Although do remember glass tilted away from the vertical has much worse insulation qualities as it improves its ability to interact with more new 'airspace' at once (think about the cooling effect and air dropping, being horizontal allows the glass to cool its whole area of new air at once; rather when vertical interacting with a stack of cool to hot air in a room. Being horizontal reduces insulation qualities by about 50%. This is not silly science, its a known effect, ask anyone who installs skylights for a living.. or check out our online R-Value tool). Therefore you will have to improve the insulation qualities of the glass to offset this effect in Winter.
Correct building orientation saves energy
It is reckoned that a correctly orientated passive solar building will reduce its energy consumption by 30 to 40 percent. When combined with additional qualities, like the right levels of insulation, this saving can be further boosted. For further advice on passive solar principals see this detailed article.
Note: If you do not have a perfectly aligned house, a lot of these principals can still be applied, its just that the benefit returned to you will be less.
Solar energy use for Power and Heating
Something not to be forgotten is that a correctly orientated building will usually have a roof line running perfectly East to West. This is ideal for mounting on Solar water heater panels (Solar water heating article
) or solar panels
for electrical generation (Solar power article
You can also add on solar 'air heaters' or Trombe Walls
to further utilise the Sun. You can even create a 'solar greenhouse' to trap solar heat within a conservatory joined to the house.
Roof space heat reclaiming
Another benefit of a Eat to West alignment is that your roof space will rise and lower in temperature during the daily solar cycle. Air fan systems are available which can make use of this cycle to help Heat your house in Summer and cool it overnight in Summer, for a fraction of the equivalent running costs of split cycle air conditioners.
How big should the windows be?
How big the windows should be all comes down to three things: How 'strong' the Sun comes into the room, which side of the house the window is on and the floor covering..
For North facing windows:
If the solar access is good (i.e. nothing blocking the sun as it tracks across the sky) and the floors are concrete slab (or slab with tiles on them):
- The area of the North facing windows should be large; somewhere between 10-15% of the building's total floor; and
- The area of the North facing windows in each individual room can be up to 25% of the room's floor area.
If the solar access is good and floors are timber:
- The area of the North facing windows should be large; this time around 10% of the buildings total floor area, and
- The area of North facing windows in each room can be up to 20% of the room's floor area.
If it is the case that solar access is poor (i.e. lots of trees):
For South facing windows:
- The area of the North facing windows be kept small; less than 8% of the total floor area, and
- Keep the window area in each room less than 15% of the room's floor area.
Keep the South facing windows small:
For East facing windows:
- Total window area should be less than 5% of the total floor area.
- Windows in individual rooms less than 15% of the room's floor area.
Less than 5% of the total floor area and 15% of the floor area of each room.For West facing windows:
Less than 3% of the total floor area and less than 10% of the floor area of each room.
Also make sure you get the size of the Eaves above the windows correct on the Sun facing side of your property, so the Sun comes in during Winter and is shaded in Winter, we have an online tool
to help you with this.
Conclusion on building orientation
Correct building orientation is critical to reducing your energy consumption and creating a living space that is naturally comfortable to live in. Also by reducing your energy consumption you are doing a lot to help the environment and live a more sustainable lifestyle. It is something that every building should really take into account and fully utilise.
If all the techniques are used in this article you will end up with property that costs very little to operate day to day compared to other properties not designed to harness the daily & yearly solar cycles.
If you would like to learn more, please look at the articles and links below.
Related Articles and Links