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Ishika Dutta
- Civil Engineer
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Thermal insulation is a method to reduce the transfer of heat from outside to inside. Insulating a house helps to maintain a comfortable living environment by maintaining inside temperatures and reducing energy costs.
The main purpose of insulation is to create a barrier around the building, that is, over the roof, on the wall, and beneath the floor, which reduces the amount of heat entering the home on a warm day, and reducing the amount of heat loss on a cold day.
A house with insulation can reduce heating and air conditioning costs by up to 40%. This translates to massive savings on energy bills and a lot less pollution due to less energy usage. The money saved from reduced energy consumption greatly outweighs the cost of the insulation which, in the end, essentially pays for itself.
Working principle of insulation:
On a hot day, like most typical Maltese days during the period from May till September, a concrete roof and walls exposed to the sun without insulation will start to absorb heat from outside the building. The roof will become hotter and hotter, and will start to emit this heat in the building, which will result hotter environment within the building. Due to the concrete and bricks' heat capacity, the roof and walls remain warm during the night, and the inside of the building becomes uncomfortably hot during summers.
The opposite happens during winter, in which the heat from the house is absorbed by the roof and walls, and emitted outside. During night-time the inside temperature can easily match the chilling outside temperature.
Heat always travels from the hotter area towards the colder area. The only way to stop this process is through good insulation. In a house with insulation, heat flow through the ceiling ceiling and walls is vastly limited, depending on the thermal conductivity of the material installed.
Heat transfer:
Insulation products are designed to frustrate the transfer of heat across the material itself. There are three methods of heat transfer: radiation, conduction and convection.
Radiation
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.
Conduction
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
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.
The process is actually initiated by an energy transfer due to conduction, and is complicated by the level of water vapour that is supported by the air. The water molecules store heat given to them through conduction from warm surfaces. The water vapour and the air cannot be separated as gases. They will only part company when the saturated vapour pressure is reached, i.e. the quantity of water (albeit in vapour form) exceeds the level of heat available to maintain it as a gas (vapour), and therefore it condenses. Condensation causes this latent heat to be released; the temperature to water vapour ratio alters, and once it has altered far enough the process will start again. The world's weather systems follow a very similar cycle.
If air could be kept still and dry it would perform as a highly efficient insulant. However, if air is heated, its molecular structure expands and becomes less dense relative to the air surrounding it, and so rises. As it progresses further from the heat source, it begins to cool. The molecules contract and increase in density and sink back down. Air molecules are in a constant state of flux, dependent on the ambient temperature, and interference from any point, or background heat sources. This process of heat transfer 'convection' is complicated by the fact that air will cool at a rate dependent upon the amount of water vapour saturation. The greater the saturation, the slower the cooling
Insulation Materials:
Fiberglass insulation products come in batt, roll, and loose-fill form, as well as a high-density board
material. Many manufacturers use recycled glass in the production process. Fiberglass is used for
insulating virtually every building component – from foundation walls to attics to ductwork.
• Cellulose insulation, made from recycled newsprint, comes primarily in loose-fill form.
Cellulose batt insulation has also been introduced in the marketplace. Loose-fill cellulose is used
for insulating attics and can be used for walls and floors when installed with a binder, netting, or
covering.
• Rock wool insulation is mainly available as a loose-fill product and can be installed in attics or
blown using damp spray methods into walls. It is fireproof and manufacturers use recycled
materials in the production process.
• Molded-expanded polystyrene, often known as beadboard, is a foam product made from molded
beads of plastic.
• Extruded polystyrene, also a foam product, is a homogenous polystyrene product made primarily
by three manufacturers with characteristic colors of blue, pink, and green. It is an excellent
product for below-grade applications or exterior sheathing.
• Polyisocyanurate and closed-cell polyurethane are insulating foams with some of the highest
available R-values per inch. Another benefit of these foams is that they provide structural
support to the bracing members and sheathing.
• Open-cell polyurethane is used primarily to seal air leaks and provide an insulating layer.
Polyurethane is one of the only spray foams which can be used in existing buildings, as it will
not expand and damage the interior finish.
• Isocyanate foam, used primarily to seal air leaks and provide an insulating layer, is foamed with
carbon dioxide.
