Passive Solar Heating

Passive solar heating energy is nothing new – if you have ever sat in a car during a sunny day, you must have experienced the effect of passive solar heating…you might have noticed that car’s temperature is relatively high than outside temperature. The same logic is applied for homes; passive solar design tries to make best use of the amount of energy which can be collected directly from the sun. This is done by carefully designing the buildings so that maximum heat is collected by the building and which will in turn reduce the need for heating. Building material, fabric, windows and doors are carefully considered, so as to increase the heat gain and reduce the heat loss. For efficient passive solar heating of a house, a house must function as a solar collector, heat storehouse and heat trapper.

In Australia, north facing glass and thermal mass will help in absorbing, storing and distributing heat are the basic requirements for a passive solar heating house. The main purpose of all passive solar heating systems is to entrap the sun’s heat, that heat should be absorbed within the building’s materials and that heat should be released during periods when the sun is not shining.

For getting the maximum heat gain in winters, following passive design principles are followed for passive solar heating:

• North facing glass windows for heating the interior of house from direct sunlight.
• Insulated thermal mass for storing heat.
• Insulation and draught sealing.
• Floor plan zoning as per the heating needs.
• Superior glazing solutions.

Following are three main approaches for passive solar heating of the house:

Direct Gain:

Direct gain refers to the absorption and temporarily storing of the sunlight as it enters a home through windows. When Sunlight enters the house through the north-facing windows, it strikes masonry floors and/or walls, which absorb and store the solar heat. In summer, an overhanging sunshade or roof overhangs on north facing windows can prevent the home from overheating.

Indirect Gain:

Trombe Wall or a thermal storage wall is the most common approach for the indirect-gain of solar energy for passive solar heating. These walls are specially designed for harnessing the energy of the sun. The wall is an 8–16 inch-thick wall, which is built from stone or concrete or an array of water tanks on the North side of a house. These materials work as a thermal mass, and there is insulated glazing from outside, and then these walls effectively become a solar thermal collector. When the room temperature is less than that of the wall’s surface, heat begins to radiate and transfer into the room.

Isolated Gain:

The most common example of an isolated gain system is a sunspace (solar room or solarium or Solar greenhouses). These solariums make use of features of both direct gain and indirect gain systems. Sun rays entering the solarium are preserved in the thermal mass and air of the room. Sun’s heat gets in to the house by means of conduction via a shared mass wall in the rear of the solarium, or by vents which allow the air between the solarium and home’s interior to be exchanged by convection.

Passive solar heating should be incorporated during the initial design and construction of the building. This will help in lowering the energy costs spent over the life of the building and with very little maintenance on going in general.