Our initial impression that there was a gradient of light in the typical classroom was corroborated by this study.
We were able to quantify the contribution of each of four light sources. Each contribution was individually measured and calculated as a percentage of the whole, or total amount of light available at the student desktop, and its light emittance graphed throughout the room. The comparisons to a total refer to the unadjusted lighting conditions present the time period we collected our data.
A more complete post occupancy evaluation (POE) of this kind would need to account for orientation, weather, time of day and season. Our study focused on a South-facing classroom. It is simply a snapshot glimpse of a single four-hour period measured on two separate days and does not attempt to suggest that similar results would be measured any other time of the day or year. We were fortunate that the weather was sunny one day and overcast the other. This way we had the chance to observe the lighting system response to very different solar radiation amounts.
Boora has provided a design solution that combines both high-tech and low-tech lighting control systems into an integrated lighting strategy. The room occupants have access to the two low-tech controls: a wall switch (off only) and venetian blinds (off only). Even so, teachers could not totally darken their rooms in order to watch videos, for instance, because the solatubes and clerestory windows did not have blinds or dampers. We observed user adaptations such as paper shrouds and shields taped around the solatube diffusers to block extra light.
It was also clear that the teachers were adjusting to an automated system. Lights turn on only by automated control. Because the occupancy sensor has a timer function, we observed a paper flap user adaptation to trigger the system on. This flap was connected to a string that followed a paperclip pulley system along the ceiling from the teachers desk.
|Uneven lighting on a sunny day. Photo: M. Brown|
|User adaptation to control lighting. Photo: S. Hill|