Following two consecutive summers of record-breaking heatwaves across the UK and Europe, our homes are facing a dual challenge. The dilemma facing the present UK home building stock, most of which will make up the building stock in 2050, is how to keep them both efficiently cool and warm, during summer and winter months, respectively.
The traditional British house was built like a thermos flask—designed exclusively to trap heat inside. However, as our climate changes, we must adapt our living spaces to block extreme summer heat while still retaining warmth during colder winters.
To keep our homes, cool during the hotter summer months, passive measures should be tried before electing to install air conditioning which could possibly be avoided to prevent the high cost of operating them over the long term, especially with high electricity tariffs. Some of these possible measures are outlined as follows.
1. Upgrade Windows and Shading (The Top Priority)
Windows are the primary way heat enters your home in the summer and escapes in the winter. Controlling the sunlight before it hits your glass is a very effective step you can take to prevent overheating
- Install External Shutters or Awnings: Shading your windows from the outside blocks up to 90% of the sun’s heat. Once sunlight passes through the glass, it gets trapped inside like a greenhouse.
- Use Light-Coloured, Reflective Blinds: If external shading is not an option, choose internal blinds with a reflective white or silver backing to bounce sunlight back outside.
- Upgrade to Smart Glazing: When replacing windows, look for modern double or triple glazing with “low-E” (low emissivity) coatings. These clever coatings act as a two-way mirror, reflecting harsh summer solar heat away while bouncing indoor heating back into the room during winter.
2. Insulate and Seal (The All-Weather Shield)
Property insulation is often only associated with winter savings, but it acts exactly like a cooler box in the summer—keeping the external heat out.
- Top Up Loft and Cavity Wall Insulation: High-quality insulation slows down the transfer of heat. In the summer, it stops a baking-hot roof from heating your bedrooms; in the winter, it helps to retain your heat within the homes living spaces.
- Draught-Proofing: Seal gaps around doors, windows, and floorboards. This stops cold winter winds from entering and prevents precious cool night air from escaping during a heatwave.
3. Master the Art of Natural Ventilation
A reputable engineering firm always looks at airflow. You can use physics to cool your home for free, provided you open and close your windows at the correct times.
- The Golden Heatwave Rule: Keep windows and curtains completely closed during the hottest parts of the day. Only open them at night or early in the morning when the outside air is cooler than the inside air.
- Create a Chimney Effect: If you live in a multi-story home, open windows on the ground floor and the top floor at night. Warm air naturally rises and escapes out of the top windows, drawing cool air in through the bottom.
- Work to promote ventilation: Outside of the hours of intense and direct heat, open up windows on different elevations of the homes and open door to facilitate airflow throughout the building
4. Harness Nature and Low-Energy Technology
Long-term modifications can significantly reduce your reliance on fossil fuels while keeping your home comfortable.
- Plant Strategic Greenery: Deciduous trees (trees that lose their leaves in winter) planted outside south-facing windows are nature’s perfect engineering tool. In summer, their thick leaves block the sun. In winter, the leaves fall off, letting the welcome winter sunlight pass through to warm your home.
- Switch to LED Lighting: Traditional halogen lightbulbs waste 90% of their energy as heat. Switching to LEDs keeps your home cooler in the summer and lowers your electricity bills year-round.
- Consider a Heat Pump with Cooling capabilities: If you are looking to replace your boiler, standard heat pumps provide highly efficient winter warmth, and some models can gently reverse their cycle to provide low-energy cooling during peak summer days.
To adapt our homes for extreme summer heat and cold winters, the best solutions depend heavily on when and how the properties were built. Traditional UK homes hold onto dampness and heat differently than modern buildings. Here are some high-level measures for the most common property types found across the UK
Flats & Apartments (High-Rise & Low-Rise)
Flats—especially modern, well-insulated ones—are highly susceptible to severe summer overheating because heat from lower flats rises, and they often lack cross-ventilation.
- Summer Heat Mitigation: Install light-reflective, thermal-backed blinds on all windows. Because you cannot easily install external shutters in a flat, investigate applying a professional solar control window film to reject solar heat before it enters.
- Winter Warmth Retention: Ensure your balcony doors and windows have high-quality rubber draught seals. Since flats are surrounded by other heated properties, minimizing draughts is often enough to keep heating bills very low.
- Airflow Strategy: If your flat only has windows on one side (single-aspect), use a mechanical eco-fan near a window to force stale, hot air out at night, drawing cooler air inside.
Victorian & Edwardian Terraces (Pre-1919)
These iconic homes were built with solid brick walls (no cavity), large windows, and open fireplaces. They are naturally breathable but can feel like an icebox in winter and a greenhouse in summer if the loft gets baked by the sun.
- Summer Heat Mitigation: The slate or clay tile roofs on these properties absorb massive amounts of heat. Focus heavily on installing thick loft insulation (at least 270mm) to stop that roof heat from radiating down into upstairs bedrooms. Depending on the type of roof tiles, consider painting the roof white to increase its albedo and to reduce the solar gain
- Winter Warmth Retention: Install a chimney balloon or draught-excluder in unused open fireplaces to stop massive amounts of warm room air from escaping up the chimney.
- Structural Care: Because these solid walls rely on breathing to prevent dampness, never seal up traditional air bricks. Use thick, heavy floor-to-ceiling thermal curtains in the winter to block draughts from the original sash windows.
Semi-Detached Houses (1920s–1950s)
Properties from this era often introduced cavity walls, though they were rarely insulated when built. They typically feature large bay windows which let in beautiful light but create major temperature control issues.
- Summer Heat Mitigation: Bay windows act like small sunrooms. Install external awnings or heavy vertical blinds inside to block the intense morning or afternoon sun.
- Winter Warmth Retention: If you have not already done so, invest in cavity wall insulation. It is one of the most cost-effective ways to trap heat in a semi-detached home and stops your warmth from escaping through the large external side wall.
Modern Detached Houses (1990s–Present)
Modern detached homes should be well insulated and sealed to meet strict building regulations. While excellent at staying warm in the winter, a lot of these homes may have been constructed from lightweight materials that do not absorb heat well, leading to rapid overheating during UK summer heatwaves.
- Summer Heat Mitigation: Because these homes are tightly sealed, the use of purge ventilation is important to reduce overheating throughout the year. Open windows on opposite sides of the house fully during the night to flush out the trapped heat. Consider installing a Mechanical Ventilation with Heat Recovery (MVHR) system with a “summer bypass” mode to provide fresh air without bringing in the daytime heat. As previously outlined, any heat pumps installed should be flexible to be used in heating and cooling modes. If there are underfloor heating/cooling coils, this will create even more of a comfortable cooler environment.
- Winter Warmth Retention: These homes should be good at retaining heat. If the home has one-controlled central heating or underfloor heating parameters, occupants should ensure controls are set correctly so that heat is not wasted in unused rooms.