Passive Solar

By George Harvey

There an allegory about a certain man, who was walking through a construction site, when he accidentally kicked over a bottle that happened to be standing in his path. The bottle opened, and out popped a Jinni. “You have freed me,” said the Jinni, “so I will grant you three wishes.”

“Nothing doing,” said the man. “I knew a poor couple once, who got three wishes for Christmas. The man wished for a turkey dinner. The woman was so angry that he wasted the first wish, that she wished the turkey would stick to his nose. He had to use the third getting it off. Wishes are useless.”

“I promise to help,” said the Jinni. “What is your first wish?”

“I wish I could heat my house without having to buy fuel,” said the man.

“Okay, but I have to point out that granting that wish alone would leave you chopping wood. So what is your second wish?”

“I wish I did not have to do any work to get the house heated.”

“Wise wish,” said the Jinni. “But you might want to cover the potential problem of overheating in the summer.”

“Right. So I wish that nothing has to be changed to keep my home both warm in the winter and cool in the summer.” And on that, the Jinni granted all the man’s wishes.

The easy explanation of the allegory is that the Jinni is nature and science, and the wishes granted are what we call Passive Solar. And the good news is that these wishes have been granted in the real world.

There is really nothing magical about passive solar houses. They capture heat from the sun and store it in what is called a thermal mass. They take advantage of the seasonal path of the sun to capture heat when it is lower in the sky during the winter, and reflect it away when it is higher in the sky during the summer. Many passive solar houses have solar hot water and solar powered electric systems, as well. Indeed, all the energy needs of a house can be provided by the sun. Personally, I would have a grid electrical connection. I would also have a wood kitchen range, just because I really love cooking on one.

There is a problem with passive solar we have to remember. It has to be done intelligently. The design has to be thought through. And it should probably be done by someone who has a background in the subject. There are some points that would be easy to miss, unless the designer is prepared.

One is that a house is more likely to need heat in the early spring and cooling in the late summer, even though the path of the sun in the sky might be identical. Another is that a thoughtless application of large windows might mean too much heat is captured in the summer, and too much is lost in the winter. As I said, it has to be done intelligently.

There are some good points. An overhanging roof can shade a window in the summer, when the sun is high, but allow sunlight in the winter, when the sun is low. Plants that are just starting to grow leaves in the spring can provide cooling and shade in the late summer. It can all be done, with a little thought.

One of the really great things is the idea of thermal mass. Large, heavy objects, like concrete and stone, can be used to store heat, soaking up excess when it is hot, and letting it out into the air when it is cold outside.

It can all be done in a new building fairly easily, with good design. It is not intuitively obvious, but a lot of research has been done over the past sixty or seventy years, and the things researches have discovered are not secret.

It does not require a new building, and can be done in an old building, providing it is sited in a place where it can be done at all. It is more expensive, and requires a bit more thought. It very likely will require better air sealing and insulation. But it can be done.

Imagine – free heat. The wish has been granted to our society. What we have to do now is take advantage of it. Green Energy Times will have more in subsequent editions. Stay tuned.

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Advantages to Passive Solar:

1. Naturally helps to warm your home in the winter.
2. Keeps your home cooler in the summer.
3. Increases natural light in the winter months when we need it most.
4. Improves home efficiency – saves you money on heating and cooling bills.
5. Virtually no maintenance or upkeep.
6. Environmentally friendly by making your home less dependent on fossil fuels and nuclear power.
7. The contributing factors of the passive solar concept are environmentally friendly, continuous, and dependable.
8. The passive solar concept works best beween 32 and 52 degrees of latitude, north or south.
9. It’s renewable thermal energy from a star!