Energy cost of clean air delivery with portable air cleaners - a case study in two kindergartens

The recent COVID-19 pandemic has heightened awareness of how airborne pathogens spread in indoor environments. Room air cleaners, when properly selected, can increase the non-infectious airflow in a room and help control infection transmission by reducing the concentration of airborne pathogens in indoor air. In an intervention study, 45 portable air cleaners were installed in 40 rooms at two kindergartens in Helsinki, Finland, to investigate the effect of portable air cleaners (PACs). Their power consumption was continuously monitored using smart plugs. We compared the energy costs of the PACs with those of the HVAC system. The PACs consumed 5784 kWh and 3256 kWh of electricity annually in kindergarten A and B, respectively. At an electricity price of 0.16 ¬/kWh, their energy costs were 911 ¬ and 524 ¬. To achieve the same increase in equivalent clean airflow rate with the HVAC system, we would need to spend 4831 ¬ and 3114 ¬ on electricity and heating energy in kindergarten A and B, respectively. We concluded that PACs can be a flexible and cost-effective way to reduce the concentration of airborne pathogens in indoor premises during sudden incidents, such as a pandemic.