Impact of High-Efficiency Filtration Combined with High Ventilation Rates on Indoor Particle Concentrations and Energy Usage in Office Buildings National Air Filtration Association (NAFA) Friday, August 28, 2015 Michael S. Waring Associate Professor Director of Architectural Engineering Program Civil, Architectural and Environmental Engineering at Drexel University Indoor Environment Research Group (http://www.indoor-envi.com/) Drexel Air Resources Research Laboratory (DARRL) Building Science & Engineering Group (BSEG) msw59@drexel.edu

Introduction Motivation Introduce upcoming NAFA + ASHRAE funded research project Examine the impact of using high efficiency filters at the same time as using high ventilation rates (VRs) in offices Why do this work? ASHRAE minimum for VRs in offices is ~17 CFM/person Yet, increased VRs, particularly in offices, may have many positive effects on occupant wellbeing Lower infection risk, less Sick Building Syndrome (SBS), reduced absenteeism, better productivity and decision making However, higher VRs will increase particulate matter (PM) indoors PM exposure = reduced health! Impact of High-Efficiency Filtration + High Ventilation Rates in Offices Slide 2/11

Introduction Motivation E.g. Impact of CO2 exposure on human decision making: Experiments: Mock office Clean air CO2 added to: 600, 1000, and 2500 ppm Aptitude testing Satish et al. (2014) EHP Impact of High-Efficiency Filtration + High Ventilation Rates in Offices Slide 3/11

Methodology Filtration impact field and modeling study Conduct field experiments to demonstrate ability of filters of different efficiencies to mitigate indoor PM concentrations with varying VRs Third floor of Drexel University campus building Measure in ambient air, supply air, and return air: Fine particles (TSI DustTrak DRX 8533) Ozone (2B Technologies 205) Nitrogen oxides (2B Technologies 405) Carbon dioxide (PP Systems, WMA-4) Fan energy determined with installed sub-meters Other energy used with building automation system (BAS) reporting Model impacts for 14 cities in U.S. climate zones Impact of High-Efficiency Filtration + High Ventilation Rates in Offices Slide 4/11

Methodology Filtration impact field study Conduct three weeks of testing, at three times in one year: 3 weeks in Winter 3 weeks in Spring 3 weeks in Summer At least 63 days of testing Week 1 Week 2 Week 3 MERV 8 MERV 11 MERV 15 Day 1 2 3 4 5 6 7 VR High Low High Med High Low High Impact of High-Efficiency Filtration + High Ventilation Rates in Offices Slide 5/11

Methodology Filtration impact field study Air handling unit (AHU) and sampling schematic: Impact of High-Efficiency Filtration + High Ventilation Rates in Offices Slide 6/11

Methodology Filtration impact field study E.g., PM2.5 sampling at three locations: Impact of High-Efficiency Filtration + High Ventilation Rates in Offices Slide 7/11

Methodology Filtration impact field study E.g., PM2.5 indoor/outdoor (I/O) ratios as a function of OA/SA: 1.0 MERV 8 pre-filter + MERV 11 V-filter, Supply flow = ~5500 cfm 0.8 I/O ratio 0.6 0.4 0.2 0.3 0.4 0.5 0.6 Fraction of Outdoor Air (OA) / Supply Air (SA) Impact of High-Efficiency Filtration + High Ventilation Rates in Offices Slide 8/11

Future Impacts Deliverables Literature review on the impact of high efficiency filtration at mitigating exposure to indoor PM of outdoor origin at different VR conditions Description of Quality Control/Quality Assurance (QA/QC) Full time series of all measured data over 63 days of experiments Measured I/O ratios at the different VRs and filtration efficiencies Results of the modeling study over the 14 U.S. cities Cost-benefit analysis of using higher efficiency filters in terms of filter cost and fan energy requirements for a typical year of operation, placed in context of energy needed to supply higher VR Impact of High-Efficiency Filtration + High Ventilation Rates in Offices Slide 9/11

Future Impacts Benefit to NAFA and society Demonstration of ability to control PM, even at high VRs Improve work performance and health in offices by using higher VRs, with least negative side effects Contextualization of energy needed for PM control at high VRs Influence building design/operation of healthy indoor spaces Advance NAFA mission to: “educate end-users about the importance of air filtration” Impact of High-Efficiency Filtration + High Ventilation Rates in Offices Slide 10/11

Questions? Acknowledgments Special thanks to: National Air Filtration Association (NAFA) American Society for Heating, Refrigeration, and Air-conditioning Engineers (ASHRAE), New Investigator Award Questions? Impact of High-Efficiency Filtration + High Ventilation Rates in Offices Slide 11/11