Why Your Flat Gets Colder at Night & How to Fix It

As the sun sets, many people notice their flats becoming uncomfortably chilly. This nighttime cooling can disrupt sleep and leave you feeling cold, especially in older buildings or poorly insulated spaces.

Why Your Flat Gets Colder at Night & How to Fix It

Your flat gets colder at night because heat escapes faster when the outside air cools and your heating system often runs less or switches off. Fix this by sealing drafts, improving insulation, and maintaining your heating to keep steady warmth after dark.

Heat moves from warm to cold areas, so when outdoor temperatures drop at night, your flat loses heat through walls, windows, floors and ceilings. This process speeds up if there are gaps or poor insulation. Cold air entering through cracks near windows and doors lowers indoor temperature quickly.

Common heat loss spots include single-pane windows, unsealed door frames, and poorly insulated walls or loft spaces. Floors over unheated basements or crawl spaces also draw warmth away. Radiators behind curtains or blocked by furniture reduce heating efficiency, making rooms feel colder.

Start by sealing drafts with weatherstripping or door sweeps to block cold air leaks. Add thick curtains or thermal blinds at windows to reduce heat loss. Use rugs on cold floors to add insulation. These steps cut heat loss and keep your flat warmer without extra energy use.

Check your heating system regularly. Clean or bleed radiators to ensure they heat efficiently. Replace or service boilers and heat pumps as per manufacturer guidelines. A well-maintained system delivers consistent warmth, preventing temperature drops at night.

1. Seal Drafts
   Use foam or rubber weatherstripping on window and door frames to block cold air entry.
2. Improve Window Insulation
   Install thermal curtains or add window film to reduce heat escaping through glass.
3. Insulate Floors and Walls
   Lay rugs on floors and consider adding insulation to walls or loft spaces if possible.
4. Maintain Heating System
   Bleed radiators and schedule boiler servicing to keep heat output steady and efficient.

Keeping your flat warm at night is about reducing heat loss and running heating efficiently. Draft proofing and insulation cut unwanted cold air entry and slow heat escape. Regular heating system care ensures steady warmth without wasting energy. These actions work together to fix the common cause of nighttime cooling.

If your flat still feels cold at night despite these fixes, check for uneven heating or cold spots caused by furniture blocking radiators or poor heat distribution. Learn how to balance radiator output or use supplemental heaters safely to target colder rooms Why Is One Room Colder? How to Fix It.

Common Causes of Heat Loss at Night

Heat loss at night happens mainly because your flat’s warm air escapes while the outside gets colder. The difference in temperature drives heat out through weak spots. This is why your apartment feels colder at night than during the day.

Windows and doors are the biggest culprits. Single-pane windows and unsealed door frames let warm air leak out and cold air seep in. Even small gaps around window sashes and door edges can cause significant drafts. Older or poorly fitted windows lose heat much faster than insulated or double-glazed ones.

Insufficient insulation makes heat loss worse. Walls, ceilings, and floors that lack proper insulation allow heat to pass through easily. Thermal mass—the ability of building materials to store heat—also matters. Materials like concrete or brick hold warmth longer than lightweight materials, helping keep rooms warmer overnight.

Heating systems can add to nighttime chill if they are set to lower temperatures or switch off completely at night. Some systems cycle off too long or don’t maintain steady heat, causing temperature dips. Radiators or vents blocked by furniture reduce heat distribution. Inefficient or malfunctioning thermostats can fail to keep the flat warm enough when the outside temperature drops.

Actionable Steps to Keep Your Flat Warm

To keep your flat warm at night, start by sealing cold drafts and making your heating system work smarter. Drafts let cold air in and warm air out, while inefficient heating wastes energy and fails to maintain a steady temperature.

1. Seal Drafts Around Windows and Doors
   Use weatherstripping tape or foam gaskets on window and door frames. Check for gaps by holding a lit candle near edges; if the flame flickers, air is leaking. Install door sweeps on the bottom of exterior doors to block cold air.
2. Apply Window Insulation Film
   A clear plastic film applied inside window frames traps a layer of air, cutting heat loss by about 30%. Use double-sided tape and a hair dryer to tighten the film for a smooth finish.
3. Close Curtains or Blinds at Dusk
   Heavy curtains add a layer of insulation over windows. Close them as soon as it gets dark, especially on single-glazed windows, to reduce heat escape.
4. Optimize Radiator Use
   Bleed radiators to remove trapped air, improving heat output. Keep furniture and curtains clear of radiators to allow heat to circulate. Use thermostatic radiator valves to control temperature room by room.
5. Maintain a Consistent Indoor Temperature
   Set your thermostat to a steady temperature overnight, around 65 to 68°F (18 to 20°C). Avoid turning heating off completely; reheating a cold flat uses more energy and causes uncomfortable temperature swings.

Heating a whole room with a 1,500 W space heater costs about $6.12 per day running 8 hours at 17¢ per kWh. A heated blanket uses around 100 W, costing about 41¢ per day for the same time. Use a heated blanket if you mainly want to stay warm in bed.

If drafts persist after sealing, check for gaps around pipes, vents, and electrical outlets. Use foam sealant or outlet gaskets to plug leaks. These small fixes add up to a noticeable boost in warmth.

Consider using a programmable thermostat to lower heating when you are asleep but keep it from dropping too low. This avoids the flat getting very cold and reduces heating costs.

Keep interior doors open to allow heat to circulate freely, except for rooms you do not use. Closing doors traps heat where you need it most.

If you have a radiator with a reflector panel behind it, check that it is properly installed. Reflector panels push heat back into the room instead of letting it escape through an exterior wall.

These steps work together to reduce heat loss and keep your flat warm all night. Draft proofing cuts cold air entry, while heating system adjustments improve heat distribution and efficiency.

When to Call Professionals for Help

Call a heating engineer if your heater frequently trips breakers, fails to warm rooms evenly, or makes unusual noises. These signs indicate a malfunction or wiring issue that needs expert diagnosis.

You need professional help when persistent cold spots remain after draft proofing and using portable heaters. These can signal insulation problems or hidden leaks that require specialist tools to detect.

A thermal imaging survey reveals where heat escapes through walls, ceilings, windows, and floors. Consider this service if you suspect insulation gaps or want precise data to prioritize improvements.

Upgrading your heating system can solve inefficiency and uneven warmth. Modern boilers and smart thermostats maintain steady temperatures and reduce running costs compared to old or manual systems.

If your heating system is over 15 years old, emits strange smells or sounds, or requires frequent repairs, a professional assessment is wise. They can recommend replacement options that fit your flat’s size and insulation.

1. Evaluate Symptoms
   Note if your heater stops working, rooms stay cold despite heat on, or if you smell gas or burning.
2. Check for Drafts and Cold Spots
   Seal obvious gaps and use portable heaters temporarily to see if conditions improve.
3. Schedule a Professional Inspection
   Call a heating engineer for system faults or a building surveyor for structural issues.
4. Consider a Thermal Imaging Survey
   Ask your professional about this to locate hidden heat loss areas precisely.
5. Plan Upgrades
   Discuss replacing old boilers or adding smart controls with the heating engineer.

Heating engineers are trained to diagnose and fix electrical and mechanical faults safely. They also advise on upgrades that improve comfort and energy use. Avoid DIY fixes on heating appliances to prevent damage or fire risk.

Building surveyors or insulation specialists handle problems beyond heating, such as wall cracks or dampness. Their expertise ensures repairs stop heat loss without causing moisture or structural damage.

Frequently Asked Questions