Building Insulation

When talking about building insulation, we are referring to thermal insulation, acoustic insulation, fire insulation and impact insulation (to protect buildings from being affected by vibrations caused by industrial applications).

Thermal insulation is the most common kind of insulation used in buildings. Thermal insulation is done to achieve thermal comfort for the occupants of the building. Thermal insulation refers to the materials, methods and processes that are used to reduce the rate of heat transfer. Heat energy is transferred mainly by conduction, convection and radiation. Heat energy is also transferred when there is a change of phase. Insulation in a building reduces unwanted heat loss or gain and decreases the energy demands that heating and cooling systems use. Examples of insulation materials are cellulose, fibreglass, rock wool, polystyrene, urethane foam, and vermiculite.

Insulation also involves designs and techniques to address the modes of heat transfer. The R-value (the bigger the number, the better) is how the effectiveness of the insulation is measured. The insulation of a building depends on the design of the building, climate, energy costs and personal preference. Fibreglass and mineral wool insulations resist the flow of heat. Thus, they reduce the amount of energy needed to heat a home in winter and cool it in summer. When the energy consumption is reduced, it means that less fossil fuel is burned to produce that energy. This further reduces the polluting gases which are emitted into the atmosphere. Fibreglass and mineral wool insulation in a building can increase its value because of the increased energy efficiency.

When choosing insulation material it is best to assess it according to its impact on the environment. Check to see the amount of recycled material or renewable raw materials used, whether it is locally available, whether there are chemicals added to it, and how it will impact on the environment when disposed of. It is also important to understand if there are any health hazards. Fibreglass and mineral wool use 20 to 25 percent (sometimes even 40%) recycled material. Fibreglass insulation is compact, and so fewer packages are required for each home. Both fibreglass and mineral wool are naturally non-combustible. Thus, they do not need any chemicals to be added to make them fire resistant. Reduced energy consumption means that carbon dioxide and nitrous oxide, as well as other harmful gases, are not being emitted into the atmosphere. These are the gases that are responsible for global warming and pollution. A ‘green’ building is one which is constructed from materials that are energy-efficient and long-lasting.

In cold climates the main aim is to keep the heat inside the building and to reduce the outward flow of heat. Windows, roofs and walls, when not properly constructed, are sources of heat loss. Faulty construction of openings can be another source of heat loss, causing air infiltration. Heat loss can be reduced by good weatherization (weatherproofing). This is achieved when a building and its interior are protected from the elements, particularly from sunlight, humidity and wind. This naturally leads to a reduction in energy consumption. Insulation reduces conductive heat flow, whereas weatherization reduces convective heat flow. Building insulation requires weatherization if it is to function properly.

Thermal radiation indoors can be retarded by using special low-emissivity glazing. This kind of glazing uses microscopically thin, almost invisible, metal or metallic oxide layers which are put on a window or skylight in order to reduce the U-factor. The lower the U-factor the greater a window's resistance to heat flow and the better its insulating value. Radiant heat is reflected, so it does not enter the house. In hot conditions, the greatest source of heat is the sun. This heat can enter the building through the windows or the building itself gets heated to a higher temperature. Light coloured roofing, heat-reflective paints and coatings help in preventing the heat from coming into the building. When windows and doors are placed optimally in a building, taking into consideration the movement of the sun and the direction of the winds, it provides a significant amount of insulation. For barns, garages, and buildings where a lot of metal is used, reflective laminates help with insulation.

Moisture compromises thermal insulation. The kind of insulating material chosen depends on how moisture and condensation are reduced on either side of the insulator. A heat bridge, or thermal bridge, is created when there is a defect in the building which allows the constant flow of heat. If the heat bridging is faulty, then it needs to be rebuilt using more insulative materials. Glass and metal are so commonly used for construction nowadays however they are poor insulators. Places in a building where such bridges can develop are the corners of the building and areas where the building has been restructured to put in items such as electrical boxes, plumbing and fire alarm equipment. Sometimes, parts of an external wall are closed off before they are fully insulated, leaving holes in the building which are inaccessible.

There are two main types of thermal building insulation: bulk insulation and reflective insulation. Bulk insulators are dense materials that block the heat flow either into or out of the building. The denser the material the better the insulation. Reflective insulation, as the name suggests, reflects heat instead of either absorbing it or letting it go through. Usually a combination of these two insulators is used in a building. It is wiser to insulate a building during construction rather than retrofitting it.

