Principles And Construction 3:
Windows And Light

The Potters' house relies on sunlight for much of its heat. The sunlight enters through their great windows, and warms the walls and floors. This is clearly useful during the winter, but what about the summer? Why doesn't the house heat up enough to become unlivable under the summer sun?

The answer lies in the way the windows are arranged, combined with the way the angle of the incoming sunlight changes during the year.

The Bancroft area, where the house is located, is in the mid-latitudes, not far from 45 degrees north latitude. One might think, then, that the noon sunlight would always hit the house at an angle of about 45 degrees to the horizontal, with lower angles towards the eastern and western horizons as the sun rose and set.

It's not that simple. Thanks to the way the Earth's axis of revolution is tilted in space, combined with the way it rotates around the sun, noon sunlight can fall on the house at angles anywhere from 68 degrees to the horizontal (in the summer), to 22 degrees (in the winter).

So, during the winter, the sun shines in at a low angle, illuminating the floors and walls far back into the rooms. The rooms of the Potters' house are sized so that this low winter sun shines all the way to the back of the room, ensuring a maximum amount of wall and floor space to be warmed, while minimising areas that never get winter sun.

During the summer, the sun shines in at a very high angle, illuminating only the fronts of the rooms. Less sunlight enters the rooms overall, and that sunlight only shines on the front of the rooms, leaving their backs unwarmed. Thus less heat enters the house.

In the Potters' house, the sun shines on planters filled with earth and growing plants.

Next: the shape of the walls.

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