Durability of future energy-efficient building components

Abstract

Over the last decade, there has been a goal-oriented focus in the European Union on energy efficiency in the building sector to free it from the use of fossil fuels. Increases in the energy efficiency of building components means increased initial costs, for both new buildings and renovations. If these increased initial costs are to be economically feasible, there must be compensation in the form of reduced maintenance costs and increased lifetime for the new building components. A method for the development of building components with considerably improved durability has been developed based on known tools. The method includes both energy analysis compared to current and future energy requirements, and analysis of possible failures in the building design (Failure Mode and Effects analysis). The method also includes an economic perspective (Net present value) given that the choice of a specific building design should be made based on a holistic evaluation. With comprehensive work focusing on possible failures and work to make the building components prepared for repair, the risk of unexpected failure can be minimized. When the building component needs maintenance, it is important that the maintenance is already thought into the solution, so that the work can be done fast and easily with a minimum of expense. Minimizing costs is an important aspect in the complete solution so that we not only develop energy-efficient solutions, but also solutions that are economical. Two case studies were carried out based on the proposed method: an example of a long-lasting window and flat roofs with drying-out potential. The proposed window solution was a triple glazed non-sealed unit which included an air filter and drying remedy to avoid moisture and dust accumulation in the cavities. Analysis showed that it was possible to develop a long-lasting window solution that meets future energy requirements based on the calculated energy contribution. Further analysis was made to investigate the optimum glass-combination for distribution of outer condensation and transparency. It was concluded that future-proof glazing units made as described can achieve the same service lifetime as the window frame. The case study on flat roofs was based on the fact that leakages in the top membrane result over time in moist insulation, which means that not only the membrane, but also the insulation need to be replaced. Replacement of insulation and membrane is a large-scale job and therefore also expensive. By including air channels in the layer of insulation combined with a leakage detection system, it becomes possible to identify when leakages happen and then initiate drying out of the insulation as soon as the failure has been fixed. Analysis showed that correct execution of the proposed construction with regard to air tightness is vital if future energy requirements are to be met. It was concluded that the service lifetime of flat roofs can be increased by at least a factor of 4 compared with today’s level.