Commissioning of thermal performance of prefabricated timber frame insulation elements for nZEB renovation

The current study contains a commissioning of thermal performance of highly insulated building envelope, located in cold and humid Estonian climate. The focus is on the renovation of old apartment building to nearly-zero energy building with prefabricated timber frame insulation elements with designed thermal transmittances U=0.10-0.12 W/(m2∙K). Air tightness, heat flux and temperatures were measured after renovation. Results of commissioning are showing some deviations from designed values, possibly caused by internal convection, improper tightening of joints of elements and poor quality of sealing of layers which must be kept airtight. The results have shown that analysis of designed solutions before, during and after renovation is worthwhile. Thorough inspection and strict rules of quality control on work site are essential for high-quality, sustainable outcomes of renovation with timber frame insulation elements and to guarantee designed thermal performance