by Veronica Garcia-Hansen, Lecturer and Researcher with Queensland University of Technology

In sunny places like Australia we have an abundance of natural light. Skies are mostly clear with a low incidence of clouds. There are no extreme variations in summer and winter day lengths. Daylight tends to be from sunlight with a relatively low contribution from the sky.

Daylight is the visible part of solar radiation and daylight at these latitudes can also mean thermal gain. In addition, bright sky, reflected light from the ground, and direct solar radiation can be causes of glare.

To avoid overheating, daylight is normally blocked by shading devices or highly reflective glazing. To manage glare, most traditional diffuser materials and glare management systems reduce the usable output lumens as direct light is blocked and spreading increased. As a result, interior spaces can be dark and many buildings depend entirely on artificial lighting for illumination, even when external illuminance levels are very high.

These warm, sunny climates also promote an outdoor life style, and the need for shade and protection from the sun (UV radiation). We spend an increasing amount of time relaxing, socializing, even working, on decks, balconies, and under shaded streets (external awnings attached to building structures). Decks/balconies have become another room in houses or apartment in buildings. This is part of our subtropical living, yet, they increase the depth of buildings and can also have an effect on daylight harvesting for building interiors. This is a particular issue for residential and multi-residential buildings and ground floors of commercial buildings in city centers.

Solar protection in the form of shading devices, the use of tinted glasses for solar protection and glare, and deep balconies, or external shadings, in addition to the lack of regulation in terms of depths of buildings, could have an negative effect on daylight availability in building interiors, and thus is very important the right combination of daylight redirection systems, with shading devices, integration of devices into façade design, and dynamic electrical lighting design supporting of daylighting design.

The QUT Lighting Group is a multidisciplinary, cross-faculty (architecture, physics, health and psychology) cluster that focuses on lighting in tropical and subtropical climates. Below are some of our research topics:

1-     daylighting solutions for deep plan buildings

2-     daylight redirecting systems

3-     integration of daylight redirection and shading devices

4-     parametric integration of daylighting devices into façade systems

5-     Glare assessment in bright climates

6-     Light exposure during daylight our in office spaces

7-     Simulation tools and climatic based daylight metrics and ranges

Relevant publications can be accessed at: http://eprints.qut.edu.au/view/person/Garcia-Hansen,_Veronica.html