Insulation

Cellulose Insulation

According to the Cellulose Insulation Manufacturer’s Association (CIMA), over 38% of the municipal solid waste in U.S. landfills is comprised of paper products. Insulation made from cellulose (the chief constituent of all plant tissues and fibers) is comprised of at least 80% recycled paper, predominantly newspaper, which helps decrease this material’s environmental footprint from the beginning.

By its very nature, insulation is environmentally-friendly, since it reduces the amount of energy required to heat or cool a building. And while there are many types of insulation, and differing criteria for selection and optimization of a building envelope design, cellulose insulation has some distinct advantages.

In yet another piece of good news, CIMA also states that the energy required to transport, manufacture, and deliver cellulose insulation products has been documented to be far less than either its fiberglass or foam insulation competitors, further reducing greenhouse gas emissions and carbon footprint.

The high R-value and density of cellulose insulation provides an excellent thermal barrier, particularly in climates with either hot summers or cold winters. Cellulose insulation has been shown to perform better than fiberglass when the difference between indoor and outdoor temperatures increases to over 80°F differential (constant cellulose performance of R-19 compared to a reduction to R-10 of fiberglass insulation). Note that R-value is the measure of a material’s ability to resist the transmission of heat. The higher the R-value, the lower the heat loss in the winter and lower the heat gains in the summer. It also provides excellent sound insulation, due to its installation procedure.

Unlike some other insulation materials, cellulose insulation provides a barrier against air infiltration by filling gaps and voids in walls, attics and floors. This is due to the fact that its installation is ‘blown-in’ (dry) or ‘moisture-added’. There are limited applications where homeowners can install cellulose themselves, and then only in dry installations.

Cellulose insulation installation is typically a two-person operation that requires one person to feed the insulation material into a blowing machine while the other directs the hose to where the cellulose is required. The air to fiber ratio can also be adjusted to ensure complete coverage. It probably goes without saying that personal-protective equipment should worn during the installation process (mask and goggles at a minimum).

Moisture-added installations are typically utilized for new construction, and involves essentially the same procedure as above. The difference is that as the insulation is sprayed through the hose, a small amount of water is added. This helps adhesion with the sprayed surface and helps ensure the application leaves no gaps or spaces. The cavity is filled until the material actually extends beyond the face of the studs or rafters, and then the extra is leveled off.

One of the potential drawbacks of cellulose insulation is obviously concerns with regard to fire-resistance. This potential issue is addressed through application of fire-resistant chemicals, which could maybe create a concern for indoor VOC concentration in some projects.

But in addition to adding necessary energy efficiency to the building envelope, for projects pursuing LEED certification, cellulose insulation may also help contribute towards earning credits for recycled content, regional materials, and thermal comfort.

Spray Foam Insulation

Low-density, spray foam insulation may be less common than other insulation types, such as fiberglass insulation or cellulose, but its flexibility makes it ideal for many applications.

Spray foam really only came onto the building scene as recently as the 70’s and 80’s (in its modern form). While the plastic that makes up the insulation material, polyurethane, has been around since the 1940’s, advancement in spray nozzle technology allowed spray foam insulation to be used widely for the first time during the energy-crisis of the 1970’s.

Yet even within this relatively new building material sub-category, options for spray foam insulation abound such as polyisocyanurate, polyurethane and extruded polystyrene. Additionally, foam insulation can be applied in rigid board or liquid forms. For our purposes in this article, we’ll focus on spray foam application.

Heating and cooling accounts for 50-70% of the energy used in the average American home, according to Oak Ridge National Laboratory. Insulation by nature is environmentally-friendly, since it reduces the amount of energy required to heat or cool a building. And while there are many types of insulation, and differing criteria for selection and optimization of a building envelope design, spray foam insulation is a viable solution for many applications.

Currently both polyurethane, and polyisocyanurate (a variation of polyurethane) are both used for spray foam insulation (though they can also be formed into rigid insulation as well). An expansion chemical, is added by the aforementioned nozzle just seconds before being sprayed, making the mixture liquid when applied, but which then quickly expands into a foam and later dries into a hardened plastic.

