Air movement and perceived air quality

Melikov, Arsen Krikor; Kaczmarczyk, Jan

doi:10.1016/j.buildenv.2011.06.017

Cited by 90 publications

(72 citation statements)

References 11 publications

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“…This result contradicts a commonly cited assertion that perceived air quality is a monotonic function of room air temperature (Fang et al, 1998), and supports the view that perceived air quality is instead related to occupant thermal comfort (Humphreys et al, 2002), (Arens et al, 2008), , , (Kaczmarczyk et al, 2010), (Melikov and Kaczmarczyk, 2012).…”

Section: )contrasting

confidence: 53%

Effects of diffuser airflow minima on occupant comfort, air mixing, and building energy use (RP-1515)

Arens

Zhang

Hoyt

et al. 2015

Science and Technology for the Built Environment

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There is great energy-saving potential in reducing variable air volume (VAV) box minimum airflow setpoints to about 10% of maximum. Typical savings are on the order of 10-30% of total HVAC energy, remarkable for an inexpensive controls setpoint change that properly maintains outside air ventilation. However, there has long been concern whether comfort and room air mixing are maintained under low flows through diffusers, and this concern has prompted VAV minima to be typically set at 20-50% of maximum.RP 1515 evaluated occupants' thermal comfort and air quality satisfaction in operating buildings under both conventional and reduced minimum VAV flow setpoints, and measured the air diffusion performance index and air change effectiveness for typical diffuser types in the laboratory. The hypotheses were that lowered flow operation would not significantly reduce comfort or air quality, and that HVAC energy savings would be substantial. The hypotheses were almost entirely confirmed for both warm and cool seasons. But beyond this, the reduction of excess airflow during low-load periods caused occupants' cold discomfort in the warm season to be halved, a surprising improvement. It appears that today's widespread overcooling of buildings can be corrected without risk of discomfort by lowering conventional VAV minimum flow setpoints.

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Section: )contrasting

confidence: 53%

Effects of diffuser airflow minima on occupant comfort, air mixing, and building energy use (RP-1515)

Arens

Zhang

Hoyt

et al. 2015

Science and Technology for the Built Environment

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“…Moreover, following fallout from the cloud, such small droplets or their associated droplet nuclei can be resuspended by ambient air currents that usually have speeds of the order of ⇠1 cm s 1 (e.g. Melikov & Kaczmarczyk 2012). The ambient conditions also influence the buoyancy of the cloud and so the range of contamination of its suspended droplets.…”

Section: Discussionmentioning

confidence: 99%

Violent expiratory events: on coughing and sneezing

2014

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Violent respiratory events such as coughs and sneezes play a key role in transferring respiratory diseases between infectious and susceptible individuals. We present the results of a combined experimental and theoretical investigation of the fluid dynamics of such violent expiratory events. Direct observation of sneezing and coughing events reveals that such flows are multiphase turbulent buoyant clouds with suspended droplets of various sizes. Our observations guide the development of an accompanying theoretical model of pathogen-bearing droplets interacting with a turbulent buoyant momentum puff. We develop in turn discrete and continuous models of droplet fallout from the cloud in order to predict the range of pathogens. According to the discrete fallout model droplets remain suspended in the cloud until their settling speed matches that of the decelerating cloud. A continuous fallout model is developed by adapting models of sedimentation from turbulent fluids. The predictions of our theoretical models are tested against data gathered from a series of analogue experiments in which a particle-laden cloud is ejected into a relatively dense ambient. Our study highlights the importance of the multiphase nature of respiratory clouds, specifically the suspension of the smallest drops by circulation within the cloud, in extending the range of respiratory pathogens.

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“…al. [24][25][26], and extended the positive effect of air movement on PAQ to higher temperatures and humidity.…”

Section: 226mentioning

confidence: 99%

“…Studies have also shown that air movement significantly improves people's PAQ in warm temperature and moderate humidity conditions up to 30°C [17] [22][23], and in humid environment up to 28°C [24][25][26], although the causal mechanism behind this is not well understood.…”

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confidence: 99%

Comfort under personally controlled air movement in warm and humid environments

Zhai

Zhang

et al. 2013

Building and Environment

184

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This study examined the effects of personally controlled air movement on human thermal comfort and perceived air quality (PAQ) in warm-humid environments. At temperatures 26, 28, and 30°C, and relative humidity (RH) 60% and 80%, sixteen human subjects were exposed to personally controlled air movement provided by floor fans in an environmental chamber. The subjects reported their thermal sensation, thermal comfort, and PAQ during the tests. Two breaks periods with elevated metabolic levels were used to simulate normal office activities. Results show that with personally controlled air movement, thermal comfort could be maintained up to 30°C and 60% RH, and acceptable PAQ could be maintained up to 30°C 80% RH, without discomfort from humidity, air movement or eye-dryness. Thermal comfort and PAQ were resumed within 5 minutes after the breaks. The 80% acceptable limit implicit in comfort standards could be extended to 30°C and 60% RH. The average energy consumed by the fans for maintaining comfort was lower than 10W per person, making air movement a very energy-efficient way to deliver comfort in warm-humid environments.

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Air movement and perceived air quality

Cited by 90 publications

References 11 publications

Effects of diffuser airflow minima on occupant comfort, air mixing, and building energy use (RP-1515)

Effects of diffuser airflow minima on occupant comfort, air mixing, and building energy use (RP-1515)

Violent expiratory events: on coughing and sneezing

Comfort under personally controlled air movement in warm and humid environments

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