Most builders will change their standard designs to some extent.
The builder of the last house we built, Metricon, was fairly flexible.
Here are some of the changes that you could talk with the builder about if their standard is close to what you want.
Handing. This means swapping the design around so rooms on the left become rooms on the right. Generally this should be available at no cost.
Partial handing. This means swapping either the front or the back of the house while leaving the remainder the same. We have done this when we wanted the bedroom and the garage on the opposite sides of the house to the original plan. (Again this didn’t add to the cost)
Raising the cill height of windows. We adjusted the cill height of most windows on the south side of the house decreasing the the size . At that time this was a no cost alteration. N.B. The builder will not usually allow any changes to the front of the house.
Swapping position of windows. We wanted to change the position of a patio door with a window, this was a no cost for this as long as the total of windows and patio doors stayed the same.
Providing additional internal walls and doors. We wanted this to reduce the amount of open plan living. This was achieved at what we thought was a reasonable cost.
Relocating internal walls. This was a no cost alteration.
Decreasing the size of rooms. We wanted to reduce the size of one room by 1 metre which reduced the overall length of the house by the same amount. For this change we made a saving.
Additional power outlets, light fittings and switches. These were standard extras.
Extra outside taps. Makes watering the garden, and washing the car easiser. These were standard extras.
What have your experiences been when looking to change a standard design?
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:
Summer
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.
Winter
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)
Shading
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.
In a post about Passive Solar I talked about shading North facing windows.
That doesn’t mean installing roller shutters, or blinds that pull down over the window.
Shutters and blinds tend to make the rooms very gloomy and depressing, and with good design are unnecessary.
The best methods of shading North facing windows are:
• Overhanging eaves
• A well designed veranda
• A pergola
How Much Shade?
For areas North of Brisbane its better to have enough shade to keep the sun out of the house as much as possible.
For areas from Brisbane and South the keys are:
Keep direct sun off the window during the summer months of; December January and February.
Allow full sun to shine on all of the window in June July and August.
Dimensions
Keeping the summer sun out for areas South of Brisbane can generally be achieved by making sure the eaves overhang is 45% of the height (H) the shade is above the bottom of the glass.
The eaves, or other method of achieving shade, should also extend horizontally along the wall window 45% of H to either side of the window.
To minimise shading of the window in winter the shading needs to be around 20% of H above the top of the glass.
West and East Facing Windows
West and East facing windows are almost impossible to effectively shade in summer and get minimal benefit from winter sun.
Have you got visions of being able to look out of your upstairs bedroom windows like this lady.
Not anymore if you are building a new house. New laws to protect children falling out of windows have come into force.
Since 1 May 2013, the Building Code of Australia (BCA) requires “protection for openable windows in new homes where the floor below the window is more than 2m above the surface beneath” (i.e. 2-storey homes).
The protection is either a device to restrict the window opening, or a screen, so a 125mm diameter sphere (representing the size of a young child’s head) cannot pass through. The device or screen must also be able to withstand an outward horizontal force of 250 N.
The picture is called “By the open window” painted by Konstantin Makovsky.
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:
Size
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%.
Orientation
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.
