We don’t feel comfortable in our houses and offices if we feel hot. If the room temperature exceeds the body temperature of 37°C (98.6°F), the human body reacts by cooling itself down (sweating), which makes us thirsty, uncomfortable, and unproductive. Healthy people can recognize and handle overheating, but children, elderly people and sick people can’t always.
We need to pay more attention to overheating of our buildings, exceptionally because we live in the warm climate of the Caribbean. A cooling system is an easy solution, but it costs lots of energy to use on a daily basis. Are there any simpler design solutions? Yes, there are!
What causes overheating?
The sun emits a broad spectrum of electromagnetic rays, most of which we can’t see. The invisible rays, which we can feel as heat on our skins, are ultraviolet (UV) rays and infrared (IR) rays. Our atmosphere, the clouds and our glass windows absorb or reflect many of the invisible rays. But infrared (IR) rays go straight to glass and gets trapped inside buildings.
If the heat builds up inside rooms and exceeds 24°C (75.2°F), we begin to feel uncomfortable, usually in sleeping rooms and living rooms.
How can we prevent overheating?
1. Insulation and ventilation
The use of insulation sheets or heavy materials such as concrete increases the amount of heat which it can absorb (thermal capacity). You can store your low inside temperature in concrete walls and floors, if they are insulated. A great insulation goes hand-in-hand with a great ventilation. During nighttime, all windows should be opened (ideally with anti-mosquito and anti-burglary provisions), which creates an airflow of cool night-time air and cools down the building.
2. Be smart with your windows
The most intense sunrays are present around noon, which is from the south direction in winter and from the north direction in summer, for Aruba. This means that big (unshaded) windows on south and north façades of buildings are a bad idea. Sloped roof windows let even more sunrays inside. By simply designing a building with strategically placed windows, a lot of sunrays will be blocked.
Also the type of glass has an influence on how much infrared rays passes through it. First of all, double layered insulated glazing (HR++) should replace all single pane windows, because it insulates the heat and sound from outside. Secondly, there are coatings for the windows, which reflect sunrays (it acts like a mirror, yet is see-trough from the inside).
Shade all your windows as much as possible. A small simple solution is to use curtains or luxaflex on the inside which you can close. But be aware of the fact that this does not prevent the entry of sunrays entirely, since the heat has already gone through the glass.
That’s why sunshading on the outside of your windows is the biggest solution for overheating. Use traditional Caribbean style louvre shutters, which we offer in modern sustainable materials like UPVC and aluminium. The louvres can be fixed or can be movable, depending on what you’d like.
Also, overhangs and big trees can shade windows, which also does the job of preventing the sun’s rays from entering your building. But be aware, that the afternoon sun from the west is also intense and is low hanging. Windows on west façadas therefore can't be properly shaded with overhangs. Direct outside sunshading like louvres/shutters are the best solution.
All these factors can help to prevent your building from overheating, without the need for an A/C. GRP Architects & Construction offers many green products and methods to create comfortable and energy-efficient buildings. Contact us if you would like more information on this topic.