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by Tracy Will
Wed, Aug 18th 2010 08:00 am


According to the latest US Commercial Buildings Energy Consumption Survey (CBECS), lighting accounts for more than 41 percent of electricity use in commercial buildings in the Mid-Atlantic region.  What this means is, if a facility in WNY makes lighting improvements that decrease their lighting energy use by 25 percent, they'll be reducing their overall electric use and associated costs by more than 10 percent.  That's why upgrading lighting and adding lighting controls can make such an impact, and why incentive programs that defray a portion of the upfront costs exist and are so popular.

With all of the incentives out there, now is the perfect time to make energy-efficiency improvements, and CIR wants to jump on the proverbial bandwagon and make those lighting improvements at our office and warehouse facilities.  In fact, we've already started the ball rolling...  So I thought I'd do an amateur lighting audit on our office building as a very basic example of how you might get a rough idea of what energy savings you could see at your facility.

I should start by telling you that I am not an estimator or project manager.  I had to ask my coworkers about our existing light fixtures and how they would be improved, and I'm passing this on to you...

In our office I counted 77, 2-foot by 4-foot, recessed, 4-lamp, 32-Watt T-8 light fixtures that were here when we moved in almost 5 years ago.  One way to make them more efficient would be to retrofit them with High Performance/ Reduced Wattage (HP/RW) T-8 lamps and ballasts that use 28 Watts per lamp.  What's that you say?  That's only a savings of 4 Watts per lamp.  How much energy could that really save?  Read on...

As I mentioned before, we have 77 of these light fixtures, and each one has 4 lamps, at 4 Watts per lamp that's a savings of 1,232 Watts or 1.232 kW in electricity demand.  So what does that mean exactly?  The next thing we need to do is calculate average hours of occupancy for the building, assuming that the fixtures would be on during this time.  CIR is open 7:30 am to 4:30 pm, Monday through Friday, but people are typically here before and after hours, so we'll say 10 hours a day, 5 days per week.  That would give us 2600 hours per year times 1.232 kW, for a total savings of 3,203 kWh per year.  That's 3,203,200 Watts of savings all from those first 4 Watts!

A 4-Watt savings per lamp may not sound like much, but for a 32-Watt lamp it's a 12.5 percent savings.  With lighting accounting for 41 percent of electricity usage, that 12.5 percent reduction can decrease overall electricity use by more than 5 percent.

Now comes the part everyone is interested in, "Show me the money!"  The simplest way to calculate your energy rate per kWh is to divide the current month's charges on your bill by the total kWh used.  For our latest electric bill, I calculated a rate of $0.151893.  So if we retrofit all of our existing T-8 fixtures, we could expect to save approximately $487 per year at the current electricity rates, more if the rates go up, which they usually do.

Now this doesn't account for things like task lighting or emergency lighting that's on 24/7.  Upgrades to that equipment would provide additional savings as well.  Lighting controls like occupancy sensors, ambient light sensors and dimming controls can significantly lower lighting loads by turning lights off when they aren't needed or reducing the power used to account for natural light.

This is also only a portion of what is looked at for a lighting energy audit.  Equipment replacements and savings calculations would be much more thorough, you wouldn't be looking at just one fixture type or reduction strategy.  You would also take improvement costs and available incentives into consideration to determine the payback period, or how long it would take for your anticipated energy savings to "pay back" what you spent to make the improvements; then the real savings begin... 

But I'm saving that for next month!

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Ed wrote: At Saint-Gobain Structural Ceramics, we built three clearly marked boxes out of 1/2" plywood with handles that are marked for battery recycling.


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