Lighting controls:
Best practices begins
with a strategy
ASHRAE Standard 90.1 requires lighting professionals to include power
allowances, daylighting controls, functional testing, and submittals in their
lighting designs. This discussion includes an overview of lighting control
options along with best practices for lighting designers and electrical engineers in working with their clients.
BY ERIC KAMIN, PE, DLR Group, Omaha, Neb.
Learning
objectives
Learn how to create a lighting control strategy through
client inquiry.
Identify best practices for
lighting designers to work
with clients in making smart
lighting decisions.
Identify how human factors
impact lighting outcomes and
energy strategies.
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ighting controls, coupled with
lamp technology, have evolved
toward more automated design
and away from reliance on
human intervention with the
goal of saving energy. This automated
approach contributes to a net zero or near
net zero building design by adjusting the
artificial lighting output to ensure the
room is not overlit.
A critical part of successful energysaving lighting control design is occupant
education—making sure the occupants
understand how their lights are controlled
and how they can best use the designed
system. This also may include recommendations for users to schedule regular
adjustments to the light output over the life
of the lamp, allowing for less use when
new lights are more intense, and increasing light output as lamps lose intensity
toward the end of life, thus saving energy
and money.
Best lighting control practices begin
with determining a lighting control
strategy. Almost all states have adopted
an energy code, with the primary code
used being equivalent to ASHRAE Standard 90.1-2007 or International Energy
Consulting-Specifying Engineer • JANUARY/FEBRUARY 2015
Conservation Code (IECC) 2009. Many
more states are moving toward adoption of ASHRAE Standard 90.1-2013
or IECC 2012.
Although there are specific codes and
standards, many options fit within those
guidelines. The following five questions
can assist in the decision-making process
for clients and engineers:
1. How will the facility be used? The
type of facility and how it will be used will
determine a general direction for the lighting controls. For example, a 24/7 mission
critical facility such as a hospital, correctional facility, or data center will have different functional requirements and goals
than a general office building or an educational facility. So, levels of importance
for lighting controls will vary between the
type of facility as well as the individual
spaces within each facility. For example,
a large cafeteria space requires different
controls than a corridor or classroom.
2. What are the client’s energy
goals? The facility owner’s energy goals
and municipal code directives will mandate specific lighting control requirements
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Figure 1: In public gathering areas of Alfonza W. Davis Middle School, Omaha, Neb., daylighting not only dramatically impacts the
need for lamp solutions, but also offers expansive views for student enjoyment. All graphics courtesy: DLR Group
that, in turn, will inform potential decisions
with respect to a lighting control strategy,
whether it is a new facility or an existing
facility. Such considerations may include
meeting a net zero challenge, a Watt/sq
ft requirement, facility owner standard or
preference, energy rebates requirements,
and cost of installation and maintenance.
3. What type of user will operate
the facility? The level of complexity of
a system, as well as the sophistication
level of the users, can determine if a central lighting control system is affordable
and preferred, or if individual spaces
will be controlled independent of one
another. If an end user does not have a
tech-savvy facility management team,
it might be in its best interests to keep
the system as simple as possible with
individual room controls, such as standalone occupancy sensors and manual
switches for daylight controls.
4. What are the safety and emergency requirements? Lighting controls
that consider maintaining safety during
power outages while saving energy is
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Madonna Rehabilitation Hospital, Lincoln, Neb.
CHALLENGE: Design of a light-filled, 110-bed,
250,000-sq-ft rehabilitation hospital, which
requires and is dependent on direct access to
natural light to nurture a healing environment.
SOLUTIONS:
The lighting power density was 0.78 W/sq ft,
compared to the code maximum of 1.2, which
is a 35% improvement.
The lighting controls were designed around
ASHRAE Standard 90.1-2007.
Patient rooms: Individual room controller
with combination of 0 to 10 V dimming and
switched lighting loads. Manual daylight zone
control.
Figure 2: Indirect lighting in this
space at the Madonna Rehabilitation Hospital in Lincoln, Neb., also
reduced glare of direct lighting,
giving the space a softer light with
heavy reliance on daylighting.
Corridors: Bi-level switching throughout
all corridors. Lighting to 50% is always on,
although controlled by a relay if future adjustment of the control scheme is desired, with manual control of the additional 50% output
at the nurses’ stations.
