Daylighting of road tunnels through external ground-based light-pipes and complex reflective geometry
Metadatos
Afficher la notice complèteEditorial
Elsevier
Materia
Tunnel lighting Light distribution Energy savings Diffusive hyper-geometry Conoidal geometry
Date
2023Referencia bibliográfica
Peña-García, A. Cabeza-Lainez, J. Daylighting of road tunnels through external ground-based light-pipes and complex reflective geometry. Tunnelling and Underground Space Technology, 131, 104788, 2023.
Résumé
The transfer of solar light to the interior of tunnels to complement electrical lighting during daytime, contributes
to save energy and decrease the number of installed projectors. The solutions traditionally implemented, based
on light-pipes hanging from the vault, seemed reasonable because the leakages of light-pipes can emit luminous
flux like projectors, but had the disadvantage of needing higher clearance gauges with the consequent costs in
drilling, building materials, works and maintenance. Furthermore, these hanging light-pipes cannot be installed
in working tunnels if they were not foreseen in the initial project. In this article, a new concept of light injection
and distribution in tunnels is proposed. It consists of the coupling of three main elements: collectors, light-pipes,
and one reflecting vault whose design is optimized to ensure the photometric requirements on the pavement. The
proposed system can collect more than 1.5 Mlm of solar flux with not excessively large collectors installed on the
ground of the road shoulder, and project them to the vault that finally distributes the light towards the pavement.
With this flux, average illuminances of 3478 lx and uniformities of 0.73 can be achieved, which means pavement
luminance around 350–400 cd/m2, in good agreement with the requirements during daytime. The savings can be
higher than 40 %. Besides these savings, this system can be easily implemented in existing tunnels. The proposal
and some estimations are discussed.