A method for evaluating building retrofit effects on a decentral energy system by a sector coupling operation and expansion model

The building sector has high untapped energy saving potential. The main tool to exploit this potential is conducting a building retrofit. Building retrofit does not only reduce the heat demand, but can cause peak shifting as well as major alternation in the technology requirements within a system. This paper presents the model DISTRICT-HP, which is developed as a novel methodology to quantify the system effects of building retrofit on a decentralized energy system. The paper includes a detailed description of the developed optimization model as well as an exemplary case study based on a German decentral energy system. Results show that the economic feasibility of building retrofit varies depending on the perspective of the investor. From a building owner's point of view, retrofitting is a less economically attractive measure than from a system point of view. Depending on the system conditions, the resulting system including retrofitting can have lower cost than a system without retrofitting. Savings from the demand reduction as well as from a flexible operation can lead to an increase in the economic attractiveness of building retrofit. This effect is emphasized from a system perspective since the room for using the flexibility potential increases. The decrease in temperature levels resulting from retrofitting a building, add to that flexibility, as shown in the case study, a heat pump can produce low temperature heat with higher efficiency, which can be stored in low temperature and then heated up when required.