Figure 1: Whole Foods market outreach to promote sustainable seafood choices. (4)

We will explain the general Life Cycle Assessment theory now, and then use a simplified LCA to quantitatively compare the true benefits and costs of incandescent versus compact fluorescent (CFL) bulbs. There is a three step process to a Life Cycle Assessment. First, researchers outline the goal and scope of the assessment. This tailors the system boundaries and centralizes the analysis around a specific sector or product. For example; do we care only about the direct emissions from our building, or are we interested in the emissions behind the meter? Second, researchers use one of several quantitative methods to build an inventory of the inputs and outputs for a given product system throughout its entire life cycle or supply chain, capturing the total material, emission, and energy flows within the system boundaries. Third, researchers conduct an impact assessment based on the inventory analysis. These impacts broadly fall into categories such as ozone depletion, human toxicity, or global climate change. Taken together, a thorough LCA provides the quantitative measures to draw conclusions and iterate a service or product.

Generally, there are two methods to conduct a life cycle assessment. An Economic Input-Output (EIO-LCA) approach quantifies the material, energy, and financial flows resulting from economic activities within different sectors. This was developed principally by Wassily Leontif in the 1970’s and brought into mainstream use by Carnegie Melon University[5]. A Conventional (or Process-Based) Life Cycle Assessment approach focuses on a specific product or service rather than a sector, typically defined by a function and normalized with a functional unit. For example, the purpose of a PV plant is to supply electricity (function), and the basis for the LCA could be a kWh of electricity (functional unit). The major advantage of this method is the ability to differentiate two products or services that have the same function.

To put this theory to practice, let’s consider the decision to replace a light bulb with either a CFL or incandescent bulb using a Process-Based LCA. Since we’re concerned about both our pocketbook and the environment, let’s use our LCA to quantify both the financial aspect and two emission streams (mercury and CO2 emissions), and limit the scope to lighting and disposal.

Using a simple LCA to determine the most 'sustainble' lighting choice (6).

The function of the light bulb is to provide lighting for 6 years (6 hours / day), with a required functional unit of approximately 700 lumens of lighting (fairly standard bulb). A quick Home Depot search turns up two bulbs capable of providing the necessary illumination: an incandescent bulb ($1.30, 60W, 986 hr lifetime) and a CFL bulb ($6.50, 13W, 9855 hr lifetime). A deeper look reveals that the CFL has up to 0.03% mercury content, a concern amongst some homeowners. At first glance, it may be enticing to go with the incandescent; the low cost and lack of mercury may seem like an easy decision. But let’s expand the analysis.

The six year lighting scope translates to 13,140 hours of illumination. This means we need to purchase 2 CFL’s and 14 incandescent bulbs, based on our manufacturer lifetime guarantees. When we account for the electricity consumption, this translates to ~171 kWh for the CFL, and ~788 kWh for the Incandescent. Using a price of $0.12/kWh for electricity, this becomes ~$20.50 for the CFL and ~$94.60 for thei. Suddenly the financial picture shifts; the total cost for the CFL bulb becomes ~$33.50, and the Incandescent bulb ~$113.30, a difference of nearly $80 in favor of the CFL.

The environmental picture is a bit more complicated. The US grid emits ~0.012 mg of mercury and 0.66 kg of CO2 per kWh of electricity. If we assume all of the mercury already in the bulb ends up in the landfill, the CFL releases a total of 9.2 mg of mercury and 113 kg of CO2. The incandescent bulb releases 9.4 mg of mercury and 520 kg of CO2. Essentially, the increased energy consumption penalizes the incandescent’s CO2 emissions inventory.

Life cycle inventory of cost, mercury, and CO2 emissions.

This simple Life Cycle Assessment exercise highlights the importance of thinking holistically, giving us the measurements to make a ‘sustainable’ choice. From a financial perspective, the CFL is the clear winner. From an ecological perspective, the CFL has a much better CO2 emissions profile, and both bulbs perform equally with respect to mercury emissions.

