Sustainable Urban Energy Transition for the City of Bitola, North Macedonia : A City-Scale Urban Building Energy Model

Abstract: Cities play a crucial role in sustainable energy system transformation. Urban energy systems account for 75% of global primary energy use, and 70% of global greenhouse gas (GHG) emissions (IEA, 2021). There is currently a large, untapped potential for reducing both energy demand and emissions by focusing measures on one of the largest consumers of energy: buildings. In North Macedonia, there is an estimated energy savings potential of 57% in the residential sector, and 29% in the public service sector (Apostolska et al., 2020). In the midst of the country’s ambitious targets of decreasing energy demand and GHG reductions, the city of Bitola is in the process of developing an action plan for a sustainable transition of the city. For this purpose, there is a need to investigate the current challenges in the energy system of the city and to evaluate potential future pathways to address these challenges, with a focus on the built environment. In this thesis, a city-scale urban building energy model (UBEM) of the city of Bitola was developed using the software City Energy Analyst (CEA). This involved modeling a total of 14 024 buildings in the city ranging from residential buildings to commercial and industrial facilities. Out of these 14 024 buildings, 10 792 were included in the analysis after excluding abandoned buildings which account for an estimated 25% of the total residential building stock. One Baseline scenario based on the current energy use in the built environment in the city, and four scenarios investigating building retrofit measures and alternative heating solutions were developed for the time period 2023-2040 which were then assessed based on three key performance indicators (KPIs). A 2% implementation rate was used for the measures included in the scenarios, resulting in a total of 34% of the buildings being included in the scenario assessment. The scenarios included in the analysis are Business-as-Usual (BAU), decentralized natural gas boilers (NGB), district heating (DH) and decentralized heat pumps (HP). The KPIs include the total primary energy demand, the total operational CO2 emissions, and the economic performance of the system, measured as a net present value (NPV). All scenarios were also evaluated with and without solar photovoltaic (PV). The results showed the BAU scenario to be the lowest performing scenario for all three KPIs, while the HP scenario showed to be the best-performing scenario regarding the reduction of energy demand and CO2 emissions, with a 99% reduction of CO2 emissions and a 65% lower energy demand than in the baseline year. However, this comes at a relatively high cost compared to the other scenarios. The DH and NGB scenarios performed moderately regarding demand and CO2 emission savings while performing better from an economic standpoint. All scenarios showed a low share of buildings on an individual level having a positive NPV, thus failing to reach a positive total NPV for the entire system. On the other hand, the sensitivity analysis demonstrated how a reduction of the capital expenditure (CAPEX) led to a positive NPV for all scenarios with PV, and for all scenarios except BAU without PV. This indicates that subsidies provided by local or national stakeholders could result in a profitable investment. Two important conclusions can be drawn from the results: firstly, taking any action and implementing either of the HP, NGB and DH scenarios will be more beneficial than taking no action, and secondly, the sustainable development of the city needs to be led by the local municipality, as well as national stakeholders to enable a long-lasting transition.