How to Reduce Greenhouse Gases in Comfort
The biggest energy villains in most modern homes are the windows. We build houses with walls of glass facing the hot afternoon western sun and then wonder why they are impossible to air condition.
During summer, good window shading is essential for a comfortable and energy efficient home. If direct sunlight falls on your windows in summer you are unlikely to be comfortable no matter how large an air conditioner you have.
To be most effective you need to stop the heat before it gets into the house. External shade keeps up to 80% of the sun's heat out, while blinds or curtains typically only stop about 30% of the sun's heat. In other words if you have vertical blinds for example, you still get more than 2/3 of the suns heat coming in. You will probably barely notice the improvement with the vertical blinds, while you will definitely notice the improvement if you install, for example, some matchstick blinds.
The main types of shading are:
- roller shutters
- bamboo or matchstick blinds
- trees and shrubs
Each of these types have their strengths and weaknesses
- also give security benefits
- if motorised, can become part of a future home automation system
- colours to suit most house styles
- motorised shutters are very controllable
- reasonably expensive, especially for large windows
bamboo or matchstick blinds
- cheapest quick solution
- matchstick blinds still allow a good view out
- for maximum life, you need to take them off each winter and reinstall each summer.
- may not aesthetically suit some house styles
- If you wanted an outdoor entertaining area anyway, you can get the shading as a bonus
- give a good view from the room
- particularly effective on east and west windows if used with a deciduous vine
- for most effectiveness you need to have a deciduous vine on it, so you get shading in summer, and let the sun in winter
- if you use shade cloth for shading, you lose the benefit of winter sunshine
- if you use translucent sheeting, you can increase the heat in the room, rather than reducing it
- on the North of the house, they can give too much shading in winter, even if they have deciduous vines
trees and shrubs
- cheapest solution
- get all the benefits of having vegetation, more birds, and a pleasing garden
- need to use deciduous trees to get the benefit of winter sunshine
- need to wait until they grow (many natives are fast growing and will give reasonable shade within 2 years, but they aren't deciduous).
Further information on this subject is available in House Taming: How to reduce greenhouse gases in comfort
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