Solar House Plans - How to Design for the Sun

Solar House Planning involves 4 main factors:

• Orientation
• Window Sizing
• Materials
• Shading

If you correctly align all these elements, your house will perform well. The aim is for a house that is energy efficient, warm, sunny, and comfortable to live in summer and winter.

Orientation is important because the earth's axis is tilted.

This means that during winter, in the Northern Hemisphere, the sunlight comes from the south. So if you position your house to take advantage of this fact, you can maximize your sunlight during winter.

Another orientation principle is placing rooms for morning and afternoon light. If you bedroom faces East, you will get the first rays of the sun. A dining room that faces West will receive afternoon light. A kitchen that has windows to the West and South will receive afternoon sun during winter.

The photo above is a classic example of sun energy storage. The windows face south, and winter sun is entering the building. This sun coming through the glass is warming the tiled floor.

The floor gradually heats up during the day. As it has a high specific heat, the slab takes some time to heat up, but once it is warm, it stays warm for many hours. It radiates this heat back into the room during the night. This technique is also known as a thermal heat sink.

This same technique can be used on insulated floor slabs and walls.

In the photo above, the house is also taking advantage of the greenhouse effect. The sunlight passes through the glass in the form of shortwave radiation. It then is absorbed by the tiled floor. The tiled floor heats up, and radiates the heat out as longwave radiation. Most of this longwave radation is reflected back into the room by the glass, keeping the heat trapped inside.

A conservatory like this will be a very warm and sunny place during the day. During the night, the floor will stay warm for several hours, but a lot of heat will be lost through the glass. Therefore, many houses with conservatories either shut them off from the main house during the night to prevent heat loss, or have blinds or curtains to insulate the glass, reducing heat loss.

It's important to place windows not only for the view, but for sunlight as well. In everyday living, people will seek out a sunny spot over a shady spot with a view.

When planning your window placement, use the principles of orientation. Windows on the southern border get winter sun. The thing to consider is that windows loose more heat the walls. A lot more. So if you place large windows on the northern side (for example to capture a northern view) you will lose a lot of heat from these windows.)

There is a ratio of window orientation for each climate. For example: 50% windows face south, 20% east , 20% west, 10% north. This ratio is different for each climate. However, after finding the ratio for your climate, this gives you a framework to use when placing windows.

SImilarly, there is a ratio of wall to window area. eg. 20% window to 80% wall. Again, this varies by climate. But by following your climate's ratio as a rough guide, you can design your house to require less heating.

Shading can be designed for winter and summer. By taking advantage of winter angle and summer angle of the sun's light, you can design shading the allows the winter sun in and keeps the summer sun out.

The way to do this is to find the winter sun angle for where you live. This corresponds to your latitude. Once you know the lowest angle of winter sun, you can size shade canopies arounnd your house so that winter sun penetrates into your house. These same canopies will provide shade in summer, because the summer sun will come from more directly overhead.

A covered porch or balcony can shade your house during summer and allow sun in during winter. This approach also extend the living area of your house, providing shelter and shade. These 'soft edges' moderate the inside environment of your house and the outdoors.

This is one way to create indoor-outdoor flow.

So in conclusion, by using the principles of orientation, shading, window placement and material selection, you can design a house that works with the sun.