Understanding your site orientation and taking it into account when making design decisions is vital for a successful home design for a home full of light and that doesn't get overheated if you live in a hot climate, and that takes advantage of the heat from the sun if you live in a cold climate.
Getting the design right with respect to the site orientation will mean that you take full advantage of the sun exposure for light, passive heating, and to generate electricity if you're contemplating solar panels. You'll also make sure the areas of your home that need protection from the sun are adequately protected.
There's also site orientation to the wind to consider.
Here's what we're going to be looking at in this topic:
Orientation is about the direction your home faces in relation to the points of the compass.
You may well have heard talk about which way a home faces. Usually this is referring to the way where the main outdoor area (usually the back yard) lies in relation to the rest of the home. To find out the orientation of a home, draw a line from the home through the back yard and see what direction that is on the compass.
We all know that the sun moves around in the sky and around our homes. The nature of the light from sunrise to sunset varies enormously and it's essential to understand the nature and quality of light from each of the compass directions to make good design decisions relating to your solar site orientation.
The information on light from different directions is from the perspective of homes in the northern hemisphere where the sun travels through the south in the sky.
In the southern hemisphere, the sun travels through the north so you'll have to switch north and south if you're in the southern hemisphere.
Of course the sun rises in the East and sets in the West everywhere.
The sun rises in the east so let's start there.
When the sun first rises, since the sun is just appearing over the horizon the light is flat and horizontal and sometimes we can be treated to a marvelous sunrise.
In the mornings, the shadows are long. Anything to the east of your site is going to cast a long shadow in the mornings.
The fact that the rays are coming in at quite a flat angle mean that they penetrate a long way into your home. The light is shining straight through the window. The flat angle can cause glare which can be uncomfortable to look at and can bounce off other flat horizontal surfaces in your home like tables, countertops and the floor.
The easterly light might also be reflected into your home bouncing off a pool or pond, or a wet driveway.
You can use design to manage the glare an avoid unwanted reflections.
Do you have a view of the sun rise? Remember that the position of the sunrise changes throughout the year. Your sun path chart will show you the position of the sunrise during the year.
The stronger the sun (based on the season) and the longer it’s shining into your home, the more your home will heat up.
The closer to the equator your site is, the stronger the sun is, so it won’t take long until the infra-red radiation starts to warm up your home.
In a temperate climate, during the cool season, we welcome the heat from the sun. During the hot season, the heat from the sun will need to be managed.
If possible, design your home to have some space receiving eastern light so that you can enjoy the morning light. It gives a sense of starting the day.
Thinking about the activities in your home in the morning will inform which spaces would be served well by having exposure to easterly light (provided it's properly managed by shading).
In cooling dominated climates the East side (and in particular the south east side) is also good for living rooms. The Eastern light doesn’t bring too much heat and once the light has passed through to the south, you can enjoy the outlook to the east without worrying about your home heating up too much.
Next we'll look at light from the west as it's similar to light from the east in some ways.
As the sun heads towards setting at the horizon, the rays become more and more horizontal the closer the time gets to sunset. Shadows become long again. Anything to the west of your site is going to cast a long shadow.
Like light from the East, the flat light can lead to glare and heat gain, both of which need to be managed.
Managing the heat will depend on your climate. In a cooler climate, the western sun can be wonderful for warming up rooms, whereas in a hot climate, warming up rooms is exactly what you're trying to avoid.
Do you have a view of the sun set that you want to take advantage of in your home design?
The decision about which rooms to face west depends on your climate. If you're in a cool climate it would make sense to have living areas exposed to the west to some extent.
In hot climates, your home should effectively turn it's back on the west, with rooms like the laundry, bathrooms, storage and garaging / parking on the western side.
In all climates, it's probably best to avoid bedrooms having the main windows open to the west, to avoid bedrooms becoming too warm.
