INSULATION & AIR SEALING

Creating a good thermal barrier in a building that holds ideal temperatures and humidity levels efficiently is more complicated than it appears at first glance. A building envelope is a complicated system with different interacting components. Heat and moisture move through a wall by different mechanisms, and building envelopes are exposed to widely varying conditions outside.

Creating an effective building envelope is about more than just insulation. Some types of insulation that work well in a laboratory do not perform as well in real-world conditions. Wholesale air movement through a building can account for as much as 40% of a building’s thermal loss, and air movement also brings water vapor with it, which can cause damage to the interior of building envelope components.

Meadowlark Energy is staffed by experts in insulation materials. We know what works in buildings and what does not. You have a big investment in your home or office – don’t leave the most important component, the structure itself, to chance.

Energy Loss and R-Value
Quality in Building Envelopes

Energy Loss and R-Value

The R-Value is a measure of thermal resistance of insulation, the higher the R-Value the better. R-Value is just one part of how a building can maintain a proper thermal barrier between the interior and exterior, however. Air infiltration can cause up to 40% of the loss of conditioned air. It is therefore just as important to air-seal as it is to install proper levels of insulation. Some types of insulation are better than others at air-sealing while providing R-Value.

Buildings transfer energy through the envelope in three different ways:

Conduction

Heat that moves through materials such as insulation or metal studs. This is the measure of ‘R-value’, the ability of a material to resist heat flow. Glass and steel have a very low R-value, while insulation has a much higher value. The higher the R-value, the longer it takes for energy to move from one area to another. R-value is an important consideration, but is not the whole story. The R-value of a material is measured in a vacuum, hardly a real-world scenario.

Convection

The Department of Energy states that 40% of heat gain/loss in a building is due to air leakage. Air currents strip energy from a building as they move through it, and water vapor moves with this air. Good air-sealing using foam insulation and caulking is essential to building performance. Ventilation is good, but we want to control where it occurs.

Radiant Energy

This is the energy that you feel emanating from a South-facing brick wall after the sun has gone down. Heat also moves as electromagnetic waves, and can be reflected by a mirror much the same as visible light. It is this infra-red radiation that allows us to take pictures of heat loss with thermal cameras. For a time in the 50’s and 60’s, it was thought that if we could reflect this energy back with mirrored wall, our home’s energy loss would be minimized. This works well in the vacuum of space, but in the real world conduction and convection have a much bigger impact on a homes energy performance. Radiant energy loss is a factor, but far less than the first two types of energy loss.

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Quality in Building Envelopes

Insulation is made to address R-value, but it should also factor in air movement as well. Insulations such as standard fiberglass and tri-polymer foam are not effective in stopping the movement of air through the framing members of buildings.

Moisture permeability is also a key consideration for insulation materials in a building envelope. How does the material react to water intrusion, moisture laden air and changes in temperature? Does the material allow moist air to collect in the wall or ceiling assembly? Does moist air have a tendency to turn to water and create mold or other problems?

Energy-efficient buildings are achieved through a combination of excellent air sealing and good R-value. Cellulose and acrylic-based fiberglass can be effective in tandem with an excellent air-sealing package. Polyurethane spray foam can address both issues with one product, however. There are different types of polyurethane spray foam for different applications.

Although we perform excellent air-sealing and cellulose work, our open-cell spray foam can also have truly superior performance. In fact, foam insulation has some significant advantages in many buildings where traditional air-seal and cellulose techniques will fall short. Because it is adhesive, it sticks to and encapsulates framing members. We can spray onto open rafters and other areas whereas other types of insulation would succumb to gravity over time.

We can also realize large energy gains by bringing attic areas into the conditioned envelope with open-cell spray foam for a home with ductwork in the attic space. Open-cell spray foam also is flexible and forgiving with water intrusion. Due to it’s cellular structure, it allows liquid water to permeate it without absorption, while inhibiting the movement of water vapor.

“Decoupling” the building framing members can also yield good results. Framing members can act as thermal bridges, syphoning energy from a building. With infra-red imaging, we can detect each and every framing member that connects the inside to the outside due to on-going energy loss. A builder can greatly reduce heat transfer by installing an air space and/or an insulation product over framing members. Conductive heat flow is interrupted with these techniques.

Insulation materials can also be sound attenuators, particularly in tandem with decoupling the framing. Noise between rooms and from outside can be mitigated with insulation. Sanitary lines between floors are another area where sound attenuation can improve the quality of life. Open-cell spray foam insulation is one of the most effective materials to deaden sound transmission.

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