Development of a life cycle net zero carbon compact house concept

Abstract

The paper presents the development process of an innovative, prefabricated compact house, which aims at creating a net zero greenhouse gas emission building design over the whole life cycle. Building Information Modelling helped to quantify the required building materials. Dynamic building simulations were performed in DesignBuilder to calculate the energy demand of the building for the operational period. To evaluate the financial feasibility and the carbon balance of the building, life cycle assessment and life cycle costing were used. A heat and moisture transfer simulation was carried out to provide a more accurate analysis and to identify possible moisture problems.The assessment showed that the ratio of embodied impacts and operational impacts is typically 1:2 for wooden buildings and 1:1.5 for brick buildings. Life cycle carbon neutrality could be achieved in both cases with additional photovoltaic panels installed on the roof. However, a major difference between timber and brick buildings is the time factor: while the initial emissions from the production of brick buildings are gradually offset with excess solar energy, timber buildings act as carbon storage with negative emissions over the study period and the carbon is only released at the eventual end-of-life stage. The necessary size of photovoltaics is largely influenced by the avoided grid impact: if dynamic decarbonization of the electricity mix is considered, the size of photovoltaics required is about 1.5 times larger to offset the environmental load of the construction due to the diminishing benefits.