Daylight in Buildings

Bounced lighting


João Lima, Arthur Melo, Bruna Barbosa


Juliana Batista,

Ricardo Cabús


Universidade Federal de Alagoas



Bounced lighting

Project Description

The city of Maceió, located at Brazil’s northeast in a low latitude region (9°S), is known by their beaches and the hot and humid climate, “where summer lasts the whole year”, with large amount of daylight and monthly mean temperatures near 25°C. A good architectural design should include elements able to control daylight and heat gains, filtering direct sunlight, introducing it diffusely into the buildings. The Main Library of the Federal University of Alagoas, Maceió campus, was chosen as the object of study. It has a large lobby, illuminated by artificial light all day long. We proposed an intervention in that space, introducing daylight and creating a connection with external environment, helping to promote the perception of daytime and producing a circadian stimulus to the people. The project idea was to create an architectural element that would allow daylight to enter in the library through zenithal opening, in order to provide users health and well-being. Thus, by bouncing the sun's rays on the structure, direct light would be converted into diffuse light, allowing a smooth natural lighting and improving the building's energy efficiency. In order to bring diffused light to the library’s lobby, the existing top roof was retrofitted, substituted by a pyramidal metallic structure, covered with glass panels. On the bottom, other pyramid made by louvres was positioned and becomes part of the building structure. The metallic T shaped louvres and the light shelves bring daylight, in a diffuse and pleasant way to the lobby. Regarding thermal comfort, we designed the structure in such a way that there was a reduction of thermal load in the environment, since the metal sheets do not allow direct radiation in the double glass panel below the structure. Hot air is dissipated through the upper opening, between the roof and the skylight, and through the sides of device to the attic.