Retrofit Solutions for Overheating
QWe live in a newly renovated 1970s home with a south-facing aspect and lovely views to the south. We have a lot of glazing to maximise the views, but have an overheating issue in the summer. What can we do to manage the heat? We don’t have a limitless budget and we don’t want to spoil the view.
AIf it is only the windows that are letting the heat in, there are several ways of managing the overheating. We will look at keeping the heat out and also heat mitigation once it has already entered the property.
The best way to keep the property cool is to not allow the sun in. Deciduous trees would disrupt your view but you could construct a pergola-type framework and grow deciduous plants on it such as grapes. The size of the pergola depends on you and how much shading you require. The sun is at its peak in summer but you will still get morning and evening sun that is lower so the actual shading area will need to be carefully calculated.
Alternatively, you could introduce shading using a retractable awning, but it would need to have reflective coatings to make sure that the radiant heat did not pass straight through. They can be simple external vertical blinds or structural horizontal units. Depending on the structure of the building you can have them fixed to the wall and then cantilever out on a hinged arm, or they could be fixed on a four-post framework with a guide rail on each edge. Another version of a variable awning is the louvred metal roof that has variable full width flaps that open and allow light in when required. When they are closed they form a continuous roof that is watertight.
A brise soleil is a fixed angle louvred roof that keeps summer sun out and winter sun in with a series of slats that are angled to optimise the winter sun but shade the summer sun. They can be horizontal or vertical (probably best to use horizontal to preserve the view) and can also be mounted on the envelope of the building or built into a freestanding framework.
Once the sun is in though, it needs to be managed. Installing internal blinds and louvres does not really keep the heat out. It does keep the incident light out so we don’t feel as hot as we would if we were sitting in direct sunlight, but the room will still heat up. Air requires around four times less energy to heat up than a solid mass so we need to introduce thermal mass if we can. Try to use some solid, high density brick or block walls in the south-facing room, or put a minimum of around 20 to 25mm dense plasterboard on the stud walls.
Cross ventilation is also a good way to evacuate heat, as are roof windows, but if you are not at home during the day they can be a security risk, and automated roof windows with rain sensors would also be needed. Of course the roof window would also need to be in the room that was getting too hot, which is not always possible.
Another solution is active cooling. Many ventilation systems will help alleviate the effects of overheating but the volumes of air that you will realistically need to move will result in the unit running on boost rate and the ducts potentially being noisy. Real cooling is only really achievable with air-conditioning systems. You could place a number of wall units above the glazed areas and run cold air into the space. If you have photovoltaic panels on your roof, you could use your own electricity for the cooling effect.
Many of these solutions, especially the internal ones, may not be practical now as they are fairly disruptive but when you do start planning for future maintenance it is worth bearing them in mind.