It seems like a crazy fact, however direct sunlight can actually generate the same amount of heat as a single bar radiator does over each square metre of surface. When the sun’s rays come directly in contact with a window pane, the radiant heat passing through the glass is absorbed by the interior materials of the walls, floors and surprisingly furnishings. This heat then also re radiates back into the room itself raising the internal temperature. The good news is that effective shading can reduce this heat by up to 90%! Shading is brilliant in its simplicity, it doesn’t necessarily rely on electricity, once installed there is often minimal maintenance and for a reduction of that capacity it seems like a component of design and planning that is well worth investigating.
Shading and successful passive solar design involves a combination of a few things and primarily starts with window placement. The type and amount of shading needed are dependent on your climate zone and geographical location as well as the actual topography and slope angle of your block of land. In our temperate climate in Victoria, the magic compass point of reference is north, as it has the most solar energy directed to it and is often the easiest to manage.
Well designed and thought out shading will allow sunlight into a home in winter, adding warmth and light whilst limiting it during the summer months. Correct eave width and angles along with additional horizontally constructed shading, for example a vine covered pergola, allow that glorious winter sun in whilst shading the strong and often harsh summer sun and heat. As the sun is lower in the sky when it strikes both East and West placed windows, eave and horizontal shading do not offer the same benefits and are therefore not as beneficial so considering more vertical forms or even potentially the placement of deciduous trees can be of huge benefit to these windows. Capturing your natural light not only allows for a more easily controlled internal environment but also reduces the need for artificial lighting hence reducing your electricity consumption and associated costs.
This information is great if you’re in the design process, however many ask what can be done to existing dwellings and windows to address this issue? Consider adjustable shading like blackout or external blinds or look into appropriate tree placement. Beautiful thick foliage shades you from the summer sun whilst bare stems and new growth in winter allow an abundance of light through. Whilst double glazed windows are now fairly stock standard in homes there are also companies who manufacture films to be applied directly onto existing windows essentially converting them into double glazed.
Essentially, a little time and effort spent planning and examining your shade requirements whether for a new home in the design process or adapting your existing home can really benefit your internal living environment.