Energetic performance and economic feasibility of onsite generation technologies in a nearly zero energy building

By the end of 2020, all new buildings must be nearly zero energy as instructed by the European Commission. In southern Finland, a demonstration project building tries to reach the zero energy level by minimizing energy demand and integrating photovoltaic panels, solar thermal collectors, and a ground source heat pump. An analysis of measured data has been conducted. The net energy consumption per unit area was 15 and 21 kWh/m2 in 2014 and 2015, respectively. With said measured data and a simulation model of the building, several installed capacities of photovoltaic panels and an alternative wind generation system are simulated. An economic analysis is conducted for the proposed systems, based on simple payback period, internal rate of return, and levelized cost of electricity. The results provide three lessons: i)energy self-consumption makes the investments more attractive, ii)the notion of economies of scale (cost benefits through larger output) should be taken with caution in residential generation systems, and iii)neither the commercially available photovoltaics nor the wind turbine residential systems are attractive investments under the current conditions in Finland.