Installing Local Recirculation Air Diffusers During Building Deep Renovation Reduces Energy Consumption of Ventilation Systems

AbstractCapital repairs of public buildings and, in particular, insulating external wall increase the proportion of heat consumption by the ventilation system in the total building energy consumption. Surplus internal heat can be observed in rooms with high heat generation values (over 30W/m2) even during the heating season. Using surplus internal heat to heat the outdoor air during the heating season can help reduce the heat consumption of the ventilation system.The probability of excess internal heat occurrence in public buildings during the heating season has been analyzed. To this end, changes in specific thermal losses in buildings of various volumes occurring over the heating season in various Russian regions with different climate conditions have been compared with specific internal heat generation values typical of public buildings. Specific heat losses have been identified on the basis of rated values of the building's specific heat insulation value. The application area of ventilation systems with local recirculation air diffusers is outlined based on the outcomes of the analysis; it is concluded that these systems have a huge energy saving potential, both in case of reconstruction or deep renovation of an existing building, and when new public buildings are designed.On analysing the characteristics of ventilation systems with local recirculation air diffusers, it has been established that these have an advantage over traditional through-flow ventilation systems, or central recirculation systems.A local recirculation air diffuser delivering outdoor air inside the building at a low temperature (from +6°C) has been designed. The supply air is heated to the comfort temperature as it enters the working area by mixing the outdoor air with the internal air, thus assimilating internal surplus heat.A design solution for the recirculation air diffuser is proposed. Computer simulation of air flows generated by the recirculation air diffuser has confirmed that comfort parameters of the supply air jet can be reached at the inlet to the work area when outdoor air is supplied at temperatures starting from +6°C