As traditional energy sources become more scarce and costly, people are scrambling to develop new sources of energy that are plentiful in the most cost effective way. What often gets lost in the shuffle is the “greenest” form of energy of all – the energy that is never used.
The environmentalist as well as the economist inside you will agree that saving energy is always the best decision. The very first place to look for energy conservation measures, or ECMs, is your building envelope. The building envelope encompasses a facility’s walls, windows, doors, roof and floor – basically anything that separates the inside from the outside.
There are numerous ECMs to be found in the various parts of the building envelope. The topic of this article will be the different types of insulation that can be used to save energy that flows through the building envelope through a process called heat transfer. There are three different types of heat transfer: conductive, convective and radiative. Proper insulation will help minimize energy (heat) loss through the building envelope via conductive heat transfer.
Conductive heat transfer is governed by Fourier’s equation Q = UA(T2-T1), where Q is the rate of energy or heat transfer, A is the area of the material heat is passing through, T2 is the inside temperature, T1 is the outside temperature, and U is the reciprocal of resistance R. This law is important to know, because insulation is rated by its R-value, where the higher the R-value, the less heat will be transferred through the material. The R-value is determined by the actual conductive properties of the material as well as the thickness of the material.
Insulation is typically installed in the walls and roof structures. According to an expert from Skilled Fencing, standard types of insulation are blanket (batt), foam board and loose fill, and are made of materials such as fiberglass, mineral wool, polyurethane, cellulose as well as natural fibers such as sheep’s wool. Some of these materials are more sustainable than others, but they all perform well when it comes to insulating your home.
Cellulose insulation is made of recycled wood fibers, typically news print. Mineral wool can be either rock or slag wool, and often has a large percentage of post-industrial recycled content. Fiberglass is a material made with tiny glass fibers, and polyurethane is a type of material similar to what a foam cup is made of. Sheep’s wool is a very sustainable form of insulation, as well as different forms of cotton insulation such as recycled blue jeans.
Some newer wall building technologies already have insulation built in. Structural Insulating Panels, or SIPs are prefabricated wall structures that consist of a foam board sandwiched between two oriented strand board (OSB) pieces. Insulating Concrete Forms (ICF) are forms poured for concrete walls that remain as part of the wall structure.
Any way you look at it, a BTU or kWh of energy saved is a unit of energy that doesn’t have to be produced using either fossil fuels or renewable sources of energy. Insulation typically has a fairly quick payback, usually within 5-10 years and therefore is often a good ECM to implement.
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