Tunable White LED
Paul Kistler | NAVFAC-EXWC
The objective of this project is to answer two fundamental questions related to workspace lighting:
- If personnel are given the ability to reduce their workspace illumination levels in response to a change in correlated color temperature (CCT), will the increase in brightness perception and visual acuity from higher CCT result in lower illumination levels? Dimming their lighting will result in less energy use.
- If personnel are given the ability to change their workspace CCT, what are the CCT preferences of the occupants and how do these preferences vary through space, time and occupant characteristics?
If personnel voluntarily dim their office lighting in response to lighting with higher CCT and if higher CCT lighting is acceptable to personnel, then future lighting projects can be designed using higher CCT and lower illumination levels thus saving energy with no loss in personnel productivity.
To determine preferred illumination levels in response to a change in CCT and determine preferred CCT by office workers, Light Emitting Diode (LED) pendent lighting that has the ability to individually dim and adjust the CCT will be installed in selected Naval Facilities Engineering Command Engineering and Expeditionary Warfare Center Public Works 8 office spaces. This location was selected since a prior lighting project was performed in this space using dimmable T5 fluorescent pendent lighting, thus lowering the cost for this project and having previous data for comparison. The CCT of the lighting will initially be fixed and personnel will be allowed to adjust their illumination levels. After a period of time, the CCT will be changed and measurements will be taken to see how personnel adjust the illumination levels. After sufficient data is taken, personnel will be allowed to adjust their CCT and personnel preference will be recorded.
Assuming that personnel dim their lights in response to higher CCT values and lighting with higher CCT is acceptable to personnel, any lighting where CCT can be changed, such as fluorescent, LED, Organic Light Emitting Diode or in the future, laser, illumination levels may be reduced by up to 20% thus realizing a possible energy savings of approximately 20%.