Towards Development of a Label for Zero Emission Buildings: A Method to Evaluate Potential Zero Emission Buildings

There are many concepts and labels developed with the aim to promote sustainable building. However, most of these concepts address mainly energy aspects and do not consider the entire environmental impact of a building construction. In contrast, the concept of Zero Emission Buildings (ZEB) integrates energy and material (biomass, water) flows, resulting in buildings, which do not produce harmful emissions and on the contrary produce energy, water and resources. It envisions maximum decentralisation of a building implying closed resource cycles and hence no environmental impact during its operational use. However, the concept of ZEB lacks a general framework under which potential buildings can be easily assessed. Consequently, the ZEB Assessment Method was developed in order to easily evaluate potential ZEBs regarding their environmental performance. The ZEB Assessment Method is based on a two-step process: firstly, the Sector Assessment and secondly the ZEB Assessment Tool. The Sector Assessment was developed to ensure a minimum integrity of the concept. It evaluates potential buildings regarding in how far they address the three sectors Water, Energy and Biomass based on the list of "eligible technologies" and the requirements to fulfil the sectors. If a building passed the Sector Assessment it was further investigated with the ZEB Assessment Tool in order to quantify and benchmark the environmental performance. The ZEB Assessment Tool was developed by considering specific decision parameters and appointing an appropriate characteristic to them. These decision parameters were (i) System boundary, (ii) Quantification of environmental impact, (iii) Database for UBP, (iv) Quantification of qualitative aspects, and (v) Calculation of target value. The evaluation of several case studies from Switzerland with the ZEB Assessment Method showed that the method with its tool is well adapted to the requirements of the ZEB Concept. Firstly, it requires a small amount of input data, which enables a simple primary assessment of a specific building. Secondly, it has the advantage that it evaluates a wide range of factors regarding the building's environmental performance. These are energy, water, biomass and a set of qualitative aspects. Furthermore, it takes into account various environmental impacts and can be applied for buildings with different type of use and in different countries of location.