Can façade treatment cool your building?
First, what is a façade? A façade is the vertical outer face or external surface or wall of a building.
It is a technical term for the walls enclosing the internal accommodation including external cladding systems, curtain wall systems, windows and doors all the wall components that are built to enclose a space.
The building envelope is made up of the roof, walls (façades) and floors and they perform two key functions. First they clad the building and make significant contributions to its thermal performance (is it naturally cool or hot and sticky without air conditioning); and second they are a key element of the expression of design; treatment of these elements determine the comfort, look and feel of a structure and is the difference between having “kerb appeal” or not.
In other words is your building cool, sexy or attractive to potential investors or owner occupiers. It will often be the main contributor to quickly selling or letting your property.
A simple example of a traditional façade that has been used for centuries is the mud hut with small window openings; mud walls have low thermal conductivity, which means that heat travels slowly through those walls and therefore minimises the build-up of heat internally.
It also insulates the interior compartment from the heat outside keeping the interior cool. We don’t expect mud huts to be built in Lagos but the soundness of their wonderful insulating properties can be replicated in more modern ways.
Innovative earth blocks have been produced which have better-insulating properties than pure concrete blockwork. Where glass is used extensively either as large individual windows or continuous glass described as curtain walls, then extensive shading devices can be used in modern decorative ways.
Either as large horizontal canopies that give extensive shade to the sun as has been done at City hall; or structured vertical or horizontal louvres that can be fashioned in concrete, wood, aluminium or metal to provide attractive screening of the glass from the harmful direct rays of the sun; Again avoiding heat build up.
Aluminium cladding panels are another popular choice for façade treatment. These can work well where properly installed as they are designed to be insulated panels; However, if they are used to cover existing windows they defeat the purpose having closed off natural ventilation and light.
South orientation of a substantial glass face is also another way to minimise heat; we know that the south face of a building is the coolest face and so any large glazing areas should face that side only.
North West and East walls should minimise the number of openings and /or have smaller recessed window openings and where affordable also utilise heat resistant glass. A note of caution with heat resistant glass- it isn’t a cure all, and doesn’t perform as well as shaded windows or a solid wall.
• Fisher is the Alternate Vice President, Commonwealth Association of Architects and Managing Partner, FA Global