Building Science, as it relates to thermal energy transfer, represents the foundation of our business model. Saying our products outperform conventional insulation materials holds no weight without the science to back it up. Understanding and applying the concepts of thermal energy transfer is how Ecologic is able to deliver on cutting your energy bills and reducing your pollution output.
A Brief History of Building Insulation
Since World War II when the Federal Government mandated building code regulations to include insulation standards (R-value limits) a booming industry emerged in the US; building insulation. The goal of the Federal Government in enacting this building code was to reduce oil and natural resource consumption for war efforts. For the time period, fiberglass, asbestos and rock wool were the primary insulation mediums being used. During the 1970's, in response to the national oil crisis, a new form of insulation emerged that would completely change the way building science principles were applied. Spray Polyurethane Foam (SPF) was developed and the concept of the "thermal envelope" and air exchanges became the core principles to effectively stopping thermal energy loss. SPF was created in response to the demand for energy efficient buildings and the inability for standard insulation materials of the time to insulate effectively. Since SPF's introduction in the 1970's there have been vast improvements made to product composition and performance. Recent developments in SPF include products that are developed from organic based materials and that utilize water as the primary blowing agent.
The Thermal Envelope
The thermal envelope most specifically refers to the protective layer of a home or building's exterior shell that stops thermal energy loss (or stops thermal energy from coming in). A high performing thermal envelope accounts for radiant, convective and conductive thermal energy movement. A thermal envelope that can perform as an air barrier along with stopping thermal energy movement is considered optimal. Depending on the climate up to 40% of a buildings heat loss or gain is due to air infiltration (US Dept of Energy). This is a contrasting stance to what many industry professionals believe about construction and efficiency. For many contractors, the belief is that a home/building must breathe. This was a standard building practice and thought process prior to advancements in modern HVAC systems. It is now understood that a house or building that conventionally breathes is losing thermal energy, will have excessive run cycles on heating and cooling systems and allows unfiltered air to infiltrate. This fact is proven in blower door and thermal imagery infrared camera tests.
Once a buildings thermal envelope has been successfully established, an HVAC system is then installed to monitor and adjust air circulation, humidity and temperature levels. Due to spray foam insulation's heightened performance, tonnage size of heating and cooling units can be reduced by 1/3. Not only do these systems consume less gas, oil, wood, coal or electricity when running, they also run less often. A home or building that is "breathing" is allowing unwanted air infiltration, and unwanted air infiltration means you are losing heated or conditioned air your HVAC system is working to produce. When the thermal envelope is sealed and the HVAC system is circulating air and regulating humidity levels at a heightened efficiency level, you are breathing air that is clean, filtered and microbe free.
An R-gumentative Topic
The use of R-values in building code regulations was a welcome advancement for the American economy as well as the environment during WWII. While the use of the R-value was an effective tool at reducing the energy consumption problem, it is now understood this is not the only barometer for determining an insulation materials worth. By exploring the three methods of thermal energy transfer this fact can be better explained.
The 3 methods of thermal energy transfer:
1.) Conduction
- The east wall of your building heats up in the morning as a result of the suns rays. This absorbed, heated energy is then transferred through the walls from the exterior to the interior.
2.) Convection
- A poorly insulated attic will create a "convective loop" causing hot air to rise in the home from lower floors to upper floors and escape through attic venting. This looping results in cold air being pulled in from the basement, crawl space or anywhere on the first floor where air leaks are found.
3.) Radiation
- Solar radiant energy from the sun travels through space to heat up the east side of your wall.
R-values ASTM test standards (ASTM C518) do not account for all three forms of thermal energy transfer; particularly in relation to air infiltration. Here-in lies the argumentative topic of R-value when applicable to Building Code Insulation standards. Current building code requirements for insulation material only account for R-value. The inability for R-value to account for all forms of energy transfer make it a poor ruler in determining an insulation mediums worth. Air exchange rate is an equally important measure of energy efficiency, and should be stressed in tandem to R-value.
Only spray applied foam insulation can effectively control thermal energy loss through all 3 forms of thermal energy movement – while providing a control to moisture movement.
