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Efficient Lighting and LEDs

Lighting - Op room
Good lighting is essential to the critical activities that take place in hospitals.  (Photo: What Took You So Long? Productions)

Health facilities of all sizes can benefit from efficient lighting for increased energy efficiency, reduced maintenance costs and improved environments.  Indoor and outdoor lighting can be provided by a wide range of lighting technologies, including: incandescent, fluorescent, light emitting diode (LED), and high-pressure sodium, among others. 

Each of these technologies comes with advantages and disadvantages in terms of energy efficiency and light quality.  The correct choice in healthcare lighting depends largely on where and how the lights will be used.  Applications such as indoor general lighting, medical lighting and outdoor area lighting have different demands.  Traditionally, lighting needs in hospitals have been met by incandescent and fluorescent lighting.  Energy efficient technologies such as LEDs, however, are an increasingly attractive option, meeting both the economic and technical demands of healthcare lighting.

Over the last several years, LEDs have risen out of general obscurity to dominate a number of niche applications.  Currently, LEDs are moving into the mainstream lighting market, as well as the medical lighting market, and will continue to expand in their availability and range of applications while decreasing in cost.  As the initial cost of LEDs lowers, health facilities will be able to enjoy all of the benefits of LED technology.  Long life and low energy consumption are the hallmarks of the LED, but the quality of light, in terms of color temperature and color rendering, are also quite good and can be designed to meet specific demands.  This flexibility is one reason why LEDs are an appropriate technology for so many medical applications.

This page will explore efficient lighting technologies for healthcare applications, with a special focus on LEDs.  A technical discussion on lighting specifications and technologies will be followed by an overview of lighting demands in the healthcare environment.  Practical considerations regarding financial analysis, retrofit implementation and monitoring, and standards and procurement will be discussed for lighting.

 

Lighting Metrics 

When assessing the applicability of different lighting technologies, there are a number of parameters that should be considered.  These considerations will be of greater or lesser importance depending on the application, but efficacy, correlated color temperature (CCT) and lifetime are typically significant.

 

ConsiderationDescription
Efficacy (lm/W) The energy efficiency of lighting is commonly described in terms of efficacy, or lumens of light produced per watt of energy consumed (lm/W).  Efficacy varies widely among (and within) the various lighting technologies.  Improving efficacy is normally the primary goal of a lighting retrofit as it results in energy savings.
Color Rendering Index (CRI) The Color Rendering Index (CRI) of a lamp measures its ability to accurately reproduce colors on a scale of 0 to 100, with 100 representing the most accurate color reproduction.  Incandescent lamps, by definition, have a CRI of 100.  Typically, LEDs and CFLs have a CRI upwards of 75. 
Correlated Color Temperature (CCT) The Correlated Color Temperature (CCT) describes how “warm” or “cool” the light produced by a particular lamp appears.  Most incandescent lights produce a “warm” color around the range of 2700K to 3500K.  Many CFLs have neutral color of 3000K-4100K.  LED lamps often produce a very “cool” color (>5000K), but many LED lamps designed to replace incandescent lighting also produce light within the “warm” range (<3500K).  CCT is associated with and environment’s “mood”, affecting comfort and alertness.
Lifetime (hours) Lighting technology lifetime is measured in hours.  Longer lighting lifetime generally results in reduced maintenance costs.  LED lifetime is the longest of any lighting technology, lasting upwards of 35,000 hours.  CFL lifetime is typically around 12,000.  Because of its maintenance implications, lifetime is important to cost savings for maintenance-intensive applications like municipal lighting and some medical devices.
Luminous Flux (lm) The amount of light created by a lamp or fixture, measured in lumens (lm).
Illluminance (foot-candle) or (lux) Illuminance is the luminous flux measured at a particular surface (rather than measured at the source), and is given in foot-candle or lux (lm/m2).  Illuminance is the critical parameter when determining how much light is available for reading, typing or other tasks.  Illuminance is affected by a variety of factors, including the luminous flux of the light sources, the position of the surface relative to those sources and the color and materials of the surroundings.  The Illuminating Engineering Society (IES) publishes illuminance standards for particular workplace tasks.
Lens/Bulb Type All traditional lighting technologies employ bulbs or tubes, while lighting fixtures often have additional lenses or coverings, even LED fixtures.  These bulbs and lenses reduce luminous flux, but may also help to diffuse the light source, making it more comfortable to look at.  The correct choice of lens or bulb is a matter of task requirements, retrofit or spatial constraints and taste.
Mounting Base The mounting base of a lamp provides the physical interface with the lighting fixture that ensures an electrical connection and holds the lamp in place.  There are a large number of mounting bases in use which vary by technology and application.  Some of the more recognizable mounting types are the “Edison” screw-type base common to incandescent bulbs, and the G13, or medium bi-pin type used in linear fluorescent tubes.  Retrofit lamp replacements must ensure mounting base compatibility with existing fixtures.
Lighting - edison Lighting - FL pins Lighting - PAR
The classic "A-lamp" or "Edison bulb" describes both the shape and screw-type base of this lamp. (Photo: US DOE) Fluorescent lamps commonly use pin-type mounting bases, here a variety of tubular and compact fluoresent lamps are shown. (Photo: Christian Taube, available under a Creative Commons Attribution-Share Alike license.) Parabolic aluminized reflector (PAR) lamps have a unique shape with reflective walls designed to direct light. (Photo: Ronick Dieudonne)