Rehabilitation gymnasiums: Relay control for automatic-off control of lighting after hours,
and low-voltage switches with the room broken up into multiple zones to allow for some
lights to remain off if the entire gym is not in use.
Occupancy sensors, in a manual on and auto off configuration, were used in offices, work
rooms, storage rooms, restrooms, etc.
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Lighting controls best practices
another consideration. In these instances,
an emergency relay device is required to
turn on controlled lighting during an outage
to comply with codes and standards. This
inherently incorporates emergency egress
lighting into the lighting control scheme.
With corridor lighting controlled by a relay
panel, low-voltage switches can be locked
out when the building is occupied, which
prevents required egress lighting from
being shut off inadvertently. If the facility
is used after-hours, the switch could function normally, allowing corridor lighting to
be manually turned on and off as needed.
5. Are safety and budget issues in
balance? Sometimes, the drive to save
energy eliminates night-lighting strategies
to illuminate the interior of buildings for
security purposes. Night-lighting is often
used to deter vandalism or breaking into
and entering a building. Occupancy sensors can aid in this aspect by turning lights
on when someone is moving through the
building, inherently incorporating nightlighting into the lighting control scheme.
Minimum controls for
ASHRAE 90.1-2010
Minimum compliant lighting controls
consist of a combination of manual, time
clock, or occupancy sensing devices:
n All interior spaces require manual
control to allow occupants the ability to
turn the lights off as conditions allow.
Most spaces also must provide stepped
control in the space to allow for multiple
lighting levels. An individual control
device can control a maximum of 2,500
sq ft, or if the space is larger than 10,000
sq ft, the area it can control increases to
10,000 sq ft.
n Most interior spaces in buildings
greater than 5000 sq ft also require a
means for turning the lights off automatically when the space is unoccupied. Automatic off controls can be accomplished in
several ways. For example, a time clock
turns lights off at the end of the normal
day. Occupancy sensors turn lights off
once the space is unoccupied, with a maximum delay of 30 minutes.
n Occupancy sensors should be used in
a manual on/automatic off configuration,
when possible, which is now an ASHRAE
Standard 90.1-2010 code minimum
requirement. The more people are used to
turning lights on with a switch, the more
likely they are to turn lights off when they
leave a room. Too often, when an occupancy sensor is used as a means to automatically turn lights on, occupants do not
consider turning lights off when they leave
the room because the occupancy sensor
will accomplish that task for them, thus
leaving the lights on in an empty room for
the time setting of the occupancy sensor.
n Either manual or automatic daylight
harvesting controls are required (according to ASHRAE 90.1-2007 and IECC
2009), depending on the size and arrangement of the individual daylighting zone
(sidelight or skylight).
n Exterior lighting controls must prevent lighting from being on during daylight hours. Exterior façade and landscape
fixtures must be shut off at a certain time
during the night, and all other non-emergency or non-security exterior lighting
must be reduced by a minimum of 30%
between midnight and 6 a.m. or outside
of business operating hours.
Best practices
Several strategies, with little additional
cost, can be explored to increase savings
over minimum compliant controls:
n Consider multi-level lighting, with
switches in strategic locations. For example, in a classroom, a single switch could
be located near the entry door, which
would turn on the lights to an acceptable
level for use during normal times and/or
when daylight contribution is prevalent.
This level could be 33% or 66% if using
a traditional design of 3-lamp troffers.
Riverside High School, Carson, Iowa
Challenge: Recoup a portion of construction cost through utility
incentive rebates. Design should accommodate the changing occupancy
loads through the day.
SolutionS:
n The lighting power density was 0.98 W/sq ft, compared to the code
maximum of 1.2, which is a 20% improvement.
n The lighting controls were designed around ASHRAE 90.1-2007.
n The building was designed with vertical windows high up in walls
of the breakout spaces, corridors, and commons areas to deliver
daylighting into the central parts of the building to minimize artificial lighting.
n Classrooms include both occupancy sensor controls and bilevel switching in all fixtures, with separate control for front of
classroom versus general classroom lighting, and a manual-on,
automatic-off lighting control scheme.
