Space heating retrofits with rooftop photovoltaics in Norwegian buildings: tailoring financial support levels to drive localised investments in green technologies

Abstract

Globally, the energy supply systems (ESSs) of buildings are increasingly integrating clean energy technologies to reduce energy costs while supporting the transition to a net-zero-emission future. In this regard, the role of energy use in buildings in the European Union (EU) has already been established. Norway also has ambitious climate goals, with improvements to energy use in buildings representing a significant part of the effort. There is consensus among Norwegian energy experts, consumers, and prosumers regarding the need for greater consumer involvement in ESSs and financial incentives to support it. However, the necessary support levels and supported actions have not been explored deeply in regard to sustainability of energy supply and flexibility, both of which are recognised as important factors for future energy systems. Therefore, we analysed the impacts of financial support relative to the living area on the sustainability and flexibility achieved by retrofitting ESSs in buildings and by considering different support priorities. The genetic algorithm (GA) was utilised to derive an optimal equipment set for each sub-scenario and perform scheduling with a hybrid (optimisation and rule-based) control for three buildings in Norway. To better evaluate the flexibility of energy use, we devised a new parameter called the energy cost flexibility improvement factor (ECFIF) . The results indicate that support focused primarily toward improvements in sustainability provide the most benefits overall, with indications that a support strategy that does not enforce equipment selection could be even more successful. For the studied Norwegian buildings, a support of 10–40 EUR/m 2 represents the highest increase in profitability while a support of 20–35 EUR/m 2 achieves the highest impact on ESS performance. However, separate determination of the support level may be necessary for high-cost and high-impact projects, such as rebuilding commonly used electric-based space heating to hot-water-circulation-based systems, to achieve the envisioned climate goals.