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P-2 Energy Efficient Lighting Blog
Wednesday, 04 December 2013 13:39
On the surface, a commercial electricity bill can seem pretty simple. Every month you get charged for the electricity your business uses. But when you start asking why you get charged what you do, how much other businesses pay or what all the extra tariffs and fees mean, things can get pretty complex pretty quickly.
We're going to look at a few of those questions, and give you some resources that will help you break down what you see on your energy bill every month.
Most energy-efficient lighting retrofits begin with the goal of saving energy, but it's hard to know how much energy you can save if you don't know how much you're using. Understanding your electricity bill is an important step toward answering that question, and ultimately it’s one of the first steps toward saving money on your bill every month.
Different Rates for Different States
At its most basic, electricity is billed as a charge per kilowatt hour -- kWh. Depending on the type of customer you are, where you're located and (in deregulated states) who you choose as your energy provider, this rate can vary widely.
For example, during July of 2013, commercial customers in Hawaii paid $0.34/kWh. During the same month, industrial customers in hydroelectric-rich Washington state paid just $0.04/kWh. That's a pretty big difference -- and it explains why companies that use lots of electricity have been moving their power-hungry facilities to places with low electric rates.
If you're interested in seeing how your rates stack up, the U.S. Energy Information Administration's Electric Power Monthly Report is a great place to start.
If you don't know what your rate is -- you can look at your latest energy bill. Sometimes it'll be listed outright as something like a "blended rate" -- otherwise you can divide your electricity charges by your total kWh to get a close approximation.
More than Just Cents per kWh
While the cost per kWh is the simplest way to look at your electricity bill, there's quite a bit more to it than just that. To make things extra-complex, the bill you get from one utility provider could be very different from the bill you get from another utility provider. Quite a bit also depends on different regional and local taxes and assessments, and on local and regional rules and regulations.
Still, even with all the differences, most electricity bills can be broken down into just a few broad categories.
Basic Energy Usage
This is the base charge for the actual energy you will use. It will probably look something like, "Energy (kWh) Charge". It may be broken down further into "distribution" and "energy" charges, so you can see what you're paying for creating and for distributing electricity, separately.
Different Rates For Different Times
Instead of a single flat rate for energy use, time-of-use (TOU) rates are higher when electric demand is higher. This means, when you use energy is just as important as how much you use.
Time-of-use rates better align the price of energy with the cost of energy at the time it’s produced. Lower rates during partial-peak and off-peak hours offer an incentive for customers to shift energy use away from more expensive peak hours, which can help you save money and reduce strain on the electric grid.
Winter, typically November through April, can have two rate periods: off-peak and partial-peak. Summer can have three: off-peak, partial-peak and peak. During peak periods, defined as weekdays from noon to 6 p.m., May through October, your business’ electric rates will be the highest. In return, time-of-use rates at all other times will be lower than the peak rate.
Many utilities have tiered rates. The rate you pay per kWh within each identified tier is different. Some utilities charge higher rates per kWh as your electricity usage increases and moves into higher tiers. Some utilities charge lower rates as your usage moves into lower tiers. It is important to understand tiered rates when considering the energy cost-reduction opportunities of an energy efficiency project.
If an energy-efficient lighting retrofit can help you move your energy usage down from a higher and more expensive tier, to a lower and more affordable tier, the benefits of the retrofit could be even more significant.
Power Factor Charge
Power Factor (PF) is the term used to describe how efficiently a facility utilizes all of the electrical power it consumes. Some utilities will penalize a consumer if the Power Factor is below a certain threshold, say 90 percent for example. To address this, a power factor correction system can be installed on a customer’s side of the utility metering, so power factor penalties are eliminated and/or a reduction in billing is achieved.
Improving your Power Factor can reduce your overall energy cost in multiple ways, including:
1: Reducing peak KW billing demand.
Inductive loads which require reactive power are the cause of low power factor. This increase in required reactive power (KVAR) causes an increase in required apparent power (KVA), which is what the utility is supplying. So, a facility's low power factor causes the utility to have to increase its generation and transmission capacity in order to handle this extra demand.
2: Eliminating the power factor penalty.
Utilities usually charge customers an additional fee when their power factor is less than 0.95. In fact, some utilities are not obligated to deliver electricity to their customer at any time the customer's power factor falls below 0.85.
The typical payback period for this type of project is 12 to 24 months, and overall energy savings range from 5 to 30 percent.
Surcharges & Fees
Besides your charges for energy usage, chances are your electric bill includes at least a few extra fees or surcharges. These can cover anything from energy efficiency incentives to electrical grid maintenance.
