Making daylight more available in buildings is highly desirable for reasons of energy efficiency, visual comfort,
occupant well-being and health. The Anidolic Integrated Ceiling (AIC) is a highly efficient daylighting system, designed
to gather and redirect daylight from the outside of a building into its interior with minimal losses. The reflective coating
materials used within AICs have a major impact on the optical efficiency of such systems. The first part of our article
presents a new computer model of an AIC consisting of more than 30 distinct components. We discuss on which of them
the use of expensive, highly reflective coatings makes the most sense. We conclude that coating the component
"Anidolic element 1" is always a good choice and that considerable financial savings can be obtained by following an
appropriate optimization sequence.The second part of our article discusses chronobiological properties of Anidolic
Daylighting Systems (ADS). We recorded daytime irradiance values for several weeks from March to May 2009 in an
experimental office setup in our laboratory using a portable digital spectroradiometer. Our results showed to which
extent different sky conditions influenced daylight exposure of office workers in an ADS-equipped office room. We
conclude that for the tested ADS-equipped office room, daylight supply can be considered largely sufficient during long
periods on most working days. However, complementary artificial lighting with blue-enriched polychromatic fluorescent
tubes might be useful on days with predominantly overcast skies as well as before 09:00 and after 16:30 on all days.
Electric lighting is responsible for a significant fraction of electricity consumption within non-residential buildings.
Making daylight more available in office and commercial buildings can lead as a consequence to important electricity
savings, as well as to the improvement of occupants' visual performance and wellbeing. Over the last decades,
daylighting technologies have been developed for that purpose, some of them having proven to be highly efficient such
as anidolic daylighting systems. Based on non-imaging optics these optical devices were designed to achieve an efficient
collection and redistribution of daylight within deep office rooms. However in order to benefit from the substantial
daylight provision obtained through these systems and convert it into effective electricity savings, novel electric lighting
strategies are required.
An optimal integration of high efficacy light sources and efficient luminaries based on non-imaging optics with anidolic
daylighting systems can lead to such novel strategies. Starting from the experience gained through the development of an
Anidolic Integrated Ceiling (AIC), this paper presents an optimal integrated daylighting and electric lighting system.
Computer simulations based on ray-tracing techniques were used to achieve the integration of 36W fluorescent tubes and
non-imaging reflectors with an advanced daylighting system. Lighting power densities lower than 4 W/m<sup>2</sup> can be
achieved in this way within the corresponding office room. On-site monitoring of an integrated daylighting and electric
lighting system carried out on a solar experimental building confirmed the energy and visual performance of such a
system: it showed that low lighting power densities can be achieved by combining an anidolic daylighting system with
very efficient electric light sources and luminaries.