Lighting Miscellaneous

In this section, we will discuss some interesting developments in lighting and other miscellaneous information about lighting.

Induction Lighting

Induction lamps are basically fluorescent lamps without electrodes. Current is induced through electromagnetic field. The induction lamps are slightly more efficient than fluorescent lamps but with much longer bulb life of 65,000 to 100,000 hours. These benefits offer a considerable cost savings of between 35% and 55% in energy and maintenance costs for induction lamps compared to other types of commercial and industrial lamps such as high pressure sodium (HPS) lamps or metal halide lamps which they replace.

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The following video explains the technology behind induction lighting.

(Source: https://www.youtube.com/watch?v=dlU-_WtyIFM)

Below are some induction lighting case studies that shows the before and after effect when HPS lamps are switched to induction lamps in tunnels, gyms, warehouses and industrial settings.

induction-lighting-before-and-after.jpg

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Energy-saving lighting controls

So far we have discussed saving energy for lighting by using more efficient lamps. But there is another strategy that can be just as effective at saving energy and money: turn lights off when they aren't needed. Remembering to do that, however, is often easier said than done. Fortunately there are a number of simple, inexpensive lighting controls - both automatic and manual - that will turn lights on and off, helping you to reduce your energy costs. We will discuss here:

A simple automatic timer can control when and how long a light stays on. It can be located at a light switch (as shown below), at the wall plug or in a light socket. A timer will turn lights on and off on at prearranged times. This can prevent inadvertently leaving lights on all night, for example, and a timer can turn on a light before you get home in the evening. By automatically turning lights on and off for you, timers can give your home the appearance of being occupied - a valuable safety precaution when you're away.

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Photosensors measure light levels and turn on lights when it gets dark. These are particularly effective with lights that stay on all night - outdoor security lights or even small night-lights inside. 

If your primary need for outdoor lighting has to do with security, or for a few minutes of light now and then when you're putting out the trash or letting the dog in, motion detector controls might be a good investment. Motion detectors sense the motion of somebody walking up or driving within range of the detector and activate a switch to turn on the lights. Most can be set to keep the lights on for a specific period of time, such as three, five or ten minutes. The better products also include manual override features. The savings possible by installing motion-detector controls depends on how long the lights would be left on unnecessarily without these devices.

Occupancy sensors sense occupancy of a space. These sensors replace a standard light switch and automatically turn lights on or off depending on the occupancy/vacancy of the space. Occupancy sensors save energy during periods when a space is unoccupied. There are three mechanisms for these sensors to detect occupancy:

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To apply occupancy sensor properly, we need to consider a number of factors including:

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Lighting Efficiency in Action - UC, Davis

The video below shows how UC, Davis improves its lighting efficiency by application of lighting control and LEDs.

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(Sources: https://www.youtube.com/watch?v=TfDiYw0staw)

Lighting Control Application #1

A warehouse is considering installing motion sensors in each aisle. They estimate that any one aisle is accessed, on average, 3 times over a 24 hour period. It takes about 15 minutes to complete each access activity. Each aisle is served by 10, T5 high bay fixtures (4 bulbs per fixture), each bulb uses 70 watts and lasts 10,000 hours. Lights are on 24/7 all year around. There are a total of 20 aisles.   The passive IR sensors cost $60 plus $40 installation. What is the expected payback? Electricity costs 8c/kwh.   Replacement bulbs cost $4 and changing a burned out bulb costs $2 in labor.   Recycling bulbs will cost $0.50/bulb.

Solution 

General Approach: The savings will come from reduced hours of operation for these lights. What would reduced hours of operation save, exactly?

Hours of operation is a key number, it allows calculation for # of replacement bulbs per year per fixture, and consequently savings in purchasing replacement bulbs, labor involved in changing bulbs and disposal cost of burned out bulbs.

Now can you figure out hours of operation (hours on per year, remember we are trying to figure out annual savings) for the existing and proposed system?

Existing system:

Without the sensor, hours of operation = 24 hr/day x 365 days/year = 8760 hours on per year

Proposed system:

With the sensor, the lights will only be on when there is an access activity. On average, 3 access activities over a 24 hours and each take 15 minutes, i.e. 3 x15 minutes/24hr or 0.75hr/24hr (i.e. 0.75/24 of the existing hours of operation, note we need to convert unit for time)

Therefore, with the sensor, hours of operation = 0.75/24 x existing hours of operation = 0.75/24 x 8760 hours on per year = 273.8 hours on per year

 

Now let's work on exact savings or expense (i.e. disposal cost) occurred in a year (remember we are trying to figure out annual savings)

a) Savings in electricity = cost of electricity for existing - cost of electricity for proposed

Cost of electricity = unit cost of electricity ($/kWh) x electricity consumption (kWh)

For existing T5:

Electricity consumption (kWh) = Watts × hours of operation/1000 = (70 watts/bulb x 4 bulbs/fixture x 200 fixtures) x 8760 hrs/yr/1000 =490560 kWh

Cost of electricity = $.08/ kWh x 490560 kWh = $39,244.80

For proposed "T5 with motion sensor":

Electricity consumption (kWh) = Watts × hours of operation/1000 = (70 watts/bulb x 4 bulbs/fixture x 200 fixtures) x 273.8/yr/1000 =15330 kWh

