Energy Savings Calculations for Retrofit LED Lighting Fixture Installations

The major factors involved in determining the dollar value of potential energy savings using FLUSH MOUNT WIDE AREA DISPERSION ARRAY CHIP BASED LED LIGHT FIXTURES are as follows:

Fully burdened cost of electricity at the installation site

Hours of system operation per day/month/year

Location of the system, indoor vs. outdoor: and if indoor, potential reduction of air conditioning energy

Applicability of use of “intelligent lights” to reduce or eliminate load at times when it is not needed

Cost of Maintenance of the existing system

Fully burdened cost of electricity at the installation site

It is often difficult to determine the actual cost of electricity by looking at an electric bill. Most electric companies divide the bill power charges into several individual charges that in some cases may not look like they effect the cost of electricity on a cost per Kw-hr usage basis. Do not be fooled by this, they almost always actually do.

Typically, an electric company will have a system charge per kw-hr of electricity. This system charge is sometimes even further divided into generating charges and distribution charges per kw-hr of usage. There is also often a fuel surcharge per kw-hr added in as well. In addition most energy companies bill for a maximum capacity charge based on peak usage at the time they chose. This is not presented as a usage fee, but can be converted into a usage fee by simple math. This demand based fee is most generally charged on a Kv-Amp basis. It is not time related, it is just a peak demand figure at a time period specified by the power provider. If you reduce demand, your bill will drop proportionately. Some energy companies also charge a power factor correction charge to the user. It is important to know the power factor of the current equipment being replaced as well as the power factor of the replacement items in order to calculate the effects of this cost item of an electric bill. Many other charges and fees listed in an energy bill are also indirectly if not directly related to energy usage. If all these facets of the energy bill are not understood and properly added to yeild the true total cost of a Kw-hr of energy, the potential savings of a proposed upgrade may be drastically underestimated.

Hours of System Operation per day/month/year

It is important to know how many hours per day/month/year the current lighting system is being operated. The more hours the system is being operated, the quicker the system payback, and the higher the return on the owners investment in a lighting upgrade. A system upgrade seldom makes sense for retrofits if the lights are only operating a few hours a day.

An LED bases lighting retrofit generally becomes more feasible when usage rates approach at least 50- 60 hours/week. 12 hour/day- 7 day/week 52 week/year installations usually fall in the area that is very favorable in areas of average electrical power costs. 24/7/52 installations are a slam dunk in even the cheapest energy cost environments.

If you have a facility with a significant number of lights running 8 or more hours/day, an LED Fixture retrofit program should be considered.

Location of the System, Indoor Vs. Outdoor; And if Indoor, Potential Reduction of Air Conditioning Energy Use

If the lighting system is located indoors, there are additional potential energy savings related to the possible reduction of air conditioning energy usage. The amount of energy savings from this source is related to the geographic location of the installation and therefore the number of days that air conditioning is used in the facility. It is also related to the temperature at which the room is conditioned to maintain. Most people do not realize that nearly every watt of power for any light source ends up as heat in the room. Regardless of the source, the photons of light race around the room at the speed of light bouncing off surfaces until they are finally absorbed and converted into heat the same way sunlight heats a surface. This load becomes an additional load for HVAC cooling load calculations.

It is possible to estimate how much extra HVAC energy is required to remove this heat if the SEER rating of the HVAC unit is known. It is a difficult set of calculations for all but seasoned HVAC engineers to make, so another number known as the COP can be used to estimate the minimum savings to be expected. The average COP for most current systems is 3 according to the reference below. This means that one watt of HVAC energy will pump 3 watts of heat out of the room in a system with a COP of 3. This means that for every day the air conditioning is operating, an additional 33 percent of the reduced energy amount is saved by the air conditioning. In Southern locations, this is a very significant factor. In buildings with old or poorly functioning HVAC systems, this savings can equal or even exceed the direct savings of the fixtures themselves.

Application of the Use of “Intelligent Lights” to Reduce or Eliminate Load at Times When It is not Needed

Some LED lighting fixture designers, most notably Silescent, have incorporated numerous intelligent features into their drivers and thus into their fixtures. Since these drivers are microprocessor based, they are ideally suited to interacting with the environment and numerous types of control signals. Most notably, these lights have the capability to dim in an efficient and smooth manner to very low levels (less than .1% of full power). They can also be incorporated into emergency lighting system performance mode thereby eliminating an entire duplicate lighting system. The ability to receive command signals to dim or turn off or adjust to different preselected levels on command allows these lights to save even more costs for the facility owner. Intelligent lights become important cost savers when the facility or facility area occupancy is uneven. For example, motion sensored lighting systems for public bathrooms, hallways, elevator lobbies, condo laundries, etc. can be designed to not only turn on/off, but to dim in any number of desired configurations. Reducing demand when areas are not occupied in retail areas is also an opportunity for energy savings. “Intelligent lights” can be dimmed or reset to full power levels at programmable rates to minimize visual disturbances of the dimming and resetting processes. Additional savings in these environments can equal or exceed original replacement energy reductions giving paybacks up to twice as fast as originally expected.

Cost of Maintenance of the Existing System

The LED system is maintenance free. The cost of maintenance of the present system is important to consider when considering the cost savings of installing an LED system. Present system costs include the following:

Bulb replacement costs

Bulb replacement labor costs

Ballast replacement costs (fluorescent only)

Ballast replacement labor costs (fluorescent only)

Bulb and Ballast Inventory Cost

These costs may not look significant at first glance, but over time, they are a very significant system cost. This is especially true in difficult to service installation locations. Falls are one of the largest contributors to workplace injuries. Falls from ladders account for a large number of these and are often the more serious falls. The most common reason to climb onto a ladder is to change a light bulb. The cost of this work place hazard is hidden, but is in fact a very real cost to businesses.

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