Sustainable Energy Systems Engineering
Transcript Sustainable Energy Systems Engineering
Sustainable Energy Systems Engineering
Ch 4: Energy Conservation
Brevard Community College
General Energy Saving Measures
See Home Energy Conservation Tips handout from
day 1 (posted on Angel).
See FSECs zero energy home in Lakeland:
Recycling is also a good thing. See
Power Factor Correction
Electrical loads that are not purely resistive, have a load
impedance that is at a phase angle. They do NOT
consume more energy because of it. They do however
cause more current to be cycled back and forth between
the power source and the load thereby causing greater
losses in the system.
When the load is inductive
(motors), the current in the
circuit will lag the voltage.
Work is done by the Real Power (Watts) but, the power
source and load cycle some power back and forth. This is
the Reactive Power (VAR). The power supply and wiring
must be large enough for the resulting Apparent Power (VA).
This large amount of energy transfer between the source
and load causes larger energy consumption.
The Power Factor
(PF) is the ratio of
W/VA or the cosine
of the phase angle.
note: This is why UPSs are rated in VA not Watts.
Reducing Power Factor Losses
If a capacitor with a reactance equal to the reactance of
the inductive load (motor) is place in parallel with the load
the net reactance is 0! Calculating the size of the capacitor
is left to other courses or the manufacturer of the motorized
equipment. This topic is covered in EETC1025.
If the losses due to the energy cycled back
and forth are reduced, smaller gauge wire
can be used, less heat is created, equipment
can last longer, and energy is saved.
Power Factor Correction is typically only
done when there are a lot of inductive loads.
Power Generation and Distribution Efficiency
Only 20-25% of the energy that goes into an electrical
generation plant reaches end users! The main losses are:
efficiency of the generation equipment and transmission losses.
significantly reduces these
losses: sunlight is an almost
unlimited and renewable
energy resource conversion
efficiency is less of a factor
than equipment cost. Also
distribution losses are
The BCC course EET1551 “Distributed Electrical Power
Generation and Storage” covers “Smart Grid” technologies.
Computerized Lighting Control
See Smart Grid and Smart
Home technology. These
topics are covered in
Generating and Storage”
Accomplished by such devices
as: switches, dimmers, timers,
occupancy sensors, etc. If a
“Smart Building” does not detect
any one in the building it can
turn the lights off.
Air handling, heating and
cooling can also be adjusted to
meet varying needs. For
example; a smart building can
save energy on weekends by
reducing A/C and heating.
By cutting off the flow of power for part of the 60Hz 360°
cycle power is saved. Works for lights and ceiling fans.
Not tested with CFLs. Has the common trade-off of saving
electricity but with higher up front equipment costs.
California Title 24 Electric Energy Compliance
In response to the 2000 electricity crisis, California enacted
legislation requiring indoor and outdoor lighting energy
conservation standards. The standards include control
requirements as well as limits on installed lighting power.
An approach to consuming less energy for lighting is
education. CFL or better yet LED instead of
incandescent light would reduce the energy consumption
and do it by saving consumers money.
Indoor Lighting Compliance
Requirements for lighting design and installation are
addressed primarily to lighting designers, electrical
engineers, and municipal building inspectors. Indoor
lighting is a large power consumer in commercial
By limiting the allowed power for lighting, more efficient
ways of lighting are developed.
Chapter 5 details the USGBC’s LEED program
Outdoor Lighting and Signs
Street lights, road signs, parking lot lights, etc.
consume a lot of electricity.
• Use More efficient lighting.
• Use sensors to turn lights off when sun is up.
• Use solar powered lighting when practical.
• Avoid light pollution.
See Lighting Sciences Group in Satellite Beach, Florida.
Solar Power Facts
• As of 2010 it is a very small part of US energy production,
“drop in the bucket”.
It is a demand side solution. It helps to off-set your
It is non-polluting except for the energy needed to
manufacture the equipment.
It is scalable and expandable.
It can be deployed where it is consumed.
The USA is a significant manufacturer of the equipment.
The USA is a leader in the development and R&D.
It is renewable!