higher efficiency — a change that costs nothing and which a substantial proportion of installations have not had.

Radiators

Small measures worth doing.

Bleeding, when the top is cooler than the bottom, which indicates trapped air.

Balancing, so that distant radiators heat as well as near ones.

Reflective panels behind radiators on external walls, which are inexpensive and reduce loss through the wall behind.

And not blocking radiators with furniture or long curtains, which prevents circulation.

The measures with poor returns

Worth being honest about.

Replacing a functioning boiler purely for efficiency, where the payback period frequently exceeds the appliance's remaining life.

Replacing double glazing that is intact, where the improvement over existing units is modest.

And any measure promoted with claims of extraordinary savings, which in this sector warrant scepticism.

Getting an assessment

Worth doing before spending substantially.

Energy performance assessments identify the measures relevant to a specific property, and several jurisdictions operate grant or subsidy schemes for insulation, particularly for lower-income households.

A thermal imaging survey, offered by some local schemes and community groups, shows exactly where heat is leaving, which is more useful than any general advice.

The order to do things in

Which matters, because some measures are wasted if done in the wrong sequence.

Draught-proofing first, since it is the cheapest and has the shortest payback.

Loft insulation next, topped up to the currently recommended depth, which is greater than what most existing lofts contain.

Then cylinder and pipe insulation, which is inexpensive and immediate.

Then heating controls — a programmer, thermostat and radiator valves that actually work — which allow heat to be put where and when it is wanted.

Then wall insulation, which is a larger job and which must be done correctly, since badly executed wall insulation causes damp problems that are worse than the heat loss it fixed.

And glazing last, which is the most expensive and generally the longest payback of the group.

General information only, not professional advice. Never block ventilation for combustion appliances, fit carbon monoxide alarms, and consult a qualified professional for heating and insulation work.