ingineria iluminatului - Journal of Lighting Engineering - Prof. Florin ...

Ingineria Iluminatului 2009; 11, 1: 13-26
HYBRID LIGHTING SYSTEMS
David CARTER
School of Architecture, University of Liverpool
Abstract. This paper reviews developments in hybrid light guidance systems. In these
daylight and electric light are simultaneously delivered into a building where they are
combined and distributed via luminaires. The technology used in hybrid systems, both
conceptual and realised, is discussed. The paper speculates as to their likely performance in
terms of daylight delivery; capital and running costs; user reaction to the systems; potential
impact of the systems on the building which they light; and suitable design methods.
Keywords: light guidance, hibrid systems, costs, human response
1 Introduction
In vernacular architecture elements evolved
to reflect, re-direct or control daylight.
Conventional glazed windows can provide
daylight some five metres into a building.
But since daylight levels decrease
asymptotically with distance from the
window, a disproportionate amount of
daylight and associated heat gain must be
introduced into the front of a room to
provide small amounts of daylight at the
rear. Attempts to direct daylight to areas
remote from the building envelope using
techniques such as atriums and skylights are
limited in effectiveness by contemporary
technology. Over the last twenty years or so,
a number of highly efficient reflective and
refractive materials have been developed
making possible what has become known as
‘light guidance’. Light from both daylight
and electric sources may be guided. The
main type of guided daylight is known as
Tubular Daylight Guidance Systems
(TDGS). This introduces daylight deep into
electrically lit buildings, although current
practice is to use the electric and daylight
systems separately with minimal interaction
(see Table 1).
Attempts to better combine the delivery
of daylight and electric light to the same
space use two main approaches - ‘integrated
lighting’ and ‘hybrid lighting’. Their main
characteristics are summarised in Table 1.
This paper reviews developments leading
towards the hybrid concept and describes a
number of systems, realised or otherwise. It
speculates about likely issues of system
performance, costs, user response, building
relationship and design methods.
2 System descriptions
Unless otherwise stated the performance
and other data quoted in this section is from
the sources cited.
2.1 Daylight guidance
Although TDGS is the only form of
guidance having wide commercial
application, a number of other types,
notable because their technology has been