Two of the bigger energy uses are cooling and heating. Green heating systems are designed to minimize such energy use during cooler periods.
There are several heating systems used in green homes. One type uses geothermal energy for heat. Geothermal refers to using the natural heat of the earth. Most systems work by running water from under the earth through a series of pipes called a loop. The loop takes the water to a heat exchanger where the heat is removed from the water and used for heating purposes. The most simple is the open loop. Since ground water generally maintains a constant temperature, water is pumped from one well through a heat exchange device, and deposited into a second well, usually at a distance from the first.
A closed loop geothermal system circulates the water through a series of pipes. The pipes are buried in the ground and the water picks up heat and the heat exchanger removes it. There are several arrangements of piping, but the general idea is the same. Although geothermal heat is very inexpensive, a system has to be fairly extensive to provide all of a homes heating requirements, and most systems are intended to supplement other heating sources.
A much better source of heat is sunlight. Solar power systems convert sunlight to heat for use in space heating and domestic water heating. Most solar power systems have a very high initial cost, but a very low operating cost. This low operating cost is often overlooked in the planning stages when more attention is being paid to the initial costs. In order to maximize the advantages of the low operating cost, it is important to make sure that the home is well insulated. In the case of water heating systems, all pipes must be heavily insulated.
Solar water heating systems can be either passive or active. Passive systems use natural convection to move water from the heat source to the heat exchange point. An active system uses pumps and controllers. The water is collected in a tank fitted with solar panels or heat absorbing materials where it is warmed by sunlight. The pumps move it to a heat exchanger where the heat is removed and circulated through the home. In the case of a water heater, the water can be used directly, and it is replaced by cold water from the existing water supply.
Geothermal and Solar heating systems are two examples of green construction types of alternative sources for heat and energy. The advantage is the reducing of the reliance on fossil fuel generated heat or energy. The technology for utilizing these sources of heat is still in its infancy. It is expected that the rise in green construction philosophy will encourage further experimentation in this area.