Today, various organizations have begun to promote sustainability through more rigorous quantitative frameworks. The Global Reporting Initiative[7], a non-profit organization, is striving to make sustainability reporting a standard industry practice. The International Standards Organization[8] currently has voluntary Life Cycle Assessment standards as part of its 14000 Environmental Management Series, with the intention to indentify, improve, and monitor the environmental impact of activities. The Earth Day Network[9] provides a simple tool to calculate the ecological footprint of a lifestyle, using earth’s global hectares instead of materials or dollar indicators. High end LCA software such as SimaPro[10] gives the ability to create very detailed inventories for unique systems.

Some products that claim to deliver energy efficiency are actually just energy reductions without the efficiency. Doing the same thing more efficiently does not sacrifice an end product (light levels stay the same, the amount of cooling your AC provides remains the same, etc.), energy reductions not gained through energy efficiency might sacrifice operations or comfort. Energy reductions are fine where appropriate – many commercial office spaces in the U.S. have lighting levels well in excess of modern recommended amounts and are therefore excellent candidates for removing 10-40% of the lamps – but if light levels are already appropriate, reducing the number of lightbulbs may not be a good idea.

Fundamentally, life cycle assessments attempt to measure sustainability to aid decision making. Much work remains to standardize the framework and better interpret the impact assessment, but it’s exciting that Life Cycle Assessment application has moved into mainstream discussions. In the meantime, give your personal life an ecological score with Earth Day’s nifty calculator found here.

Sources
[1] http://www.wholefoodsmarket.com/values/seafood.php
[2] http://www.amourvert.com/green/
[3] http://www.un.org/documents/ga/res/42/ares42-187.htm
[4] http://www.wholefoodsmarket.com/seafood-ratings/
[5] http://www.eiolca.net/
[6] sophia.smith.edu
[7] https://www.globalreporting.org
[8] http://www.iso.org/iso/iso_14000_essentials
[9] http://www.earthday.org/footprint-calculator
[10] http://www.simapro.co.uk/

Or maybe not. Since it is, in fact, a relatively obscure energy modulating solution. And though it has recently begun being marketed as an energy efficiency panacea, odds are you have probably not heard of it—yet.

Voltage optimization is the process by which the voltage entering a piece of equipment is fine-tuned (usually reduced). A number of technologies of varying degrees of sophistication deliver voltage optimization: many are simply adjustable transformers that step down the voltage, just as your utility reduces your voltage on your nearby poles. In theory, voltage optimization lowers energy use, because of the equation:

• P = I * V   where

• P = Real power used by a device measured in Watts
• I = Current used by a device measured in Amps
• V = Voltage used by a device measured in Volts

If we make V lower, P decreases as well. Saving Watts. Saving Power.

Sounds great. Of course, so do the best synthesized bird calls. That doesn’t make them real.

While voltage optimization solutions can deliver energy savings, principally for certain kinds of motors, in many cases their value has been grossly inflated by marketing efforts. Voltage optimization advertisements saying you’ll reduce carbon emissions in your home by 10% are in most cases simply greenwashing.

What is greenwashing? It is the practice of marketing processes or technologies as environmentally-beneficial when in fact their benefits are negligible or non-existent. The Greenwashing Index through the University of Oregon tracks some corporate products and advertising that are suspected of greenwashing.

But general consumer goods companies are not the only ones that greenwash their products. Much greenwashing relates to energy efficiency. How to properly verify energy efficiency efficacy is well-established but that doesn’t mean consumers can do it or that they know to ask for it.

Some products that claim to deliver energy efficiency are actually just energy reductions without the efficiency. Doing the same thing more efficiently does not sacrifice an end product (light levels stay the same, the amount of cooling your AC provides remains the same, etc.), energy reductions not gained through energy efficiency might sacrifice operations or comfort. Energy reductions are fine where appropriate – many commercial office spaces in the U.S. have lighting levels well in excess of modern recommended amounts and are therefore excellent candidates for removing 10-40% of the lamps – but if light levels are already appropriate, reducing the number of lightbulbs may not be a good idea.

If I reduce the voltage going to your light bulb, it receives less power. But if it receives less power, it produces less light. If you do not mind lower levels of light, no problem. But then you could have just bought a lower wattage light bulb instead. Voltage optimization is usually no more than a simple energy reduction. By contrast, you could buy a 20-Watt incandescent light, but it would produce about 25% of the light as a 20-Watt compact fluorescent light. Same power, greater usefulness: that is energy efficiency.

