Well the first rule is to avoid West, or East, facing windows . . . or at least keep them as small as possible….and here is why:
West windows get direct sunlight from mid-afternoon to late in the evening in summer causing overheating.
East facing windows get sun from sunrise to midday.
This isn’t normally as bad because the house is cooler in the morning, but the heat built up during the morning does stay making the house hotter later in the day.
Because of the low angle of morning, afternoon and evening sun the over window shading that works well with North Facing windows will be inadequate for West and East facing windows.
In the winter there is minimal heating benefit with little or no direct sunlight getting into West or East facing windows.
In the last house we built the master bedroom full length windows all face west.
I would have preferred to decrease the size of the windows but the builder would not alter the size of the windows on the front. (They were quite happy to change all the other windows, just not on the front)
To shade, our west facing windows, we adopted the following three stage strategy.
A highly reflective tint was applied to the window, by Tint-a-car. This had the immediate effect of lowering the temperature in the room by about five degrees on a sunny afternoon. Even the installer was amazed at the difference it made. Expect to pay around $50-60/m2,
We planted shrubs in front of the windows to shade the bottom third of the windows and also provide a micro-climate to reduce heat loss in winter.
We have fertilised and trimmed a couple of trees on the nature strip, in front of the house, to encourage dense foliage which now shades the window from mid afternoon to sunset.(see photo below)
The Building Code of Australia requires you to have at least 10% of the floor area as windows with at least 5% of the floor area being able to be opened.
If you go in many show houses you will see windows that are much bigger, typically 40 – 50% of the floor area.
They do this to give a light airy feel to the house.
In reality, for most modern house on a typical size blocks you could finish up with floor to ceiling windows looking directly at a fence!
Why Have Smaller Windows?
Well glazing is an expensive building element. You may save money on a custom build by having smaller windows. Even with project homes builders will often reduce the size of windows as a no cost option.
Single glazing transfers over 20 times as much heat as a modern brick veneer wall. With the step up in cost to double glazing you will still transfer more than 10 times the heat through windows compared with a brick wall.
Windows that go down to the floor restricts where you can put furniture.
If you stick to sensible glazing ratios and get away from floor to ceiling glazing by raising sill heights, you can reduce the area of glazing considerably.
By considering the positioning of glazing and room layout relative to external shading elements you do not really need to compromise on natural light.
The surprising thing is that if you follow these principles you can get a more sustainable house and save on heating and cooling.
If you also want the added benefits of double glazing you will also save money as the smaller windows will be cheaper. (See the following link for more information: Smaller Windows or Double Glazing?)
For myself I have tended to aim for glazing around 20-25% of floor area in South facing rooms and around 40% in North facing rooms.
There is a lot of rubbish talked by big builders about sustainability costing you more!
In my opinion considering sustainable design for your new home will save you money as well as the environment. Here are three reasons why:
A key sustainability principle is to minimise the use of resources. Getting a Smaller House means you save money on materials. The smaller house also has less wall and roof area where heat is lost. Reducing the size by 20% should reduce heat transfer through the roof by the same amount, and reduce the heat transfer through walls by around 10%.
Getting the Correct Orientation can add an extra star to the house energy rating at no extra cost, which is going to save on your heating and cooling costs. It will also fill your house with light without causing overheating in summer.
Right Sizing Windows
Windows are the least effective element of the house as far as heat transfer is concerned, even if double glazed. Most windows are also much bigger than they need to be. Reducing windows on the West and East of the house and reducing the size on the South is normally a no cost option.
Get these things right and you will be saving money on the mortgage, and on your heating and cooling bills.
When I saw this Billboard the other day I had turn round to drive past it again, as I didn’t believe it the first time!
They are making it appear that it’s a big deal that they are selling what are the worst blocks on the estate!
A North Facing Block mean that the house gets very little warming sun during winter, as half the front of the house will probably be garage door.
A typical house will also have lots of East and West facing windows which will really soak up summer sun making the house a real sweatbox. With winter there will be no sun coming in but lots of heat going out through those windows.
It just goes to show that if you want honest advice don’t rely on Real Estate Agents or Land Developers.
Driveway Crossover Many blocks now come with the driveway crossover already constructed which causes further restrictions unless you want the expense of removing the crossover and constructing a new one in a different location.
Take Advantage of the Sun My aim to get most of the main rooms facing North for a solar passive performance and which helps with the energy rating performance (A good orientation can boost the environmental rating by at least one star). This tend to give you a north facing roof pitch for future Solar power panels.
Avoid Shading I like to place the house fairly close to the Southern Boundary so that the I can have a garden on the sunny side of the block which you can see from those North facing rooms. The wider garden also helps prevent shading from the house next door.
When looking at block orientation a key issue is using the sun to warm the house in winter and keeping the sun out of the rooms in the summer.
Typical blocks in Australia are rectangular. About twice as long as the block width, as are most home designs. This limits the way you can place the house. In my experience the order of preference of blocks is.
1. Facing East
2. Facing West
3. Facing South
4. Facing North
If you have got a block at an angle it will require a bit more thought unless you can orientate the house in one of the above preferred directions. Larger blocks and square blocks make adjustments to the house orientation easier.
My reasons for the preferences are as follows:
This orientation allows one of the long sides to face north making the best use of the sun in a passive solar house. Usually the master bedroom is at the front so even in the summer the low sun morning sun only warms the bedroom from the chill of the night. Windows can be minimised on the west side to stop the house overheating in the afternoon and evening. This orientation also gives you plenty of roof area for the most effective location of solar hot water and solar electricity panels.
Again like the east facing block you can have one of the long sides to face north making the best use of the sun in a passive solar house. With a master bedroom at the front you will need to take steps to keep the afternoon sun out of the room to stop overheating. Like the East facing orientation this is useful for solar panels on the roof.
With a house facing south the best layout is to have as many rooms as possible having large windows facing north which can be difficult on a narrow block. To make the best of this orientation you may need to have plans drawn up as most standard plans don’t suit this orientation. It’s also best to minimise west facing windows.
A north facing house is probably the least desirable on a suburban block as it makes it hard to get the sun into the house. I certainly wouldn’t want big north facing windows allowing passers by to look in.