Page 193 - Solar Power in Building Design The Engineer's Complete Design Resource

INDOOR LIGHTING COMPLIANCE 163

To prevent a loss of settings due to a temporary loss of power, timers are required to
have a 10-hour battery backup. Astronomical timers also are capable of storing the
time of day and the longitude and latitude of a zone in nonvolatile memory.

Automatic multilevel daylight controls Mandatory requirements stipulate
that automatic multilevel daylight controls be used when the daylight area under
2
skylights is greater than 2500 ft . In these circumstances the power consumption
must not be greater than 35 percent of the minimum electric light output. This is
achieved when the timer control automatically turns all its lights off or reduces the
power by 30 percent.
Multilevel daylight control devices incorporate calibration and adjustment controls
that are accessible to authorized personnel and are housed behind a switch plate
cover, touch plate cover, or in an electrical box with a lock. They must have a mini-
mum of two control steps so that electric lighting can be uniformly reduced. One of
the control steps is intended to reduce lighting power from 100 percent to 70 and the
second step to 50 percent of full rated power.
Fluorescent dimming controls, even though somewhat expensive, usually meet the
minimum power requirements. Controls for high-intensity discharge (HID) lamps do
not meet the power requirements at minimum dimming levels; however, a multistage
HID lamp switching control can.

Outdoor astronomical time switch controls Outdoor lighting control by means
of astrological time switches is permitted if the device is designed to accommodate auto-
matic multilevel switching of outdoor lighting. Such a control strategy allows all, half,
or none of the outdoor lights to be controlled during different times of the day, for dif-
ferent days of the week, while ensuring that the lights are turned off during the daytime.
Incidentally, this feature is quite similar to the indoor multilevel astronomical con-
trol with the exception that this control scheme offers a less stringent offset requirement
from sunrise or sunset. Mandatory certification for this device requires the controller to
be capable of independently offsetting on-off settings for up to 120 minutes from sun-
rise or sunset.

INSTALLATION REQUIREMENTS
Automatic time switch control devices or occupant sensors for automatic daylight
control must be installed in accordance with the manufacturer’s instructions. They
must also be installed so that the device controls only luminaires within daylit areas,
which means that photosensors must either be mounted on the ceiling or installed in
locations that are accessible only to authorized personnel. Requirements for specific
items are as follows:

Certified ballasts and luminaires. All fluorescent lamp ballasts and luminaires are
regulated by the Appliance Efficiency Regulations certified by the CEC and are
listed in the efficiency database of these regulations.