Abstract

Renovation measures aimed at recovering heat from exhaust air were assessed for their energy performance and economic feasibility in three Swedish apartment buildings. Case Building 1_C‑HRV (Växjö) implemented a central heat recovery ventilation (C‑HRV) system, achieving the largest improvement: a 23% reduction in primary energy use (22 kWh/m²/year). Case Building 2_DE‑HRV (Ljungby) installed decentralised HRV units (DE‑HRV), which increased energy consumption by 2 kWh/m²/year and incurred the highest annual service costs (SEK 14 000). Case Building 3_EAHP (Växjö) integrated an exhaust air heat pump (EAHP) in one building, reducing primary energy use by 15% (12 kWh/m²/year) while supplying heat to three buildings on the premises. Despite the energy savings, none of the renovation measures were economically feasible under current conditions; the shortest payback period was 19 years for the EAHP. Future integration of smart controls and photovoltaic panels could improve economic viability, particularly for Case Building 3_EAHP, where operational patterns favour complementary technologies