The aim of making use of daylight is to achieve visual comfort inside buildings and save electricity, as well as to improve living conditions in interior spaces more generally, by combining light, views, ventilation, and the use and control of incoming solar energy.
When designing daylighting systems, it is particularly important that natural light meet as much as possible of the lighting requirements, depending on the use of the building and the work carried out in its spaces.
To use daylight for the benefit of the building and achieve visual comfort, appropriate systems and techniques must provide the interior functional spaces with a sufficient quantity of light (illuminance level) and an even distribution, so as to avoid sharp variations in level that cause glare. Both the adequacy and the distribution of lighting depend on the geometry of the space and its openings, and on the photometric characteristics of the opaque surfaces (colour/texture) and the glazing (light transmittance/reflectance).
A daylighting system is understood to be the combination of:
• Glazing or another light-transmitting element
• Frame
• Shading device (whether a structural element or otherwise)
Daylighting systems fall into four main categories: openings in vertical walls, roof openings, atria and light wells.
Likewise, the various techniques applied to the system and/or the interior space increase the system’s performance and improve visual comfort conditions.
The main daylighting techniques are:
• Vertical openings (windows and transoms) of suitable geometric dimensions
• Roof openings
• Atria
• Light wells
• Special glazing
• Prismatic light-transmitting materials
• Transparent insulating materials
• Light shelves/reflectors and louvres
• Shading devices
The architectural design of both the spaces and the lighting systems (openings) must ensure the desired illuminance levels and the required views of the external environment (and, where appropriate, highlight characteristic architectural features), always in combination with the other requirements of energy design for thermal comfort and air quality.
Source: Centre for Renewable Energy Sources (CRES)
