We designed our house to include multiple energy saving features in addition to tapping into solar energy. One of these features is a central heating system that heats an area only when we intend to be in that area.

Heating control

The computer for the heating control system operates according to pre-programmed information.. One packet of information is a schedule that indicates when a zone is expected to be occupied.

The house is divided into six zones for individual heating control. When an area is to be occupied, a computer opens a valve that allows hot water to flow through the radiators for that area and the temperatures rises to a preset level. When we are away at work, each zones is considered unoccupied and the central heating system allows the temperature to drop. A schedule of occupancy for each of these parts of the house ensures that my wife's office and the living area are cozy during the times she is occupying one or the other. The schedule for the master bedroom indicates occupancy for only a couple of hours in the evening. So long as it is reasonably comfortable when we jump into the bed, we're fine – we like sleeping in a cool room.

You might wonder how much heat transfers through the interior walls from one zone to another. The answer is very little because we filled most interior walls (both bathrooms and the master bedroom) with fiberglass insulation. This keeps heat where it is intended and allows different areas to remain at different temperatures.

It means no area is warmer or cooler than we want it to be. And that an area isn't heated unless we are present.

Here's a graph of the temperature in one zone over several days. Click here for a better view.

Entering from the driveway, the most noticeable feature is the pole-mounted solar assists. The array houses tubes for heating water and panels for generating electricity from sunshine. These don't have enough capacity to meet all our water heating and electrical needs, but they do make a difference.

We're not off the grid. So we sell excess electricity that we produce to the electric utility. We are paid 15 cents per KWH for what we transfer to the electric line. Also there are quarterly rebates based on the electricity we produce. There are two meters that keep track of this.

I'm keeping a log of our electrical production and how much we save. A bottom line number is that so far our electric bill has been less than $50 per month. Since we turned on the solar electric production, we have generated 1025 kWh, though most of that was used in the house.

The evacuated tubes do a good job of collecting heat from the sun. They can provide water at around 150 degrees on a sunny day. The time of the year doesn't matter much because the tubes are like thermoses with a clear outside. Sunlight warms a central core, called a heat pipe, which contains a special liquid that has a very high boiling temperature. Heat transfers to fluid in a manifold at the top of the tubes that passes through a heat exchangers in the hot water storage tank. During the summer the temperature in the storage tank often exceeded the setting for the tank's boiler, so for some time during these days the boiler seldom cames on.

So we feel we have made a couple of good steps toward using more renewable energy.

We planned our home for several years, knowing we wanted to use the least energy possible for this climate and our location, west central Washington in the Cascade foothills

We aren't just cheap, we have accepted since the beginning of this century that two things are true – the supply of fossil fuels is limited and these forms of energy contribute to climate change. Don't think that we have any kind of early warning vision – these two facts have been reported in scientific articles since the 70s, when we first experienced energy shortages as domestic production of petroleum declined. So we are just being sensible.

We studied alternative types of construction that reduce energy consumption. There are several interesting types: straw bales and rammed earth using old times, to mention two. Interesting they are, but not well suited to our damp, cool climate. Straw bales are subject to mold and rodents, of which we have many. We don't have a suitable site for a rammed earth house, and there are construction codes that rule out that option. Mud, straw and stucco construction also fails to fit into our site on a hill with water streaming down during the rainy season.