Conceptual design metrics for daylighting

Daylight is a key component of green building; however, no prevailing metric has emerged to help identify buildings that are well-daylit buildings. This paper proposes a ‘daylighting dashboard’; a visual representation of a design’s potential to meet eight design goals: average illuminance, coverage, diffuse daylight, daylight autonomy, circadian stimulus, glazing area, view and solar heat gain. This metric allows for informed decisions to be made early in the conceptual phase of design, and highlights aspects of design that may need further development, while there is still the opportunity to make modifications. These eight goals should be prioritized as appropriate for individual projects, rating systems or code requirements. This early indication of performance of conceptual design alternatives is likely to guide architects to better daylit buildings. </jats:p

Testing a provisional model of scene brightness with and without objects of different colours

A provisional model of brightness perception for illuminated outdoor scenes was recently proposed based upon a combination of photopic and short-wavelength cone spectral sensitivities, where short-wavelength cone sensitivity increases with radiance. An experiment was undertaken to determine whether coloured objects within the illuminated scenes affected overall scene brightness perception and, in so doing, to provide a test of the provisional model. The results suggest that overall scene brightness perceptions are, for the range of light sources and light levels selected, consistent with the provisional model and that scene brightness perception is independent of object colours within the illuminated scenes. </jats:p

Spectral sensitivity and scene brightness at low to moderate photopic light levels

A study of scene brightness perception was conducted to assess whether spectral sensitivity for scene brightness perception at low to moderate light levels (∼3–110 lux) could be partially explained by a contribution of intrinsically photosensitive retinal ganglion cells (ipRGC). An experiment was conducted at two different light level ranges and using two different spectral power distributions. The results suggest an increase in short-wavelength spectral sensitivity as a function of increasing light level. The results also confirm that including ipRGC as well as cone photoreceptor input in scene brightness spectral sensitivity resulted in improved predictions compared to including either cone input only or rod as well as cone input. </jats:p

Toward the development of standards for yellow flashing lights used in work zones

Flashing yellow warning lights are important for worker and driver safety in work zones. Current standards for these lights do not address whether and how they should be coordinated to provide directional information to drivers navigating through work zones. A field study was conducted to assess driver responses to warning lights. The luminous intensities and flash patterns of warning lights along a simulated work zone were varied during daytime and nighttime. During the daytime, driver responses were relatively insensitive to warning light characteristics, although drivers preferred sequential and synchronised flash patterns over random, uncoordinated flashing. At nighttime, the combination of a temporal peak luminous intensity of 25 cd and a sequential flash pattern was optimal for providing directional information. A single initial warning light having a higher luminous intensity may help drivers detect the work zone without creating unacceptable visual discomfort. </jats:p