This quick paper check could show whether leaky windows are raising your heating costs

Basic, low-cost insulation can be much cheaper than constantly turning up the heat.

Instead of immediately calling a technician or boosting the thermostat, homeowners can try a fast check that requires only a sheet of paper.

What to know

Tom's Guide says weak heating efficiency is not always caused by a boiler issue in a five-point cold-weather checklist. Many people first assume they need more heat, but the real problem may be poor insulation. The guide points to windows, attic insulation, radiators, exposed pipes, and hidden drafts as common places where warmth escapes.

“Homeowners often focus on their boiler or thermostat when preparing for winter, but heat can also escape through small gaps and poorly insulated areas around the property,” said Kaitlin Wood of Travis Perkins, according to Tom's Guide.

To carry out the simple test, open a window and place a sheet of paper inside. Then close and seal the window.

The goal is to see how tightly the window seals. If the paper slips out too easily after the window is locked, that suggests the seal is not tight enough and warm air may be leaking through the gap. Once problem areas are found, the fix may be as simple as adding draft-proofing strips.

With energy prices high, simple insulation measures can be much cheaper than continually increasing the heat.

There is no universal fix

Even if a window fails the paper test, draft-proofing strips are not always the right answer. Rob Haddock, Senior Group Commercial Category Manager at Travis Perkins, said the best repair depends on what is causing the issue.

“A joiner or window fitter can establish whether the window needs a replacement seal, an adjustment, or a more substantial repair, helping homeowners avoid applying a product that is unsuitable for the window,” Haddock said, according to Tom's Guide.

Check the attic too

After windows, Tom's Guide identified attics as another easily overlooked source of heat loss. Insulation can become less effective when loft boards or stored boxes compress it or move it out of place. Homeowners can use a tape measure to compare insulation depth in heavily used sections of the attic with emptier areas. Depending on the home's climate zone, the depth should typically range from 10 to 24 inches.

However, insulation alone does not always solve the problem of keeping heat inside.

“Adding more insulation will not necessarily solve the problem if it is then compressed beneath boxes or loft boards. Raising boarding can provide storage space while allowing the insulation underneath to retain its intended depth,” Haddock said, as quoted by Tom's Guide.

Where can I learn more?

For more ways to retain heat and keep energy bills lower, these stories offer practical, low-cost ideas for homeowners.

• Simple steps like sealing windows and weatherizing can help keep homes warmer with less energy.

• Budget-conscious homeowners have used room dividers to trap heat and avoid warming unused space.

• HVAC experts have said aluminum foil behind radiators can help direct more heat inward.

• A meteorologist warned that turning up the thermostat can waste money without fixing drafts.

• Closing interior doors changes airflow in ways that can affect a system's efficiency.