Utfackningsvägg av lättbetongblock i passivhus
AbstractThis report intends through a case study to investigate if lightweight concrete isappropriate as main material in the outer wall of a seven storey residential building.A technical design is carried out in accordance with the definitions and requirementsfor passive houses, given by FEBY?s1 ?Demand specification for passive houses?.A literature review is also carried out for a comparison between regular bolt wall andlight weight concrete wall, with a focus on the safety of moisture.The lightweight concrete block used in the report is as a celblock produced by thecompany H+H Sweden AB.The methods used have resulted in compliance with requirements andrecommendations from authorities. Calculations of energy, noise and moisture riskassessment has been carried out.The work has resulted in the conclusion that the lightweight concrete itself is notable to isolate in the extent necessary to obtain chosen U-value of 0,1 W/m2 ° C,without getting to thick. Therefore additional insulation is needed. There are fewrelevant reference objects built with only light weight concrete. A villa in Lomma,Sweden, has been designed but is not yet built. The house has no additionalinsulation and the climate screen consists only of light weight concrete and plaster.The multi storey building designed within this report has generally large windows,also to the north, which in passive house context is unusual. The large window areasresult in greater thermal bridges around the windows and greater losses of heatthrough transmission.As compensation a very low U- value of 0,1 W/m2 ° C was set as a prerequisite fromthe start ensuring a positive energy balance. This action has proved necessary whenimplemented energy balance calculation resulted in the heating demand of 42kWh/m2 per year. Maximum allowable energy for a passive house is according toFEBY under 50 kWh/m2 per year.There are several advantages identified when using light weight concrete. Allproblems related to moister are avoided with this completely mineral material. Lightweight concrete offers good thermal insulation by its porosity. It has heat storingproperties during the winters. The material is fireproof and free from chemicals.Together with additional insulation a quiet and healthy indoor environment isderived.It has been difficult to find potential risks of using concrete in the climate screen ofa passive house. Passive house technology is relatively new, and passive housetechnology with concrete is even newer. In fact, the villa in Lomma is said to be thefirst in Sweden carried out in light weight concrete. A minor estimation upon thecosts of a the insulated light weight concrete wall, contra a wood bolt wall has provedthe light weight concrete wall to be twice as expensive. Perhaps the future will proverisks that have not yet been revealed?