Cecil College
One Seahawk Drive
North East, MD 21901
White Paper: Light Timers
and Occupancy Sensors
Amanda Fender
ENV116
Spring 2010
Introduction
Cecil College will recently break grounds for the new Math and Engineering Building located on
the North East Campus. In doing this, the College will have the opportunity to make the building
green and environmental friendly. The LEED Certification, which was created by the United
States Green Building Council, was designed to set standards and goals to create greener
buildings in America. By improving energy savings, water efficiency, CO2 emissions, indoor
environment quality and stewardship of resources, an organization can be certified in four
different levels. These levels include: Platinum, Gold, Silver and Certified. Cecil College has
taken the path to become Silver Level certified. To receive the Silver Certification, Cecil College
should install light timers and motion sensors to improve their energy savings.
Timers and Sensors
The costs of lighting an office building are not cheap. The US Department of Energy stated that
at least 22 percent of the total electricity used in the United States goes to lighting an area
(Greenyour.com, 2010). Costs of lighting an office include the following: luminaries, controls,
energy, replacement lamps and maintenance. Out of these costs, energy and maintenance are the
most expensive. The best solution for decreasing energy use and cost would be to install light
timers and motion sensors.
Light timers work by automatically turning on and off light sources in a room. The best areas to
place timers include: doorways, foyers, hallways, individual offices, boardrooms, bathrooms and
restrooms. There are three main types of timers that would work effectively at Cecil College.
Pre-set switch timers consist of a simple wall switch conected to a fixture. Closets, storage areas,
and indiviual bathrooms would be the best areas for pre-set switches since they use the light
source for a short and specific amount of time. Program timers are more developed and energy
efficient since it allows the user to set several time intervals throughout the day. The areas in the
College that would benefit the most from this type of timer include labs, lobbies, hallways and
entranences since they need to be either on or off at certian times of the day. Lastly, photo timers
are the most energy suffiecent and high-tech out of all the timers. Photo timers sense light
changes and will turn off automatically when there is not enough natural light in the room. Areas
such as indoor classrooms that have natural light from windows would be the best places for
these timers. By installing these timers, the consumer extends the life expectancy of the light
bulbs as well as giving a long term energy savings.
Occupancy sensors are another way to make buildings greener. Sensors are generally wall or
ceiling mounted models. Wall-sensor models work well in smaller rooms compared to ceilingsensor models which work better in larger areas such as boardrooms or conference rooms.
Occupancy sensors come in three main types which include: Infrared sensors, ultrasonic sensors,
and audio sensors. Infrared sensors are made to sense infrared radiation. This may include heat
from humans or other living organisms. These sensors work well in long distance areas because
they typically pick up objects within a 15 foot radius. These areas may include boardrooms,
storage areas, classrooms, labs, and hallways. Ultrasonic sensors work almost the same as
infrared sensors but instead of picking up light, it detects objects by sound waves. Motion of any
kind is detected when frequency is reflected off of an object. The rooms that would best benefit
from ultrasonic sensors are large offices, individual offices, unusal shape rooms, storage areas
and stairwells. Audio sensors use microphones to detect sound such as voices and/or
movements. These sensors are the least expensive out of all the sensors and work great in
obstructed areas. The best suited areas would include rooms of unusal shape, bathrooms, offices,
classrooms and labs.
Light Timers
Type
Pre-Set Timers
Programmable Timers
Photocell Timers
Type
Infrared Sensors
Ultrasonic Sensors
Audio Sensors
Description
Areas That Will Benefit
Connects to specific
Storage Areas, Closets,
fixtures;
Individual Bathrooms,
Best for short periods of
Small Rooms
time
Allows to set several time Labs, Lobbies, Hallways
intervals for different
and Entranences
days
Turns on and off when
Unusal Shape Rooms,
light changes is sensed
Bathrooms, Offices,
Classrooms and Labs
Occupancy Sensors
Description
Areas That Will Benefit
Sense Infrared Radiation Long Distance Areas such
as Boardrooms, Storage
Areas, Classrooms, Labs,
and Hallways
Detects Objects by Sound Large Offices, Individual
Waves
Offices, Unusal Shape
Rooms, Storage Areas
and Stairwells
Use Microphones to
Unusal Shape Rooms,
Detect Sound such as
Bathrooms, Offices,
Voices and/or
Classrooms and Labs
Movements
Savings
Light timers and occupancy sensors can save an organization money in several ways. The life
expectancy of a light bulb may be shorten drastically every time it is shut off and turned on. To
extend the light bulb’s life, set timers that will only have the lights on when needed. Another
way an organization saves money is that lights will not be left on if the last individual in the
room forgets to turn off the lights. Lights being left on always use up energy and will increase
the electricity bill.
Light timers and occupancy sensors not only save money, but they reduce the amount of
emmisions of greenhouse gases. Lighting areas, indoor or outdoor, is one of the largest
comsumptions of energy in larger buildings. According to Greenyour.com, approximately 22
percent of the total electricity used in the United States is lighting (Greenyour.com, 2010). This
amount will add up to 450 million tons of carbon dioxide being outputed as well as 3 million
tons of smog-gennerating nitrogen oxides and sulfur dioxide yearly (Greenyour.com, 2010).
Energy and the amount of lighting will reduce by 35 to 45 percent if office buildings install light
timers and occupancy sensors (Greenyour.com, 2010).
Recomendation
My recomendation to Cecil College for the upcoming Mathmatics and Engineering is to install
light timers and occupancy sensors. To recieve a Silver Certification, Cecil College will need to
earn between 40 to 47 points. By focusing on the insertion of light timers and occupancy sensors,
Cecil College can earn approximately 5 points for minimum energy performance, light pollution
reduction, and controllablity of systems. It would be in the best interest of the College to install
timers and sensors to recieve the Silver Certification and to save energy.
References
GreenYour (2010, April). Office Lighting – Control Office Lighting with Timers and Motion
Sensors. Retrived from <http://www.greenyour.com/office/office-space/officelighting/tips/control-office-lighting-with-timers-and-motion-sensors>
United States Green Building Council (2005). LEED-EB – Leeds Certification Powerpoint.
Retrieved from http://www.usgbc.org/showfile.aspx?documentid=1893
United States Green Building Council (2008, May). LEED for New Constrcution v 2.2
Registered Project Checklist. Retrieved from <http://www.usgbc.org/show
file.aspx?documentid=3998>