Friday 10 May 2013

Cool your Windows

As I travel the length and breadth of the city, I come across many houses that use shading or a permanent awning to protect the windows from heat gain, and in affect the house during peak summers.  Some designs work and a lot of them don't, and that hardly is a matter of instinct, its all in the design.  It is abundantly clear to me, that there are some places that a permanent awning will work.  We did a project for a Gurgaon based house and found out the following things :

1.  East and West facing overhangs don't work.
2.  South facing overhangs work beautifully.
3.  For East and West facing windows use an external shading device.
4.  It is best to utilise an external shading that has a reflective surface on its outside.
5.  Also it is best to be able to have a ventilating cooling combined with shading for locations that are hot during the day and mild in the night.
6.  An overhang on a south facing window is most helpful when there is direct sunlight.
7.  It also occurred to me that the numbers seemed to suggest that the direct radiation only accounted for 50 percent of the heating, the rest was indirect or reflective radiation.
8.  A combination of internal and external overhangs work the best.

I worked out the numbers and they seem to suggest that overhangs for shading would work best to reduce AC bills and still in some cases totally eliminate the need for an AC.  Awnings and Trellings though expensive are great for cutting down on heat absorbtion during summers, what may seem like a case for 20 deg C on the Aircon could be reduced to 26 deg C, thereby getting a huge saving on the annual AC bill

A few of the external shades that work very well are Trees and External Shades.  Good landscaping can tremendously help in bringing cluster of trees from locations around the house to shade in the summer and also prevent the winter winds from getting to the house.  Trees planted in the East and West are most effective to prevent the summer sun from gaining an entry while the south of the house can be left open to promote solar radiation.  Trees planted in the North cool down the surroundings of the house.

This project opened up new vistas in my brain, I had hardly recovered from my discovery of Solar when I realised that a good Renewable artist must get to the bottom of the muddle and discover what causes heat losses and heat gains
Creativity thy name, you are the window to my world

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