Table of Contents

Difference Between Active & Passive Solar Heating

Aruna Murthy Anaparti
Table of Contents

Solar energy is nonpolluting and renewable. Different kinds of technologies can harness solar radiation and convert it into solar energy. Buildings can employ either active or passive solar heating. Each method has its own set of advantages and disadvantages.

A greenhouse is a classic example of passive solar heating system.

Active Solar Heating

The active solar heating system captures solar radiation through mirrors and mirror plates. The solar radiation is absorbed by a collector, which converts the harnessed solar radiation into heat. The collector is designed in the form of a box or a pipe, which contains water, anti-freeze substances or air. As the solar radiation falls on the mirror plates, it is directed to the collector, and solar energy is produced. The air or the liquid present in the collector gets heated up because of the solar energy. The heated gas or liquid from the collector is transferred to various parts of the building using a pump or a venting mechanism, and this helps in heating up the entire building.

Active Solar Energy Use

Liquid-based active solar heating systems are used to heat water in swimming pools, homes, industrial setups or commercial buildings.

Air-based active solar heating systems are used to heat up homes. Solar panels can be used to power the pumps and fans, which are used to circulate heated air around closed spaces such as rooms, hallways, kitchen areas and garages. This heating system is also perfect for use with an existing heat-radiating system. The heated air or liquid can be easily pumped through the arrangement of pipes or tubes that are concealed beneath the floors of the building or behind the walls.

Passive Solar Heating

Passive solar heating systems use the architectural design and construction material of a building to produce solar energy. The building, along with its thick, absorbent walls, functions as the collector of solar radiation during daytime. The building material absorbs heat, retains it throughout the day, and starts emitting it during evenings, providing heat to the building when the sun sets. A greenhouse is another classic example of passive solar heating systems.

Best Settings

Passive solar heating is best achieved by planning the building construction in such a way that the walls receive maximum exposure to sunlight. South-facing windows are an important part of implementing passive solar heating as they get exposed to more sunlight throughout the day. Concrete or tile floors that have embedded radiant heat coils help in keeping the entire place warm and cozy. Proper airflow is also an important aspect of planning passive solar heating so as to distribute the heat all over the building.

Active vs. Passive Solar Heating

Installation of either active or passive solar heating systems provides monetary benefits in the long run. While both passive and active solar heating systems are similar in terms of the renewable nature of the energy source used, they have several differences. The most important difference is that while active solar heating systems can be easily incorporated in the existing building, a passive solar heating system needs no equipment to be installed. A passive solar heating system does not cost anything in terms of additional infrastructure or equipment. The initial planning and construction costs, however, cannot be ignored.