Techno-Economic Analysis of the Heating System Robustness

Abstract

A techno-economic analysis of different heating systems of a multi-apartment building is performed. The final energy savings and the economic benefit under different boundary conditions are investigated for a Passive House that has been realized and monitored in Innsbruck, Austria. Eight different system combinations are considered, varying the heat generation (direct electric (as-built), air/water heat pump (HP) and groundwater HP) as well as the size of the photovoltaic (PV) system. The systems are investigated with a building model with two different parameterizations: the pre-design stage and the model adapted to the monitored boundary conditions (BC: climate and user behaviour) and monitored energy consumption. The monitoring of the first two years of operation revealed a significantly higher space heating demand (29 kWh/(m²a) compared to 8 kWh/(m²a)). The most robust system (i.e. the system that performs best independent of the BC) for primary energy optimization is identified as an air-source heat pump with a 32 kWp photovoltaic system. This system also allows economic savings in case of high heating demand (adapted building model) and slightly higher costs in case of low heating demand (pre-design model). The groundwater-source HP is cost-effective only in scenarios with high heating demand due to significant investment and installation costs. Monthly primary energy factors are used to account for seasonal effects of the energy demand, providing an assessment of system efficiency that accounts for the so-called winter gap.