Heat in the loft: tips for cooling your attic in summer

As the sun's rays strike your roof directly and hot air naturally rises from below, the rooms in your loft can get particularly hot. The heat in the loft builds up over the day and, if it’s trapped in your loft with no way to escape, your loft space will feel stifling at night.

Several factors cause heat to accumulate in your loft: 

• Structural factors: these are linked to the physical characteristics of your home and its roof. The type of roof, poor insulation and ventilation can all lead to a build-up of heat in your loft.
• Environmental factors: these are linked to external conditions and climate. Exposure to the sun, the position of your property and weather can all make your loft heat up.

Heat in your loft can be the result of a combination of these factors, let's consider them one by one.

If you want your loft to never get too hot and to always feel comfortable, air needs to circulate well up there.

Hot air rises and when it’s trapped in your attic, it can make your loft space feel boiling.

For your loft to be pleasant throughout the summer months you need natural ventilation and roof windows are great for this. Opening roof windows during the coolest times of the day on hot days will keep a steady flow of fresh air flowing through your living space. If you can also open vertical windows beneath your roof windows, you create a ‘chimney effect’, where hot air naturally rises up and out of your roof windows, while cooler air comes in from the windows below. 

In addition to controlling the temperature, good ventilation also stops your loft space from getting humid and prevents mould growth. Breathing fresher, cleaner air makes you feel better too, so it’s a win win all round.

A well-insulated loft plays a crucial role in keeping your loft comfortable on hot summer days and cold winter nights. 

If your roof insulation is non-existent or insufficient, the sun's heat will easily heat up the space below, making your loft unbearable throughout the summer. 

A well-insulated roof limits the amount of outdoor heat entering your loft, keeping it cool and reducing the need for fans or air conditioning.

Roof insulation also stops heat escaping from your home during the colder months and helps maintain a stable temperature throughout your house all year round. 

Loft insulation is a great investment. It makes your home more energy efficient and reduces your bills. 

The type of roof you have plays an important role in the energy efficiency and temperature of your home. 

Flat roofs, for example, accumulate more heat in the rooms below, because the entire surface is exposed to the sun. 

Gable roofs are designed to allow rainwater to drain away and minimise leaks; without adequate ventilation, heat gets trapped making rooms very hot during a heatwave.

If you’re building, extending or refurbishing your home and are adding a roof or changing its roof line, ask your architect to design the roof in a way that will ensure optimal energy efficiency and thermal comfort.

During the day, the sun directly hits your roof, heating it and transferring that heat to the rooms below. 

To reduce this effect, you can choose reflective roofing materials that reflect, rather than absorb, heat. 

Using sunscreens on your roof windows will also limit the direct impact of the sun’s beams.  VELUX anti-heat blackout shutters, for example, block up to 96% of the heat that hits them, helping to lower your indoor room temperature by up to 5 degrees.

In addition to the heat coming in from outside, the services and appliances you have in your loft can also be heating it up. 

Placing appliances, such as water tanks, boilers or other devices that generate heat, in your loft can increase the temperature up there.

To limit this, think carefully about where best to position these devices in your loft and make sure that there are suitable airducts for any appliances that require them. Get into the habit of turning off or reducing the use of non-essential equipment during the hottest hours of the day too. 

Draughts can have a significant impact on the temperature of your loft.

Unsealed gaps and joints allow warm air to enter your loft and make your loft insulation less effective.

To avoid this, fill in any holes and insulate your windows to make your loft feel comfortable all year round.

There are several quick and effective solutions that will help keep your loft cool. 

In the summer months, natural ventilation from open windows helps remove the heat that builds up in your loft. 

To ensure that the temperature in your loft never gets too high, you must keep out the hot air during the hottest part of the day and stop the sun's rays from hitting your roof windows. 

On very hot days, open your windows and doors in the early morning, late evening and at night, when temperatures are lower, to bring in a steady flow of fresh cool air. Keep them closed when the sun is at its strongest to stop hot air coming in.

If you have them, open roof windows and vertical windows together to create a stack effect, where hot air leaves through the roof and cool air comes in from windows below.

To stop your loft getting too hot, it's best to prevent heat from entering it in the first place.

Roof windows accessories, such as external blinds and shutters, will block heat before it reaches the glass in your roof windows, making it easier to keep your loft cool.

VELUX offers several solutions for heat protection:

• External anti-heat blackout shutters are constructed from durable aluminium and suit all climates. Solar or electric powered, these stop heat from entering your loft space and help keep out external noise too, ideal if you live on a busy road. They completely black out your window, so they are particularly suited to bedrooms.
• Made from a soft, durable fabric, solar-powered VELUX anti-heat blackout blinds block out heat and light. Easy to install from the inside, they run on free energy provided by the sun
• To let daylight filter through and still stop your loft from getting too hot, opt for VELUX anti-heat blinds. Made from a transparent mesh fabric, they let light filter through to your room, while still shading it from the heat of the sun. They are ideal for home offices or living rooms, where you want cooler temperatures and reduced glare.
• VELUX blinds and roller-shutter systems can be controlled automatically with our intelligent home solutions that allow you to programme their opening and closing. For example, the VELUX Active system uses sensors that monitor your room temperature and automatically close your electric or solar blinds and shutters to protect your loft from excessive heat. 

Visit the VELUX Shop to learn more about our automated systems and to find the right model for your windows.  

To sum up, when the temperature rises, these few simple strategies can help keep your loft cool even in the heat of summer:

• Insulate your loft space to limit the amount of heat coming in through the roof.
• Ventilate your loft in the early evening and night when the temperature drops and keep your windows closed during the hottest part of the day.
• Screen your roof windows with VELUX external shutters and anti-heat blinds to block out heat from the sun.
• Stop hot draughts from entering your loft by filling in any holes in your loft space.
• Remove thick rugs and carpets. While these warm up your home in winter, in the summer they trap heat and limit your floor’s ability to cool the room. Bare floors, especially tiles or hardwood, stay cooler, helping reduce the temperature in your attic.
• Opt for lightweight, breathable textiles throughout your loft. Swap heavy curtains, throws and bedding for cotton or linen alternatives. These natural fabrics improve air circulation and will make your loft feel fresher and cooler.
• Where possible, turn off or unplug devices and appliances that generate heat even in standby mode.

Together, these small steps will make your loft feel more pleasant throughout the summer.