• Aerated Concrete, including lightweight, autoclaved (processed at high temperature) concrete
can provide a combination of moderate R-values and thermal mass for floors, walls, and ceilings.
The main purpose of insulation is to create a barrier around the building, that is, over the roof, on the wall, and beneath the floor, which reduces the amount of heat entering the home on a warm day, and reducing the amount of heat loss on a cold day.
A house with insulation can reduce heating and air conditioning costs by up to 40%. This translates to massive savings on energy bills and a lot less pollution due to less energy usage. The money saved from reduced energy consumption greatly outweighs the cost of the insulation which, in the end, essentially pays for itself.
Working principle of insulation:
On a hot day, like most typical Maltese days during the period from May till September, a concrete roof and walls exposed to the sun without insulation will start to absorb heat from outside the building. The roof will become hotter and hotter, and will start to emit this heat in the building, which will result hotter environment within the building. Due to the concrete and bricks' heat capacity, the roof and walls remain warm during the night, and the inside of the building becomes uncomfortably hot during summers.
The opposite happens during winter, in which the heat from the house is absorbed by the roof and walls, and emitted outside. During night-time the inside temperature can easily match the chilling outside temperature.
Heat always travels from the hotter area towards the colder area. The only way to stop this process is through good insulation. In a house with insulation, heat flow through the ceiling ceiling and walls is vastly limited, depending on the thermal conductivity of the material installed.
Heat transfer:
Insulation products are designed to frustrate the transfer of heat across the material itself. There are three methods of heat transfer: radiation, conduction and convection.
Radiation
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.
Conduction
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
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.
The process is actually initiated by an energy transfer due to conduction, and is complicated by the level of water vapour that is supported by the air. The water molecules store heat given to them through conduction from warm surfaces. The water vapour and the air cannot be separated as gases. They will only part company when the saturated vapour pressure is reached, i.e. the quantity of water (albeit in vapour form) exceeds the level of heat available to maintain it as a gas (vapour), and therefore it condenses. Condensation causes this latent heat to be released; the temperature to water vapour ratio alters, and once it has altered far enough the process will start again. The world's weather systems follow a very similar cycle.
If air could be kept still and dry it would perform as a highly efficient insulant. However, if air is heated, its molecular structure expands and becomes less dense relative to the air surrounding it, and so rises. As it progresses further from the heat source, it begins to cool. The molecules contract and increase in density and sink back down. Air molecules are in a constant state of flux, dependent on the ambient temperature, and interference from any point, or background heat sources. This process of heat transfer 'convection' is complicated by the fact that air will cool at a rate dependent upon the amount of water vapour saturation. The greater the saturation, the slower the cooling
Insulation Materials:
Fiberglass insulation products come in batt, roll, and loose-fill form, as well as a high-density board
material. Many manufacturers use recycled glass in the production process. Fiberglass is used for
insulating virtually every building component – from foundation walls to attics to ductwork.
• Cellulose insulation, made from recycled newsprint, comes primarily in loose-fill form.
Cellulose batt insulation has also been introduced in the marketplace. Loose-fill cellulose is used
for insulating attics and can be used for walls and floors when installed with a binder, netting, or
covering.
• Rock wool insulation is mainly available as a loose-fill product and can be installed in attics or
blown using damp spray methods into walls. It is fireproof and manufacturers use recycled
materials in the production process.
• Molded-expanded polystyrene, often known as beadboard, is a foam product made from molded
beads of plastic.
• Extruded polystyrene, also a foam product, is a homogenous polystyrene product made primarily
by three manufacturers with characteristic colors of blue, pink, and green. It is an excellent
product for below-grade applications or exterior sheathing.
• Polyisocyanurate and closed-cell polyurethane are insulating foams with some of the highest
available R-values per inch. Another benefit of these foams is that they provide structural
support to the bracing members and sheathing.
• Open-cell polyurethane is used primarily to seal air leaks and provide an insulating layer.
Polyurethane is one of the only spray foams which can be used in existing buildings, as it will
not expand and damage the interior finish.
• Isocyanate foam, used primarily to seal air leaks and provide an insulating layer, is foamed with
carbon dioxide.
• Aerated Concrete, including lightweight, autoclaved (processed at high temperature) concrete
can provide a combination of moderate R-values and thermal mass for floors, walls, and ceilings.
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