 

Lighting Technologies 

Lighting technologies may be distinguished by the manner in which light is produced.  With few exceptions, artificial light is traditionally produced when an electrical current is used to either burn a filament or excite gas molecules housed in a bulb.  Light emitting diodes produce light when supplied an electrical current.  Four principle categories arise from these basic technologies: incandescent (burning filament), fluorescent and high intensity discharge (both gas excitation), and solid-state (LED).  These technologies are described in more detail, followed by a discussion of the advantages of LED lighting.

Lighting - halogen
Halogen lamp, notice the inner chamber containing halogen gas. (Photo: US DOE)

Incandescent:  Incandescent lamps are the oldest and typically least efficient lighting technology.  Incandescent lighting relies on a burning filament held in a gas-filled bulb to produce light.  Over time, incandescent lamps have found a role in nearly every lighting application and have evolved into a number of forms.  The ubiquitous A-lamp or ‘Edison bulb’ is perhaps the most widely recognized lamp shape.  Parabolic aluminized reflector (PAR) lamps use reflectors to direct light rather than allowing omnidirectional light as does the A-lamp.  In halogen lamps the burning filament is surround by halogen gas, increasing efficiency.  Due to their high CRI, halogen lamps are commonly used in medical lighting, such as microscope lighting and exam lighting.

Fluorescent:  Fluorescent lamps are a type of gas discharge technology where light is produced by heating electrodes to excite gasses held in a tube.  Fluorescent lighting is generally more efficient than incandescent while also being relatively inexpensive, making it a common choice in commercial applications.  Color temperature is a defining feature of fluorescent lighting, which typically have a high CCT (cool light).  

Linear fluorescent tubes (e.g. T12, T8, T5) are often used in office lighting and many other indoor area lighting applications.  Compact fluorescent lamps (CFLs) are increasingly taking the place of screw-in incandescent A-lamps, but also come in a wide variety of other sizes, wattages, mounting types and shapes, including the circline (circular tube) format.

High Intensity Discharge (HID):  High intensity discharge lamps utilize the same gas discharge technology as fluorescent lamps, but produce a very high luminous flux.  These lamps tend to have higher efficacy (even greater than LEDs), but relatively poor color rendering.  Their high output and low CRI make HID lamps well suited to outdoor, municipal and high-bay lighting applications, where large areas require illumination but color is generally unimportant.

The principle types of HID lighting include: mercury vapor, high pressure sodium and metal halide.  Each type differs somewhat in efficacy and CRI, with high pressure sodium being the most efficacious and metal halide having the best color rendering.  All of these types are in common use as street lighting or in similar applications.

Another HID technology is the induction lamp.  Unlike other gas discharge lamps, induction lamps utilize the principle of magnetic induction to heat their gases, rather than metal electrodes.  This feature extends the life of the lamp considerably because electrodes burn out over time, and are often the first point of failure in a lamp.  Since they rely on the same gaseous mixtures as other HID technologies (e.g. high pressure sodium), induction lamps to do not necessarily have an advantage in efficacy.  They are most often used in street lighting, as their long life translates to reduced maintenance costs.

