Wireless Sensor and Actuator Networks for Lighting Energy ...

Table 2-1 summarizes each of the control strategies [19, 25, 26].
Table 2-1 Summary of energy efficient lighting management strategies.
Lighting control
strategy
Strategy definition
Potential energy
savings
Adoption percentage
in commercial offices
New
Retrofit
Daylight harvesting
(daylight-response,
daylight-linking)
Automatically dim the electric
light or toggle the electric light off
in response to increased daylight
level
35-40% in daylit
areas
12% averaged over
the entire area
11.7% 7.5%
Light level tuning
Adjust electric light level
according to occupants’ preference
15-25% - -
Occupancy sensing
Automatically turn off lights after
space is vacated
25% compared to
manual switching
61.7% 59.7%
Time switching
Automatically dim or switch off
lights according to a predefined
schedule
- 54.3% 41.5%
Load shedding
(demand response)
Voluntarily reduce light levels
during peak demand period N/A - -
2.1.3 Challenges of Current Technologies
Although the lighting control strategies introduced in the previous section may
introduce more than 40% of energy savings, most of them have not been widely
adopted in commercial buildings, resulting in a missed opportunity for significant
energy savings. In fact, each of the control strategies has specific shortcomings that lead
to unaffordable costs or unsatisfying performances.
The difficulty of implementing a daylight harvesting system lies in the
complexity of design and commissioning. Poor operations can easily result from
improper zoning and inappropriate sensor locations [26]. A single photosensor can only
18