In many cases, voltage optimization delivers temporary power reductions. But in many of these cases, these power reductions do not actually provide overall energy savings because of the nature of the energy consumption. Some specific cases will help illustrate this point:

• If you reduce the voltage to a 2000 W space heater by 10%, so that it now only uses 1800 W, it will also produce less heat. You will need to run it longer to give you the desired effect though, so there are no real energy savings.
  
• If you reduce the voltage to your hot water kettle, it will take longer to boil. There are no shortcuts to the specific heat of water: it needs 1 BTU of energy to increase its temperature by 1 degree Fahrenheit. Reducing the voltage just means the kettle will need to draw less current for a longer time.
• If you reduce the voltage to your refrigerator, it will run the compressor for longer. You will not save energy, because your refrigerator has to produce a set point temperature. There are no shortcuts to thermodynamics.
• If you reduce the voltage to a motor outside its recommended 10% tolerance you will degrade the motor’s operation. The U.S. Department of Energy has helpful papers on this topic. If the motor is fully loaded, then even on a small voltage drop the motor will draw more current to meet the load. This will cause it to run hotter, shortening its life. A voltage drop will also reduce torque and motor efficiency (see p. 385 in this IEEE article for a more thorough treaterment). Not good at all. If you reduce voltage for a motor serving a variable load, there will be some energy savings (this happens because of the relationships between slip, load, efficiency, and voltage and the fact that magnetizing losses are lower at decreased voltage; the short explanation here is the slip at a lower load is less, which actually is more efficiently served by a lower voltage, so in this regime a lower voltage will still meet the load requirements while reducing magnetization losses. Therefore, the optimal voltage decreases as load decreases). Nonetheless, a Variable Speed Drive is still widely considered a more robust and more cost-effective solution for variable loads.

As you can see, the devil haunts the details of each application. The above is only a summary. The United Kingdom’s Ministry of Defense (MoD) conducted a wide-scale review of the energy savings opportunities resulting from Voltage Optimization. Their conclusions broadly match with those of our team.

Voltage optimization has been a major topic in the United Kingdom in particular because of reports of systemic overvoltage. This results partially from 1995 EU regulations that required voltages to come down to 230 Volts. In many areas of the UK, this did not occur. As a result, reducing the voltage that enters homes and offices offers some savings opportunities for consumers. But because transformer losses in voltage optimization equipment are still a few percent, a better solution would be to reduce voltage levels fed into the grid and, especially, to adjust the step-down equipment along the grid so that it produces the targeted 230 Volts. Skeptics of voltage optimization in the UK abound.

In a normal grid, proponents of voltage optimization argue it can reduce energy consumption by as much as 10%. It can. In select circumstances: mostly in industrial concerns, sometimes in commercial concerns, and almost never in homes. The main advantage of voltage reductions on the grid are temporary power reductions when the grid is stressed, not overall energy savings.

At Carbon Lighthouse, our excitement for technologies like voltage optimization is muted partly because too often voltage reducers are simply a greenwashed product. More importantly, voltage optimization, while it has its limited place, does not bring us closer to a more sustainable planet. Compact fluorescent lights cut the lighting energy needed in a home by 75% but still deliver the light we need. High efficiency washing machines use less energy and less water while providing the same clean clothes. Variable speed drives cut motor energy by 20-80% and deliver the power we need to pump chilled water and ventilate our buildings. Drawing window blinds on a hot day reduces heat load on our buildings. These are the kinds of changes that bring us closer to where our planet needs to be.

Not all that glistens is green.

End Note

Voltage imbalance in a motor can be a serious problem, causing substantive reductions in energy performance. For such motors it would be beneficial to undertake voltage correction (which frequently can only be solved not with a silver bullet “voltage optimizer” but rather with a comprehensive analysis of the building’s electrical one-line diagram, ground faults, 120 Hz vibration issues, and faulty power factor correction equipment).

The answer to those questions is tools. The very items that separate us from the rest of animalia (ignore those pesky Chimpanzees for a moment) also help differentiate reliable, proven clean energy from guesswork.