Solid-State Lighting (SSL):  Light emitting diodes are a lighting technology that is fundamentally different from other, traditional lighting technologies like incandescent or fluorescent.  Diodes, the silicon devices that allow computers to process, communicate and store information, are a common element of all modern electronics.  Rather than sending signals in a computer circuit, a light emitting diode produces photons – light.  LEDs differ from traditional lighting because there are no gasses involved; it is a ‘solid state’ lighting technology.  This key difference results in a number of advantages over older technologies which will be discussed in detail in the next section.

Although LEDs are the most advanced form of solid-state lighting, other SSL technologies are also in development, such as the organic light emitting diode (OLED).  OLEDs differ from traditional LEDs in that they utilize organic compounds (typically a polymer) in place of silicon.  As OLED development progresses, the technology promises several advantages over LEDs, such as lower cost, higher efficacy and mechanical flexibility.  Before realizing this promise, however, OLEDs must overcome challenges in production methods and low lifespans resulting from the degradation of their organic compounds.

 

CategoryTechonology/TypeEfficacy Range (lm/W)*Applications
Incandescent A-lamp 10 - 17 General purpose
Halogen 12 - 22 Specialty applications
PAR 12 - 19 Outdoor, specialty applications
Fluorescent Linear (T12, T8, T5) 30 - 110 General purpose, high bay
CFL 50 - 70 General purpose
Circline 40 - 50 General purpose
High Intensity Discharge Murcury Vapor 25 - 60 Municipal lighting, high bay
High Pressure Sodium 50 - 140 Municipal lighting, high bay
Metal Halide 70 - 115 Municipal lighting, high bay
Solid-State LED (cool white) 60 - 92 General purpose, municipal lighting, high bay, specialty applications
LED (warm white) 27 - 54 General purpose, municipal lighting, high bay, specialty applications
OLED 15 - 60** Specialty applications

*DOE EERE Lighting Basics

**Philips Lumiblade Roadmap

 

Lighting - CFL Lighting - LED lamp Lighting - HID Lighting - LED tube
Compact Fluorescent Lamps (CFLs) can be found in many sizes and forms, like this common spiral lamp. (Photo: US DOE) LED lamps require heat sinks, like the large grey column of this A-lamp style LED lamp. (Photo: US DOE)  HID lamps, like this mercury vapor lamp are commonly used in street lighting. An LED replacement lamp for conventional tubular fluorescent lamps.   (Photo: Mcapdevila, available under a Creative Commons Attribution-Share Alike license.)

 

Light Emitting Diodes (LEDs) 

As a fundamentally different type of lighting technology, LEDs command a number of advantages over traditional technologies.  LEDs are a rapidly advancing technology that benefit from innovations across the field of solid-state electronics.  

The primary advantage to LED lighting is high efficacy, which arises from their low-temperature operation.  Traditional lighting technologies, incandescent in particular, rely on heat in order to generate light, thus much of the energy used in their operation is lost as heat.  Light emitting diodes create very little heat as their light output results from electrical current rather than thermal energy.  The following table summarizes the efficacy of various traditional lighting technologies and their LED alternatives.  In health facilities the beneficial consequences of cool operating LEDs are decreased facility cooling loads and more comfortable environments for practitioners working in the vicinity of medical lights.

 

Common Lamp TypeIncandescentFluorescentLED (warm white)
Standard "A-lamp" 15 73 94
PAR 20 - 78
4' Linear tube - 108 118

DOE EERE LED Basics

Lifetime is another key advantage of LED lighting, and a major driver of cost savings in LED retrofits.  Well-designed LED fixtures will typically last 35,000 to 50,000 hours or more before reaching their end of life, considerably longer than other lighting technologies.  This translates to reduced maintenance and replacement costs over the life of a lighting system, an especially important factor in high maintenance applications like street lighting and medical lighting. 

Lighting - LED
A single, white Light Emitting Diode. (Photo: US DOE)

LEDs are also different from other lighting technologies in that they emit unidirectional light.  Traditional lighting emits light in all directions; that light must then be directed towards targeted areas (e.g. desks, streets, and operating tables) by reflectors.  LEDs emit light in only one general direction, allowing them to deliver light to targeted areas more efficiently.  This difference in directionality, however, can lead to problems in light uniformity when LEDs are used in reflective fixtures designed for conventional lights.  LEDs perform best in fixtures designed to take advantage of their unidirectional nature.  LEDs can use this advantage in medical lighting, where focusing light on a specific location is often of great importance.

