A COMPARISON OF FOUR DAYLIGHTING METRICS IN ASSESSING THE DAYLIGHTING PERFORMANCE OF THREE SHADING SYSTEMS

The assessment of the daylighting performance of a design solution is a complex task due to the changing nature of daylight.A few quantitative metrics are available to designers to assess such a performance,among them are the mean hourly illuminance(MHI),the daylight factor(DF),the daylight autonomy(DA)and the useful daylight illuminance(UDI).Each of these metrics has a purpose,a set of criteria and limitations that affect the outcome of the evaluation.When to use one metric instead of another depends largely on the design goals to be achieved.Using Design Iterate Validate Adapt(DIVA)daylighting simulation program,we set out to examine the performance behavior of these four metrics with the changing dimensions of three shading devices:a horizontal overhang,a horizontal louver system,and a vertical fin system,and compare their performance behavior as the orientation changes of the window to which these devices are attached.The context is a typical classroom of a prototypical elementary school.Our results indicate that not all four metrics behave similarly as we vary the size of each shading device and as orientation changes.The lesson learned is that not all daylighting metrics lead to the same conclusions and that it is important to use the metric that corresponds to the specific goals and objectives of the design and of the daylighting solution.The UDI is the metric that leads to outcomes most different than the other three metrics investigated in this paper.

IMPACT OF DAYLIGHT EXPOSURE ON HEALTH,WELL-BEING AND SLEEP OF OFFICE WORKERS BASED ON ACTIGRAPHY,SURVEYS,AND COMPUTER SIMULATION

The purpose of this study is to examine how daylight exposure affects the health and well-being of office workers.Sleep actigraphy and health and well-being related survey data were the main dependent variables in this study.Research samples were composed of participants from the United States and South Korea,each set of workers divided into those having daylight at their workplaces and those without.Fifty participants in total wore for two weeks actiwatches equipped with light sensors to measure sleep quality and exposure to ambient light levels.Additional health and well-being measurements were taken using well established survey instruments such as the SF-36 for general and mental health,and the Pittsburg Sleep Quality Index(PSQI)for sleep.In order to estimate the levels of daylight participants were exposed to,computer simulation was used to generate the total annual daylight levels in each participant’s office.Our results seem to indicate that working in daylit office spaces would lead to higher sleep quality and higher scores of the health and well-being scales compared to those who do not work under daylight conditions.Our findings indicate that it is important to provide and maintain significant daylight levels at the workplace.Consequently,in terms of architectural design,building orientation,building dimensions,and the size and height of windows should be taken into consideration to optimize or maximize daylight exposure.