Solar energy and green building

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Affordable, Low Maintenance Solar Energy
Green Building: Solar Power
By: Dean Dowd - Wednesday, January 30, 2008
Source: CalFinder Residential Solar

Two basic methods are utilized to garner solar energy: active and passive. Between the two, active seems the more dynamic, requiring the use of pumps or fans to direct solar heat. But don’t be misled by its name, as passive solar heating is anything but flaccid. On the other hand, passive solar methods go a long way to heat the home resourcefully, requiring little maintenance, and acquiring low to no costs for upkeep.

Passive solar heating is called such because it absorbs and distributes energy from the sun without the use of mechanical or electrical devices. This is done through building structure and design.

For instance, homes built around a passive solar plan are oriented in relation to the sun. In the United States, this means that they face southward, with all the high-use rooms located in the southern end of the home and low-use areas situated on the northern end.

The south side of the home also incorporates multiple windows for maximum exposure to light and heat. In order to lower cooling costs in the summer and minimize heating costs in the winter, passive solar homes integrate foliage into a home’s energy plan. Strategically planted deciduous trees shed in the winter, allowing light in through the windows during the colder months. In the summer, the trees are leafy, providing shade when the weather heats up.

Multiple window placement is an example of direct gain, passive solar heating. This is where the living space itself collects, absorbs, and distributes solar heat. Temperature is controlled through shading. Deciduous trees can be used in combination with solar shades, or with conventional curtains and blinds to manage excessive heat or insulate from the cold. Skylights and heat-absorbing material in the walls and floors are other examples of direct gain, passive solar heating.

An indirect gain, passive system stores solar heat and moves it out of an isolated space through a duct, door, vent, or other access point via natural air convection. One area is between the south-facing windows and the living spaces. A Trombe wall is the most common example in this space. This 8- to 16-inch-thick masonry wall is erected with a frontal glass layer on the south side of the house to collect solar heat and distribute it into the living space. Water walls and roof ponds are examples of indirect gain, passive solar heating methods, as are sunspaces, greenhouses, or solar closets.

Finally, isolated gain solar systems are passive forms of solar heating that utilize solar water collectors to collect heat, transferring that heat to a storage area through ducts or pipes. The placement of system elements help to direct heat from one area to the next through natural convection.

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