LEDs also have an advantage over some traditional lighting technologies in how they respond to voltage fluctuations.  Inconsistent power quality plagues electrical grids in many developing countries.  Generator power too, is responsible for spikes and surges in voltage.  Medical equipment as well as lighting is sensitive to these voltage fluctuations.  Halogen lamps, the traditional light source for most medical lighting, are especially sensitive and are prone to frequent blow-outs due to unstable power supply.  By contrast, LED lighting is better able to endure voltage fluctuations.  Rather than experiencing a complete blow-out, LEDs take a penalty in lifespan when subjected to poorly regulated voltage.  So while the quality of power supply is still important for LEDs, the risk of complete light failure due to unstable voltage is less than with halogen lamps.

 

Related Equipment 

Lighting technologies are commonly differentiated by their light source or lamp type, but there are a number of other components that are needed to create efficient and aesthetic lighting.  When specifying lighting systems (lamps, fixtures, ballasts and controls) it is important to ensure that all components are compatible.  For example, fluorescent lamps will differ in their mounting base, size and ballast compatibility, all of which affect the selection of luminaires and controls.

Luminaire/Fixture: Beyond the light-producing lamp, other components are needed to create a functional light source, specifically: ballasts or drivers, electrical wiring, structural members, light reflectors and lenses.  These components (including the lamp itself) are collectively termed the luminaire, or light fixture.  Luminaires will differ greatly in their form and function based on the tasks or areas they are designed to illuminate.  Street lights, medical exam lights, 2’x4’ troffers and track lighting are all examples of luminaires designed for very different lamp types and applications.

Ballasts/Drivers: All gas discharge lighting (including fluorescent and HID lamps) and LEDs must receive a precisely regulated electrical current from either a ballast (gas discharge) or a driver (LEDs).  A ballast or a driver is a piece of electrical equipment that regulates the electrical current sent to the lamp.  The principal difference between the two is that a ballast provides a high-frequency AC current, while a driver provides a DC current.  

These devices may be either separate pieces of equipment, as is the case for linear fluorescents, or may be integrated into the lamp, as with most CFLs.  As electrical components, ballasts and drivers have a small electrical consumption of their own which should be added to lamp wattage whenever ballasts are separate from the lamp rather than integrated.  Ballasts, in particular, come in a variety of types and it is important that ballast and lamp types are paired correctly when the two are separate.  

Lighting Controls: Broadly, lighting controls comprise switches, timers, dimmers, sensors and even energy management software.  While a control may be as simple as an on/off switch, more advanced devices are used to optimize lighting usage and limit consumption.  Controls can lead to high energy savings by reducing lighting operational hours.  This is often accomplished through timers or occupancy sensors which turn off or dim lights based either on a set schedule or the presence of occupants, respectively.

Lighting - fixture Lighting - ballast
Luminaires incorporate all of the electrical and optical components of a lighting fixture; aesthetics is often an important consideration. (Photo: US DOE) All gas discharge lamps must be connected to a ballast, a device that regulates the voltage applied to the lamp's electrodes. (Photo: Dennis Brown, available under a Creative Commons Attribution-Share Alike license.)

 

Health Facility Lighting 

Health facilities range widely in their size and the services they provide.  Small clinics may provide only basic health services, requiring minimal electrical equipment and low lighting loads.  By contrast, large medical facilities are among the most energy-intensive building types, providing specialty medical services, laboratories and in-patient treatment.  Healthcare lighting is therefore expected to meet the demands of diverse environments and applications.

Electrical loads typically seen in small health facilities include: lighting, vaccination refrigeration, radio communications and essential laboratory equipment.  Lighting at a clinic may comprise general indoor lighting, outdoor security lighting as well as laboratory lighting such as microscope lights.  Since energy resources are often limited or expensive for small facilities, energy efficiency is of great importance.  LEDs can play a prominent role in achieving greater energy efficiency in such facilities, because lighting makes up a greater proportion of total energy consumption when compared to larger facilities.  

For facilities that employ solar photovoltaics and backup battery banks the efficiency of LEDs can impact energy system costs significantly.  Alternatively, a reduction in lighting load can allow for the use of more laboratory equipment.  The bottom line is that energy efficiency measures, like the use of LEDs, allow for a reduction in energy system size (i.e. generation, storage) or an expansion of energy dependent health services.  For example, lowering facility lighting consumption may allow for more vaccine storage or the use of basic laboratory equipment like a centrifuge.  In this regard, LED technology has a direct effect on the quality of healthcare delivered at the facility.

