Evaluation of energy use for heating in residential building under the influence of air exchange modes

This paper focuses on the investigation of natural ventilation mode influence on final energy use in the typical Ukrainian apartment with intermittent heating mode that correlates to the occupancy mode. For the purposes of the study, calculations of apartment final energy use were performed both using experimentally obtained actual air change rates and values required by the current norms (EN 16798-1:2019, ASHRAE Std 62.2:2019 and DBN V.2.2-15:2019) for different parts or for the apartment as a whole. Based on experimental results and EN 16798-1:2019 requirements hourly air change rate schedules adapted to the operating mode for weekday and weekend were created. Scheduled ventilation consumes no doubt less energy compared to constant air exchange at the level of the upper values of the variable schedule. For example, results of research for weekends showed that using of scheduled ventilation approach results in lower energy use of about 25% compared to constant air change rate. For weekdays, on the contrary, there is an increase of about 50% in energy use when using scheduled ventilation approach due to the higher values of air change rates during the occupied hours and a decrease in outdoor temperature at night by about 30%. Therefore, a comparison of air exchange mode approaches in the apartment was conducted from point of view of energy use as well as from comfort conditions and indoor air quality. In terms of indoor air quality more efficient ventilation approach is scheduled with increased flow rate during occupied hours. The conducted analysis shows that the use of scheduled ventilation approach primarily makes sense when individual thermostatic control using set-point and set-back modes in combination with air heat recovery can be carried out.