An often overlooked area is acoustic insulation. Loud sounds can be stress-producing. For homes and for buildings where business dealings take place, or where learning and academic pursuits take place, loud sounds can be very distracting. Sound travels in waves and so any opening, even the tiniest hole, will let noise in. Many new homes are designed and built in such a way that the kitchen and living spaces are large, however the noise levels in the house will increase. Unscrupulous builders use thin building material and this does not insulate one section from the other, thus allowing noise to spread easily in the building. Acoustic insulation is important for the privacy of the home or even the office. Sound-dampening insulation should be installed during construction. This will reduce, if not prevent, sound travelling from room to room. The insulation material should fit snugly in place and fill all the wall cavities. All gaps and holes should be filled and the insulation should be stapled to the inside of the wall. If the insulation around electrical boxes, pipes and other obstructions has to be cut, a utility knife should be used to cut the insulating material neatly.

During shipping and storage, the material used for acoustic insulation should be kept dry. Thick carpets and padding help a great deal. Partitions such as walls and floors are rated according to how much they can reduce sound or noise levels. The better the material used, the higher the rating. Consequently, the acoustic insulation also works better. Musicians, or those with home theatre systems, usually require good soundproofing. Naturally, this zone would have to be completely redesigned. A combination of pre-fabricated wall inserts and sound-dampening panels would help to make the room soundproof. If the room has windows, then these will have to be specially designed so that they do not allow sound to enter or leave the room.

Fire is a major hazard in all buildings. When the building is being constructed, it is important to ensure that the materials being used are fire resistant. Judicious use of rock wool, gypsum boards, asbestos cement, perlite boards, calcium silicate boards, treated lumber plywood, and treated vegetable fibre in construction helps insulate the building against fire.

Impact insulation is often overlooked however it may be necessary in some circumstances. Vibrations from industrial applications can cause damage to buildings that are in the vicinity. Prolonged vibrations have been known to cause structural damage. Bioceran, a compact resin foam, is one material that acts as cushioning. Another material that absorbs impacts and provides a cushioning effect is a needle-punched material which is non-woven and includes at least one type of ballistic fibre.

Some buildings use panels made of galvanized sheet steel on the inside and on the outside and have a core of water resistant foam polyurethane. Also, since the floors are made of rigid panels, they do not allow cold or damp to penetrate. Double-glazed and sealed windows complete the insulation of the building.

How important is the insulation of a building? Going green is not just a slogan; it is a reality. The Earth’s fuels and natural gas supplies are dwindling. We have to make sure that we don’t destroy the Earth. Even a small air leak can cause significant heat loss so use expansion foam where necessary. Canned expansion foam that uses HFC rather than HCFC or CFC is best. Attics can be a cause of significant heat loss, so it is best to use insulation which has 75% recycled content and which does not emit formaldehyde. Use cellulose, fibreglass or urethane foam to fill all the gaps.

Wrongly or carelessly fitted windows are a great source of heat loss and, at worse, allow moisture and wind to enter the building. It would be wise to remove the trimming, on the inside or the exterior, so that the frame is exposed and fill with insulating material. Here again, use canned expansion foam that uses HFC. Choose foam that is used for windows so that they do not get warped by the pressure from the foam. Floors and walls should also be insulated against cold weather. Walls should be well insulated and all holes sealed as this increases comfort levels and reduces energy bills. It is best to apply the foam to the entire outside wall of the building to reduce heat loss as well as create thermal bridging. It will also help infiltration of air through any opening that might have been previously overlooked.

In today’s world there is so much awareness of energy issues and, due to carelessness and indifference, the Earth’s natural resources are being rapidly depleted. It is extremely important to live in a manner that will not cause any more harm and destruction to the Earth. Builders have to build with more integrity and ensure buildings are designed in keeping with regional climate, while also considering budget and personal preference.

The kind of building that looks good and is energy-efficient in one country may not work for another country. For instance, tall buildings with a full glass façade work well in climates that are not hot, but in countries or regions where the sun can be very sharp, these buildings are completely ineffective. In order to insulate them properly, the expense can be huge, but not insulating them could cause untold damage to the environment. It is always a good idea to study the indigenous ways of building houses and work within that system. The design of a building or house in a magazine or in one country does not mean that it will suit the demands of climate in another country. There are more and more inventions every day to find newer and more effective ways of insulating buildings without harming the environment.