Lighting also takes on new importance in laboratory settings, as lab work depends on good lighting.  Even during the day, laboratories and exam rooms require artificial light in order to achieve the illumination levels necessary for the critical tasks taking place.  LED lighting is capable of providing general illumination for such spaces, as well as dedicated task lighting.  Most medical lighting equipment such as microscopes and exam lighting are available with LEDs which save on energy and maintenance costs while providing exceptional lighting quality.

In-patient facilities such as large hospitals, especially those with emergency care, are in operation 24/7.  LED lighting can provide greater benefits in facilities under constant operation, both in terms of energy consumption and occupant well-being.  First, the absolute energy savings attainable through the use of LED lighting is increased as the lighting operational hours increase.  Areas that require 24 hour lighting will yield the greatest savings from a conversion to LED lighting, especially when the maintenance needs of LEDs are compared to those of typical fluorescent lamps.  Secondly, the light output of LEDs is nearly full spectrum light, much more so than light from fluorescent lamps.  Full spectrum light more closely resembles daylight and has been shown to help maintain proper sleep schedules.  The high quality light output by LEDs can enhance the health of patients and the awareness of facility personnel, especially those that work at night.

A wide range of LED products are available that are able to fulfill these diverse lighting needs.  Virtually any lighting technology in place today can be substituted with a properly designed LED light.  The color temperature of LED products, for instance, covers a wide range from about 3000K, like incandescent lamps, to 6500K like some super bright fluorescent lamps.  This allows LEDs to be used in place of incandescent lamps in waiting rooms, where low, soft light is desirable, or fluorescent tubes in corridors and exam rooms.  Furthermore, LEDs are designed into low-ingress lighting fixtures, which cut down on the accumulation of dust, and are intended to meet standards for hospitals.  LED technology can be adapted to meet a variety of lighting applications and are constantly being advanced to serve new purposes, especially in the medical field.

Lighting - microscope Lighting - exit sign Lighting - general area
Specialty medical lighting applications, like the microscope light seen here, are needed for labs, operating rooms and other healthcare areas. (Photo: What Took You So Long? Productions) LED exit signs are a low-cost lighting efficiency measure.  Since exit signs are always on, savings add up quickly. (Photo: US DOE) Much of the lighting in hospitals is not specialty lighting, like the general area lighting seen here. (Photo: US DOE)

 

LED Medical Lighting 

There are numerous advantages to using LED technology over traditional lighting types in medical lighting applications, and their adoption for this purpose has been widespread.  These advantages go well beyond energy efficiency as LEDs actually enhance the functionality of medical lighting.  Traditional lighting technologies that are commonly used in medical lighting include: halogen, xenon and fluorescent lamps.  Halogen lighting is the most prevalent lighting type seen in medical applications.  This is due primarily to its relatively high efficacy, light output and color rendering abilities.  Good color rendering is critical in many medical procedures as it aids in correctly identifying and differentiating between tissues.  LEDs can be designed to provide superior color rendering abilities that rival those of halogen lights.  

In other respects LEDs surpass halogen lamps.  Excess heat generated by halogen lamps creates discomfort for doctors performing surgical procedures as lamps are often located close to the doctors’ heads.  LEDs do not produce excess heat, effectively solving the problem of doctor discomfort due to heat.  LEDs are also easier to focus than halogen lamps.  LED surgical lights, for instance, are able to direct light and eliminate shadows more easily than halogen lights.  In fact, some LED surgical lights actually have the ability to change their color temperature, allowing for surgeons to make adjustments that facilitate tissue identification.

Dimming is another ability for which LEDs have superior performance.  While other lighting technologies also have the ability to dim, the process is less complex for LED lights.  This is because the light output of an LED is proportional to the electrical current that it is supplied.  To dim an LED simply lower it’s current.  This makes dimming capabilities for LEDs less expensive and more flexible than for other lighting technologies.  Dimming is quite useful for healthcare lighting and can be applied in general lighting for corridors and patient rooms or in surgical lighting, providing another level of control to surgical teams.

