Cost-optimal renovation solutions to maximize environmental performance, indoor thermal conditions and productivity of office buildings in cold climate

The paper presents cost-optimal renovation solutions and economic viability of different renovation measures to maximize environmental performance, thermal comfort conditions and productivity of workers in office buildings built in the late 1970s and 1980s in cold climate regions. The study also analyzes optimal combinations of renovation measures and HVAC system set points to maximize thermal comfort conditions and productivity of the building users. The productivity loss caused by unfavorable indoor thermal comfort conditions was integrated in the LCC analysis (15-year life-cycle period) of the study using an appropriate method to estimate the amount of lost performance of workers caused by the productivity loss. Simulation-based multi-objective optimization analysis was used as the research method of the study. Environmental impact of the renovation measures was studied by assessing the CO2 emissions of the delivered energy consumption. The results demonstrate that as high as 65% return on investment and 63% reduction in the CO2 emissions of operation can be achieved in owner occupied office buildings, when both the energy efficiency and the thermal comfort conditions are cost-optimally improved simultaneously. According to the results, the cost optimum energy production system concept is a ground source heat pump system used for combined heating and cooling.