Insulating a home or office is one of the easiest and most cost effective things to do to protect the environment. As we all know, insulation reduces the amount of energy needed to hear or cool a space. What is less well known is that there are a variety of different insulating materials with a range of environmental attributes, costs, advantages and disadvantages. Just because insulation helps conserve energy does not mean that the product itself is environmentally friendly.
The National Resources Defense Counsel has concluded the following:
– Cellulose insulation manufactured from paper is the least polluting and most energy efficient.
– Cellulose has the highest post-consumer recycled content. The fiberglass industry averages 35% recycled glass, while the cellulose industry averages a minimum of 75% recycled content.
– It takes more than ten times more energy to produce fiberglass insulation as cellulose insulation.
– Due to air circulation and natural convection, the R-Value of blown in fiberglass insulation decreases by as much as 50% as the temperature drops from 7 degrees Celsius to -8 degrees Celsius.
– In contrast to fiberglass, cellulose has a better resistance to air flow and prevents upward movement of air cause by temperature differences. The R-Value of cellulose actually improves during cold weather. Heat flow problems associated with fiberglass make cellulose an attractive alternative.
– Substantial and well-documented public health threats are associated with fiberglass. Fiberglass insulation is required to carry a cancer warning label in compliance with OSHA’s Hazard Communication Standard.
– No adverse health effects from cellulose have been identified.
R-Value measurements of insulation do not include energy losses due to air leakage, convective loops within the wall membrane, or gaps and voids commonly found in walls insulated with batt materials. Batt type insulations are often unable to conform to actual wall construction because they are designed to fit an exact spacing between structural membranes. They must be cut, torn, compressed, or otherwise deformed to fit an irregular space. Obstructions in the walls such as wiring, plumbing or blocking further impair proper placement. Such imperfections result in enough increased air infiltration to reduce the thermal performance by as much as 30-50% below the laboratory R-Value.
By contrast, WallBAR laboratory R-Value and field performance R-Value are identical. There are two main reasons why WallBAR performs better in an actual building. First, because the material is injected into position, it forms a seamless, void free fit. It conforms to all obstructions and irregularly shaped cavities. Second, air movement through WallBAR is less than that through glass batt because the fibrous mass of WallBAR is considerably more dense. The physical difference between the two types which gives WallBAR superior R-Value and resistance to air movement.
How To Tighten Up and Quiet Down When You Insulate
Air leakage can carry substantial water vapour and lead to condensation moisture problems in wall cavities. Here, the water vapour turns into real, wet, water. Water in the walls leads to soaked, ineffective insulation and possible structural damage.
When properly installed, Weathershield insulation’s short, dense fibers will fill every small cavity and resist settling indefinitely. The raw insulation is specially treated to yield an insulation that is inert, non-toxic and non-irritating. Both spray-on and loose fill types protect against air leakage and moisture damage for many years.
Case Study 1
In 1926, a home in Saskatoon was insulated with Weathershield type insulation (loose fill, walls and ceilings). The home had no vapour barrier. The home was one of several built for staff of the University of Saskatoon, and it was heated by a boiler. In 1975, almost fifty years later, the homes were sold and dismantled for research by the National Research Counsel.
No evidence was found to suggest any damage due to moisture or condensation!
NRC staff felt that the natural backwicking properties of the cellulose insulation and its resistance to air and moisture flow prevented structural damage.
Case Study 2
A Cold Climate Demonstration House in Edmonton is evaluating a variety of mechanical, window and wall systems. A 10 mil poly air/vapour barrier was installed on the interior of the house and sealed at all joints and penetrations. The 7″ wall cavity was loosefilled with Weathershield insulation to the manufacturer’s recommended density.
Prior to drywall and stucco, the house was pressure tested for air leakage and found to be very tight at only 1.1 air changes per hour. In preparation for a second leakage test, the poly was slashed in several places throughout the home. The second test was performed under otherwise identical conditions, but there was absolutely no measured difference in air leakage, even after the poly barrier had been slashed.
Engineer Wil Mayhew stated: “We fully expected more air leakage after cutting the vapour barrier, but there was no increase. Even a smoke pencil didn’t show any signs of air movement through the slits. We are pleased with the effectiveness of Weatherhield insulation for air leakage control.”
What about other forms of insulation?
Light density mineral fiber insulation offers little resistance to air leakage. There is air movement right through the loose fill, and around poorly fitted batts. Gaps at ends and edges, as well as around electrical boxes are particularly prone to air leakage.
In theory, exterior foam board insulations could provide an effective, though expensive, air barrier. However, all joints must be properly taped and sealed, and such a system could eventually lead to water vapour condensation being trapped in the wall cavity. Foam board insulation manufacturers recommend against taping and sealing joints.
Case Study 3
In a 1984 study done by three Princeton University researchers, David Harrje, Gautam Dutt, and David Jacobson, cellulos-type insulation (like Weathershield) was shown to be most effective in reducing air leakage.
They built a simulated attic floor with intentional cracks and a controlled air pressure device. Air was forced through the uninsulated attic section, and the leakage rate measured. The attic floor was then insulated successively with Weathershield-type cellulose, blown glass fiber, and vermiculite and the air flow was measured with each.
Weathershield-type insulation proved the best, with a 90% reduction in air leakage. This compared with 58% for vermiculite and 52% for fiberglass.
These researchers also performed before-and-after tests on three real houses that were insulated with Weathershield-type insulation, and air leakage was reduced by factors ranging up to 47%.
Compare the alternatives and make the right choice. Choose the insulation that not only keeps the heat in, but also cuts air leakage and makes buildings quieter!