Sometimes, they're tied to how much energy you use. Other times, they can be a flat fee that everyone pays, no matter how much electricity they use.
Either way, they won't generally make up a significant portion of your energy bill, but they're worth understanding and giving your attention.
Learning How to Read Your Energy Bill
Now that we've given you some general guidelines about what's on an energy bill and how they get there, the next step is to find out exactly what's on your particular energy bill.
The best resource for this is your utility. In fact, many utilities provide guides to help their customers do exactly this.
Duke Energy has a great guide for their business customers in Ohio; SCE has a less detailed guide for their Southern California customers.
Chances are, if you google "[Name of your Utility Provider] Understanding Your Bill" -- you'll come up with something similar from your utility. If not, a phone call to your utility's business support department will probably get the job done.
Tuesday, 19 November 2013 09:55
One of the biggest benefits of an energy-efficient lighting retrofit is increased lifespan. The current generation of both LED and fluorescent lighting fixtures have much longer lifespans than fixtures that were available just a few years ago. In fact, for some businesses the maintenance cost savings can be even more valuable than the energy savings of a retrofit.
However, if you want to make a smart choice about the lighting you use in a retrofit, you'll need to understand what we really mean when we talk about the lifespan of a fixture.
Getting Dimmer with Lumen Depreciation
The first principle we need to understand is that every light source gets dimmer over time. We refer to this dimming as lumen depreciation.
The first time it's turned on, a light source will be its brightest. We call this the light source's "initial lumens". At the end of its rated lifespan, the light source will be its dimmest, which we refer to as the fixture's "end of life" or EOL lumens. The difference between a fixture's initial and end of life brightness is referred to as "lumen maintenance". If a fixture had a lumen maintenance of 50%, that would mean it lost half of its brightness during its rated life. If it had a lumen maintenance of 90%, that would mean it lost just 1/10 of its brightness during its rated lifespan.
Different lighting technologies have different levels of lumen depreciation. For example, older metal-halide fixtures typically have lumen maintenance ratings of 50%-70%. The latest energy-efficient LED and fluorescent lights stay bright for much longer, and have much longer lifespans.
LED vs. Traditional Lifespans
Traditionally, a fixture's lamp (what people outside of the lighting industry would call a bulb) is the first source of failure. Just like incandescent bulbs in the home burn out after a year or two of use, in commercial and industrial HID and fluorescent fixtures the lamp will burn out after a certain time period. So with HID, fluorescent and most other fixtures, the light source's lifespan has been defined as the length of time that it's expected to take for 50% of the lamps in a large group to burn out.
That means that if you were installing 100 HID high bays, their predicted lifespan would be how long you expect it to take for 50 of them to go out.
The name for this rating method is LM-40, or to be more specific, the "Illuminating Engineering Society of North America Approved Method for Life Testing of Fluorescent Lamps, IESNA LM-40-01".
The problem is, it doesn't work for LED lighting. That's because LED lighting doesn't "fail" in the same way as other lighting technologies. Instead of going out like a traditional light source, LEDs just get dimmer and dimmer over time. In reality, it's likely that other parts of a light fixture would fail before an LED went completely "out".
So, the lighting community developed lifespan rating standards for LEDs based on the amount of time it takes for the light source to dim below usable light levels. Usable light levels can be defined as L90, L80 or L70 — the point at which the fixture has dimmed to 90%, 80% or 70% of its original output.
The IESNA has developed two standards used to rate the lifespan of LED light sources. LM-80 is a standard for measuring lumen maintenance and depreciation in LEDs. TM-21 takes the LM-80 data of an LED light source, and uses thorough, complete algorithims to make a prediction of the lifespan of a fixture.
It’s worth noting that there are two different types of TM-21 ratings, “reported” and “calculated” ratings. Without going too far into the technical details, it’s helpful to understand that "reported" TM-21 lifespans are typically more conservative than “calculated” TM-21 lifespans.
Reported TM-21 values have an upper limit of 6-times the number of LM-80 test hours. So if an LED chip is tested for 6,000 hours, its max reported TM-21 lifetime would be 36,000 hours. If the chip was tested for 10,000 hours, its max reported TM-21 would be 60,000 hours.
Calculated TM-21 lifetimes are the final result of the algorithm calculated from the LM-80 data, not limited by hours of chip testing.
TM-21 lifespans have become the standard in the industry, and that's why [P2] cut-sheets say things like, "reported L70 over 60,000 calculated 153,000 hours per TM-21". We like to give both reported and calculated TM-21 lifespans so that our customers can get the whole picture.
