US: The Building Science Corporation (BSC) has released a report detailing the results of a multi-year insulation research project. The most significant finding from the report is that sealed walls of the same R-value perform equally well regardless of the type of insulation used.
The study entailed a baseline set of seven test walls using various insulation types including fibreglass, cellulose, spray foam and extruded polystyrene.
Other selected highlights from the report include:
- When walls are constructed with the same installed R-value in the stud space and are air sealed both inside and outside, they exhibit essentially the same thermal performance regardless of the type of insulation material used.
- All of the reference test wall assemblies were subjected to significant temperature differences. Natural convective looping was not noted in any of the wall assemblies.
- Conventional energy models may over-predict the negative energy impact on walls that have a significant interaction effect (e.g. air moving through insulation).
- All wall assemblies experienced a loss in thermal performance due to air movement through the assembly. This is true for all of the assemblies tested, regardless of the type of insulation material used (e.g. cellulose, fiber glass, open cell spray foam, closed cell spray foam or extruded polystyrene.)
- Commercially available 2D and 3D heat transfer models provided good predictions of thermal bridging in the assemblies tested, as did the parallel path method described in the ASHRAE Handbook of Fundamentals and other texts.