As with any tool, having the right one for the job is critical. Since we live in a world teeming with devices that heat, cool, light, ventilate, refrigerate, wash, dry, humidify, make phone calls, and hundreds of other energy consuming tasks, it turns out we need many different tools for many different size jobs. Below is some of the gear that a proper energy study will utilize:

Senses. Your five senses are fast-acting and valuable, albeit imprecise, energy analysis tools. Plus, you can never forget them in the office. Loud noises coming from a rooftop unit might suggest a loose belt. Hearing fans kick on in an unoccupied building in the middle of night tells you that there is equipment in need of a time clock. Strange smells may reveal broken units. Excessive pressure when opening a door alerts you to an air pressure balancing problem. Eyes detect uninsulated pipes and unnecessary lights. Best not to taste anything though.

Data logger. These do what you’d expect them to do: record information. They can be as little as a deck of cards or the size of a brick. Either way, these little boxes are the energy engineer’s favorite pal. You don’t leave home without them. They can record almost anything that can be transformed into an electrical signal: temperature, voltage, current, lighting levels, humidity, magnetic fields surrounding a motor. They can take measurements every second or every hour. They’re limited by memory storage space, but usually provide at least a few months worth of measurements.

Light sensors. These go in a light fixture right near, but not touching, a lamp. Then you link them to a data logger (many data loggers have light sensors built in). They record the lux or footcandles – units of lighting levels – every five minutes. This makes it easy to see how often your lights are on and therefore how much energy you’d save by installing occupancy sensors or more efficient lamps.

CT clips. Not to be confused with ammunition clips or movie clips, these are small metal rings that are wrapped around a wire. Disappointing, it’s true. But current transducer (CT) clips should not be underestimated. Simply by putting them around a wire, one can measure how much current is flowing through a wire. No need to actually touch the wire. Sound impossible? Turns out, electricity and magnetism can do more than make souvenirs stick to your refrigerator door. The amazing basic principle behind most current transducers is the Hall Effect. The Hall Effect is an extremely powerful property of electrical systems used in all kinds of other applications including your anti-lock brakes. (This principle is related but not identical to how transformers work. Transformers are those boxes at the end of your cell phone charger that steps down voltage from 120V to 12V).

Real power meters. Perhaps you’ve learned that Power = Current • Voltage, but that’s not the whole story. In AC circuits, energy is lost when current and voltage get out of phase. The amount of this loss is quantified by a “power factor”. To be efficient, you want Power Factor to be 100%, but that isn’t always the case. A real power meter takes live measurements of current and voltage as well as the phase shift between them (the bigger the phase shift the lower the power factor). This let’s you know exactly how efficiently equipment is using power.

Ratchet. No kidding. There’s no substitute for a good 5/16” ratchet to quickly access packaged air conditioning units.

Humility & Brain. It’s true. A humble brain is your best tool. We try to use it almost every day. Generally, we succeed. If you’re dealing with anything electrical, even if it’s only 120 volts, be humble. Do not touch anything you do not understand, and if you think you understand it, question your understanding. If you don’t know what lineman gloves are or what an arc blast event is, you definitely should not be touching anything.

Energy monitoring gear is fun and powerful. And there’s a lot of it. Hundreds of useful tools were not mentioned here including: carbon dioxide sensors, infrared temperature guns, flow meters, sling psychrometers, motor loggers, and solar pathfinders. But please remember that even for properly-trained personnel, tinkering with electrical equipment can be lethal, even at low voltages. If you’re not trained in how to use this equipment and really want to learn (which we hope you do), get trained! Then start measuring. And you’ll soon be able to quantify how much more sustainable you can make our planet.

Much time is spent talking about solar project finance. Not least of all by us: here, here, and here. There are a number of reasons for this: solar projects involve large dollar amounts, they are more commonly financed than efficiency projects, and they are highly visible. They are, however, generally less profitable investments than energy efficiency projects. Which leads to a reasonable question: why don’t more people implement energy efficiency projects?

Reasonable, but mysterious. This question has caused a lot of headache and heartache for energy developers, financiers, contractors, and policy makers for decades. And for good reason. If you were guaranteed a 60% return on your money, you would take it. Unless, apparently, it were an energy efficiency project. It happens all the time. Last week, Carbon Lighthouse identified an equipment controls opportunity that provided a property owner a 141% internal rate of return. The project paid for itself in six months. We guaranteed the savings. The office building owner remains undecided. Our team isn’t surprised. Why not?