Real World Lifespan Differences
Now that you understand how different technology lifespans are rated, let's talk a bit about what those differences mean in the real world.
When a traditional light source reaches the end of its lifespan, it fails. Completely. The light won't come on anymore. When an LED light source reaches the end of its lifespan, it still comes on, but it's dimmer than it should be.
There are advantages to both.
When an LED light source needs to be replaced, it's not obvious. Since lumen depreciation happens gradually over time, no one's going to walk into a building one day and notice that the lights are significantly dimmer than they were five years earlier. But inadequate light levels can be dangerous, so it's important to be proactive about planned lighting maintenance with LED fixtures.
With HID lights, it's obvious when a fixture needs to be relamped, because it won't turn on. The downside is that fixtures that are completely out can be even more hazardous and noticeable than dimmed fixtures.
Fluorescent lights are a bit different from either HID or LED. They use the same method as HID lamps to define their lifespans, but unlike HID lamps, most fluorescent fixtures have built-in redundancy. This redundancy comes in the form of multiple fluorescent lamps in a single fixture. With a 4-lamp or an 8-lamp high bay fluorescent fixture, even if 50% of the lamps were to fail at the end of their rated lifespan, you’d still have 2 or 4 of the fixture’s lamps giving off light. Like HID, it’s easy to tell when a fluorescent fixture needs to be relamped, but like LED lighting, you won’t be left totally in the dark when you reach the end of a fluorescent fixture’s rated life.
With either fluorescent or LED technology, it's important to plan and execute your lighting maintenance proactively. Even though modern energy-efficient lighting lifespans can stretch for years into the future, planning at the beginning of the process can help you avoid costly headaches in the future.
Rated Lifespans vs. Your Needs
The last important point we'll discuss about lifespans is that it's important to understand that your needs might well be different from a fixture's rated lifespan.
If you're performing a retrofit with fluorescent lighting, ask yourself if your facility will be okay operating with 50% of the lamps in its lighting fixtures out. If the answer is no, you need to plan to relamp ahead of your fluorescent fixture's rated lifespans.
If you're performing a retrofit with LED lighting, ask yourself if your facility will be okay with its lighting at 70% of its original brightness. If the answer is no, you need to plan lighting maintenance ahead of your LED fixture's rated lifespans.
As always, the best way to make these decisions is with the help of a qualified lighting pro. We'd be happy to help you find one.
Thursday, 07 November 2013 13:54
When you're evaluating an energy-efficient light fixture there are three primary factors you want to look at. How much electricity it consumes, how and where light is delivered and how long it lasts.
We covered electrical consumption in our first Lighting Basics blog post, and today we're going to talk about light output.
A Disclaimer for Lighting Engineers
A quick disclaimer for our engineer friends: We're going to give a high-level overview of lighting output, without getting into the technical details. If you're a lighting engineer, you'll probably feel like we've glossed over some important details. We’re not trying to give everyone a perfect understanding of illuminance and luminous emittance. We’re trying to give our readers some tools to help them make informed decisions when they're picking a light source.
Now, with that out of the way, let's move on to a basic understanding of light output.
The Basics of Light Output
There are three terms used to describe a fixture's light output that you'll hear frequently when you're shopping for a light source: lumens, lux and foot-candles. This is true whether you're shopping for energy-efficient high bay fixtures for your warehouse, or a headlamp for your next backpacking trip. And either way, it's important to know what they mean.
Lumens are a measurement of the amount of total light created by the light source. Lux and foot-candles are measurements of the amount of light that falls on a specific area.
So, for example, if you were to shine a flashlight onto a wall 10-feet away, you would measure the total light coming out of the flashlight's bulb in lumens, and you would measure the light that hit the wall 10-feet away in either foot-candles or lux.
Foot-candles vs. Lux
The primary difference between foot-candles and lux is that foot-candles refer to the amount of light delivered in a square-foot, and lux refers to the amount of light delivered in a square-meter. Here in America where, as Grandpa Simpson said, "My car gets 40 rods to the hogshead and that's the way I likes it," foot-candles tend to be more commonly used. In the rest of the world, which tends towards metric measurements, lux are more commonly used.
Without getting too far into the details, we will note that there are some other differences between foot-candles and lux which lead some lighting engineers to argue that lux is a more useful measurement of delivered light, but that's a different topic for a different time.
That said, 1 foot-candle is roughly equivalent to 10 lux.
