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Pergolas

 While packing to move house, my daughter found some sketches that I had done several years ago for a pergola outside her living room. The room has full-height glazing across the entire width of the east-facing room, making the whole flat very hot in summer. Pergolas are an excellent way of adapting your indoor temperature, especially if you use deciduous plants to cover them, providing shade to the window in summer and letting the winter sun into the room when the plants lose their leaves. They are one of the most cost-effective and environmentally sensitive ways to adapt indoor climate, on any sun-facing side of your home.

In the southern hemisphere, pergolas or awnings can be quite narrow on the north side of the building - the sun angle at mid-day is about 70 degrees on the equinoxes, so the depth of the pergola should be about half the height of the window or glazed door so that the sun is not blocked through the winter. 

The angle of the sun in summer, winter and at the equinox
Creative commons licensed: https://commons.wikimedia.org/wiki/File:Solar_altitude.svg
This varies with the latitude, but you can check it by downloading a sun angle chart. Trace the line for 21 March (the equinox) and where it intersects the graph on the vertical centre-line it will intersect or be close to one of the concentric circles - this gives you the angle you need from the ground to the rays of the sun at mid-day.


Sun angle chart for 47 degrees north
Creative commons licensed: https://www.flickr.com/photos/mitopencourseware/5324404210

On the east and west sides, the pergola can be as deep as you have space - it can even become an outdoor room perfect for al fresco eating or just lounging. When the leaves die back in autumn, it can become a very pleasant sun-trap. Ideal plants for this would be white jasmine or wisteria, with beautiful scented blooms in spring as a bonus. You can prune these quite vigorously in autumn to allow maximum sun in and to encourage new growth in the following summer.

Wisteria in flower
Creative commons licensed: https://www.deviantart.com/koala2all/art/Wisteria-Walk-165698901

The pergola I designed for my daughter is for a flat in a large complex, so we needed to get planning permission from the body corporate. It is important to find out what restrictions and processes are required before you start building. This is for any building work on the outside of your unit if you live in an apartment block or any other type of multiple dwelling complex. Sometimes the restrictions relate to the aesthetics, such as the colour or detailing of any feature on the outside of the building, and with some complexes, there is a complete ban on any addition or modification to the exterior. In most cases, if an addition is allowed, you will need to have drawings prepared, so that the body corporate can have a clear idea of what the finished alteration will look like. I worked from a couple of photographs when doing the perspectives to give an accurate depiction of the new addition.

The original design with a sloping structure

The building was completed in the 1990s, in a very crisp modern aesthetic, so we aimed to have a structure as simple and minimalist as possible. The first design had a slope, to maximise the shading effect, but we decided that it looked better if the pergola was horizontal, lining up with an expansion joint in the wall on one side.

The final design lining up with the expansion joint
We decided not to have any vertical supports, as we were aiming for the least obtrusive design, both to fit in with the building's aesthetic and to preserve the view from indoors. The detailing was as simple as possible for a streamlined effect.

Looking to the north side and some of the detailing
In general, vegetation is an excellent way of adapting your indoor climate, whether in pots if you are living on an upper floor or planted directly into the soil if you are on the ground floor. Apart from the shading effect, the vegetation cools the air through evapotranspiration, which also improves the humidity. As a bonus, the plants improve the air quality, through absorbing carbon dioxide and replacing it with oxygen. 



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