Solar Home Designs - The Five Principles
Solar home designs explained. Get help with planning your active or passive solar design.
The sun's energy can make your home comfortable year round. The energy from the sun can be converted into electricity to both heat or cool your home and your water.
Homes can be designed using a passive solar design or an active solar design. Passive solar design takes advantage of local breezes, landscaping with shade trees and windbreaks, and uses a simple system to collect and store solar energy that requires no mechanical controls. The other earmark of passive solar home design is that the design of the home optimizes the benefits of heat received from the sun with standard construction principles.
When you build a passive solar home it takes careful planning but the project itself is relatively simple provided you understand and incorporate the five basic principles of solar design presented below.
Principles Of Passive Solar Home Designs
Ready to learn more about solar home designs? You will find more detailed information at the bottom of the article as well.
The primary key to a solid solar home designs is to site it with a good southern exposure.
It is best to situate longer walls toward the south so they can absorb the most heat possible from the low winter sun. Designing a long porch for the south side of the home helps to shade the house and keep it cooler during the summer when the sun is higher.
The longer axis of the building (ridge line) should be oriented east/west. When you do that the longer dimension (side) of your home will face the south. Optimum positioning to obtain the maximum solar benefit is true south but the orientation can vary 20 degrees or less of that direction with minimal effect. Depending on your location, designing the building with the right shape, siting it in the right direction and properly placing windows can cut a home's total energy use by 30 percent to 40 percent at no extra cost.
The most frequently used rooms should be placed along the longer, south side of the house, where sunlight can enter through windows in the south side. The shorter east/west side reduces the amount of surface area exposed to the sun and cuts down the amount of sun heat.
Garages, storage or laundry rooms are good choices to be sited on the home's east/west "short side" where they will function as an additional heat (thermal) buffer.
In a properly designed passive home, windows play an important functional role. They are not for aesthetics and decoration alone.
Windows serve as solar collectors that bring in light and heat while providing ventilation when temperatures rise.
Most of your home's windows and doors should be located on the south side. This allows them to collect solar energy when heat is needed and at the same time, to let in breezes when you need cool air.
It is best to place fewer windows on the east/west and north facing sides of the home. This helps insulate against cold and reduces summer heat as well.
A common mistake in passive solar home design is to use too many windows (glass) on the south side of the house. If you plan too many windows (overglazing) for the amount of heat storage capacity (thermal mass) it can make your home's temperature uncomfortable, either too hot or too cold.
When overheating happens, you are forced to open windows to provide ventilation and lose the benefit of stored heat that can be used later. To decrease heat loss during winter nights and to help control the build up of too much solar heat during the summer it is useful to install insulated window coverings such as drapes or shutters.
Overhangs are one of the best and inexpensive solar home design elements to include in your home for shade.
Overhangs should be designed in such a way that they will completely shade a room during the high summer sun and at the same time allow full sun to enter during the winter when the sun is lower in the sky to warm the air, and the floor.
Overhangs must be properly sized. If they are too short south-facing glass can act as a solar cooker making rooms unbearably hot. If they are too long your rooms will remain dark and cool not only during the summer but also during the winter when you need light and warmth.
The best way cool your home is not to let it get too hot in the first place. In addition to overhangs, you can create shade cover by placing panels over skylights, using insulated drapes, shutters, exterior shades, awnings and landscaping. Trees and vine-covered trellises that are strategically placed can stop summer sun on the south, east and west sides of your home.
Landscaping is one of the best methods for cooling your home. Temperatures inside a house can climb as much as 20 degrees (sometimes more) if there is no shade on east/west facing windows and walls. There is a great benefit for using deciduous trees and vines because they lose leaves in the winter and that permits more sunlight to come in during the winter. Trees also help to lower roof and attic temperatures by shading the roof as well as blocking direct solar sun. Careful planning is needed to determine your landscaping because you do not want any shadows to fall on your solar collectors used for water heating.
When a home has no insulation it is the same as leaving windows and doors open year round. In the winter you lose heat and in the summer you lose cooling. In passive solar design insulation is a key ingredient to successfully managing efficient heating and cooling.
Insulation materials do not conduct heat well. Instead of passing heat, they create barriers between inside and outside spaces. In other words a barrier is formed between warm rooms and cold weather, or cool rooms and hot weather. Since insulation is as equally effective in both hot and cold conditions, less energy is required to cool homes in hot weather or heat homes in cool weather. Well-insulated, energy-efficient houses maintain an even temperature all through the year. Every exterior wall and every wall, floor and ceiling between your living area and an unconditioned portion of the interior, like a porch, garage, attic, basement, utility room, crawlspace or cellar should be insulated. There are many insulation choices. There are loose fills, batts or rolls on insulation, rigid boards and foam products that can be sprayed into place. Some materials insulate better than other insulation materials.
Smart energy-builders prefer insulating a home about 30% above general recommended levels. Insulation must be done correctly so hire professionals that are experts in insulation.
Some builders have a strong preference for using liquid foam insulation that is sprayed in ceiling cavities and walls as a liquid. The liquid expands and converts into a solid. Products made of liquid foam produce an airtight seal and can repel water. Even a small amount of water that gets into standard insulation products can reduce their resistance to the flow of heat. When that happens, it also lowers the product's ability to insulate. The liquid form of insulation almost doubles its ability to insulate but the product itself is very expensive.
In order to use solar power when the sun is not shining there must be a way to collect and store enough heat for those hours when the sun is not available. Thermal mass is best described as material (solid or liquid) that has the capacity to absorb and store heat or cold until it is needed.
Concrete, stone or water has a much better storage capacity for heating and cooling than air. Thermal mass can prevent large fluctuations of indoor temperature as outdoor temperatures rise and fall. In a well designed solar home interior temperatures generally hold between 68 and 70 degrees if there is the proper balance between the square footage of glass (solar collectors) used and the right amount of effective thermal storage mass (concrete, stone, brick tile etc).
During the winter thermal mass absorbs heat by direct sunlight. During the night thermal mass releases heat, warming rooms by radiation, convection or conduction. During the summer, thermal mass requires shade so that it draws the warmth from the surrounding air and cools the room. The greater the area of thermal mass, the greater its ability to store heat and maintain a uniform temperature.
Brick, tile or thick concrete floors are all examples of thermal mass materials. Thermal mass materials can also include interior wall made of adobe or brick, stone or tile fireplaces, masonry or concrete walls even water filled containers used as walls. All of these materials can be used to absorb heat and cold.
Any passive solar home design must be carefully thought out paying close attention to balancing the amount of glazing (heat trapping materials ie; windows) with thermal storage mass (ie; walls, floors).
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