Scenario-based analysis of energy retrofit strategies and their impacts on building energy demand using a validated multi-building energy model: A university campus case study

The building sector accounts for approximately 40% of global energy use and greenhouse gas (GHG) emissions, making it a critical focus for achieving climate and energy goals. With many existing buildings constructed before modern energy standards, improving the energy performance of existing buildings is essential for achieving climate targets and reducing energy use at scale. In Norway, where two-thirds of the building stock was constructed before 1990, energy retrofitting plays a particularly important role. This study presents a scenario-based analysis of energy retrofit strategies applied to the Gløshaugen campus in Trondheim, Norway, using a calibrated and validated multi-building energy model (MBEM). The campus buildings were first classified into distinct cohorts based on construction period and energy performance characteristics, allowing for a more targeted and effective implementation of energy conservation measures (ECMs). A series of ECMs were then developed and applied within each cohort to assess their impact on heat and electricity demand. From the results, most ECMs demonstrated strong energy-saving potential, particularly in mid-aged buildings constructed between 1950 and 1970, where individual measures achieved up to 13% annual savings. The economic evaluation, based on multiple indicators, showed that ventilation-related ECMs delivered the most favorable outcomes across all cohorts. These measures were especially effective in older buildings, achieving savings of up to 500 kWh per NOK of investment. This combined technical and economic assessment supported the prioritization of retrofit measures to maximize both energy savings and cost-effectiveness at the district scale.