Energy Efficiency Projects

Let’s back up for a moment to consider what exactly is an energy efficiency project. There is all kinds of equipment in buildings, and the lights over your head and your desktop computer and monitor (hopefully an energy efficient flat screen) are just the beginning. Rooftop heat pumps suck up electricity to compress refrigerant fluid. Supply fans blast air through ducts and into rooms. Return fans suck stale air back out to the roof. Giant pumps thrust chilled and hot water through loops inside the building’s skeleton. Induction motors power chillers and elevator banks. Natural gas combusts inside small locomotives of boilers. It’s busy.

All this equipment not only obsolesces, but also stops working as designed, is not properly maintained, and is often running when no one needs it. You can replace the old motors and lights with more efficient ones. You can control fans and chillers and waste much less energy by putting VFDs on them. You can adjust heat pumps so that they turn off automatically when people don’t need them so that, for example, they don’t consume energy at 4 am on a Sunday when the building is locked. To implement an energy efficiency project means to identify these opportunities and put in new lights, motors, pumps, fans, controls, and drives and save people a whole lot of energy, carbon, and money.

EE Financing

The paybacks on such energy efficiency projects can be very high, but the initial capital cost is sometimes too much for a property owner. For example, if a school can implement a $50,000 lighting project that saves $20,000 annually for seven years, it should; but it might not have $50,000 available.

This is where energy efficiency financing becomes so critical. The school does not have to pay anything up front; it can simply split the savings for five years with a financier who will pay for the project. The school receives less savings than it would if it had paid for the project itself, but doesn’t need to front the capital. After five years, the school enjoys the full savings of the project. Because energy efficiency projects are so profitable, they are an easy way for both school and financier to make or save money while benefitting the environment.

It’s not a new idea. In 1985, the US government authorized the first Shared Energy Savings (SES) agreements. These contracts were ultimately enshrined as Energy Savings Performance Contracts (ESPC), energy efficiency project financing mechanisms used throughout  the federal government. Energy efficiency expert John Frenkil has an excellent piece on their history. But while ESPCs in federal contracts are a promising mechanism and have provided proven savings, as of 2008 only 500 projects had been implemented. There are 5 million commercial buildings in the United States. There’s a bit of room to grow and accelerate.

So why isn’t energy efficiency finance a bigger industry? What are some of the chief obstacles?

Let’s Count the Ways

• Agency problems between corporate managers and facilities engineers have resulted in underinvestment. Many corporations do not view infrastructure upgrades as investments, and facilities engineers with set annual budgets do not receive economic returns from efficiency projects. Any project that takes longer than 12 months to pay for itself is not implemented. (We’ve been delighted to note that several property management firms we’ve met with of late now provide their facilities chiefs with 36 month budgets).

• Interest Rate mindset. Energy efficiency savings sharing agreements (like solar power purchase agreements) provide financing so the purchaser saves money without having to pay anything up front. It would be a more profitable investment for the facility if it put forward its own capital, and this unsettles CFOs. They know their organization can borrow money at say, 7% interest, and instead of thinking about the project as an energy savings agreement, they take the stream of payments they’re making to the financier and try to back out an effective interest rate. While rational, this misses the opportunity for what it is: a chance to save money without spending any. The problem is that too often the organization looks into borrowing more money, decides it doesn’t want to take on more debt, but also decides it doesn’t want anybody else’s money either and shelves the energy savings agreement and leaves the efficiency opportunity to languish. This makes the environment cry and cry. Just look at poor Niagara falls. Won’t stop weeping.

• Energy is cheap compared to rent. Even now, if office space in Manhattan costs $50/sq ft, utilities only cost $6/sq ft. To commercial real estate owners, lowering energy expenses only merits so much attention when compared with retrofitting a lobby or finding other ways to improve property values.

• Are the savings real? Measurement and verification has much improved over the past few decades. Data logging methods and equipment now produce reliable analyses of energy consumption. Those who conduct energy studies, as we do, have a bevy of mechanical and statistical tools at their disposal. Temperature, humidity, occupancy rate, and operating hours can all be accounted for when baselining energy usage over many months and compared year to year. The Department of Energy’s eQuest program is an impressive piece of software, and the scope of the DOE’s guidelines on implementing M&V for energy savings contracts reveals how far energy savings measurement has come. As a result, a quality energy study can determine with very high accuracy the savings created, enough for energy service companies to guarantee them. But few property managers understand this, nor are they used to structuring contracts around energy savings.

