Wireless Sensor and Actuator Networks for Lighting Energy ...

newly calculated light settings may be significantly different from the previous one, and
the light change may become noticeable to the occupants. The system needs to ensure a
smooth transition when encountering a change of occupancy in order not to irritate
people with a series of annoying light adjustments.
9.5 Commercial Implication
As the energy crisis and global warming continues to worsen, the proposed
lighting system could potentially generate over 50% energy savings and high user
satisfaction with both legacy buildings and new constructions. With the development of
wireless sensor and actuator network technologies over the years, this section provides
an analysis of the commercial implications of the research system, including the current
and projected payback period and potential bottlenecks.
9.5.1 Payback Period – Current and Projected Payback Period
A payback period analysis on the research intelligent wireless lighting system is
provided in this section. Since the energy savings are different from building to building
largely dependent on occupancy pattern, available daylight, etc., educated guesses have
to be made to estimate some of the parameters required in the analysis.
Consider a 150 square-meter open-plan office space originally designed with a
single wall switch to control all luminaires in the office. The number of luminaires and
ballasts required to light the space is calculated from the lumen method for average
illuminance [110]. The average illumination calculation sheet attached in Appendix C.1
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