solar cooler

solar cooler

« Previous12345Next »

The position a home is one of the main keys to building an energy efficient passive solar home. The position is different depending on where the home is located in the world. In Arizona 13 degrees east of magnetic south is the perfect position. At high noon in the summer months the sun is at the southwest corner of the home. The winter months when the sun is low in the sky, the south windows absorb sun for radiant heat. There are some very good books on the market with charts that will help with the positioning.

Know the land in all seasons before building. Learn the directions of prevailing winds in winter and summer months. If wind scoops, vents or tunnels are used for cooling, knowledge of the wind direction is crucial. If there are any trees, be sure that they are at least 20 feet from the south side of the home. Know whether they are deciduous (loose their leaves in winter) or evergreen trees. The sun needs to be able to reach the windows in winter. Trees can also direct air flow to or away from the home. They can also be used to gradually cool down the area outside the home. Gradual cooling helps the feeling of a cooler home. Temperature is not the measure of how warm or how cold we feel. It is the instant change from hot to cold or cold to hot that makes us feel the change. It is like getting out of an air conditioned car as opposed to a car with the windows rolled down. The outside temperature is the same but the transition is quicker so we feel warmer.

Learn which way the water flows off the land. Check erosion or gullies to see what has already happened on the land. Go to the land during or after a rainfall. Observe which way the water flows or pools. Do not build in a low spot as flooding or standing water after a rainfall may become an issue. Adobe homes may be in danger of erosion and straw bale can mold if the foundation is not high enough.

Window placement is a trade off. Basically no or very small windows on the east or west side of the home. Sometimes this is not possible if there is a view that just must be seen from inside the home. Be very careful in an off grid application where there is no mechanical cooling system. The trade off for a view may not be the best choice if the temperature inside becomes unbearable. The glazing should be enough to allow the winter sun in for radiant and thermal heat but not so much that the summer months are scorching.

Room and window position should also be taken into consideration. Rooms that need to stay cooler such as the kitchen should be placed on the north side of the home. Rooms that need to be warmed first by the morning sun should be on the south side such as a bedroom. Depending on the design of the home clerestory windows can be placed so that rooms on the north of the home receive sun for light and heat. These windows can be stationary or opening windows. Many times they are made stationary due to leakage problems. Skylights may also be used for natural light. Be sure they are not placed near a ceiling fan unless a strobe light effect is desired.

The walls of some passive solar homes do not go to the ceiling. The advantage of this design is passages are not blocked and warm air can easily pass through the home. Vents placed low on one side of the home and high on the opposite side may help bring in cool air pushing hot air up and out in summer. One of the disadvantages is loss of privacy if the home is relatively small. The other disadvantage is a room that needed to be enclosed to retain heat.

Keep in mind that a gain in one area may mean a loss in another. For example: a dry arid climate where the summer temperatures reach above 100 degrees and the winters are in the teens at night. Cooling in the summer may be more of an issue than heating in the winter. A passive solar home can achieve about 20 degrees below ambient temperature with no mechanical devices to assist during the summer. This can be done by opening up vents during the night cooling down the walls and completely closing up the home during the day. With air circulation from ceiling fans, the temperatures are tolerable. This is more true with off grid passive solar, but the whole point is energy savings no matter if the home is on or off grid.

http://www.offgrid-desert-living.com

My husband Ron and I built an offgrid dry stack concrete block home in the Arizona desert. We knew nothing about offgrid when we started our venture. We have learned alot about ourselves and our dreams (mostly that we still had some). I decided to share some of our experiences with others who are considering building offgrid.

Solar Cooler Ch. 3 Local Coverage