The importance of building orientation

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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):

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.

For South facing windows:
Keep the South facing windows small:

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.

For East facing windows:
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

Keeping cool in Summer and warm in Winter for free! - explains various techniques on keeping cool or warm for free that you can use.
What is Passive Solar? - An in depth article that explains whats passive solar is and how to achieve it in your house. When passive solar is combined with getting your building orientation correct it can lead to massive running cost savings.
What is convection and how it effects your heating costs - basically how convection 'steals' your heat and how to stop it.
What is a Trombe Wall and how can you use one? - how to use a Trombe Wall to provide heating (and cooling) for free, this works well with a correctly orientated building.
R-Value and U-Value Insulation Calculator - works out combined material R and U Values for you.
Solar Power - the facts about setting it up

Ennis said:

I thought the south facing windows were supposed to be the largest?

ON Wed, 11 Aug 10, 10:52pm probably from United States Reply to this comment

Eco Guy said:
In the Northern hemisphere, yes; but in the Southern hemisphere its the North facing windows.
ON Sun, 17 Apr 11, 1:17am probably from Australia Reply to this comment

Amanda said:

I am building a house on a block where my views are to the East and the access/front of house will be facing East. How can I make the most of the Solar passive effect as possible? I thought about building an L shaped house with large glass doors at the rear facing North. Would this get enough light in?

ON Thu, 8 Dec 11, 2:51pm probably from Australia Reply to this comment

Eco Guy said:
Hi Amanda,

Do you have any access to the North at all, e.g. good Northern access to the Sun. You can be up to about 20% off true and still get good benefit.

Also remember that regardless of orientation your roof space will still get warm - there are systems available that can capture roof space heat and inject them into the living area below - look up Ventis.
ON Fri, 9 Dec 11, 11:07am probably from Australia Reply to this comment

Jordan said:

This might be the dumbest post I've ever seen on the internet.

You assume the goal of the home builder is to gain heat (ie during the winter) yet for the southern third (to a half) of the people reading they want to MINIMIZE heat gain. -- Your simply saying houses should be East-West is as moronic as saying no matter what ails you an antibiotic is the right prescription. [What if I have a broken arm?]

Really, if you are going to put so little thought into your writing, don't even bother cluttering the net with babble.

Just sayin'

ON Wed, 21 Dec 11, 4:13am probably from United States Reply to this comment

Eco Guy said:
Hi Jordan,

I'm assuming, which I thought was reasonable at the time writing the article, that if you have no need to capture solar heat, you wouldn't enact what I have written.

Also there is another article on here called "Keeping your home Cool in Summer or Warm in Winter for free!" which covers cooling techniques if your property has too much heat to deal with.
ON Wed, 21 Dec 11, 8:00pm probably from Australia Reply to this comment

Rubi said:

what is the disadvantage to give the glass windows in south facing

ON Sat, 7 Jan 12, 6:41am probably from India Reply to this comment

Arvind said:

Hi, I am from India, which is the best direction for a Poultry and Dairy farm, I live near Mumbai (formaly known as Bombay) Thanks

Arvind

ON Mon, 16 Jan 12, 11:10am probably from India Reply to this comment

Anu said:

i am designing a boys hostel in haryana karnal district what should be the orientation of my buildimg

ON Tue, 31 Jan 12, 11:06am probably from Australia Reply to this comment

Rahul said:

what is your comments about south facing house as per buildig planning and orientation of building as per the sun digram.

ON Tue, 6 Mar 12, 12:18pm probably from India Reply to this comment

Eco Guy said:
Basically you need to orientation the building so that the rooms you use the most are those that face the Sun the most. Northern hemisphere this will be the South side, Southern hemisphere the North side.
ON Sun, 11 Mar 12, 10:47am probably from United States Reply to this comment

Bron said:

The sun path diagram is not correct. In the southern hemisphere in Winter the sun rises to the north of East, and sets to the north of West. In Summer it rises a fair way south of East, and sets to the south of West.

ON Tue, 15 Jan 13, 3:46am probably from Australia Reply to this comment

Eco Guy said:
Hi Bron,

I assumed people will adjust their comprehension of the diagram if they are in the Southern hemisphere.
ON Tue, 15 Jan 13, 5:39am probably from Australia Reply to this comment

Saif said:

What I understood is that this article is focused on heating based design for freezing countries (Am I right?) For Indian climate, temperature in winter on average is 20°C and in summer it is around 40°C with high humidity. We require cooling on most of the months and no cooling is required (with exception of few places). So can you please give link to any design articles for such scenario?

ON Sun, 18 May 14, 11:04am probably from Qatar Reply to this comment

Please read as "no heating is required instead of no cooling is required"

ON Wed, 21 May 14, 5:39pm probably from Qatar Reply to this comment

Raj said:

I am planning to construct a house in Vellore,India which is famous for dry summer with high heat and the house has west facing for the main entrance and south side has a building and north and east side are open as of now. Can you advise which side of the wall should have more windows so that the house is comfortable for living during extreme summer. I am little worried about the internal heating during summer in Vellore

ON Thu, 11 Aug 16, 12:28am probably from United States Reply to this comment

Hannah & Kate said:

Hi, were doing a school project on energy efficiency for a north facing house in the Southern Hemisphere (Seaford Rise, SA) we’re stuck and are not sure on where to place our windows,which materials to use, keeping the house cool in summer and warm in winter.

ON Thu, 22 Mar 18, 1:49am probably from Australia Reply to this comment

Mike said:

I'm thinking about building a earth ship, minus the tires and earth, in Iowa and know it has to face south, but also slightly east I believe? I'm envisioning a two story wall of glass facing the winter sun. Your calculator is suggesting a almost 3 meter overhang? All other sides will be close to passive house standards with a grass roof to set a gazebo on, and bermed earth sides mainly for storm resistance. Use twin-wall polycarbonate panels on the majority of The wall, and glass where you want the view. And this property has the view too.. Thanks

ON Sat, 24 Jun 23, 5:53pm probably from United States Reply to this comment

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