Why Both Light Output and Delivered Light Are Important
Now that we understand the difference between lighting output (lumens) and delivered light (foot-candles or lux), let's talk about why both measurements are important.
If you know a fixture’s input watts and its output lumens, you can get a good idea of its overall efficacy. In fact, the efficacy of a fixture is typically given in terms of lumens per watt, which is simply how many lumens of light the fixture produces for every watt of electricity it uses. A fixture that uses 100 watts to create 10,000 lumens would have an efficacy of 100 lumens/watt. That rating is a good starting place to understand the efficacy of a fixture.
On the surface, it may seem like looking at a fixture’s lumens and input wattage will give us an apples-to-apples comparison between two fixtures or two technologies. A 1,000 lumen metal halide fixture should be equivalent to a 1,000 lumen fluorescent or 1,000 lumen LED fixture, right? Well, not exactly.
Every lighting fixture and technology has unique light distribution characteristics. Some deliver a lot of their light to a very concentrated area, others spread their lumen output over a large area. Depending on your application, either characteristic could be valuable. Additionally, some lighting technologies like LED can do a better job of delivering useful light.
If you were trying to provide even light over an entire large warehouse floor, you'd want fixtures that delivered their light over a wide area. If you were lighting individual workstations for delicate tasks, you'd need concentrated light on those areas, and any spillover would be wasted light.
Since recent advances in lighting technologies have improved the ability to deliver light, today we can often swap out existing fixtures using replacements with fewer lumens, while still maintaining or even improving delivered light levels. For example, if you were replacing a legacy 20,000 lumen metal halide high bay with a modern LED high bay, you might only need a 10,000 lumen LED fixture to deliver the same foot-candles as the original fixture.
The challenge is that there’s no simple rating like lumens per watt that can give us the overall effectiveness of a fixture at delivering lumens in a specific application. There are however computer modeling tools that lighting pros can use to model the effectiveness of specific fixtures at delivering light in specific applications. Combined with their experience and knowledge, a qualified lighting pro can help you pick the best fixtures for your lighting project. If you’d like some help finding one, our [P2] sales team would be happy to connect you with a qualified lighting pro near you.
Next Up: Lifespans
Now that we've gone over both electricity and light output, our next post in the series will talk about the third critical factor in evaluating an energy-efficient lighting fixture: lifespan.
Until then send an email to
with any comments or questions, and we'll be back soon with the next post in our Lighting Basics series.
Monday, 04 November 2013 16:01
This year marks [P2]'s 21st year as an energy-efficient lighting manufacturer. Today - things are a bit different than they were 21 years ago.
Back then [P2] fixtures were made out of sheet metal made on borrowed machinery in Placentia, California. Today, our fixtures are manufactured at advanced facilities in two states.
Back then, the company's founder Mike Mogan was also the company's only employee. Today, [P2] has a national sales force spread across the country, along with hundreds of employees in our combined manufacturing, sales and support centers.
Back then Mike only made a couple different products. Today we have a catalog filled with hundreds of customizable fluorescent and LED fixtures and retrofit kits.
But one thing Mike started way back 21 years ago, hasn't changed today. Mike built his very first fixture to be exactly what his customers needed. He built it to keep his customers happy. He built it to be the best solution for that customer's application. And those are the same reasons we build lighting solutions today.
We know that without you, our customers, we could have never made it 21 years. So our plan for the next 21 years, is to keep giving you the products you need, along with the service and support you want.
Thanks for a great 21 years, here's to 21 more.
Wednesday, 30 October 2013 14:39
"First master the fundamentals."
Welcome to the first post in our Lighting Basics series, where we'll take a look at some of the fundamental concepts behind energy-efficient lighting.
If you're a building owner or manager considering a lighting retrofit in your facility, understanding these concepts will help you make informed decisions when you're working with a lighting professional to plan your retrofit.
If you're an energy-efficient lighting pro, you probably already know most of what we'll be covering. Still, we could all use a refresher course from time to time, and we'll try and provide some good information that you can use to help educate your customers.
We're going to start our series with an overview of the "energy" part of energy-efficient lighting. Don't worry - we're not going to take you all the way back to high school science class and talk about electrons, protons and ions. Instead, we're going to focus on understanding the terms that will be useful in understanding the electrical requirements of energy-efficient lighting fixtures.
Amps, Volts & Watts Oh My!
The amount of electricity required by a fixture is typically listed as wattage. Wattage is determined by a combination of amps and volts. So let's look at these three terms and see what they really mean.
