The main objective of thermal insulation of heat insulation of a building is to conserve a constant heat or temperature inside building, irrespective of temperature changes outside.
Methods of Heat Insulation or Thermal Insulation
The heat in a building structure is mainly transmitted through the roofs, exposed walls and exposed wall openings, such as windows, doors, ventilators, etc. and accordingly the methods of heat insulation usually adopted are as follows:
- Methods of heat insulation of roofs
- Methods of heat insulation of exposed walls
- Methods of insulation of exposed windows, doors & ventilators etc
1. Methods of Heat Insulation of Roofs
It is desirable from comfort considerations that thermal transmittance ‘U’ of exposed roofs should not exceed 2k.cal. per m2 h0C. Hence, methods are adopted to bring down the excess of ‘U’ value by treating the roofs. The following methods of thermal or heat insulation for treating the internal and external surfaces are generally employed.
- Heat insulating materials described are applied externally to the roofs. In case of external application, heat insulating materials may be installed over the roof but below a waterproof course. In case of internal application, heat insulating materials may be fixed by adhesives or otherwise, on the underside of roofs from within the rooms.
- The false ceiling of insulating materials may be provided below the roof with air gaps in between.
- Shining and reflective insulation materials may be installed or laid on the top of the roof.
- An air space may be created on top of flat roofs by arranging sheets of asbestos cement or corrugated galvanized iron over the bricks.
- Flat roofs may be kept cool by flooded water either by storing or by spraying regularly. This helps in reducing the outside temperature considerably. Water loss due to evaporation in such cases can be compensated by installing make up arrangements.
- White washing of the roof before onset of each summer also helps in heat insulation.
- Suitable shading of roof on the exposed surfaces also reduces the surface temperature.
2. Methods of Heat Insulation of Exposed Walls
For walls, also in view of comfort consideration, it is desirable to have the thermal transmittance (U) of exposed walls not greater than 2 k.cl per m2 h0C. To achieve this objective the following methods are adopted for thermal insulation of exposed walls:
- The thickness of the walls may be increased, depending upon the extent of insulation derived.
- Hollow wall or cavity wall construction may be adopted.
- The walls may be constructed out of suitable heat insulating materials provided structural requirements are met.
- The heat insulating materials of different types can be installed or fixed on the inside and outside of the exposed wall in order to reduce the thermal transmittance to the desired limits. In case external application, overall water proofing should be done.
- For partition walls, an air space may be created by fixing the sheathing of hard boards or battens on either side of the walls.
- Light colored white-wash or distemper may be applied on the exposed surface of the wall to increase thermal insulation value.
3. Methods of Thermal Insulation of Exposed Windows, Doors, Ventilators etc
All windows, doors, ventilators etc. which are exposed, transmit heat to a considerable extent. The following methods can be suitably used to achieve heat insulation of exposed windows, doors etc.
Reduction of Incidence of Solar Heat
The incidence of solar heat on exposed doors and windows can be reduced by the following means
- By use of external shading, such as louvered shutters, sun breaker and chajjas or weather sheds.
- By adopting internal shading, such as curtains in heavy folds, Venetian blinds etc
Reduction of Heat Transmission
Where glazed windows and doors are provided, the reduction of heat transmission may be achieved by insulating glass or double glass with air space in between or by any other suitable means.