The sun reaches it’s highest point in the middle of the day to the south. When the sun is highest in the sky this is called ‘solar noon’. Solar noon isn’t at exactly noon and due to daylight saving solar noon is more like 1pm in the summer.
Light from the south is the brightest and most abundant natural light. It’s the light that your design should work hard to capture. It’s the light we like to spend time in.
Light from the south is direct and strong. It creates strong blocks of light and shadow. It makes interior spaces feel light and bright makes them come alive.
The further away from the equator you are, the lower the sun is in the winter. Low sun can cause glare and reflections that we’ve already discussed.
In hot climates south eastern exposure is prized to prevent your home becoming too hot in the evenings.
In colder climates south westerly exposure is prized so that your home can enjoy the benefit of the radiant heat of the sun into the afternoon and evening.
Heat gain from southern sun will need managing in rooms where there is lots of glass, or where there is glass that's sloping or horizontal (ie skylight or roof light).
Your living spaces like your kitchen, living room and dining spaces should face south. Give priority to your the room you plan to spend most time in.
If you put a study or home office to the south you will need to manage the glare of the southern light when the sun is low in the winter. If this light falls onto a screen it’s very hard to see what’s on the screen.
Try and avoid wasting south facing space on parking, laundry, utility and storage space.
Rooms that face north do not receive direct sunlight during the winter. In summer, depending on your latitude (distance from the equator), the northern exposure of your home will get some light at the beginning and the end of the day.
The steady flat light is ideal for offices, studies and artists studios. In fact Vermeer is best known for his Northern light paintings that he painted in his northern facing studio where many of his other masterpieces were produced.
Bedrooms are also suitable to face north – it will keep them cool in the summer time in a hot climate. Although there's an argument for children's bedrooms to face south as they spend a lot of time in their bedrooms.
Try and avoid having living spaces to the north, unless they have another source of light (preferably from the south) as well.
Garage, storage, laundry, utility and services are good to place to the north.
The diagram below shows how the amount of solar radiation on vertical surfaces (ie windows) varies during the year.
In summer, when the sun rises and sets in the north, it shines into our homes from the east and west. During the day when the sun is in the south, it is high so it doesn't shine into your home much.
In winter, the sun rises and sets in the south, so it doesn't shine for very long into the east and west of your home. During the day, when the sun is in the south it is low in the sky so it shines into our homes.
The trick is to understand site orientation to harness and/or protect from the sun as required.
The ideal orientation for homes in the northern hemisphere is south, which is to say to have your living areas and outdoor space to the south side of your home, and your solar panels on the south side of your home.
Having said true south is the ideal orientation, there is a degree of flexibility in this.
You can swing the orientation towards the east by up to 30 degrees and to the west by up to 20 degrees. You could to up to 30 degrees to the west if you want to make use of western light for solar gain.
In the image below, notice where the homes are placed on the lots to allow for the maximum amount of space to the south.
What would be the best orientation towards the sun for your home and living areas on your lot?
An awareness of the movement of the sun goes a long way to help you achieve a good solar site orientation for your home. If you want to be more exact and are aiming for a high degree of home efficiency, ask the professionals you're working with about using energy rating software to assess your site and current property.
The Building Performance Institute is a good place to start.
If your lot is on a south facing slope you'll likely get good access to southern sun. If you're on a north facing slope, your uphill neighbors may overshadow you.
Remember that it isn't just all about your home when it comes to solar site orientation. Just as you're on the look out for obstacles to your solar access, bear in mind the impact that your home will have on the homes surrounding you.
Play nice with the sunshine!
Don't forget to factor in the direction of the wind when you're considering the site orientation of your home. Are there any breezes that could help cool your home, or any particularly cold winds that you want to protect your home from?
The wind will be much more of a factor for your home design if you are in a rural location. In urban areas, the speed of the wind is slower and more turbulent. Urban wind also picks up heat from urban buildings so it of slightly less utility to cool your home. On the flip side, you will be protected from cold winds to some extent by the surrounding buildings.