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.
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.
Information on dealing with these windows can be found at:
West and East Windows
Do you want a house that is filled with natural light in the summer without overheating, and minimises your heating bills in winter? ……….If you do, then a passive solar house is what you need.
Here are some of the things you consider.
Get The Winter Sun Into The House
From Wikimedia Commons
This means having most of the main living rooms facing North with lots of windows.
It also means making sure the
Windows aren’t shaded by fences, trees etc. Maximising Thermal Mass
This means having dense absorbent materials like concrete and brick inside the house.
In winter the thermal mass heats up during the day and releases the heat during the evening.
During summer if you open the house in the evening/night the thermal mass cools and helps keep the house cool the next sunny day.
Ideas for increasing thermal mass include:
Have the house on a concrete slab rather than stumps.
Have tiles or a slate floor especially in front of the north facing windows.
Brick feature walls and or brick fireplaces.
Keeping the Summer Sun Out
Minimising West and East facing windows. These windows are the worst for heating up the house with the low morning and evening sun. (In winter they hardly get any benefit from the sun)
Shading North Facing Windows.
Typically the shading will be in the region of 1 m from the outside wall. It can be either deep eves, a veranda, or a pergola. Minimise Heat Transfer
That’s transfer of heat from outside to inside in Summer days, and inside to outside in Winter.
To minimise heat transfer:
Provide good insulation to walls and ceilings.
small windows on the South Side. Closing curtains at night in winter.
The first house we built in Australia was built according to these principles. Although we lived in it for 10 years we never felt the need to fit air conditioning. We didn’t require awnings on the windows or wanted to shut the curtains on hot days.
The above advice applies to Australia and other Southern Hemisphere Countries such as New Zealand and South Africa. If you live in the Northern hemisphere you need to have the Large windows on the south side of the house.
What Passive Solar ideas have Worked for you?
Here is a new town house development in Melbourne.
Just a couple of ‘small’ problems
Those huge master bedroom windows face west so they are going to get the summer sun all day from around 2.00pm until late in the evening.
What makes it worst is it has full length mirrored wardrobes on the North Facing Wall
With the glare you will need to be wearing sunglasses just to go into the room. On a hot day it’s going to be around 60 degrees plus!
For more Fails and unusual houses go to