Occupants’ mood responses to daylight in buildings: a pilot study

© 2015 Allen Kim LoMany studies have been carried out on the effects of daylight on the occupants of a building in order to determine the benefits of exposure to daylight. However, there have been only a few studies conducted on the effects of daylight in Australian conditions. The Australian Glass and Glazing Association (AGGA) has noticed a trend of reduction in glazing area to meet energy efficiency code requirements. The Association is concerned that, apart from commercial reasons, this is done in the absence of a full understanding of the potential impacts, positive or negative, of the occupants’ access to daylight. This project came about as result of the association’s interest. This research firstly investigated the beneficial effects of daylight on building occupants by reviewing existing literature on the subject and then initiated a pilot study on means to effectively measure the occupants’ psychological response to various levels of daylight. The breadth of this pilot study’s methodological approach was intentionally kept wide to aid the exploration of using different ways of conducting or of using a combination of established methods to conduct research of this kind and measuring the test subjects’ responses. This strategy has yielded a number of experimental design refinements which would benefit future studies. This research occurred over only three consecutive Friday afternoons and was conducted in the Sidney Myer Asia Centre and the new Melbourne School of Design building in Parkville campus, Melbourne. Undergraduate students were the test subjects. They self-reported their responses through a survey that was based on Thayer’s Activation and Deactiviation Adjective Checklist (ADACL). The illuminance was logged during the course of the experiment rather than on a ‘snap shot’ record basis, used by most researchers. The advantage of continuous data logging in capturing the dynamic nature of daylight, which could affect the occupants’ psychological responses, was illustrated in this research where an increase of 11,000 lux of outdoor light reading and an accompanying indoor illuminance increase of 670 lux within a short span of 20 minutes was detected. A ‘snap shot’ lux recording approach would have missed this sizable fluctuation and the mood response data would have been cross referenced with a much lower lux value taken at a different time, thus giving an incorrect correlation between light level and mood response. The original sample size of 80 had to be reduced to approximately 65 due to a limited number of lux meters/loggers available. Further subdivision of the group of 65 into 4 cohorts rendered the sub sample size to be statistically insignificant. Although, no conclusive result as to the effects of daylight on the students under different lighting levels could be drawn from this research project. However, valuable ‘lessons learnt’ were gained. It was also observed in the last experiment sessions on 24 October 2014 that students sitting closest to the windows reported a slight improvement in their moods. A different approach was adopted for this last set of experiments after lessons learnt from the previous weeks. Whilst this could not compensate for the inadequate sample size, the refinement has provided insights into how this experiment could be improved. In order to obtain higher quality data from future experiments, a better control of independent variables and maximisation of sample size need to be put in place. Test subject selection (the ‘Convenient Sample’ approach did not work for this experiment), characteristics of test location such as colour, colour temperature, reflectance, acoustic properties, ambient noise, air temperature, humidity should be as consistent as practicable for all experiments. If at all possible a means to control the daylight level so that it could remain reasonably constant would be ideal