Hello Brian, et al,
I am not belaboring the procedural methods of scientific testing, or outcomes of what can and are done in laboratories every day...and will continue to be. These, "are what they are"...and...we learn new and wonderful things all the time with them...including how wrong we are about things we "thought we knew," as well as, how narrow our view often has been on many things we had been "so sure about"...
Brian Knight wrote:Most folks measure the performance of building envelopes by air leakage, insulation and fenestration.
Many areas, even within their CODE systems, are looking at "draft-proof," and not "air-tight" as a better method of construction. Further, I would point out that the U.K. (to name just one) uses U factor not R factor in examining thermal efficiency, as they have a very dominated "mass wall" design in their vintage, and current housing stock. This is why cobb, stone, and brick are still in use there as well as, "infill" timber framing methods, both in restoration and new construction.
Paint with "narrow brush strokes," when describing modalities of measuring building efficiency can lead to narrowness of scope and understanding...There are many different and valid ways of assessing applicability of method. Many manufactures/facilitators in the "mainstream" building industry demonstrate "hubris" whenever a narrow parameter to anything is applied...especially when discussing something like "building comfort" or even the more tangible like, "what is efficient."
Brian Knight wrote:What about thermal mass walls like cob, stone, rammed earth, and logs? As my quick statistic was meant to show, they can be a huge problem when we are trying to heat or cool a home or building. The only climates where thermal mass walls have been proven as effective as walls with insulation is where there is consistent, year-round temperature swings between day and night. While this can happen in all climates during certain times of the year, its very rare for a climate to experience this most of the year especially for the diurnal swings to bracket the 70 degree human comfort zone.
It has also been shared many times that MW designs are too complex to examine with the same parameters as a high R value systems. When someone has built many of these MW designed structures, and studies them in depth over many years and speaks of their "challenges" I tend to really take note...yet not as much, when "faults" are reflected by others with little or no tangible knowledge of these building modalities, there historical application, and/or never having lived in one...let alone several; including more than one climate range. I agree, they may not always be the most applicable for a region...yet often the are, or can be made to be within environmental and economic logistical reason.
Again, the U.K. and other areas focus on U factor...not R factor in designing thermal resistance wall/roof systems. It really pays to be as thoroughly informed in both metric and understand their application when address the challenges with any thermal resistance system.
Many of us...more everyday...feel that "airtight" is not the goal in the way walls/roof assemblies should be designed...permeable (breathable for those that understand better this term) and draft-proof presents as a much better function to be aimed for. We are not designing "submarines or spacecraft," but homes and as such, they are extensions of the clothes we wear in a given biome. Breathable is always more comfortable a garment than none or slightly breathable attire. Wrapping houses in plastic and foam...then relying on more "technology" to make sure there is enough
oxygen inside them to breath and not become polluted seems to be a move backwards to many...yet many "professionals" in the building field thinks this is a wise direction to move in...especially the materials industry behind the manufacture products that support them.