Perhaps the greatest advantage of LEDs over halogen and other traditional lighting technologies is lifetime.  LEDs are often rated up to 50,000 hours of useful life, and never less than 10,000 hours.  Compare this to the 1,000 – 4,000 hour life of a halogen lamp.  The costs of lamp replacement and maintenance are considerably higher for halogen lighting.  This fact is exacerbated by the delicate nature of many medical instruments, including lighting.  Often, a technician trained in the repair of medical equipment is needed to perform this routine maintenance, even for relatively simple tasks such as changing a light bulb.  Halogen bulbs in particular must be treated with delicacy, as their quartz housing can be significantly damaged by oils in the skin.  The cost and effort of maintenance is even more troublesome in remote clinics, where materials and expertise may take a long time to arrive.  These advantages are made more appealing by the fact that LED medical lighting is typically not a great deal more expensive than traditional alternatives.  

 

Product Selection 

LEDs are bringing exciting advancements to the lighting and medical industries, but some thought should be given as to their selection.  The use of LEDs in general lighting applications is still developing.  When considering the replacement of fluorescent lights with LEDs, special care must be taken to address concerns over product quality.  Many LED products have recently entered the market, but since this type of product is relatively new, claims regarding lamp life, lumen output and color characteristics may be unsubstantiated.  Furthermore, electronic systems supporting the LEDs (i.e. driver, heat sink) will also affect the overall product. 

If possible, third-party testing of the LED lighting system should be conducted.  See the section on Lighting Standards below for a list of standards that should be reference when specifying lighting systems; of particular relevance to LEDs are: IES LM-79-08 (photometric measurement of LEDs) and IES TM-21-11 (determination of LED lifetime).  A manufacturer’s warranty of at least three and preferably up to five years is also highly recommended.  For medical lighting in particular, a period of trial usage, allowing for personnel feedback, is common.  Whether selecting LEDs for general lighting or medical applications, taking the time to choose quality products will ensure that the full potential of LED lighting is reached.

 

Lighting Retrofit Implementation and Analysis 

Financial Analysis: Life-Cycle Cost (LCC) Analysis

Since alternative options are available for nearly every medical and general lighting application, it is important to understand the different factors that play a role in the financial viability of those alternatives.  For example, the increase in initial cost, reduction in wattage and extended life of LED products influence their competitiveness with traditional lighting technologies.  The cost of electricity and lighting operational hours will also have an effect on any financial comparison of technologies.  While each potential project must be assessed individually, the life-cycle cost components of a lighting retrofit typically comprise:

  • Capital Costs: Retrofit capital costs include equipment and installation costs and any costs associated with the design, planning or periodic monitoring of the retrofit.
  • Operating Costs:  Operating costs are determined by the energy consumption of the new, efficient lamps.  A kWh estimate of post-retrofit lighting consumption can be made by multiplying the wattage of each retrofit lamp by the total number of hours it operates each year and summing these consumption values for the entire facility.  This consumption figure can then be multiplied by the facility’s electricity tariff rate to yield the annual operating cost.  High electricity rates and long operating hours typically result in faster retrofit paybacks.
  • Replacement Costs: Sometimes the energy consumption of a particular application is low (e.g. microscope lighting); lamp life may still be an important parameter in these cases.  For example, while energy savings from an LED microscope is unlikely to recuperate the increase in initial cost, the difference in replacement costs over time will make the LED lamp an attractive option.
  • Disposal Costs: All lamps and fixtures require disposal at their end-of-life.  This may represent an additional cost to the facility.  This is especially true of fluorescent and some HID lamps which contain small amounts mercury.  Depending on the number of lamps being disposed of, and local regulations, these lamps may require special disposal measures, at added expense.

(Note: Disposal costs will also be incurred at a retrofit’s outset as old lamps are replaced with efficient retrofit lamps.  This initial disposal cost, while important to the project’s budget, should not be considered in the LCC analysis unless the old lamps would not otherwise require replacement.)

LED products are more likely to be competitive with traditional technologies in situations where the lamp experiences long operating hours, energy costs are high and the lamp life of the traditional technology is short.  Because initial cost, energy consumption and lamp replacement costs are all important considerations in a lighting retrofit, any financial analysis should be performed on a life-cycle cost basis.  By evaluating all associated lighting costs (capital, operation, replacement, and disposal) over a 10 or 20 year period, the full benefits of efficient lighting will be captured.