• Financing risk: If an energy efficiency financier is only funding a handful of projects there is credit risk that a single default could imperil the investments. In theory, financing hundreds of short-term efficiency projects should obviate some risk. Lax mortgage underwriting practices of course, recently showed some of the limits to the power of bundling, as you may recall, and the larger financing entities are still trying to wrap their heads around how to provide financing for energy efficiency.

• Secured collateral concerns: If a property owner goes bankrupt and can no longer meet its energy savings payments, the collateral, half-used lamps and ballasts, have minimal resale value. So too, with a variable speed drive. Even in the best market conditions, half-used energy efficiency equipment will not command half the initial sale price. If a customer is delinquent but not bankrupt, however, the threat of removing or remotely disabling the equipment can be an effective lever.

• Collapse of PACE: PACE (Property Assessed Clean Energy) financing is a recent mechanism through which special, local bonds are issued for purposes of investment in (principally) residential energy efficiency and solar projects. PACE could have quickly deployed far-reaching efficiency project investments. Due to concerns about municipalities taking a lien senior to that of mortgage lenders, however, the Federal Housing Finance Agency asked local governments to reconsider. Interestingly, the battle between mortgage lenders and local government over property lien seniority is nothing new.

• On Bill Financing is still being worked out. Some utilities finance energy efficiency measures, with customers making monthly payments to pay down the project cost via their utility bills. But balancing rebate levels, loan terms, and loan amounts to incent owners to sign up has been challenging to get right, and these programs still remain uncommon.

• Efficiency is unsexy. Solar panels look sleek to most. Windmills enrapture some. Light bulbs are boring to all. Ditto for motors. Ditto for going through a rusty roof hatch and taking a metal panel off a rooftop cooling system to install an evaporative condensor. But this perception is partly a marketing shortfall on the part energy efficiency service providers. The environmental good of efficiency is as real as solar, and the financial implications to the customer a heck of a lot better. It is the best first step to take.

In summary, obstacles abound. That’s the bad news. The good news is they are surmountable. And as organizations and companies seek to help the environment in the most cost-effective ways possible, the potential for energy efficiency finance expands. We already find certain subsectors much more interested in financing than others, and who will lead the way is still up for grabs. The opportunity is enormous, and we at Carbon Lighthouse are trying to make it real.

Before investing in any major efficiency upgrade, corporations should ask exactly how the proposed savings will be Measured and Verified after the installation is complete. Why? Replacing the central air conditioning system of a 50-floor high-rise might cost $4 million dollars. This could be a good investment if it saves $800,000 per year for the next 25 years, but what if it only saves $400,000? $200,000? For efficiency (and really all renewable energy issues), the devil is in the details. Luckily, the details of accurately measuring efficiency really are not all that complicated.

Here’s how efficiency projects can be reliably measured and verified. (These are not my ideas, by the way, but are common practice by the best efficiency firms and regulatory agencies throughout the country.)

Lighting:

Lighting is the easiest type of efficiency project to verify. Most commercial and manufacturing spaces are full of fluorescent tubes, so I will use fluorescent tubes as an example, (but this method works for any lighting replacement).

The first thing to know about most commercial/industrial lights is that the wattage on the lamp (what most people call a bulb), e.g. 55 watts, is NOT the wattage that is used by the bulb. Fluorescent (and most other) lamps are driven by a “ballast,” a device that sends electricity into the lamp at the exact right voltage and frequency. Ballasts have a “ballast factor,” which allows the lamp to be over or under-driven, drastically changing the amount of electricity the lamp draws. Think of this as a permanently set dimmer switch. To get the actual watts used by the lamp, you simply multiply the lamp wattage by the ballast factor. (Technically, the ballast factor represents the percent of rated light you get out, not the percent of watts actually input, but the relationship in this case is linear so multiplying lamp wattages by ballast factors gets you accurate to within half a watt.) Ballast factors are usually 0.78, 0.88, 1, or 1.2. To figure out your watt savings, multiply the wattage and ballast factors for your old lamps and new lamps, subtract the two sets, and you have your watt savings.

