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Daylighting, or using sunlight to illuminate your building, is an effective way to both decrease your building’s energy use and make it more enjoyable for people. 

In commercial buildings, electric lighting accounts for 35 to 50 percent of total electrical energy consumption. Using daylight can reduce this energy demand.  Daylight also improves people's comfort and performance: people can perform routine tasks 10-25% faster, student test scores can rise up to 20%, and retail sales can increase up to 40%.

Even when you can’t use daylighting, good lighting design can reduce energy use significantly. Both are important in Net Zero Energy Buildings.

Daylighting and Lighting Basics:

Strategies to increase the amount of sunlight within a space include using skylights, light shelves, reflective materials, and larger windows.  Skylights can provide an even distribution of filtered light but can only be used where there is access to a roof. Large perimeter windows are ideal, but can cause glare without careful design. Nearby buildings can also cast shadows on your building, so pay attention to existing buildings and anticipate future buildings.

Visual comfort is a complex issue involving window positions, solar angle/latitude and glare. To make sure you’re providing the right amount of light for various activities, reference a list of common illumination levels. Good daylighting practices also take into account the thermal comfort of occupants and any increased in heat gain from the sun’s radiation.

You’ll have to use electric lights when natural sunlight can't satisfy all of your lighting needs and when daylight isn’t available due to cloud cover or nightfall. Task lighting, like desk lamps, ensures there’s enough light for a particular activity. Ambient lighting ensures that the overall space has enough light. Task-ambient lighting handles these two needs separately and leads to more efficient designs. Good user controls and automatic controls that can sense and adjust to light levels can both help optimize comfort and energy efficiency.

Simulation for Lighting and Daylighting

Autodesk software can simulate your lighting and daylighting designs to ensure the building performs well as the sun’s position changes.

Using Revit or Vasari, you can simulate the Sun’s path to see how shadows will be cast from your building and any other surrounding buildings or trees. For more detailed visualization and analysis of shadows, daylight factors, and solar radiation you can use Autodesk Ecotect Analysis. For further study, see these Lighting Analysis Tutorials.

To get a very visual sense of the lighting, you can create photo-realistic renderings.  Take a look at the Light Measurement Tutorial Set to learn how to take advantage of the Mental Ray engine included within Autodesk 3D Studio Max, which produces physically accurate sunlight, reflections and shadows, and can measure the footcandles of light within the image.