- Law of Heat Transfer.
- Heat flows from the higher level to lower level.
- In building the heat transfer takes place from the hotter area to the cooler zones.
- Heat flows as per the capacity of the building materials or units like floors, walls, roofs, doors, windows.
- The property is measured in “thermal transmittance”.
Prevention of Heat Transfer in summer from exterior to interior
- Thermal insulation of external shell like floors, roofs ext. wall to be adequate.
- Lesser temp. diff between outside and inside.
- Lesser overexposed area of external part of the building.
- The area of door and window exposed outside should be minimum. As the heat transfer is 3 time that of the walls, so the orientation should be w.r.t. sun movement.
- The air space, cracks, opening, etc. should not exist in roof, walls as heat transfer will take place through air infiltration.
Insulating material should have the following properties
- It should have high thermal resistance.
- It should be reasonably fire proof.
- It should be insect proof.
- It should be durable.
- It should be non-absorbent of moisture.
- It should be cheaper.
- It should be readily available.
Method of insulation of exposed window, doors, ventilators
- Reduction of incidence of solar heat: by use of external shading, such as louvered shutters, sun breakers, chajjas or weather shed, by adopting internal shading such as curtain in heavy folds, venetian blinds, etc.
- Reduction of heat transmission: Where glazed door and windows are provided, the reduction of heat transmission may be achieved by insulating glass or double glaze with air gap in between or by any other suitable means.
Thermal insulation material is in the following form
- Slab or block insulation
- Blanket Insulation
- Bat Insulating Material
- Insulating Boards
- Reflective Sheet Material
- Thermal insulation is retention of temp. Within the building irrespective of the change in temp. Outside the building.
- It maintains the comfort conditions during summer the thermal insulation should not allow the heat to transfer from outside- and during winters the heat should not leave the building thus giving comfort for the users.
- Due to thermal insulation, the demand of heating in winter and cooling in summer is considerably reduced.
- This results in lot of fuel saving and maintenance cost.
- The use of thermal insulation material further reduces the risk of water freezing in case of pipes and heat loss of hot water system.