Careful building design makes the best use of natural daylight. In order to make the best use of solar energy, it is necessary to understand the climate of the region. Buildings that are inappropriate for the local climate cause energy wastage (Howell 1986). In order to gather radiation directly by devices, house roofs are constructed as discrete solar collectors.
It is possible to consider a south-facing window as a kind of passive solar heating element. Solar radiation will enter during daylight hours, and if the building’s internal temperature is higher than that outside then heat will be conducted and con – vected back out. Here, the main question is whether more heat flows in than out, so that the window provides a net energy benefit. The answer depends on the following several points:
1. The internal temperature of the building
2. The average external air temperature
3. The available amount of solar energy
4. The transmitting characteristics, orientation, and shading of the window
5. TheU-value(see Sect. 7.3.3) of the window whether it is single or double glazed
The total amount of heat needed for supply over the year can be called the gross heating demand, which can be supplied from three sources:
1. The body heat of people and heat from cooking, washing, lighting, and appliances are together named as “free heat gains” in a house or apartment. Although, individually, they are not significant, collectively they may amount to 15 kWh/day. Free heat gains help in reducing the space heat loading.
2. Passive solar gains occur mainly through the windows.
3. Fossil fuel energy exploitation from the normal heating system.
If the house is insulated properly, it is not necessary to have large areal collectors, because the energy need will be small. Here lies the key problem in active solar space heating: either to insulate the house to have less energy demand or to build poorly insulated houses and try to implement solar energy for space heating.
