Throughout the literature reviewed on log wall thermal performance several key findings come forward.
walls, despite lower-appearing steady-state #R-values
, have been shown to provide
equal or superior annual #heating and #cooling #performance when compared to #lightweight #wood frame walls of higher steadystate R-values. Example: a log wall with a #calculated steady-state R-9 value performs similarly for both
heating and A/C loads to an R-13 to R-15 #insulated
lightweight wood frame wall in a temperate climate.
- The homogeneous assembly of the log wall has fewer #thermal #short-circuits than lightweight wood- or steel
frame walls. This property leads to closer agreement between steady-state #calculated thermal transmittance
levels and their actual thermal performance. Both calibrated testing and sophisticated computer modeling
have confirmed this observation.
- Studies indicate that log #construction #ThermalMass "integral" to its assembly is nearly as effective as
exterior insulation on #concrete and #masonry walls, per unit of insulation and heat capacity. In a log wall, its
"insulation" is mixed with the heat capacity and provides dual functionality of both structure and thermal
- #Concrete, block and #brick walls have higher heat capacity but also have
higher heat flow conductivity compared to solid wood wall sections.
Hence masonry walls may require adding conventional insulation to meet #code
in most U.S. #climates
versus comparable log walls where the insulating material is the structural material.
- The greatest thermal mass effect has been observed for exterior insulated mass walls. Interior insulation
applied to a mass wall severely decreases its heat capacity benefits. To get the most advantage from
thermally massive construction, insulation materials should either be placed on the exterior of walls, or
mixed within the structural section such as with log construction.