The building sector in the European Union accounts for over 40% of the final energy use, where the usage of non-residential buildings may be up to 40% higher than the residential sector. Improving building energy efficiency across all categories of buildings is one key goal of the European energy policies, made prominent by the Climate and Energy package, Energy Performance of Building Directive and Energy Efficiency Directive. In this study, the profitability of an on-site combined heat and power supply system for an office building is investigated. A reference model utilizing solely district heating was constructed and used for validation purposes. Then, a photovoltaic assisted ground source heat pump model was developed and investigated with and without electrical storage to reveal the most cost-effective investment scenario in cold climate regions. The reference model was validated using consumption data provided by the facility owner, after which an investigation of the energy saving potential along with the economic viability of adapting a new heat- and power supply system was conducted. It was concluded that a ground source heat pump in combination with a standalone rooftop photovoltaic system, was successful in satisfying thermal requirements while lowering the building specific energy demand compared to utilizing a district heating system. The photovoltaic assisted ground source heat pump system including a battery bank is the most profitable when incentives are granted, a higher self-consumption of 93.1% is achieved with a battery capacity of 38.4 kWh.