Marginal Price Control of Buildings Utilised as Thermal Energy Storage - Optimising the heating cost of a modelled residential building

Abstract

District heating networks often experience significant variations in heat load on an hourly timescale, with one or two noticeable peaks per day. These peaks are associated with increased marginal heat generation cost and environmental impact, and it would therefore be beneficial to reduce the daily variations. It has been previously shown that heavy residential buildings, thanks to their high thermal inertia, can be used as short-term thermal energy storages for the purpose of load shifting. In this thesis project the economic viability of implementing load-shifting control systems was investigated. A dynamical building model was created based on data collected by Göteborg Energi. Control systems were designed that minimised the overall building heating cost under the assumption that district heating prices were proportional to the marginal generation cost. It was found that, when only focusing on temperature stabilisation, a 10% reduction in heat use leads to less than 7% reduced heating costs due to naturally high indoor temperatures coinciding with low marginal costs. When applying a combination of temperature stabilisation and load shifting however, savings above 13% were achieved without negatively impacting thermal comfort.