Performance comparison of heat recovery systems to reduce viral contagion in indoor environments

Strong ventilation increments are currently suggested for containing the airborne diffusion of COVID-19 in indoor environments. However, it can involve an unacceptable growing of energy consumption. Therefore, maximum care must be addressed to improve efficiency of ventilation heat recovery (VHR). For this purpose, this paper investigates the opportunity of a technical solution. Consisting in adding downstream of the most diffuse heat recuperator, a heat pump using exhaust air as a cold source. An autonomous high efficiency air handling unit (HEAHU) was modelled for a school application. By simulation a performance comparison was carried on with two alternative systems based only on an exhaust air heat pump (EAHP) or on a heat recuperator for different weather conditions. Results indicated that the milder climate strongly penalizes heat recuperator and this fact deeply influences the conclusions. HEAHU saving compared to energy consumption of only heat recuperator is between 31% and 46%. For EAHP this saving varies from 2.5% to 48%. Only with a milder climate, EAHP presents a lightly greater saving than HEAHU. Heat pump technology looks to be very performing to foster the efficiency of VHR, especially in presence of high ventilation rates.