Strategies for reducing human exposure to particulate matter are varied and each is associated with a unique energy penalty. Often metrics used to quantify particulate matter removal in spaces do not account for the energy usage associated with the method of removal being assessed. This study examines energy and IAQ tradeoffs in one particular situation in which we spend roughly one third of our lives: sleeping. Two methods for particulate matter removal, a free-standing whole-room cleaner and a personal air purifier, are analyzed.

 

A series of experiments was completed to determine the effectiveness of both a personal air purifier and a popular room air cleaner at reducingparticle number concentrations in the breathing zone of a sleeping individual. A spectrum of particle sizes was considered, from ultrafine to greaterthan 10 μm in diameter. Experiments were completed in a state-of-the-art climate-controlled test chamber and in the master bedroom of a testhouse (UTest House) at the University of Texas at Austin. A thermal, breathing mannequin was used to simulate a sleeping individual.Particle measurements were made in the breathing zone of the thermal/breathing mannequin and in the exhaust vent of the experimental chamberor a centralized location in the UTest House master bedroom. Measurements were completed using a six-channel optical particle counter and anultrafine particle counter at each location.

 

While the room air cleaner performed marginally better in removing particles from the bulk air space in the chamber, the personal air purifier was more effective in removing particles from the breathing zone, and did so while less than 1/5th of the energy used by the room air cleaner. For experiments conducted in the house, the personal purifier performed better than the room air cleaner in the breathing zone and relatively better than it had performed in the chamber experiments. These results suggest an opportunity for the refinement of metrics used to evaluate particulate removal devices in low-energy homes.