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Consulting-Specifying Engineer • JANUARY/FEBRUARY 2015
n Central corridors and general occupancy rooms/areas are controlled
via a series of networked programmable relay panels in various
electrical rooms located throughout the facility. Programming
includes a programmed time off function with override to on at entry
points to the building. Daylight dimming controls with occupancy
sensor override were used for the cafeteria area, which also serves
as a commons area.
n Lighting controls in the gym, fitness, music, and other larger occupancy rooms are based on bi-level manual lighting reduction and
overall occupancy sensor override control.
n The design team worked with an outside energy consulting firm as part
of a local electrical utility incentives program to estimate the payback
based on various energy measures and incentives.
n Exterior site lighting consists of LED pole fixtures in the parking lot
with integral dual drivers capable of reducing 50% lighting output
for each fixture. Mounted fixtures are designed to turn on at dusk
and off at dawn.
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Alfonza W. Davis Middle School, Omaha, Neb.
CHALLENGE: Ensure maximum natural daylighting into a threelevel, 185,000-sq-ft, grade 6-8 middle school on an extremely
sloped site.
SOLUTIONS:
The lighting power density was 0.92 W/sq ft, compared to
the code maximum of 1.2, which is a 24% improvement.
The lighting controls meet IECC 2009.
Classrooms include both occupancy sensor controls and
bi-level switching in all fixtures, with separate control for
front of classroom versus general classroom lighting, and
manual-on, automatic-off lighting control scheme.
Corridors are controlled by relays with automatic-off via
time of day.
Occupancy sensors, in an automatic-on and automatic-off
configuration, are used in offices, work rooms, storage
rooms, restrooms, etc.
Automatic daylight harvesting and bi-level switching controls were installed in the large cafeteria space and media
center.
Gymnasium: Relay control for automatic-off, low-voltage
switches with the room broken up into multiple zones to
allow for some lights to remain off if the entire gym is not
in use. Bi-level switching allows for multiple uniform light
levels that can be selected according to task.
Additional switches could be placed
near the teacher’s desk for those times
when more artificial light is required.
The natural action for many people when
entering a space is to turn all switches
on at the bank of switches near the door,
but the additional location requires the
occupant to make a conscious decision
to increase the amount of artificial light
in the space.
Attempt to reduce the amount of
general illumination within a space and
include task-based lighting as much as
possible. In an office environment, carefully consider the task lighting at the desk
and select fixtures that are flexible to
accommodate varying ages of occupants
with differing lighting needs.
When appropriate, these strategies can
provide additional savings:
Consider automatically dimmed fixtures for daylight zones and areas beyond
(load shedding). These could be addressed
individually or in groups. Either way,
when lighting output is reduced automatically by properly commissioned lighting controls, maximum savings can be
achieved because human intervention is
not required.
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Figure 3: The variety of lighting and daylighting options at Alfonza
W. Davis Middle School, Omaha, Neb., work together to create the
most cost-effective use of lights for a high-performance outcome.
For spaces with audio-video systems, which could be as simple as a single projector and screen all the way to a
sophisticated boardroom, use motorized
shades as necessary to darken the room
when the projector is used and to raise
the shades when not in use. Occupants
tend to avoid manually raising and lowering the shades, and instead leave them
down, thus limiting the effectiveness of
daylight contribution to the non-audiovideo lighting control schemes.
The human factor
Since the widespread adoption of ever
more stringent energy codes, as well as
movement toward meeting the Architecture 2030 challenge of net zero or near
net zero buildings, the ultimate goal is to
minimize artificial lighting and human
intervention of controls. However, recognizing there will be instances where
both artificial lighting and human intervention are needed, the intent should be
automation and task-based intervention
when appropriate.
Providing owner training on what
control schemes were provided, how
occupants can adjust the lighting lev-
els in their space, and how to maximize
energy savings is of critical importance.
Under ideal conditions, all spaces would
contain ample natural daylight and automatic dimming controls to improve and
reduce the lighting energy use in a facility. However, not all building owners can
afford these control strategies. Additionally, educating building owners about
the payback of more efficient lighting
systems is difficult in some regions of
the country due to low electricity rates,
which greatly lengthens their return
on investment. However, an integrated
design team can design systems that
maximize energy savings by having a
coordinated effort between architectural,
mechanical, lighting, and lighting control design.
Eric Kamin is a principal leader in DLR
Group’s electrical engineering practice.
He is skilled in developing specifications
for primary and secondary power distribution, standby power systems, voice and
data cabling systems, security systems,
interior and exterior lighting design, and
sports lighting design.
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