Solar House Design – Passive and Active Systems

Tuesday, November 17th, 2009 at 1:14 pm

As with everything else, there are varying opinions about the best way to approach a solar house design. The two primary systems, although there are variations, are passive and active systems. The central theme for both systems is to reduce dependency on fossil fuels and, at the same time, save on heating, cooling, and operational costs.

The passive home is designed to use as much of the heat and warmth of the sun in winter as is physically possible. In the summer, it is designed to close out the sun as much as possible. This is done passively, without the use of a great deal of mechanical help.

The underground home is one design that lends itself to passive solar construction. Because the air temperature six feet below ground remains a constant year round, a design that puts the home within that envelope needs little in the way of heating and cooling. Some claims are that a house with dirt on three sides and the roof can easily be designed to use no heating or cooling system.

In the underground home, the solar collectors may be designed with a battery backup system to store electrical energy for minor electrical uses at night. Without heating and cooling to contend with, the dependency on the utility company would be reduced to the base monthly rate.

Design features of the passive solar home include:

* Orienting the home to take full advantage of the site. This would face the longer sides of the home to the south and north.

* Installation of operable windows to control heat gain.

* Lots of windows on the south side of the house for the collection of light in the winter. These windows might be designed with shutters to close out some of the sun during warm months.

* Light tubes that allow light into all areas of the home to reduce electric light usage during the day.

* Over insulation to control heat and cold passage, especially in the attic space. Along with using more insulation, the home is weatherized to reduce the amount of energy entering or leaving.

Many of the same features are built into the active solar house. The chief difference in the active solar home is the use of mechanical elements that coordinate heat and cold to the best advantage possible. This might mean pulling air from one place that is too warm and directing it to one that is too cool. It sounds simple, but this requires constant monitoring that is done by a computer program.

In the simplest terms, a passive solar home is one in which you do your best to use the elements to your advantage, knowing there are some trade offs in your final results. This is sort of like the country home. An active solar house design uses the elements, but it also uses technology to help the elements along, sort of like the city home. And if neither one suits, there are some designs in the middle.