Technical Guidance

Natural Daylight

The provision of natural daylight within the built environment can deliver genuine, positive benefits to the finished construction; benefits that can enhance the financial and environmental performance of the building in service and improve the internal environment and make it a more pleasant place to be.

Natural daylight is associated with a whole range of positive effects on building occupants, from increased productivity and mental alertness to an improvement in general health. There is also anecdotal evidence of improved recovery times among patients in hospitals where the levels of natural daylight have been increased.

The Workplace (Health, Safety and Welfare) Regulations 1992 state: “Every workplace shall have suitable and sufficient lighting which shall, so far as is reasonably practicable, be by natural light.” As a purely commercial, project cost consideration, it’s completely free of charge.

All of which would point to natural daylight being the obvious principal consideration for the design of any building in which human beings are expected to spend any significant amount of time.

For any building, there is an optimum target percentage of rooflights which will deliver the optimum level of natural daylight into a building, making the optimum saving in energy usage and costs. Though solar gain can add to the energy consumption is powered cooling systems become necessary for instance. That is why it is important to properly consider a daylighting plan at the design stage of the building.

For further information on natural daylight and delivering the right balance within a building, you can download the section from our technical manual here. The next section explains the process and behaviour of natural daylight passing through rooflights, known as light transmission.