When designing for the sun, there are several key elements to consider. These are:
No matter what climate you live in, these key factors are what makes a design successful. So let's backtrack a bit and explain what solar house plans are. When you design for the sun, you are creating a house that responds to its environment. Every house will gain heat through the day as the sun shines through its windows.
And during the night as the temperature drops, this same house will lose heat to the outside through its walls, windows and roof.
By using solar planning in your design, you can create a house which maintains a comfortable temperature during the day, and retains its heat during the night.
During winter, the sun dips low in the horizon and the days are shorter. During this time, sunlight will come into your house at a lower angle. In the southern hemisphere, the sunlight will shine from the north, and in the northern hemisphere, sunlight angles from the south.
This is the basic promise behind orientation. By facing your house to the south (in the northern hemisphere) you will get the rays of the winter sun. This is the reason why the northern side of your house will seem like the 'cold' side in winter.
For this article, we are going to assume you live in the northern hemisphere. (For people living in the southern hemisphere, just do the opposite.)
Taking advantage of orientation means that you position your living room, kitchen and most trafficked areas on the southern side of your house. This means that during winter, sun will shine right to the back of these rooms.
Conventional wisdom positions your bedroom on the eastern side of your house. This means you will catch the first rays of the sun. If you prefer to sleep in and do not have early morning sun, do not do this.
Afternoon sun comes from the west, so rooms like the dining room and living room can be placed on this orientation. The southwestern corner of the house will be the sunniest – winter and afternoon sun.
On the northern side of your house, place service rooms. Service rooms are rooms that do not get used as much. This includes passageways, bathrooms, storage rooms, closets, and possibly the laundry.
2. Window Sizing
This is an important aspect of solar house planning. Out of all the materials your house is made of, windows lose the most heat. There is a balance here, because windows allow sunlight into your house. However, glass has almost no insulating properties, so it is very easy for heat to escape through your windows.
In very cold climates, windows are double or even triple glazed. The layer of air between the panes of glass prevents some of the heat from escaping. Even even triple glazed glass allows more heat to escape than a well insulated wall.
When deciding on the number and size of your windows, there are two things to take into account.
The first is where your windows face. This comes back to orientation. If you have most of your windows on the northern side, these windows will not get much sun during winter. They will be losing heat, but not gaining solar energy.
Therefore, you want to have the majority of your windows on the southern, western and eastern sides of your house.
The second point to consider is the overall area of your windows. There is an optimal ratio of windows: wall for every climate. For instance in temperate climates, a window to wall ration could be: 30% window area to 70% wall area. This varies for every climate.
The other ratio is in windows and orientation. For instance, in this same temperature climate, your optimum ratio could be 50% windows face south, 10% face north, 30% east and 30% west. By optimum, I mean that you will gain the most sunlight and lose the least heat with this organization of window placement.
Unfortunately, this article is a general guide and these ratios are specific to climate. Therefore it would require some research to find the ratio that best matches your situation.
When considering heat loss, you need to also consider insulation. Insulation is the resistance of a material to heat moving through it. For instance, highly insulated walls will keep the heat inside your house. This can be compared to wearing a warm coat on a cold day.
When analyzing your heat loss through your windows, you can gain some leeway through insulation. For instance, if you have very insulated walls, these can 'make up' for the heat that you would lose through your windows, so allowing you to have bigger windows.
It's also important to note that you lose the most heat energy through your roof – as heat rises. So when insulating, the roof needs the most insulation, followed by the walls and floor. Windows which tend to lose heat very quickly can benefit from curtains or blinds. The advantage of curtains is that they trap a layer of still air between the window and the curtain. This air forms and insulating layer, slowing down heat loss.
Another way to use materials in your solar house plan is to take advantage of heat storage. Have you ever stood next to a stone wall after a long sunny day? Even though the air temperature is cool, the stone wall will be warm. It is radiating heat. You can use this principle in your house too.
The simplest way of doing this is to have large southern window that lets sunlight shine all day on a insulated tiled floor. The floor is insulated underneath to prevent heat loss. It is tiled (over concrete slab) because of thermal mass.
Each material has properties. Stone, tile or concrete takes a long time to heat up, but once it is hot, it lasts hot for a long time. Using this principle, you can heat a floor slab all day using the sunlight that comes through your window. Then at night, the floor stays warm, very slowly losing heat until the morning, when it can be heated once more during the day.
This principle can be used on floor slabs, walls, etc. A well designed thermal heat sink will stay warm all night long.
Shading is an important part of the solar house plan. This is important not only for heat gains, but for preventing heat gains. In hot climates it is more important to keep the sunlight out than allow it in.
If you look at traditional designs from tropical countries, they all incorporate certain elements. They have broad overhangs, covered porches and open ventilation. In temperate climates as well, shading can be used to keep summer sun out and let winter sun in.
Using our orientation principle: your house is facing south. During the winter the sun angles low and reaches far into the house. However, during the summer the sun is directly overhead during the heat of the day.
So a canopy or shading structure on the southern border of your house will keep the summer sun from overheating your house. This same shading will allow winter sun into your house.
When designing shading, the factors to consider are the amount of shading you require and your latitude (where you are on the map of the world.) Your latitude effects the angle of the winter sun. Once you know these key factors, you can with accuracy design shading that regulates both your winter and summer sun.
In conclusion – solar house plans are a great way to design homes that are warm and comfortable to live in, and save you money off your heating and air conditioning bill.
Using Orientation, Window Placement, Materials and Shading, you can design a house that responds to its environment and creates its own micro-climate of comfort.