HOW TO TURN THE SUN INTO FREE HEATING FOR YOUR HOME
If you only get one thing right when designing your home, let it be this: know where the sun moves and design your house around it.
You will create a house that is cool in the summer and warm in the winter. You won’t need the lights on in the day and your heating and cooling bills will be significantly lower.
Its not all about energy bills either. Natural light has been scientifically proven to positively impact our moods, our health and our well-being. A house designed around the sun not only works better, but it feels better too.
Designing and positioning your house in direct response to the movement of the sun is the single most important thing you can do to create a home that works well. Whats even better is that it wont cost you anything, just your time during the design stage.
The basics – what is orientation?
Orientation is essentially how your house or plot is located in relation to the passage of the sun.
The sun rises in the east and sets in the west, and in the southern hemisphere the sun moves through the north (south if you are in the northern hemisphere). It travels in an arc through the sky, rising to its highest point in the early afternoon before beginning its descent again. It might sound obviously but thats a really great place to start!
Heres what that means in practical terms:
- North – This is the side of your home that will get the most sun
- South – This is the coolest side and gets the least warmth or light from the sun.
- East – This is where the sun rises and this side receives the more gentle, morning sun.
- West – This is where the sun sets and it is often the hottest in the afternoon.
In in the summer this arc is arc is much higher in the sky and the angle of the sun is much steeper. In the winter the sun is lower in the sky and its rays hit your home at a much lower angle.
Find your orientation
A compass is a great place to start.
If you have a smart phone, you might also consider the ‘sunseeker’ app, which is an augmented reality tool showing you exactly where the sun will be in the sky at any given time. Its pretty cool!
The best method, however, is just to spend time there. Observe where the sun rises and sets and what parts of the building or site it hits at different times of the day and on different days of the year. Take photos or do sketches to record your observations and note any areas of shade from nearby buildings or vegetation.
Passive Design rules of thumb
You may have also heard the term passive heating. This is about using the sun as a free source of heating by letting as much of it into your home in the winter as you can, whilst keeping the unwanted summer sun out.
Passive design is a much larger subject, and something I will write about in more detail in a later post. However, the following rules of thumb will get you pretty close:
- Orientate the building along an east-west axis where possible.
- Maximise access to winter sun with lots of north facing windows.
- Interior spaces requiring the most heating and light should be arranged along the northern face of the building, with lesser used spaces along the south (reverse this for northern hemisphere projects).
- Use shading to prevent unwanted summer sun from entering the building.
- Minimise south and west facing windows to reduce heat loss and potential for overheating.
- Maximise exposed thermal mass to absorb, store and distribute heat (such as polished concrete floors and exposed brick walls)
- Well insulate walls, floors and ceilings to maintain a stable temperature throughout the year.
A Room-by-Room Breakdown
So what does this mean for the specific rooms in your home?. Lets look at each of the main spaces and the optimum area to locate them on your site (as well as the major mistakes to avoid):
Garages go on the south, or south west corner of the site where possible. Avoid placing things like car-ports or sheds to the north of your property as they are likely to cause over-shadowing, and waste all of that lovely sunlight.
Living areas should be located to the north or north east of the plan. If this is too difficult, look at getting north light into living areas using high-level windows, skylights or by creating courtyards or small voids to drop light in from above. Avoid south facing living spaces as they are likely to be dark and cold most of the time (you wont want to spend time in them).
Bedrooms should ideally be arranged to the east to capture morning sun. This also allows them to cool off during the day as the sun moves around, so that they are nice and comfortable by bedtime. If that isn’t possible then arrange them along the south where there isn’t a lot of heat around. Avoid west-facing bedrooms and they will be too hot to sleep in during the summer.
Kitchens are also good facing east, so that you can enjoy a little relaxing sunshine at breakfast time. Avoid west-facing kitchens at all costs as they will get unbearably hot in the summer.
Service areas – bathrooms, laundry areas, and storage items are best located on the west because you don’t spend a lot of time in them (the west is often the hottest part of the house). Avoid wasting precious northerly orientation on these spaces as they are largely just functional rooms.
Finally, Studies & home offices are best facing south as the light is pretty constant and even – so you can avoid any screen glare! Though, it is worth bearing in mind that this part of the house will be cooler if you are going to be sitting working for long periods.
The Importance of Shading
In order to prevent your house becoming an oven during those scorching Australian summers, it is vital to provide some horizontal shading above all that north facing glass.
Correctly designed, overhanging eaves are the simplest and least expensive method of achieving this. During the summer months, when the sun is highest in the sky, the eaves will shade your walls and windows from the sun, keeping the house cool. In the winter, the sun angle is much lower and the eaves will allow it to enter your house and keep you warm.
A good rule of thumb when designing overhanging eaves is that the overhang should be approximately 45% of the height of the window. So for a 2.4m full height window you would need to overhang by just over 1m.
If you are renovating a property, you might consider changing north-facing verandahs into pergolas, by replacing the roofing material with slats or louvres, and allowing access to sunlight.
Another simple solution is to plant deciduous trees along the northern edge of your plot. When in full bloom during there summer month they can effectively shade your property from the harsh sun, yet they drop their leaves in winter allowing sunlight to penetrate when you need it.
One Size Doesn’t Fit All
There is no one design that suits every plot.
Every single situation will be different, and every house needs to be specifically designed to suit. There will be desirable views and the relationship with the street to consider, as well as privacy and overlooking issues, as well an overshadowing from nearby properties and vegetation.
There is a lot to think about and it can be very difficult, in reality, to design the perfect passive house. However, don’t let that stop you trying to design the best house for your site.
Make the most of what you have and worship the sun, you won’t regret it.