We hear more and more about it every day, we want to update our existing lighting technology to LED but how do we know what we need to look for? Whether you are new to the lighting retrofit business or a seasoned expert, picking the right LED fixture, lamp or kit for your space can be challenging. There are so many choices: some good, some bad and some ugly. How do you choose? The following blog will attempt to discuss current and projected benchmarks for the efficacy of LED packages and complete luminaires, as well as providing comparisons to conventional technologies.What Are Lumens?Just as Watts measure the amount of energy in a light, lumens measure how bright it shines. The term “lumen” actually means “light,” so that’s an easy way to remember exactly what it is. It’s also important to realize that Lumens in LED lights are the way to choose LED lights, not watts. This way of measurement is much more reliable than watts. Why Lumens?In 2011, the US Federal Trade Commission made it a requirement to measure LED lights by lumens because they deemed it more important to dictate how bright the bulb was, rather than power output. Overall, the importance of lumens in LED lights is made clear when it becomes easier for you to determine minimum requirements for outdoor lighting and other applications.How to Find the Lumen Output of Your Existing or New LightingThe only way to make sure that you will get the correct amount of light for the area that you intend to light is through a professional lighting layout. A lighting layout will define the lumen output of your old fixtures and help to analyze new possibilities that give you the maximum amount of light while also saving money on your electric bill. XtraLight provides our clients with a FREE lighting layout and design.With LED Lighting there is a lot to take into consideration. One of the biggest arguments is light wattage versus the lumens and determining brightness. The old way of looking at how bright a light will be is to look at the wattage, and with incandescent lamps, the higher the wattage the lamp is, the brighter it is. Now we need to focus on the lumens of the lamp to determine the brightness of the lamp, especially when it comes to LEDs.We are all familiar with incandescent lamps and how they are measured in watts (e.g. 40w, 60w and 75w). With LED lighting you may assume the higher the wattage, the brighter the lamp. However, this is not what you should think about as you choose LED replacements. Watts and lumens are measured in different ways and are very different. A watt is a unit of electrical energy – input. A lumen is a measure of light intensity – output. A light bulb uses watts to make lumens. As there are so many different types of LED chips with different lumen outputs, you cannot assume that, for example, all 4w LED lights offer the same lumen output. There are different types of LED chips: High Power LED, Dip LED, Lamp LED, SMD, Flux LED and COB LED.With LED lighting being more directional, the lumen output to achieve the same brightness will be lower for LEDs than traditional lighting because a large percentage of the lumen output is wasted with older technologies.The energy efficiency of LED products is typically characterized using efficacy (ratio of power input to light output) or technically lumens divided by watts. Sounds pretty simple right? There are some important nuances we need to be aware of. LED products are made up of packages with their own efficacy.• Individual Chips • LED Luminaire• LED Driver• Thermal and Optical LossesBaseline – package level efficacy have many variables that may not be noticeable to specifiers and consumers:• Drive Current• Generating White Light• Color Quality AttributesDo I get all the information I need from the Specification Sheet?The specification sheet will show in most cases what the watts and lumens are of the fixture package. However, what about how the light is distributed? What happens if it’s a flood, spot or any other optic pattern? For example, LED lighting is far more focused than traditional HID lighting. You can take a traditional 400wMH (458w) and replace it with a new light fixture with far less wattage, lumen depreciation and better efficacy. 400W HID has wattage of 458W, lumens of 20,130 and luminaire efficacy of 44 LPW. With LED fixtures the designer can choose where the lumens go by choosing the right optics and directing them only where needed, eliminating wasted lumens.Insert XtraLight Viento photos, show optic patterns and lumens throw of light how that is important say in a parking lot where areas are not all the sameLamp and Luminaire EfficacyThermal effects, driver losses, and optical inefficiencies all combine to reduce the efficacy of LED luminaires compared to the included LED packages. Considered collectively, these loss mechanisms can result in a decrease in efficacy of greater than 30%. Notably, the efficacy of complete LED lamps and luminaires is most relevant to building energy use.Thermal EffectsA major factor in determining the lumen output of an LED is junction temperature. As temperature increases, the light-generation process becomes less efficient and fewer lumens are emitted. For this reason, LED luminaires generally require a thermal management system. However, even in a well-designed product, the junction temperature may rise significantly above laboratory conditions, which could result in up to a 15% decrease in efficacy. Always understand the conditions of the space in choosing the right LED luminaire.Driver LossesFluorescent and HID light sources cannot function without a ballast, which provides a starting voltage and limits electrical current to the lamp. Similarly, LEDs require a driver, which is comprised of both a power source and electronic control circuitry. Most drivers convert line voltage to low voltage and current from AC to DC, and may include supplementary electronics for dimming and/or color correction. In choosing the correct driver for the system the LED manufacturer considers many variables, dimming, lumen output, voltage all important features essential to optimizing the lighting system performance.Optical LossesRegardless of source type, the use of lenses, reflectors or other optical systems to shape a product’s distribution ultimately reduces the total