Solving overheating with external shading
Written by a Human, not AI
The climate is changing, and temperature records seem to be broken most years. With the UK now experiencing regular high 30s and even occasionally 40 degree temperatures, how do we tackle overheating in our homes? Your first thought was probably air conditioning, and it works, but it can be expensive to install and run, and you need to find a suitable place for the condenser outside that won’t be an eye sore, or or a problem for planning or noise. So what else can be done?
So let's talk insulation; insulation works both ways, so it keeps heat in, but is equally adept at keeping heat out, and insulation only slows heat loss (or gain) down. Prolonged high temperatures will cause heat to build up in a home, with masonry and the thermal mass of a building absorbing heat and holding on to it during hot nights. Reducing the amount of glazing on south and west-facing facades is one of the best approaches, as is using lighter-coloured materials; think paler brickwork, render or a different approach to flat roofing - there is a good reason Mediterranean houses have white roofs!
But the best way to keep your building from overheating is not with internal shutters, blinds or AC, but stopping excessive heat from entering the building fabric in the first place. Here are the best 4 ways of doing this…
External Shutters or Screens
These are very popular in Europe in similar temperate climates to ours, i.e the Netherlands, so why are they not as popular in the UK? Are they perceived to be a pain to open, or another thing to maintain, or just twee or colonial in style? The reality is none of these; you only need them on certain elevations and they can be designed to suit the house.
Part O (Overheating) of the building regulations puts particular emphasis on passive strategies such as these, and you will see external shutters become more commonplace with new builds. We believe it is only time before the same criteria are applied to extensions as well.
Egeon Architect, NL.
Trees
Trees absorb an enormous amount of heat, plainly obvious when walking underneath one. But for further proof, look at this study of temperatures in Lambeth, London from the wonderful Create Streets think tank. The shaded pavement beneath a single tree on a hot day measured 28.1 degrees, yet on the opposite side of the street, an unshaded pavement measured 50 degrees. There are so many factors that will affect a result from the surface material and colour, to potential breeze, to the level of direct exposure during the day, and of course the species of tree. But without question trees do absorb heat, and planning a design to take account of their shade benefits is thus worthy of consideration. Being practical of course, we need to plant trees a sensible distance from the house to give them room to grow and consider their ultimate height and spread (and for your neighbours too). But these are easily addressable and the addition of new trees will always improve the kerb appeal of a house. Or even better, make the best use of mature trees that are already on a site!
Create Streets
Green Roofs
There is no perfect flat roofing material, they all have a downside. But most of the time the look of a flat roof - when viewed from a height, is fairly drab. Flat roof coverings are typically quite grey, and unless you are cleaning it every week you will see debris accumulate. But combining a flat roof material such as GRP with a green roof build-up is a fantastic way of not only retaining more heat in winter, but keeping more heat out in summer (akin to the effect of trees).
And the benefits don't end there; as well as looking more attractive, you will protect the flat roof material from UV degradation, wear and tear or accidental damage, and slow down rainwater reaching mains drainage thus reducing flooding. Plus it is a haven for insects and improves biodiversity!
Deep Overhangs
Sometimes brise-soleil are added to buildings to help keep the high summer sun out, but these can often look quite commercial, especially the 'fin' type made from aluminium. Oak-framed versions, usually part of a pergola-type structure, are better, but are chunky and won't suit every house. Slimmer, folded metal type profiles can be designed in power-coated metal or corten, and can be very architectural in look, but won't suit every house.
But a deep over-hang, designed as part of a pitched or flat roof structure, does the same shading job, without feeling like a commercial 'add-on'.
Studio Barn