After you have figured out your watt savings, divide by 1,000 to get kW, and then multiply by number of hours you will run the lights each year to get annual kWh savings. Voila. No complicated “measurement” required (except to find out the ballast factor and wattage of the lights you are replacing).

Example with numbers:

You are replacing a 55-watt lamp with a 32-watt lamp. A novice (or sleazy) contractor would tell you the power savings will be 55 – 32 = 23 watts, but reality (what you will be billed on) could be quite different. Go physically look at the old ballasts (your facilities manager will have an extra one lying around, or if not he can pull one out of the ceiling for you in five minutes). Say the old ballast factor was .78, but the new ballast factor is 1. This means the power savings will actually be (55 * 0.78) – (32 * 1) = 10.9 watts, less than half what you would expect! This means this lighting project will take more than twice as long to pay for itself than expected. You will also get substantially more light than you previously had (higher ballast factors mean more light as well as more energy use).

What if you are using a lamp without a ballast (like a Sodium Sulfur lamp)? Well, in the case of a sodium sulfur lamp it actually does have a ballast, it is just called an RF Power Supply, and it has a ballast factor equivalent. If you are using something like an incandescent that really has no ballast, then you can just look at the wattage. But for Pete’s sake stop using incandescents.

If you are really a stickler, ballasts act slightly differently if they are powering one, two, three, or four lamps, so you should look at the “system efficiency” of the new system on the cut sheets. Cut sheets are technical specifications the manufacturer will give you, and you can look up the total wattage draw of lamp/ballast combinations there. System efficiency usually only differs by one or two watts from just multiplying the lamp wattage by the ballast factor.

Final word: do not ever just change lamps, change both lamps and ballasts. A good portion of the energy savings come from replacing your old magnetic (the humming, flickering) ballasts with new quiet, non-flickering electronic ballasts.

Motion Sensors:

Motion sensors are where measurement and verification starts to get fun and require a little equipment. Unlike a lamp/ballast replacement where the energy savings can be calibrated and calculated, motion sensor savings cannot be predicted but must be directly measured.

A current transformer (CT Clip for short) is a ring you can put around a wire that measures the current going through that wire. When hooked up to a power meter that simultaneously measures voltage and power factor, CT clips allow you to tell the power being used by any wire or circuit. Power meters can be easily attached to a recording device that logs their measurements (a logger), and I will now refer to this setup as a “power-logger.” Power-logging is a way to directly meter energy savings from efficiency, much akin to directly metering the output of a solar array.

Back to motion sensors. Ideally, your lights will be on a dedicated circuit (in non-technical speak, this means the wires that connect all your lights are separate from the wires that connect all your computers, etc.). If this is the case, you can simply clamp a power-logger onto your lighting circuit and wait a few weeks.

The power-logger will give you a graph that looks something like this:

Unless those weeks were unrepresentative (e.g. you measured during Christmas), you should be able to figure out the annual hours of operation of your lights on motion sensors. Simply compare this to the annual run hours before you installed motion sensors, and you have your energy savings.

If your lights are not on their own dedicated circuit, measurement and verification is a little tougher but still not too difficult. Put power-loggers on a few representative light fixtures (one in the cubicle area, a couple in private offices, etc.), and do the same thing. You will get a couple different graphs and can back out what all the fixtures’ new run hours will be.

For private offices, expect savings of as much as 25%. For cubicle areas, expect only 10% reductions. [2]

Elevator Motors (or putting Variable Frequency Drivess on any motor):

The Measurement & Verification method is similar to lighting, even though the savings are not from decreased operating hours but are from more efficient mechanical and electrical equipment. The main difference in measurement and verification is that you need to measure usage both after AND before you change your motors or add Variable Frequency Drives too them.

Measure the energy use of your elevator motor circuit (or a couple individual elevator motors if your building does not have a dedicated circuit) with power-loggers for a few weeks. Then, do the motor change, and measure the energy use of the new motors for a few weeks after the upgrade. You can then compare the new motor usage with old and get annualized energy savings.

In my experience, average savings for elevator motors average 0.2 kW per Horsepower of elevator replaced, but the standard deviation was 0.12 kW. In other words, the variation in energy (and hence money) savings is so high with elevator motors that you have to directly measure the equipment before and after the upgrade to have any idea what your elevator motor replacement is saving you.