Cost of electricity = $.08/ kWh x 15330 kWh = $1226.40

Savings in electricity = $39244.80 - $1226.40 = $38018.40

b) Savings (or expense) in purchasing replacement bulbs = cost of purchasing replacement bulbs for existing - cost of purchasing replacement bulbs for proposed

Note the number of replacement bulbs per year per fixture = hours on per year/life of bulb x bulbs/fixture. So

For existing:

Number of replacement bulbs per year per fixture = [(8760 hrs/year)/10000 hrs] x 4 bulbs/fixture = 3.5

Cost of purchasing replacement bulbs = unit cost of the bulb x number of replacement bulbs = $4.00/bulb x 3.5 replacement bulbs per year per fixture x 200 fixtures = $2803.20

For proposed (with motion sensor):

Number of replacement bulbs per year per fixture = [(273.8 hrs/year)/10,000 hrs] x 4 bulbs/fixture = 0.11

Cost of purchasing replacement bulbs = unit cost of the bulb x number of replacement bulbs = $4.00/bulb x 0.11 replacement bulbs per year per fixture x 200 fixtures = $87.60

Savings in purchasing replacement bulbs = $2803.20 - $87.60= $2715.60

c) Savings in labor involved in changing bulbs = cost of labor in changing bulbs for the existing - cost of labor in changing bulbs for the proposed

Since we need to change a bulb every time a bulb burns out, the number of bulb changing should equal the number of replacement bulbs. Therefore,

Cost of labor in changing bulbs for existing = $2.00/bulb changing x 3.50 bulb changing per year per fixture x 200 fixtures = $1401.60

Cost of labor in changing bulbs for proposed = $2.00/bulb changing x 0.11 bulb changing per year per fixture x 200 fixtures = $43.80

Savings in labor involved in changing bulbs =$1401.60 - $43.80 = $1357.80

d) Savings (or Expenses) in disposal = disposal cost for the existing - disposal cost for the proposed

Disposal cost for the existing = $0.50/bulb x 3.50 replacement bulbs/yr/fixture x 200 fixtures = $350.40

Disposal cost for the proposed = $0.50/bulb x 0.11 replacement bulbs/yr/fixture x 200 fixtures = $10.95

Savings in disposal = $350.40 - $10.95 = $339.45

Total annual savings = Savings in electricity + Savings in purchasing replacement bulbs + Savings in labor involved in changing bulbs + Savings (or Expenses) in disposal

= $38018.40+ $2715.60 + $1357.80 + $339.45 = $42,431.25

e) Capital cost in this case involves purchasing and installation cost of the motion sensors.

Capital Cost = cost of purchasing motion sensor + installation cost

= 20 aisles x 1 sensor/aisle x $60/sensor + 20 aisles x 1 sensor/aisle x $45 installation cost/sensor = 20 x 1 x $60 + 20 x 1 x $45 = $1200 + $900 = $2100

f) Now we need to figure out pay-back. Remember pay-back is the time it takes for the the annual savings to offset the capital investment, therefore we can figure out pay-back using the following formula

http://my.ilstu.edu/%7Egjin/p2/Lighting_P2_in_Energy/ada-equation.gif http://my.ilstu.edu/%7Egjin/p2/Lighting_P2_in_Energy/lessonimages/equation_image9.gif

In this case, the capital investment is the cost of switching bulbs which has been found to be $ 2100. Annual savings were found to be $42,431.25

So payback (yr) = $2100/$42,431.25= 0.049 year = 0.049 year x 12 months/year = 0.59 months

g) To calculate Return on Investment (ROI), we need to use the following formula:

http://my.ilstu.edu/%7Egjin/p2/Lighting_P2_in_Energy/ada-equation.gif http://my.ilstu.edu/%7Egjin/p2/Lighting_P2_in_Energy/lessonimages/equation_image10.gif  

In this case, ROI = 1/0.049 = 2021%

The completed Excel worksheet for above example can be found under Unit 3 learning resources by the name of "Lighting Control Application 1".

Lighting Control Application #2

In a small office building, the photocopy room is used about 10 minutes out of each hour. Lights (two T8 fixtures each using 150 watts) are on during normal business hours (8 hrs a day for 5 days a week and 52 weeks a year). The company is considering buying and installing a motion sensor through Actonenergy.com. It will cost about $10 to install. What is the expected payback?

The savings will come from reduced hours of operation for these lights. What would reduced hours of operation save, exactly?

Hours of operation is a key number, it allows calculation for # of replacement bulbs per year per fixture, and consequently savings in purchasing replacement bulbs, labor involved in changing bulbs and disposal cost of burned out bulbs.

Now can you figure out hours of operation (hours on per year) for the existing and proposed system?

Existing system:

Without the sensor, hours of operation = 8 hr/day x 5 days/week x 52 weeks/year = 2080 hours on per year

Proposed system:

With the sensor, the lights will only be on when the photocopy room is being used, i.e. 10 minutes/hr or 10 minutes/60 minutes (i.e. 1/6 of the existing hours of operation, note we need to convert unit for time)

Therefore, with the sensor, hours of operation = 1/6 x 8 hr/day x 5 days/week x 52 weeks/year = 346.7 hours on per year

You should be able to figure out the rest, similar to Lightig Control Application #1, right?

Have I Grasped the Key Concepts Here?

 

Of the following statements on induction lighting, which one is INCORRECT?

 
 
 
 

 

Energy-saving lighting controls include

 
 
 
 
 

 

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