When did people start paying attention to indoor environments?
Although research into indoor environments has existed since the 1930s, it didn’t really become an issue until the energy crisis in the 1970s when we started trying to reduce energy consumption related to HVAC (heating, ventilation, and air conditioning). In the US, for example, the mid- 70s crisis saw ventilation of office buildings reduced by two thirds. That’s when we really started seeing complaints about poor indoor environments, and research has steadily increased since then.
Traditionally, there are four main parameters of indoor environments. First, there is air quality, which looks at what’s in the air. There is thermal quality, which focuses on temperatures and drafts. Then there is acoustics and noise, and finally: lighting. We study the impact of these parameters on building occupants. There are three main families of effects. The first is perception: how does the person ‘feel’ about the environment; is it too hot, too cold, too bright, too dark, too noisy, too quiet, etc. Then there are real physical symptoms like dry eyes, runny noses, tiredness or headaches. At the far end of the spectrum comes illness. We focus mainly on the first two – perceptions and symptoms.
Where has this research led you?
We’ve begun looking closely at productivity, and the research is very interesting. In one study, we asked volunteers to come and work for three days in offices that we have here on campus. We had them work in different indoor environments, in which we changed the temperature, the acoustics, the air quality, and so on. We recorded their performance on various tasks. What we saw was a 5-10% drop in performance in a poor indoor working environment.
When you compare this loss of productivity to what it costs to create a good indoor environment, you don’t have to be genius to figure out that you should do all you can to create a good indoor environment from the outset. Thanks to this research, we’re beginning to get more traction among architects and builders. They’re sitting up and taking notice.
What should building owners pay the most attention to?
First: building materials. You don’t want to have indoor sources of pollution. This could be anything from smelly carpets to photocopiers that produce ozone. Next, you want to have sufficient ventilation and maintain a comfortable thermal environment; we see lots of problems arise here. Then pay attention to acoustics. Not all materials that are good for controlling acoustics are good for the other parameters; you need to look at controlling acoustics with materials that don’t add to indoor pollution and that preserve the thermal environment. Like I said earlier, you have to have balance between the three.
Geo Clausen is an associate professor at the International Centre for Indoor Environment and Energy (ICIEE) at the Technical University of Denmark. He has published several comparative studies on discomfort caused by indoor air pollution, thermal conditions, and noise.