PV Gap

Roger Said:

What are all the different types of eco-friendly home heating?

We Answered:

It makes a big difference where you are located, what resources are available, if you are working with new construction or renovating old existing work.

In general, any path to energy independence is going to start with conservation. With heating and hot water this may mean point of use heaters, insulation, heating surfaces instead of the air (radiant heating costs less in operation) ventilation instead of air conditioning, earth tubes etc. Start to satisfy your existing 100% of current energy demands you may be able to achieve 20 to 30% with conservation techniques.

We feel warmer if surfaces are warmed than if only the air is warmed. It is more efficient as the surface temps can be 10 deg lower than we would normally heat the air. Radiant heating in floors and sometimes walls works well with both solar thermal panels and geothermal as a heat source.

In new construction a masonry stove (not cast iron) can be a very efficient use of wood. It may be lit once per day to a very high heat. The balance of the day and night the massive masonry structure radiates heat to the dwelling.

Geothermal, ground source heat pump applications are a kind of alternative form of heating conservation. It saves heating costs but still requires some energy. It does not yet supply more than it requires.

Solar thermal is 60 to 80% efficient vs photovoltaic which is only about 8 to 22% for the homeowner. There is some speculation that solar thermal plus a stirling generator may be several times cheaper than photovoltaic panels for producing electricity. ($1/ watt vs photovoltaic $5/watt.) Heat is also easier to store than electricity. So store heat to make electricity. Solar thermal comes in several designs for residences. In new designs it is in passive solar heating. For both new designs and retrofits a solar sun room may provide additional heat. Solar thermal systems can active or passive. Active systems have pumps. Solar thermal panels can be flat plate or vacuum tube collectors water based collectors or air collectors that have no liquids in them. Solar thermal energy can be used for heat, hot water, air conditioning and to generate electricity with a mid temp range stirling engine/generator.

It also would be possible in more rural settings to generate your own natural gas with a bio digester. It would however require massive amounts of bio fuel. However if the supply exists it is certainly a possibility.

While wind turbines are a possibility for electrical energy there is the duel problem of having power when you need it. First the wind must be blowing with sufficient strength and secondly there needs to be some type of energy strorage capacity. This storage shoud have deep cycle capacity. Heating water or a phase change material may be one option. Chemical storage may be another (hydrogen) Pumped hydro may be practical in some locations. There is some discussion of using compressed air for storage. This might give a byproduct of heat that could be used to some benefit. Otherwise we are left with batteries.

Armando Said:

solar water heating for a home

We Answered:

I believe evacuated tubing is the premium technology for heating water. Did the salesperson have something more efficient? Or was it just that their company didn't sell it?

In your area, you will need to be concerned with winter freezing. You can still get hot water in the winter, amazingly, but at night, the system can freeze under some conditions. There are several kinds of systems, some made for no-freeze (like those used in Hawaii), light freeze (they have a relief valve for the occasional partial freeze), or hard freeze (made to be drained, in areas where it will stay cold even in the daytime in winter).

To avoid the freeze issue, is it possible that you just want solar air heating? I've heard of systems that run air through collecting panels to heat it.

I'm assuming that you already super-insulated your home, which is by far the best way to save money on heating.