Passive Solar Heating vs Active Solar Heating

Active and passive solar heating are techniques that use solar energy to provide heat in a building. There are several differences between these two methods and both have their sets of pros and cons.

Basics of Passive Solar Heating

Passive solar heating does not require the use of machinery or equipments to collect solar energy. On the contrary, passive solar heating is achieved through planning and positioning of a building in such a way that it receives maximum sunlight. South facing windows are an important component of buildings that implement passive solar heating. A thermal mass is a heat-absorbing material such as water or concrete that is built into the walls or floors of the building. Throughout the day, as sunlight streams in and enters the building, the thermal mass absorbs the heat and retains it. After the sun sets, the temperature in the building starts to drop down. Now, the thermal mass begins to give up the heat it has collected during the course of the day and transfers it to the rest of the building.

Proper air flow is also essential in a passive solar heating system, because the heat must be delivered to all the parts of a building. A venting system or an air blower can come handy for the purpose of heat distribution. However, proper planning is also crucial.

Pros and Cons of Passive Solar Heating

A passive solar heating system is economical and highly efficient on sunny days. It does not cost you anything once it has been put in place. On a sunny winter day, you can feel warm and comfortable without using a furnace of space heater. You can conserve fossil fuel and save a lot of energy, not to mention the monetary savings. You can also use the heat to warm up water. Moving over to the drawbacks, the dependability on sunlight is a major one. If you have several cloudy days on end, your home will begin to feel cooler. As a result, most passive solar heating systems require the use of a reliable backup heating system such as a conventional furnace.

Active Solar Heating

In an active solar heating system, a collector that is installed on top of the roof collects solar energy. The collector is usually a box or a tube that contains air or liquid such as water or anti-freeze. As the collector collects solar energy, the medium, which is the air or the liquid, gets heated up. This heat is transferred to the different parts of the building by means of a pump and a venting mechanism. An active solar heating system is also ideal for use with an existing a radiant heating system. In such a case, the heated air or liquid can be pumped through the network of pipes or tubes behind the walls or under the floors of a building.

Active solar heating systems are somewhat more reliable than passive systems, but they still require some sort of backup for sunless days. These systems can be easily introduced in an existing building, unlike the passive systems that can only be implemented during the planning of a new building.