It’s true that a summerhouse can be enjoyed throughout the year. But the extreme temperatures in the middle of a summers day can make it unbearable as the mercury begins to rise. Taking practical steps to keep the temperature down can stop your garden building from feeling like an oven and create a comfortable environment.
We’ve all been there, opening the door to our summerhouse on a sunny July afternoon, only to find the temperature inside is unbearable and turning back around again. And this is due to most summerhouses being built in a way that will maintain heat. Most garden buildings feature little ventilation and are usually painted in dark colours that will absorb heat and quickly raise the interior temperature. With nowhere for the heat to escape, your summerhouse is going to remain stiflingly hot even after the sun has gone.
Thankfully, taking practical steps can stop the temperature from rising in the first place, and when it does increase, allow the heat to escape quickly. While many of these considerations should be taken into account during the construction phase, steps such as introducing extra ventilation can be added to pre-existing garden buildings.
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When we think of insulating a summerhouse, it’s usually to keep the building warm during the winter. But the effect of insulation has similar benefits throughout the summer as well. The way insulation works is to stop the transfer of heat between one side and the other. In the winter, this stops heat from escaping. But in warmer months, the effect is reversed and insulation stops the heat from outside warming up the walls & roof of your summerhouse, and the warmth transferring through to the interior.
The difference with good insulation can be remarkable and solve heat issues straight away by giving you more control over the climate inside. Temperatures are often highest in summerhouses with a black felt roof. In fact, the wooden beams below the felt can often be hot to touch as the heat is transferred inside. This is the ideal spot for insulation to cut off the heat transfer from outside. We also recommend insulating the walls as well to cover all sides of the building where heat can be transferred to the interior.
There are several choices of insulation available for a garden building. PIR insulation boards create an easy to use solution with high thermal values. The insulation board is cut into shape and placed tightly between the beams. Alternatively, insulation roll can be used. The thick wool packs into the wall and is also great for sound insulation. Once installed, the interior walls should be boarded over with plywood or a similar material. Insulation is not a low-cost solution, it can often cost hundreds to insulate a summerhouse completely. But it will create a comfortable environment that is less exposed to the extremes of the temperature outside.
Use a solar reflective film
Large glass windows & doors on a garden building let plenty of sunlight in which can quickly begin to heat up the temperature inside. Covering the windows with curtains or blinds may spoil the idea of a summerhouse where we want to feel partly outdoors and enjoy the garden space. A great solution is to use a film on the windows which still allows you to see outside but stops some of the heat from getting through.
Solar reflective window film works by giving a mirrored appearance to external glass, which also provides privacy when inside. UV rays from the sun are filtered out which protects furniture from UV damage and also improves interior conditions. Window film can be installed yourself and is available from several retailers across the internet.
Paint the exterior a lighter colour
Changing the colour of your summerhouse can make a noticeable difference to how hot to the touch the building is. While it can be tempting to use a modern dark grey colour scheme, this could be causing your summerhouse to absorb an increased amount of heat and create a warmer environment.
It’s well known that different colours will absorb light at different rates. Darker colours absorb more light, and since light is energy, the materials temperature increases. Darker colours are better radiators or heat, exactly what we want to avoid in the middle of a summer’s afternoon. With a lighter colour, the opposite applies, the light is reflected instead, so the material is not absorbing additional energy and the effect of increased heat is going to be minimised. When my summerhouse was painted dark grey, the exterior would often be too hot to even touch in places, creating a heat trap inside, which was in no way usable.
The best colour scheme for a cool building is white, and the reason many apartments in hot counties are always painted white. The majority of light is reflected and heat from the sun is regulated better. But let’s be honest, we don’t want a completely white summerhouse, it is going to look out of place in a UK rear garden. Instead, stick to lighter shades of paint and avoid dark colours where possible. Alternatively, consider a wood stain that will retain the wood’s natural colour and still keep it protected.
Set up a fan or AC unit
Using a fan is often a quick fix when a room becomes too hot and stuffy. This simple solution can quickly create the impression of a cooler room and keep us comfortable. A fan does not actually cool the temperature down inside a summerhouse. Instead, it works to move the air around the room, creating a cooling effect on the skin. While a good solution for warm days, extremely hot days are going to see little noticeable benefit from a fan in the corner of the room.
Air conditioning and heat pump units are becoming an increasingly popular solution for those using a garden building all year round. The AC unit provides cool air into the summerhouse, which quickly cools down the temperature and creates a colder environment, without the need to open doors and windows. For use in a garden office, air conditioning allows the temperature to be regulated, without opening doors that will let the noise in from outside.
While this may sound like an expensive investment, systems are increasingly becoming more affordable and may reduce your running costs in the long term as well. Many systems can also use heat pumps to warm up a garden building in the winter. Heat pumps are considerably lower cost to run compared with electric heaters and make a great solution for always achieving the perfect indoor temperature.
Installing a fan is a quick solution and can be purchased for little cost. The decision to install an air conditioning unit is going to depend on how much your summerhouse is used and whether the benefits can be realised throughout the year.
Place vents high up
Ventilation is essential to any garden room which is going to be used regularly. The issue with most pre-built summerhouses is that they do not contain any air vents. When we add insulation and high-quality doors & windows, we create nowhere for the air to escape and ventilate properly. As well as creating a stuffy environment, the warm moist air can lead to mould over time that could damage the building.
When the sun is shining down on a summerhouse, the temperature is building up inside and without an escape for the warm air, it is going to become increasingly hot. Installing a passive ventilation system is a quick fix that can make a big difference. Wall vents are easy to install and create an exhaust for the hot air to get out.
We recommend placing an air vent high up on an exterior wall to allow the air to escape as it rises. You could go even further and install a second vent near the bottom of the opposite wall. This will allow cooler air to circulate inwards from one side of the building and warmer air to leave on the other.
If there’s not much you can do inside your summerhouse, think about the surroundings to stop the sun’s rays from reaching your building in the first place. Positioning is important as being in a location with direct sunlight most of the day is going to provide little protection from the elements. We recommend installing a summerhouse in a location that is covered by shade for at least part of the afternoon, this will provide some respite on a scorching hot day and give the building a chance to cool down.
For summerhouses that are already installed, take a look at how you can create more shade around the building. This could be by tall plants and bushes nearby which will provide some shelter from the sun. We have our summerhouse located near a tree which provides cover for a few hours throughout the day, enough to stop the temperature from increasing too dramatically.
Overall, following these practical steps can keep your summerhouse, log cabin or garden room cool throughout the summer. With the correct steps in place, there’s no reason you can’t enjoy your building whatever the weather conditions.
Installing insulation is our favourite choice to create an interior environment that is comfortable and gives increased control over the living conditions. The colour choice of paint used has a big effect when the building is exposed to direct sunlight. Sticking with a lighter colour reduces heat absorption and leaves the outside of the building cool to the touch.