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Passive solar on the cheap

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By Lee Einer

Say solar energy and people immediately think about high tech solar panels and sophisticated electronics. While that’s one way to capture solar energy, price puts it out of the hands of many. There’s one form of solar, though, that is within the grasp of of most of us, and that is passive solar heating.

In its simplest form, passive solar heating means  setting up your home and land to make maximum use of the sun’s heat.

Just analyzing your home’s orientation to the sun, the placement of your windows, and the location and type of shade trees around your home, and making corrections where necessary,  can go far towards lowering your winter heating bills.

The sun’s path across our sky describes an arc from east to west — we all know that, or at least I hope we do. But the earth is also tilted on its axis; during the summer months, that means that the sun describes its east-west arc directly overhead, but  during the winter months, that arc is angled so that the sun shines on us from the south. We can take advantage of this.

Since in the winter the sun shines from the south, at an angle, our south wall should have the most and biggest windows, to allow the sun into our homes and heat us. And it is wise to clear any trees or other obstructions which shade the south wall of our homes .

Awnings, eaves and overhangs on the south side deserve our attention also — they should be enough to keep the summer sun out, but not so big that they block the winter sun. 

It is even better if the sun which shines in your window in the winter falls on some sort of thermal mass. Thermal mass is a fancy term for anything which is dense, holds the heat and radiates it slowly. Stone and masonry have a lot of thermal mass. If you put in a stone or tile floor where the sun will shine upon it from the south, the floor material will slowly soak up the heat during the day, and radiate it at night.

Some folks will even put up a partial masonry or stone wall, called a “trombe wall” inside their homes to catch the southern sun shining in their windows.

On the east side of your house, you receive the morning sun, year around. The morning sun provides heat, but it is a gentle heat. It is good to have a large window or two on the east side, and to  make sure that there is nothing blocking the sun from the east from shining upon eastern wall of your home.

The north side is cold in the winter. It gets no sun, and the cold north wind blows upon it. This is the wall of your house which likely loses the most heat in the winter. You can put additional insulation in or even on it, and plant a dense row of evergreen trees along the north side of your home to protect it from the wind in the winter, and from the hot sun in the summer.

The west side of your home is tricky. It gets the scorching afternoon sun in the summer, and warming afternoon sun in the winter. What to do? If  you clear away trees that shade your home on the west side, you will be hotter in the summer – but if you don’t, you will be colder in the winter. There are a couple of workarounds. One is to plant deciduous trees, trees which shed their leaves in the fall, on the west side, so they will give summer shade, but will do little to block the sun in winter when their leaves have fallen.

Similarly, you can construct a trellis and arbor and plant grapes around it. In the summer, the grapes will provide shade and fruit, in the winter, when the leaves drop, they will let the sun through, allowing it to heat your home.

Heeding the sun, and the elements, and the four directions  as our ancestors did can take us far. Maybe they were on to something.