Amps: "Electrical Volume"
We'll start with amps. Since we can't see electricity in the same way that we can see other things, it's helpful to use a metaphor of something we can see. So we're going to use the idea of water going through a hose to help understand electrical current.
In this case - amps are like the total amount of water that can fit through the hose. A bigger hose could fit more water, a smaller hose could fit less.
The same is true with electricity. A thicker wire (measured in "gauge") can accommodate more amps, just like a bigger hose can deliver more water.
Volts: "Electrical Pressure"
If we're using the same metaphor of a water hose, volts would be equivalent to the pressure of the water going through the hose. If you have a gigantic hose with low water pressure, you're not going to get too much water out of it. Hook up a high speed pump, and you're going to get quite a bit more water from the same hose.
You can think of voltage as the force that pushes electricity through the wires, and amperage as how much electricity is being pushed through the wires at one time.
Wattage: "The Right Amount of Electricity"
When we talk about energy-efficient lighting, wattage is the electrical term you'll hear more than any other. A lamp's wattage is the total amount of electricity required to make it run.
If you're trying to do the math, the power in watts can be approximated by multiplying volts by amps. You can get more info on the formula here.
Let’s go back to our water hose metaphor. Let's imagine we're trying to spin a water wheel with a hose. The wheel's "wattage" would simply be the amount of combined volume (amps) and pressure (volts) needed to get it to spin.
We could provide this "wattage" in a few different ways. If we had a pressure washer we could spray it at the wheel, and get the wheel to move with a very low volume of water at a very high pressure. Or, if we had a big hose we could probably get the wheel to move with low pressure, but a high volume of water.
Either way, the wheel's "wattage" would be the same - the overall amount of force required to get the wheel to move.
Calculating the Cost of Watts
So, now we understand the principles behind wattage, but how does that relate to your pocketbook?
Let's leave our garden hose metaphor behind, and imagine that you were considering replacing a hundred of your old T12 fluorescent lights in your building's stairwells with new energy-efficient LED lighting.
Your existing stairwell fixtures are 115 watt 3-lamp T12s. You're considering replacing them with [P2]'s LED RLL 31 watt stairwell fixtures.
The fixtures are rated in watts, but utilities sell electricity as kilowatt hours - kWh. That might sound complicated, but it's pretty simple. A kilowatt is 1,000 watts, and a kilowatt hour is simply the amount of kilowatts you'll use in an hour.
So - to calculate the cost-per-hour of your existing fixtures, you just multiply the watts each fixture uses (115) by the quantity of fixtures you have (100) to get the total wattage used by your stairwells (11,500). Then, you convert those watts to kilowatts by dividing by 1,000, to get 11.5 kw. Now you know that in an hour, your existing stairwell lighting will use 11.5 kWh. If your electricity company charges $0.10 per kWh (making sure you include taxes, surcharges and peak demand charges in that rate), you multiply your system's kWh by your electrical rate, and find that your existing lighting is costing you about $1.15 per hour. If your stairwell lighting is on 8 hours a day, you can do the math to find out that your lighting is costing you $9.20 per day, $64.40 per week, $279.83 per month or $3,358 per year.
To compare that with the RLL, you just plug the RLL's wattage (31) into the same equation. You find that once you've done the retrofit, the RLLs will cost you $0.31 per hour, $2.48 per day, $75.43 per month and $905.20 per year.
With just a bit of math, the hypothetical-you discovered that you could save $2,452.80 a year by replacing your stairwell fixtures. Of course - you won’t want to just look at one fixture or technology as a replacement. The hypothetical-you should also do the math for the RLL’s fluorescent cousin the RWS to see which is a better option for your retrofit.
Now, we should caution you that this is a very basic way to look at a lighting retrofit, and there are many other variables that could affect your actual savings. For example, by adding sensors you might be able to reduce the amount of time your lighting is on from an average of 8-hours a day to just 2-hours a day. Or, with LED lighting you might actually need fewer fixtures. Not to mention the benefits of longer-lasting fixtures and reduced maintenance costs.
Still - with a basic understanding of what watts are, and how they relate to the amount of money you have to give to the electrical company every month, you can begin to understand the enormous potential benefit of energy-efficient lighting retrofits.
Next Up: Light Output
In our next post in our Lighting Basics series, we'll look at how we measure the light that comes out of a fixture using things like lumens and foot-candles. If you'd like to beef-up your lighting knowledge in the meantime, check out our glossary of common lighting terms. If you have any questions or comments, send an email to
, and we'll be back soon with more lighting basics.
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