Insulation for buildings facilitates retention of energy to make it energy efficient and cost saving. Types, Materials and methods of building insulation is discussed.
During earlier periods, the buildings were constructed tremendously with no consideration for insulation mainly because of the reason of cheaper cost of energy. But now the condition is different. Buildings with no kind of insulation results in the waste of energy. This concern is now not a factor of economy alone but the need for sustainability.
An estimation from the studies conducted proves that the use of insulation in buildings helps to save the building energy costs by 10 to 20%. But the actual cost also depends on the extent of insulation the building possesses initially, how much more is to be added, the number of openings, say doors and windows. The efficiency of insulation also depends on the weather stripping.
Different Types of Insulation for Buildings
There are different types of insulation materials available for the insulation of buildings. These includes:
- Mineral Wool
- Reflective Foils
- Various types of Foam Insulation
Among the mentioned types of insulation, the mineral wool is widely used. These materials are either rock wool or the fiber glass type. The mineral wool material can be provided in the form of blankets or poured insulation or blown insulation and batts. These blankets come in the form of rolls. These rolls are available with or without the vapor barriers.
Those mineral wool insulation rolls without vapor barriers are called as un-faced insulation. The blown insulation consists of loose pieces of insulation that are blown with the help of air pressure into attics. Batts are available in the form of blankets which are pre-cut to length of 4 or 8 foots.
Several types of insulation are shown in figure-1 to 5
Fig.1: Loose Ceramic Fiber for Insulation
Fig.2: Blanket form of Ceramic fiber used as insulation
Fig.3: Modular form of Insulation
Fig.4: Industrial Insulation Boards
Fig.5: Textile form of Insulation
Considerations in the Provision of Insulation
There are certain considerations that need to be considered while providing insulation for the building. Proper insulation is an important factor for a building. The main objective of insulation is to resist the escape of building heat.
The quality of insulation under consideration is represented by a parameter called as the thermal resistance factor (R). The sum of thermal resistance of entire structural elements of the building including the wood, concrete, insulations etc will provide the total thermal resistance of the building.
The inverse of thermal resistance is called as the coefficient of heat transfer (U). Coefficient of heat transfer is an expression that defined the amount of heat flow through an area. This is expressed in Btu per square foot per hour per degree Fahrenheit (Btu/ft2/hr/oF). Below are the formulas used for the conversion of R to u to watts i.e. electrical units.
Thermal resistance (R) = 1 / coefficient of heat transfer = 1/ U
Watts (W) = coefficient of heat transfer / 1 = U / 3.4
Watts (W) = 0.29 x U
Various tables and formulas are provided by the manufacturers of the insulations that can be used to estimate the heat loss that is occurring in the building for different concentration. The building must be provided with enough insulation so that it will help in Reduction of heat loss.
If this is not the case, the electrical heating and the air conditioning systems will be very inefficient and become uneconomical. The basic building construction and the amount of insulation used in the building will define the heat loss of the building.
A concrete building has different amount of heat loss compared to a building completely made of wood material.
Installation of Insulation in Buildings
The exterior walls and the interior walls that is located in between heated or cooler area or unheated areas must be provided with insulation. These are the common areas of a building for which the installation of insulation is necessary.
The ceilings constructed in cold space regions must also own a proper insulation. The floors areas and walkways constructed above the cold space must be provided with proper insulation.
The determination of thermal resistance of the building or the R-value is very essential. This valued helps in knowing how well performing is the insulation within the building. This provides an idea on how extent it resists the flow of heat within the building under consideration.
The thickness at which the insulation is provided affects the R-value. Now the mineral wood batts that have a specification of R19 are 6 inches in thickness. At the same time, this is R-13 for a thickness of 3 to ½ inches. The insulation materials have specification marked on the top based on the R value in such a way that it is easily seen.
General specification of insulations for different areas of the building is mentioned below:
- Floors: R-11 TO R-19 (Mainly chosen based on the climate conditions)
- Attics: R –22
- Walls: R – 13
The change in local climate brings change in these values. Cold climates may ask for insulation of higher R-values that is economically feasible to be used as suggested by the contractors.
If necessary it is fine to have additional insulation for the buildings. In most of the cases, the installation can be carried out without hiring a contractor.
In the case of attic floors with no kind of insulation provided at the attic floors, the insulation can be provided at between the ceiling joists. When vapor barriers are provided, they must be installed such a way that it is faced down. Here there is no need for stapling the installation.
Having insulation in un-insulated attic areas helps in having tremendous energy saving. For attics areas that requires additional insulation, it is recommended to have a layer of blankets or batts that is installed over the old insulation made.
There is no need for providing vapor barrier for the new installation. This type of insulation without a vapor barrier is called as un-faced insulation.
Poured form of insulation can also be applied for attics. This type is initially poured on to the floor of attic and then leveled with the help of a board or a rake.
Those walls which are provided in the open areas have access to the framing stud wall can be easily insulated. The insulation must be provided neatly by properly stapled. When more than one layer of insulation blanket is used, proper cutting and placing must be carried out so that all the elements tightly fit together.
The provision of vapor barrier must be placed such a way that it faces towards the wall that gets heated during the winter season. While placing installation behind the pipes, ducts and the electrical boxes, they must be cut into proper pieces smaller in size and carefully placed.
The masonry walls can also be insulated by placing the vertical wood strips initially along the wall and then proceeding the normal procedure. There is special type of insulation blankets specially for masonry walls.
Blankets or batts can be placed on the floor joists for those floors that are above the cold spaces. Here the vapor barrier must be located on the top. Having wire lacing back and forth will helps in having good supports. Careful fitting of the insulation must be done.
All the installation cannot be carried out by ourselves or without the help of the contractor. In unexposed areas of walls or attic spaces, blown insulation can be placed by the contractor. Proper value of R must be maintained throughout for blown insulation.
Insulation for Duct and Pipe Area in Buildings
Another area that is more prone to heat loss is around the heating ducts and the pipes present in the building. The installation of the insulation must be done around the heating ducts and the pipes so that the excessive heat loss can be avoided.
The figure-6 below shows some of the insulation material types that are used for the insulation of ducts and the pipes.
Fig.6. (a) Insulation Wrap for Ductwork (b) Flexible Ductwork Insulation (c) Different pipe insulation sizes (d)Installed pipe installation example
Insulation for Roofs
Energy conservation in buildings can be obtained by insulating the roofs. The sheets of fiberglass roof insulation suit this application. This can be applied for flat and low – slope roofs. This idea acts as the base for built up roofing.