Passive solar buildings uses solar energy for its energy needs in different seasons. The Concept of passive solar buildings, performance and benefits are discussed.
The rate of increasing population growth with increasing innovations in the field of industries and technologies have all together resulted in the increasing energy consumption enormously. This high consumption is a concern for sustainability. This has a negative impact on the environment and energy conservation.
So, an innovation in building construction, that would perform with the existing energy, without exploiting any additional mechanical or electrical sources is called as passive solar building design concept. These buildings take the advantage of the climate, where it must be constructed. A proper site analysis would judge the performance of the building.
The concept of passive solar buildings is adopted in new buildings. But already existing buildings can be retrofitted to behave passively. The building is named passive solar buildings because we don't make use of any mechanical or electrical devices within the building to bring the concept.
Concept of Passive Solar BuildingsThe main concept of passive solar buildings is that its building elements i.e. the windows, walls and the floors are made able to collect solar energy and store them. This energy is then used in the winter for warmth and used to reject the heat during the summer seasons.
- The first principle is based on the route of the sun in different seasons. The sun in winter will be traveling in a lower route compared to summer.
- In winter, the south direction faced glass will help in energy absorption and storage in the building.
- The location of thermal mass in a position enabling easy absorption of solar energy later would help in the easy release of the same during evening time.
- The direct sun can be resisted by overhanging elements as shown in the figure below. These are also called control elements.
- Proper insulation enables warmth in winter and coolness in summer.
Elements Considered for Passive Solar Building ConstructionThe main elements considered are:
- Room types, internal doors, walls and furniture in buildings and their placement.
- The Equator faced orientation for the building
- Building dimension extension in east-west direction
- Window size fixed to get adequate solar in winter and shade in summer.
- Windows in the west are avoided.
- Use of thermal mass like floors or walls
Fig. Passive Solar Building Elements
Performance of Passive Solar BuildingThe efficiency of passive solar buildings depends upon the following factors:
- The site climatic conditions
- The passive solar building system adopted
- The passive solar building design criteria
- The building size
Results from Monitored BuildingsA set of passive solar buildings were monitored for one or more years by using twenty or more sensors that record hourly. The results from the computer analysis of data give us the following results:
- When compared to conventional home auxiliary heat usage, the passive solar building uses 70% less. On average the solar savings are in the range of 27% of the total heating load value.
- There was a tremendous decrease in the demand of electricity when compared with the conventional building arrangement.
- The cost of construction of passive solar buildings was found higher compared to that of the conventional method. This is because of time and cost used for proper optimization of energy. When compared with the final output the passive solar buildings provide, the system is economical.
Benefits of Passive Solar BuildingsThe benefits of passive solar building systems are as follows:
- The building interior are bright - The interior of the building would be filled with sufficient light. This is due to the transmission of visible light frequencies. The system is designed such a way that the control of glare and over lighting is kept in mind.
- The ultraviolet energy is blocked - The direct ultraviolet rays are harmful. The passive solar building system has the advantage of blocking almost 99.9% of the ultraviolet radiation energy. Preventing this would save the interior fabrics as well as decor and make them long lasting.
- Summer is Made cooler and comfortable - It keeps the interior cool during the hot season. This would obviously reduce cooling energy costs. This would give a low solar gain coefficient value (SHGC).
- Winter made warmer