If you are putting a Variable Frequency Drive (VFD) or Variable Speed Drive (VSD, basically the same thing as a VFD) on your motor, this could save you energy too. It is difficult, although by no means impossible, to predict the energy savings ahead of time, but you need to know some details about your system ahead of time. I will not go into too much detail here, but if you are able to measure the flow of fluid through your system, be it water or air, you can usually figure out savings using either pump or fan curves, motor drive curves, or fan and pump affinity laws. The picture to the right shows how this process starts, but when in doubt (or when in doubt of your engineering firm), make sure to measure the energy use of the motor before the retrofit for a few weeks, and then again after the retrofit for a few weeks with a power-logger. I will save the technical details of how a VFD works for another time, but for now I will just say that if you have any motors with frequently fluctuating loads, VFDs can be an amazing investment. If the load on a motor is constant and the motor is throttled, you can also save energy by using a VFD.

Chillers:

Chillers make the cold water that is used to provide central air conditioning in most large office buildings. Chillers are large pieces of equipment, and measuring the energy savings associated with replacing them can be difficult. Like a car engine, chillers are more or less efficient depending on how hard they are working. The “load” of a chiller is measured in “tons” (one “ton” means the chiller is removing 12,000 btu/hour of heat from the coolant being fed into it), and how much energy it is using is, of course, measured in kW.

Chillers have an efficiency curve, which looks like this:

Source: www.energy.rochester.edu/efficiency/chilleranalysis.pdf

You will note this chiller is most efficient when it is fully loaded. This has several implications which I will talk about in future blog posts, but for now just note that over-sizing your chillers and running them partially loaded will cost you boatloads of money unless you put what is called a VFD on them. (The engineers and chiller manufacturers will know what this means.)

To determine how much energy your chiller replacement is saving, you need to know two things: how much cold water the chillers produced (gallons and temperature), and how many kWh of electricity they took to produce it.

If you are lucky, your facilities engineers will have kept “chiller logs,” where they wrote down the output of the chiller in tons, gallons of chilled water, or some other metric allowing you (or us) to calculate the load on the chiller year round. Then, you can simply measure (again with power-loggers) the efficiency of the chiller at several different loads and calculate how much energy it used per year.

You can then couple the old chillers’ load curve with your new chillers’ efficiency curve to calculate how much energy your new chiller will use and thus determine the energy savings.

If your facilities manager did not keep a chiller log (this is common), then if you really want to figure out what your savings will be, you have to wait till summer and then power-log and load-log your chiller the entire summer before installing any new chillers.

What if you already did the chiller replacement and have no logs? Then it is time for utility bill data. A clever engineer can usually back out something as large as air-conditioning from your utility bills, but this is non-ideal. For one, many factors go into your utility bill, so if you changed tenants, added a data-server to your building, etc., it can be very difficult to determine the energy use of a single piece of equipment. A good statistician is your best bet in this case, but it is really better to measure things before changing equipment.

Windows/Envelope Changes:

Energy savings from window and/or envelope changes are the hardest to measure by far. Multiple models (UAdT, Radiant Time Series, eQuest) can be used to predict the savings garnered from these changes, but verifying them can be difficult, mostly because people rarely do a windows change without doing other efficiency projects at the same time.

Your best bet for actually Measuring and Verifying windows replacements is to get as much utility data (ideally three years, two is okay, one may make things difficult) from the building before the retrofit takes place. Then, use the above methods to precisely measure the energy savings from all the other changes to the building.

Now, wait a few months until you have new utility data and let your statistician out of the basement. Using regression techniques, (specifically, a logit model with panel data for the month, Heating Degree Days, Cooling Degree Days, a Boolean for whether or not the retrofit has taken place, and a variable containing the energy savings from all the other measures), you should be able to back out the savings from just the windows alone.

Again, this is non-ideal. If your building has major tenant changes, is operating the chiller or lights differently than before the retrofit, or makes any other number of behavioral changes, it will be very difficult to calculate the savings from windows or shell improvements.

Thankfully, models like eQuest are very good these days, and if they are relatively close (say, 10%) to your statistically calculated savings, you can be confident that your window replacements are doing close to what you expected. It is best to use a couple models to verify that the measured bill data savings and models are all telling the same story.

[2] https://www1.eere.energy.gov/femp/pdfs/light_controls.pdf