Cost-optimal energy performance renovation measures of educational buildings in cold climate

The paper discusses cost-efficient energy performance renovation measures for typical educational buildings built in the 1960s and 1970s in cold climate regions. The study analyzes the impact of different energy renovation measures on the energy efficiency and economic viability in a Finnish case study educational building located in Lappeenranta University of Technology (LUT) campus area. The main objective of the study was to determine the cost-optimal energy performance renovation measures to meet the proposed national nearly zero-energy building (nZEB) requirements, which are defined according to the primary energy consumption of buildings. The main research method of the study was simulation-based optimization (SBO) analysis, which was used to determine the cost-optimal renovation solutions. The results of the study indicate that the minimum national energy performance requirement of new educational buildings (E_primary ⩽ 170 kWh/(m²,a)) can be cost-effectively achieved in deep renovations of educational buildings. In addition, the proposed national nZEB-targets are also well achievable, while improving the indoor climate (thermal comfort and indoor air quality) conditions significantly at the same time. Cost-effective solutions included renovation of the original ventilation system, a ground source heat pump system with relatively small dimensioning power output, new energy efficient windows and a relatively large area of PV-panels for solar-based electricity production. The results and conclusions of this study can be generalized to similar climates and techno-economic environments.