Spray foam insulation can be produced in two forms:

1) open-cell (which allows water vapor to move through the material) and
2) closed-cell (which does not).

Closed-cell foams are able to provide a greater R-value than open-cell foam. (It probably goes without saying at this point that spray foam installations are best left to the professionals.)

The biggest advantage of spray foam insulation is its ability to fill in spaces around obstructions or oddly-shaped areas leaving no gaps or voids, due to its expanding characteristics. Along those same lines, it can be used to easily insulate cathedral-type attics and the underside of floors.

Typical R-value for spray applied foam insulation products is 5 per inch of material (one of the higher R-values per inch compared to other common insulating materials). Note: R-value is the measure of a material’s ability to resist the transmission of heat. The higher the R-value, the fewer heat losses in the winter and heat gains in the summer. In addition to its excellent thermal parameters, spray foam insulation also acts as an air barrier, helping reduce moisture infiltration which causes mold and mildew issues. The sprayed nature of its application also makes for excellent acoustical properties as well.

Finally, spray foam is a good choice for retrofitting attic insulation projects. You can view the ENERGY STAR recommended levels of insulation for retrofitting existing wood-framed buildings (such as houses) at http://www.energystar.gov/index.cfm?c=home_sealing.hm_improvement_insula....

Ultimately the ‘best’ type of installation would depend on application, required R-value, accessibility of the insulation location, space available, and budget.

Fiberglass Insulation

Heating and cooling accounts for 50-70% of the energy used in the average American home, according to Oak Ridge National Laboratory.

By its very nature, insulation is environmentally-friendly, since it reduces the amount of energy required to heat or cool a building. And while there are many types of insulation with differing criteria for selection and optimization of a building envelope design, tried-and true fiberglass insulation has some distinct advantages and is by far the most prevalent insulation type in modern construction assemblies. And, since fiberglass has been around since 1938, today there are many, many variations for specific applications.

As its name dictates, fiberglass insulation is made from spun glass fibers. Glass is melted and spun/extruded in a centrifuge with small holes, producing wispy hairs of flexible glass. Therefore, due to its very nature fiberglass insulation is mold and fire-resistant since it won’t burn, it will only melt (even then only at temperatures in excess of at least 2,000°F). Of course, when assembled into batts, the facing paper is combustible and will burn.

Batts are simply pre-cut panels of insulation, and can be provided with or without facing. Batt insulation is available for either 8 or 9 ft high walls and in widths of 12, 16 or 24 inches on center. Alternatively, rolls can be cut to fit any size wall cavity and installed in areas where long, unobstructed runs may be required.

Typical R-value of fiberglass batts is 3-4 per inch of material, where R-values for blown-in fiberglass installations are in the range of 2-3 per inch (this can vary by installation, when several variables can leave a blown-in installation with a non-uniform R-value). So, for example, to achieve an R-value of 19, 6.5 inches of batt (or roll) fiberglass insulation would be required, where a blown-in fiberglass installation would require 9.5 inches to meet the same R-value. Note that R-value is the measure of a material’s ability to resist the transmission of heat. The higher the R-value, the fewer heat losses in the winter and heat gains in the summer. Fiberglass insulation can be blown-in for an approximate cost of $0.40/ft2 while retail cost for fiberglass batts can be in the range of $0.45/ft2. If you decide to do the batt installation yourself, personal protective equipment (a respirator, glover, long sleeves and goggles) is a necessity.

In terms of overall R-value, compared to other insulating materials fiberglass isn’t at the top of the list in terms of performance. But it does come with a competitively lower cost, making it much more of an economical choice.

You can view the ENERGY STAR recommended levels of insulation for retrofitting existing wood-framed buildings (such as houses) here.

Ultimately the ‘best’ type of installation would depend on application, required R-value, accessibility of the insulation location, space available, and budget.