Influence of commercial glazing and wall colours on the resulting non-visual daylight conditions of an office

Daylight is ever more recognised as a major synchroniser of circadian rhythms, linking us to the 24 h solar day. However, the time that urbanised humans spend outdoors has decreased substantially during the last century, which highlights the importance of appropriate indoor daylighting. Quality and quantity of daylight in indoor environments are primarily modulated by the characteristics of the building envelope. In this context, a combined in-situ experimental (Ljubljana, Slovenia) and simulation study of a cellular office model was executed in order to evaluate the impact of different glazing types and internal wall colours on the non-visual potential of daylight. In particular, the impact of seven glazing types and six different wall cover hues at three reflectance levels was determined. Among these, three glazing types and three wall colours of equal reflectance were further evaluated through diurnal simulations of the indoor luminous environment. Low-e glazing with high visual transmittance and blue coloured wall were indicated as combinations with the highest non-visual entrainment, while the opposite is true for the combination of bronze tinted solar protective glazing and orange walls. In general, a better non-visual environment can be achieved using materials characterised by higher spectrally neutral transmissivity or reflectance than with those characterised by spectrally non-neutral properties and of lower transmissivity or reflectance