Long term energy efficiency study on different wall envelopes in Latvian climate conditions

Five test stands have been built in Riga, Latvia equipped with sensors (temperature, solar radiation, humidity, etc.) to measure energy efficiency and thermal comfort conditions. Roof and floor constructions are made the same. For the walls building envelopes differ and typical materials used in Latvia (aerated concrete, ceramic building blocks, wooden log and plywood frame with rock wool insulation) are compared. Only rock wool is used for insulation to provide moisture transport through the construction. For study to be comparative thermal transmittance of all five test stands have been calculated equal (U=0.15…0.16 W/(m2∙K)). The aim of research is to compare the integral calculation results with measured ones. Another aim is to compare the energy consumption and humidity results of last heating season to previous years and see if the initial conditions still influence the energy consumption. The heating during the period is done using electric heaters instead of heat pumps as in previous years, so that the coefficient of performance is unity. The results show that even during the fourth full heating season initial humidity in aerated concrete construction still haven't completely evaporated and the thermal transmittance is decreasing towards the theoretically calculated data provided by manufacturer. Linear heat loss coefficients are calculated for corners and results show that for such small buildings the corners' impact can be considerable.