Go Solar and Save Big!
(Page 4 of 6)
August/September 2006
By Clarke Snell
Slowing Heat movement
RELATED CONTENT
The U.S. Department of Energy's work with the city of Greensburg, Kan., over the past year is beari...
. . . ENERGY FLASHES...... ENERGY FLASHES...... ENERGY FLASHES. . . September/October 1982 POPEYE W...
A new study predicts we could have one quarter of our energy needs from renewable sources by 2025, ...
Which renewable energy technology has the best potential to combat global warming and power our fut...
Want to know how to build your own photovoltaic system, how to construct a solar water pump, or eve...
To maintain temperature, we have to slow the inevitable movement of heat. Materials placed to slow the movement of heat are generically called insulation. However, heat moves in different ways, so insulation needs to be chosen based on the type of heat movement you’re trying to prevent.
Light, airy materials such as fiberglass and straw bales slow conduction. Conduction is the transfer of heat from molecule to molecule through a material, such as the metal in a pot on a stove. It is best slowed by materials that form a complicated web that the heat must traverse. This is the principle behind most materials we normally label as insulation, including fiberglass, polystyrene foam and forms of organic cellulose such as cotton, straw bales and shredded newspapers.
Stopping air leaks slows convection. Convection is the transfer of heat by physically moving molecules from one place to another, such as the air that rises in a fireplace chimney. Many materials won’t let air move through them: Wood, concrete and plaster, to name a few, allow basically no convective heat loss through their volume. Problems often arise, however, at joints between and breaks in these and other materials. Windows, doors, plumbing vents and electrical boxes are all potential convective weak points. Once identified, though, they can be sealed effectively. One huge source of convective air loss is opening the front door. This can be greatly reduced by creating an entry room, sometimes called an airlock or mudroom, that isolates the living space from the outside.
Reflective surfaces slow radiation. Radiation is the direct transfer of heat by means of electromagnetic energy: The sun heats the Earth through space with radiant energy. Heat absorption from radiation is best slowed by using reflective materials. How reflective a surface is depends on its color. A white surface is an effective reflector of light, but a poor reflector of heat. On the other hand, a shiny metallic surface is a good reflector of light and heat, but a poor emitter of heat. If you’re trying to cool a home in the summer, a shiny metal roof does a good job of reflecting the light and heat of a sunny summer day away from the building, but at night a white roof will release the heat trapped in the attic more rapidly than a shiny metal roof.
More Benefits of Passive Solar
We’ve quickly outlined some of the basics of solar design, but they only begin to describe the benefits of living in a passive solar home. Here are a few other advantages of using solar design strategies.
Long-term savings. Ron Judkoff, director of the Center for Buildings and Thermal Systems at the National Renewable Energy Laboratory, says, “There is nothing intrinsically more expensive about passive solar construction. In fact, basically the same materials used to construct many modern homes can simply be rearranged to make a passive solar building.”
Page:
<< Previous 1 |
2 |
3 | 4 |
5 |
6 |
Next >>
