Solar energy can be used for replacing electricity, heat, mechanical power and lighting. With the help of passive solar heating, you can save considerably on the electricity bills. Passive solar heating is made possible by designing buildings in such a way that the energy is properly trapped and utilized. Windows, pumps and even fans are used in the process of passive solar heating. In areas which are exposed to high temperature, passive solar cooling designs are applied. If a normal building costs $150,000, a passive solar heating design can further enhance the cost by 15% i.e. $22,500. But at the same time, the heating system will be cut down conventional energy costs by 50 % as compared to conventional homes. Residential complexes designed using passive solar heating are very low on maintenance and have more light, open plans and airy.
What are the common elements of Passive Solar Heating?
Implementation of passive solar heat energy does not require any additional mechanical equipment. Instead, the building is designed in such a way that it acts as a heat trapping tower. For achieving passive solar heating, floors, walls, windows, roofs, landscaping and other external elements of construction are modified. Most designers make good use of thermal mass, thermal chimneys and operable windows for trapping the heat inside. Thermal mass is composed of water and masonry. It has the ability to trap heat for long duration. Use of thermal mass also helps in controlling the effects of rapid fluctuations in temperature. One of the identifying features of passive solar heating design is the wing walls that are placed vertically to the exterior as partition. These are arranged in perpendicular position to the connected windows so that the effect of ventilation is enhanced. Passive solar heating system contributes in collecting, storing, releasing and distributing the heat. Lately, the designs are also made to serve as backup systems for heating so that the traditional systems are used less and the use of non-renewable fuels is reduced to a great extent.
What are the different designs of Passive Solar Heating?
The different designs used for passive solar heating are:
Direct gain: This is one of the simplest designs of passive solar heating in which sunlight is made to enter the house by using glass. The trapped energy gets converted into thermal energy. The floors and walls are used as direct radiation interceptors that collect as well as store thermal energy. Sometimes these elements absorb reflected solar energy.
Indirect gain: In this design, the main solar energy collecting and storing elements are backed up by convection process. Thermal storage materials are used in between the exterior and the interior space of habitat. This design makes sure that the heat does not enter directly. Use of dark colored wall for thermal storage helps in trapping the solar heat indirectly.
Isolated Gain: In this design, a fluid is used for the collection of solar energy in a collector that resembles a flat plate. A bin (air storage) or tank (fluid storage) is connected with the flat plate. The solar energy is transferred with the help of natural convection process.
How to build a DIY passive solar heater ?
It is quite easy to build a DIY passive solar heater especially if you are used to playing handyman every now and then at your home.
Building a water tank is the first step. Get a good solar heater tank from the market and wash it off several times to remove the sediment deposits and clean it thoroughly. These tanks have insulation and metal shell from the outside that needs to be removed. The tank will have two major outlets-one for the water to come inside and the other to supply hot water. While buying a tank, also purchase plumbing fittings suitable for the tank size and set up. Clean the tank with sand paper and then paint it black (2 to 3 coats ) to achieve optimum solar heat absorption. Let it dry completely before starting the assembling. Placing the face of the glass is an important decision and it should be kept facing the direction from where regular supply of sunlight comes daily.
Building a collector box for your tank is the next step. For this you can get supplies from any home center or salvage supply. The material that you will need include plywood, screws, nails, 2”x4” lumber, insulation, paint, glass, and caulk. This collector box should be large enough to hold the water tank and the glass or plastic used for glazing. The plywood material is used for making exterior and internal surfaces of the box. For insulation you can use Styrofoam type insulation in 4’x8” sheets.
The last step is installing the passive solar heater. Hook up all the wire lines and attach the pipes in proper place. The top outlet will supply hot water as it get warm due to sunlight while the outlet at the base will keep on supplying cold water keeping the water tank full.
What are the considerations for building passive solar heating?
Passive solar heating helps in reducing the cost of energy. This simple system also decreases the dependency on fossil fuels. Some of the principle dimensions considered for passive solar heating are sun exposure of the building, proper ventilation and appropriate application of thermal mass. Depending upon the factors such as location of building and availability of space for use, the overall design is created. Geographical factors such as terrain, vegetation, precipitation rate and wind pattern are also taken into consideration for planning a design for passive solar heating.
What are Passive Solar energy techniques?
The common passive solar energy tecnhiques are:
Trombe Walls: Simply speaking it is nothing but a thick wall that is placed facing South or North depending upon the hemisphere you are located. This wall is painted with 3 to 4 coats of dark color, usually black and is made up of material that is good aborber of heat. A glazing in the form of plastic or glass is placed in between the sunlight and the Trombe wall just few inches away. The space between traps the solar energy which gets transmitted to the floor and helps to keep the ceiling warm during chilly nights.
Solar Ovens: These are very much like conventional ovens and are good when the meal is not needed immediately. It is a type of cardboard box that is well insulated with aluminum wrapping to trap the heat inside. These work best in bright sunny and dry climatic conditions and inexpensive. They are of great assistance to travellers who travel to remote places where ideal cooking conditions are not available.
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