amount of emitted light. For LEDs, this is another contributing factor in the difference between package efficacy and lamp luminaire efficacy. However, the magnitude of the effect is difficult to state given the large diversity of fixtures in the marketplace. Terms Commonly Used When Referring to LumensLPW – Lumens per Watt. The number of lumens produced by a light source for each watt of electrical power supplied to the light source.LUMEN DEPRECIATION – The decrease in lumen output of a light source over time; every lamp type has a unique lumen depreciation curve (sometimes called a lumen maintenance curve) depicting the pattern of decreasing light output.For instance, a 400 watt metal halide depreciates nearly 70% in the first 3 years vs a comparable LED High bay fixture which depreciates 30% over 50,000 hours, one of the distinct advantages of LED lighting.LUMEN MAINTENANCE – The deterioration in the amount of light that is emitted from a lamp over time. A lamp with good lumen maintenance will emit a consistent amount of light over its lifetime, emitting as much as 90% of its original capability at the end of its lifespan.LUMINAIRE – A complete lighting unit which contains a lamp/LED board, housing, driver/ ballast, sockets and any other necessary components.LUMINAIRE EFFICIENCY – The ratio of lumens emitted by a luminaire to the total lumens emitted from the light source within the luminaire.LUX – A unit of illuminance equal to 1 lumen per square meter.MEAN LUMENS – The average lumen output of a lamp over its rated life. Mean lumen values for fluorescent and HID lamps are typically measured at 40% of their rated lives.INITIAL LUMENS – The lumens produced by a lamp after an initial burn in period (usually 100 hours).How LED Lighting differs from other energy-efficient lighting technologies?LEDs offer the potential for cutting general lighting energy use nearly in half by 2030, saving energy dollars and carbon emissions in the process. LEDs have many unique characteristics – including compact size, long life and ease of maintenance, resistance to breakage and vibration, good performance in cold temperatures, lack of infrared or ultraviolet emissions, and instant-on performance, these are all beneficial in many lighting applications. Additionally, LEDs have the ability to be dimmed and to provide color control.Do LEDs Provide High Quality Light?Key aspects of high-quality light are the color appearance of the light itself, which is described by its correlated color temperature (CCT), and how the light affects the color appearance of objects, which is commonly called color rendition. Color rendition can be quantified using the color rendering index (CRI), or with one of several other recently developed metrics. LED light sources have demonstrated that they can achieve a wide range of color quality, depending on the demands of the lighting application. However, in order to achieve high levels of color quality, there are typically cost and efficiency tradeoffs. In general, a minimum CRI of 80 is recommended for interior lighting, and LED products can readily achieve this performance. CRIs of 90 or higher indicate excellent color fidelity; LEDs can also meet this threshold. CRI is far from a perfect metric and is especially poor at predicting the fidelity of saturated reds, for which the supplemental value R9 is often used. New metrics, such as the fidelity index (Rf) and the gamut index (Rg¬), which are described in IES TM-30-15, can provide a more comprehensive evaluation of color rendering. Learn more about TM-30-15 and LED color characteristics. How Long Do LEDs Last?LED luminaire useful life is often described by the number of operating hours until the LED luminaire is emitting 70 percent of its initial light output. Good-quality white LED lighting products are expected to have a useful life of 30,000 to 50,000 hours or even longer. A typical incandescent lamp lasts about 1,000 hours; a comparable CFL, 8,000 to 10,000 hours; and the best linear fluorescent lamps, more than 30,000 hours. A primary cause of lumen depreciation is heat generated at the LED junction. Unlike other light sources, LEDs don’t emit heat as infrared radiation, so it must be removed by conduction or convection. Thermal management is arguably the most important aspect of successful LED system design.Are LEDs Cost-Effective?Costs of LED lighting products vary widely. Good-quality LED products may carry a significant cost premium compared to standard lighting technologies. However, costs are declining rapidly. LED package prices declined to approximately $1/klm by 2016, resulting in dramatically reduced LED lamp and luminaire prices. In general, LED lighting products are still more expensive than their conventional counterparts, but when the costs of energy and maintenance are included in the total cost of ownership, LED-based products can have a distinct advantage.ConclusionThe efficacy of LED products has steadily improved since their introduction as a source for general illumination. This trend is expected to continue, thanks to new materials, better manufacturing processes, and new configurations. Currently, the efficacy of LED packages compares favorably to conventional light sources. Many integrated LED lamps and luminaires have efficacies that are comparable to their traditional counterparts, but the viability in LED products is greater than the mature technologies and the LED products are changing rapidly. Importantly, you must look at other characteristics when choosing LED technology: color quality, luminous intensity, distribution and the ability to be dimmable. Although high efficacy is an important attribute for energy savings, it is unperceivable to the users of the space. By just choosing a fixture based on wattage and lumens alone and not considering where the lumens are being used and/or lost, the project may not produce the financial success you strived for. LED technology is still rapidly changing. When considering an LED upgrade, remember that the ratio of watts and lumens is very important but also to know where the lumens are going. Are they wasted? Partner with a trusted manufacture that can perform photometric testing, can design with the right fixtures, provide precise optical patterns and recommend the right packages for your space.