Buildings

Daylighting

What Is It?

Daylighting refers to using natural light to illuminate a building. This controlled admission of natural light into a space through glazing is used to reduce or eliminate electric lighting. By utilizing solar light, daylighting creates a stimulating and productive environment for building occupants.

How To

Strategies to consider include building orientation, shallow floor plates, increased building perimeter, exterior and interior shading devices, high performance glazing, and automatic photocell-based controls.
Simple tools and calculations are used in the most preliminary of design concept stages to help determine the viability of daylighting. Simple tools and calculations include:

• Sunpath diagrams to calculate available daylight during different seasons at different latitudes
• Daylight factor calculation for available interior daylight
• Glazing factor calculation for available interior daylight
• Fisheye photography for obstruction analysis

Physical modeling is another approach to conducting analysis, with the advantage of using real natural light, demonstrating its subtle qualities, and the capacity to represent any room geometry. However:

• Cannot control the sun or weather
• Not easy to demonstrate design changes/iterations
• Need to build the model
• Local access to a heliodon or artificial sky
• Difficult to create a model with the appropriate textures and reflectances
• Difficult to mimic electric light sources
• Does not provide information on thermal impacts of daylighting or potential energy savings

Today, the trend is toward computer analysis to provide daylighting design information and feedback immediately to the design team. Historically, these tools were sufficiently complex that only researchers involved with product development and/or primary field research were able to use them. Today, however, there are many tools available that have varying levels of complexity in both input required and output obtained. There are free programs available as well as ones for purchase. From the Daylighting Collaborative - http://www.daylighting.org/designaids.php