‘Healthy Buildings’: Toward understanding user interaction with the indoor environment

Abstract

In recent years, research and the building industry have increasingly focused on issues regarding the lowering and optimising of operational energy use in buildings. This has resulted in several pilot projects illustrating how these can be achieved, e.g. Danish projects like ‘The Comfort Houses’ (some of the first Danish passive houses) and ‘Home for Life’ (active/zero energy houses). Besides exemplifying construction techniques and technical service systems as well as documenting energy use, the mentioned projects were evaluated according to the resulting indoor environment, qualitatively and quantitatively. The findings of ‘The Comfort Houses’ project show challenges in fulfilling elements of the indoor environment, primarily due to problems with overheating during summer. The study also concludes that the design process needs to contain analysis of the indoor environment, besides the development of the design, to make sure the demands can be fulfilled. The research further concludes that there should be more focus on occupants’ lifestyle and behavioural traits when designing and planning passive and active systems, as the assumptions in many cases did not fit. In one case, for example, a family was concerned about their child’s safety if opening windows sufficiently to allow cooling and therefore chose not to do so, with overheating as a result. Hence, user-friendly solutions should be important considerations to allow the ‘correct’ operation of systems while also considering realistic user behaviour. Similar findings appear in the research of ‘Home for life’. Overall, the project concludes that 50% of the altered preconditions are due to factors in the building, control and technology, and 50% are due to the family’s behaviour that was at variance with the original estimations. With regard to the passive house requirements, the main focus is on energy use. However, the passive house standard includes an overall demand for thermal comfort. Nevertheless, this is analysed by using values of the monthly temperatures in the calculation method on the overall geometry of the building. An hour-by-hour dynamic simulation, or at least a simple check of the 24-hour maximum temperature for the critical rooms, would be a more reliable methodology to state the risks of overheating in the actual design. This methodology would also allow testing of different scenarios of user-behaviour and thereby test the robustness of the design. Unmistakably, the abovementioned research states that the user-behaviour and every day practices of the occupants are of major importance in the performance of the indoor environment – issues that are not sufficiently taken into account in today’s practices. Along with the development of different low-energy and zero-energy concepts, voluntary sustainability certification schemes (BREEAM, LEED, DGNB) have been developed around the world – certification schemes that have a wider approach to sustainability than solely energy. However, the first-generation schemes still have a large focus on energy. Recently, the Danish sustainability certification scheme, DGNBDK, was developed taking its point of departure from the German DGNB certification scheme. The scheme is voluntary; however, increasing numbers of clients have requirements for sustainability and today very few buildings are built as certified passive houses in Denmark. Some of the first passive houses were built in 2008, and the last ones registered in the Passive House database were in 2013. Today, the passive house’s standard seems to have been be outperformed by DGNB. DGNB seems to appeal to many stakeholders in the Danish building industry. The certification scheme has a wider approach to sustainability and focuses on the whole life-cycle of the building while taking into account accessibility, flexibility, life cycle assessment and life cycle cost besides general issues like lowenergy use and indoor environmental goals. If the popularity of DGNB keeps growing, the criteria within the assessment will have a significant influence