Civil Engineering Reference
In-Depth Information
3.2 Passive Solar Heating Storage
The passive heating using the solar energy is a type of thermal storage technique
highly suitable for buildings that are being newly constructed or refurbished. The
term passive implies enabling the heating storage without the use of additional
mechanical equipments such as circulation pumps, fans or blower units. The
buildings intended for passive solar heat storage must be designed in such a way to
take full advantage of the solar radiation.
Albeit the building fabric components as discussed in earlier sections are
capable of absorbing and releasing the thermal energy to indoor environment, the
alternative component, that is, the glazed envelopes are considered most essential
and useful components to trap more solar radiation in buildings.
The solar glasses serve dual purposes by providing good aesthetics to the
building and capturing solar radiation that is required for heating the occupied
zones upon demand. The buildings that are oriented towards south to about 30 are
generally considered energy efficient in this regard, which would absorb more
sunlight during daytime hours. The glazed structures on such buildings allows
solar radiation to infiltrate through them to enter the occupied spaces, but simul-
taneously prevents the infrared radiations from getting transmitted back to the
ambient, thereby creating heat spaces in indoor environments.
Generically, if the ratio of glazing to floor area is designed to be 7-10 %, it can
serve to achieve better heating storage in buildings as well as to reduce any risks
due to overheating of thermal zones in buildings. Passive solar heating storage
systems are economical and include more sustainable aspects, which when
incorporated in modern buildings can enhance their energy efficiency by 30-35 %.
3.3 Active Solar Heating Storage
The active solar heating storage on the other hand utilizes a dedicated solar col-
lector, storage tank, heat exchanger, associated mechanical pumps and control
interfaces. In principle, the solar radiation being trapped by the solar collector gets
converted to heat energy. This heat energy is first transferred to the heat transfer
fluid flowing across the solar collector by means of efficient absorber materials of
the solar collector. The absorbed heat energy is then transferred to the storage tank
by the warm heat transfer fluid and the cooled fluid then travels back to the
collector, and the process is repeated for several thermal cycles until the heat
storage requirements are met.
The heat stored in the tank is then retrieved by the secondary heat transfer fluid
and is supplied to the heat exchanger (radiator or air-handling unit) installed in
rooms or zones depending upon the thermal load demand persisting in building.
Solar radiation absorbed by the flat plate and evacuated tube collectors potentially
converts the light radiation to heat energy and helps to increase the temperature of
