How to keep your house cool in summer with ventilation

On hot summer days, without adequate ventilation, the rooms in your home can become uncomfortably warm and stuffy. You may notice condensation forming on your windows too; a sign of excess humidity, this can encourage mould to grow and make your air feel damp and smelly. With a few simple natural ventilation techniques, however, you can maintain a comfortable temperature and healthier environment in your home throughout the day and night.

Opening your windows early in the morning and in the evening and night, when the temperature has dropped, is one of the most effective ways to cool your home naturally. When you do this, you let cooler fresher air in and push hot air out.

Cross-ventilation is particularly effective here. This is where you open windows on opposite sides of your home, such as in the bedrooms and bathroom, to create a continuous flow of air that cools down your entire space. 

Even more powerful is the stack effect, where you open two sets of windows, one higher than the other, to take advantage of the fact that warm air rises. You might, for example, open a window in your hall and your roof windows to create an upward draft. Cool air enters through your hall window while hot air escapes through your roof windows, rapidly refreshing your indoor air.

If you have VELUX roof windows, keeping your home well-ventilated throughout the year is particularly easy when you combine them with VELUX ACTIVE with NETATMO. This smart, automated system uses indoor climate sensors to monitor the temperature, humidity and CO₂ levels in your room and adjusts your roof windows accordingly. It opens the roof windows when fresh air is needed and closes them if conditions worsen, helping you effortlessly regulate your indoor environment.

By following these simple steps, you can improve the air flowing through your home and its temperature to make it a pleasant place to escape from the sun.

The best time to ventilate your home in a heatwave is early in the morning and late at night after sunset, when the outdoor air is cooler. Letting in fresh air during the cooler parts of the day and night will make your home feel more comfortable and help you sleep better.

If you have ventilated your home well between sunset and sunrise, it’s best to keep your windows and doors closed when the sun is at its strongest. When it’s very hot outside, opening your windows will just let in hot air, heat up your house further and make your rooms feel hot and sticky.

While natural ventilation is essential for cooling your home, blocking the sun’s rays during the hottest parts of the day is just as important. Sunlight streaming in through windows will quickly heat up your living space, especially your loft and upstairs rooms, which are more exposed to the sun.

To reduce the heat inside your home, close your curtains and blinds during the day to keep out the hot sun.

If you have roof windows, install external anti-heat blackout shutters or anti-heat blackout blinds. These help block up to 96% of the sun’s heat and are perfect for rooms that you want to keep cool and shaded.

If you want to reduce your loft room temperature without blocking out daylight, opt for VELUX solar anti-heat blinds. Made from transparent mesh fabric, they allow daylight to filter through while reducing glare and preventing overheating and are ideal for home offices or living areas.

All VELUX blinds and shutters can be easily managed with VELUX ACTIVE, which automates opening and closing based on your room’s temperature, humidity and CO₂ levels, keeping your home cool and comfortable with minimal effort.

By adopting a few new habits and making some small adjustments, your loft space will stay cool and comfortable even during the hottest days of summer. Here are some practical tips:

• Ventilate during the coolest hours: Open your windows early in the morning and after sunset, when outdoor temperatures are lower, to let in fresh air and push hot air out.
• Keep windows and doors closed during the day: This prevents hot air from entering and helps maintain a stable indoor temperature.
• Close shutters and blinds: Keep your roof window shutters or blackout blinds closed during the day to block out direct sunlight and stop room temperatures rising.
• Use fans to improve airflow: Ceiling or portable fans move air around to create a cooling breeze.
• Remove home accessories that retain heat: Store away thick rugs, heavy curtains and chunky throws during the summer months. They trap heat and will make your loft feel warmer.
• Switch off non-essential electronics: Devices like TVs, speakers and computers give off heat, even in standby mode. Turn them off at the plug when not in use to avoid unnecessary heat.