Authors: MacNaughton, P., Satish, U., Laurent, J.G.C., Flanigan, S., Vallarino, J., Coull, B., Spengler, J.D. and Allen, J.G.
Year of publication: 2017
Publication: Building and Environment, 114, pp.178-186.
Keywords:
cognitive performance,
health,
workplace wellbeing,
green buildings,
Link to publication
Studies for over thirty years have shown how big of an impact buildings have on our health and well-being. They define how much we are exposed to both outdoor and indoor pollutants, noise, temperature and its changes, they affect our circadian rhythm and therefore our alertness through lighting, and they can either isolate us from nature, or connect us to it.
These factors contribute to IEQ (indoor environmental quality) and are used when defining green building standards, such as the LEED-certificate. This article (2017) describes IEQ factors of high-performing buildings which either had or did not have a certificate, and compared the results with cognitive measures and questionnaires of environment and sick building symptoms.
Ten high-performing buildings which did not differ greatly in their indoor air quality were chosen for the study. From each building, 12 people participated to the tests (n = 120). Six of the buildings had a green certificate, while four did not. Measures of indoor air quality (temperature, humidity, Co2, noise, VOC, aldehyde, PM2.5) were taken during the week long experiment. Participants had their heart rate, galvanic skin response, physical activity, and sleep quality monitored.
There were no significant differences in the indoor air quality between the certified or non-certified buildings. However, the certified buildings had on average better lighting (374 vs. 163 lux), were noisier (51.8 vs. 48.9 db), and drier (38.4 vs. 45.9 %). Only the difference in humidity was statistically significant, and the non-certified buildings were more often outside of thermal comfort standards due to too high humidity.
The results indicate, that in the certified buildings compared to the non-certified:
- Participants did 26.4 % better on their cognitive scores
- Participants slept 6.5 % better
- Thermal comfort and sleep quality were associated with higher cognitive scores
- Were more satisfied with the natural and artificial lightings of the building, temperature, air draft, humidity, and odour
- Reported 30 % less symptoms
Only 28 % of the cognitive score results could be explained by the classification of the building. Part could be explained by different IEQ factors, such as drier air and better lighting. Researchers note, that the sample size for the buildings was small, and therefore the variables related to them (e.g. ventilation systems) can’t be properly analyzed. Because of the small sample size, it was not possible to reliably define which individual factors were driving the better cognitive scores. It is possible, that the green building standard acts as a proxy for some other significant indicator.
This research concludes, that green building certificate provides benefits on human health and cognitive performance.