Building insulation comes in various forms and is used as a means of reducing the transmission of heat flow through walls, ceilings, and floors. Basically, this helps keep heated interior spaces warmer during the winter season, and air-conditioned rooms cooler in the summer. Reducing the transmission of heat makes rooms more comfortable and it also helps reduce energy costs.
BUILDING INSULATION REDUCES HEAT LOSS
When insulating a building, you can reduce the heat loss in cold weather, and reduce a heat surplus in warmer weather. Building insulation limits the need for heating or cooling. Heat losses or heat gains arise because of differences between the indoor and outdoor air temperature. The type of insulation you select when designing and constructing a space will depend on your climate and the R-value you seek.
TYPES OF BUILDING INSULATION
Although the majority of insulation in buildings is used for thermal purposes, it also provides solutions for acoustic and fire safety. After proper air sealing, insulation is the most important building feature for comfort and energy efficiency.
There are essentially two types of building insulation:
- Bulk Insulation
- Reflective Insulation
Bulk insulation acts as a barrier to heat flow between the building and the outside. It can be purchased in rolls, boards or loose-fill, and it is typically made from earthwool, glass wool, polyester or recycled paper.
Reflective insulation is usually made from shiny aluminium reflective foil that is laminated onto paper or plastic. It is used to keep buildings cool during warm months by deflecting radiant heat.
CONDUCTION, CONVECTION AND RADIATION
Most buildings use a combination of both types to make up a total calculated system. The type of building insulation used creates maximum resistance to each of the three forms of building heat transfer:
Conduction is reliant upon physical contact. If there is no contact, conduction cannot take place. Contact between two substances of different temperature results in a heat exchange from the higher temperature to the lower temperature substance. The greater the temperature differential, the faster the heat exchange.
Convection is the transfer of energy via fluids (gases and liquids). It is this method that plays the greatest role in the liberation and transfer of heat in buildings. The most common propagation of this effect is from solid to gas, i.e. object to air, and then back again, typically as the air meets with the external building fabric.
Any object whose temperature is higher than the surfaces that surround it will lose energy as a net radiant exchange. Radiant heat can only travel in straight lines. Introduce a solid object between points A and B, and they will no longer directly exchange radiant heat. Radiation is the only heat transfer mechanism that crosses vacuums.
Insulation products should be applied in compliance with the associated building regulations, both when applied retrospectively and when deployed during construction. Building regulations should be followed for all types of insulation, including ceiling, cavity walls, solid walls, and floor insulation.
BEFORE SELECTING A PRODUCT
Before selecting insulation material for a building, the following factors are to be considered:
- The climatic conditions of the region
- The material flammability in case of an accident
- Material toxicity
- The ease of replacement of the material
- The material affordability
- Material durability
- The ease of installation
In certain construction projects, a single type of insulation may not give the desired R-value, therefore, a combination of different insulation materials must be used to obtain an optimal solution.
ADDING BUILDING INSULATION TO EXISTING BUILDINGS
Insulation can be added to existing buildings with varying effectiveness and cost depending on the construction type and where the insulation is being placed. Ceilings and suspended floors with easy access are relatively simple to insulate post-construction. Insulation board can be laid beneath floor finishes if there is no under-floor access.
Adding insulation to existing buildings can greatly increase comfort and reduce energy costs and greenhouse gas emissions. An ideal time for doing this is during renovations. Insulation can be retrofitted to various construction types.