Artificial & natural lighting analysis

Besides affecting the physical and emotional well-being of the building occupants, a building’s interior lighting system is both a dominant consumer of electrical energy and a major source of internal heat. In commercial buildings it generally accounts for more than 30% of the total electrical energy consumed.

Specifying a high quality energy efficient lighting system that utilizes both natural and electric sources as well as lighting controls can provide a comfortable visual environment for the occupants of a space. Energy efficient lighting equipment such as LEDs, T5 fluorescent lamps and dimmable electronic ballasts can be used to help cut lighting operational costs 30% to 60% while enhancing lighting quality, reducing environmental impacts, and promoting health and work productivity.

• Using advanced modeling tools, GreenBIM Engineering can help the design team to achieve highly efficient artificial lighting systems integrated with advanced controls.

Daylighting reduces the need for electric lighting of building interiors, which, if integrated into the overall approach to lighting, can result in decreased energy use. A well-designed daylit building is estimated to reduce lighting energy use by 50% to 80%.

Daylighting design involves a careful balance of heat gain and loss, glare control, visual quality, and variations in daylight availability. Shading devices, light shelves, courtyards, atriums, and window glazing are all strategies employed in daylighting design. Important considerations include the selected building’s orientation, window size and spacing, glass selection, reflectance of interior finishes, and locations of interior walls.

Commercial spaces with sufficient natural daylight and a visual connection to outdoor environments have been proven to increase occupant productivity and comfort, leading to better employee retention.

• Using advanced modeling tools, GreenBIM Engineering can help the design team to enhance daylighting availability in most regularly occupied spaces in the building, thereby providing a comfortable environment to the occupants while reducing energy consumption.

GreenBIM Engineering’s modelers use state of the art software in order to perform accurate artificial lighting and daylighting simulations.

The modeling team uses Autodesk’s Revit in order to create a simplified 3D model of the building based on the project’s architectural drawings. Through the Green Building XML (gbXML) open schema, the building properties stored in Revit’s 3D model is exported to an engineering analysis tool.

Detailed artificial and daylighting simulations are then performed on dedicated tools such as:

• Autodesk Ecotect Analysis 2011
• DIALux 4.12
• DAYSIM
• Radiance

The simulations allow to calculate a series of climate-based daylight metrics such as:

• Daylight Autonomy (DA)
• Useful Daylight Illuminance (UDI)
• Daylight Glare Probability (DGP)
• Daylight Factor (DF)

• LEED EA credit 1 “Optimize Energy Performance”: lighting design greatly affects the overall building energy performance. Designing an energy-efficient lighting system with advanced controls would allow to reduce the building energy consumption compared with ASHRAE 90.1 baseline.

• LEED IEQ credit 8.1 “Daylight and Views – Daylight”: the credit requires to demonstrate through computer simulations that 75% or more of all regularly occupied spaces achieve daylight illuminance levels of a minimum of 25 fc and a maximum of 500 fc in a clear sky condition on September 21 at 9 a.m. and 3 p.m.

• LEED IEQ credit 8.2 “Daylight and Views – Views”: the credit requires to achieve a direct line of sight to the outdoor environment via vision glazing between 30 inches and 90 inches above the finish floor for building occupants in 90% of all regularly occupied areas.