Get Sust! Issue 36

Go with the flow, or give individuals more control?

Two reports in the journal Indoor Air point to different ways of improving indoor comfort:

Researchers in Sweden say that ventilation rates in computer classrooms should be improved because the potential for overcrowding and high heat gains from people and computer equipment hamper the learning process.

The researchers, from University Hospital Uppsala’s Occupational and Environmental Medicine department, tested the effects of ventilation in four computer classrooms. Two classrooms had a higher air exchange (4.1–5.2 ac/h); two others had a lower air exchange (2.3–2.6 ac/h). After 1 week, ventilation conditions were swapped over. Throughout the experiment, students were asked to reported environmental perceptions during the last hour.

The team concluded that ventilation flow rates should be high — at least 10 l/s — coupled with passive measures such as sun shading, in order to achieve good perceived air quality.

Although their study focused on university-based learning, their results surely have wider implications for both the schools and — more importantly — offices, where similar levels of concentration are required of the occupants.

Meanwhile, in “Forty years of Fanger’s model of thermal comfort: comfort for all?”, Joost van Hoof from Hogeschool Utrecht assesses whether the predicted mean vote (PMV) model of thermal comfort created by Fanger in the late 1960s, is still relevant today.

He says that the 40-year-old PMV method may need to be adapted or extended for 21st-century applications, to take account of more recent work on: the effects of the thermal environment on productivity and behaviour; interactions with other indoor environmental parameters; and the use of information and communication technologies. But he suggests that, even with these modifications, thermal comfort for all can only be achieved when occupants have effective control over their own thermal environment.

Learn more:

	•	"An experimental study on effects of increased ventilation flow on students’ perception of indoor environment in computer classrooms", D. Norbäck, K. Nordström, in Indoor Air, doi:10.1111/j.1600-0668.2008.00530.x. See www.blackwell-synergy.com/
	•	"Forty years of Fanger’s model of thermal comfort: comfort for all?" J. van Hoof in Indoor Air 18 (3) , 182–201 doi:10.1111/j.1600-0668.2007.00516.x. See www.blackwell-synergy.com/