 

Technical Analysis: Lighting and Power Levels

Lighting - light meter
Light meters measure illuminance, and are used to determine the adaqucy of lighting levels for different tasks. (Photo: US DOE)

Light levels and energy consumption are the two most important technical aspects of an efficient lighting retrofit.  Proper lighting levels are important in a hospital setting, not only to the work of doctors, nurses and lab technicians, but also to provide a safe and comfortable environment for patients.  Light levels are measured at particular working surfaces with a light meter, which records the illuminance at that surface (in foot-candles or lux).  Energy consumption may be logged over time, or calculated based on measured lighting loads and observed operational hours.  

The potential for energy cost savings forms the basic rationale for most efficient lighting retrofits.  A quantitative and systematic measurement of light levels and power consumption is needed in order to justify the retrofit costs with energy savings.  The measurement methodology will be laid out in a monitoring and evaluation plan (see below), which specifies how, where and how frequently light levels and lighting consumption will be measured.  Such a plan will dictate that measurements are taken before the retrofit, and at least once after, in order to determine energy savings and make a proper comparison of light levels.

 

Occupant Satisfaction

Occupant satisfaction is another important factor in an efficient lighting retrofit’s performance.  Typically, retrofits are designed to meet or exceed pre-retrofit light levels.  While light measurements provide a quantitative way to gauge occupant satisfaction, other factors relating to light quality, such as glare, color, and uniformity also play an important role.  Judging occupant satisfaction in a qualitative manner, through staff surveys, will supplement the measured lighting levels as an indicator of the project’s success.

 

Monitoring and Evaluation (M&E) Plan

In order to effectively gauge the success of the lighting retrofit, a systematic, repeatable and quantitative monitoring and evaluation plan must be carried out.  This plan will be centered on pre- and post-retrofit light level measurements and electrical load data logging.  Load logging will preferably target only the retrofit fixtures, although facility-level data may also be used to estimate actual savings.  These data allow for an initial assessment of retrofit success and provide the foundation for continued monitoring.  On a periodic basis, lighting and facility load data should be collected in order to evaluate the on-going operation of the efficient lighting.  Occupant surveys may also be continued each year for comparison to the initial post-retrofit survey.  The intent of these monitoring activities is to replicate the baseline measurements following routine procedures:

  • A lighting inventory should be performed, counting and estimating the wattage of all existing lighting.  This is also an opportunity to register failed lamps and take stock of the supply of replacements.
  • Ideally, consumption data is logged for at least one week, allowing for a comparison based on weekly and hourly operating conditions (e.g. weekdays vs. weekend).
  • Light level measurements should be taken at specific working surfaces during each monitoring visit.  It is helpful to mark on a floor plan where measurements were taken so that they may be replicated.  
  • The occupant survey may also be replicated, asking similar questions and engaging similar facility occupants.  The goal will be to gauge the occupants’ perception of the efficient lighting over time, and ensure their continued satisfaction.

 

 Lighting Standards 

 

American National Standards Institute (ANSI)
CategoryStandard
LEDs

ANSI C78.377-2008: Specifications for the Chromaticity of Solid State Lighting Products

Fluorescent Lamps ANSI C78.45-2007: Electric Lamps—Self-Ballasted Mercury Lamps
Ballasts ANSI C82.1-2004: Lamp Ballasts—Line Frequency Fluorescent Lamp Ballasts
Definition/ Specification ANSI C82.13-2002: Lamp Ballasts—Definitions for Fluorescent Lamps and Ballasts
Ballasts ANSI C82.4-2002: Lamp Ballasts—Ballasts for High-Intensity Discharge and Low-Pressure Sodium (LPS) Lamps (Multiple-Supply Type)
Ballasts ANSI C82.11-2011: Lamp Ballasts—High Frequency Fluorescent Lamp Ballasts
Definition/ Specification ANSI C82.9-2010: Lamp Ballasts—High-Intensity Discharge (HID) and Low-Pressure Sodium (LPS) Lamps—Definitions

 

Illuminating Engineering Society (IES)
CategoryStandard
Measurement/ Testing IES LM-79-08: Electrical and Photometric Measurement of Solid State Lighting Products
Measurement/ Testing IES LM-80-08: Approved Method for Measuring Lumen Maintenance of LED Light Sources
Measurement/ Testing IES TM-21-11: Projecting Long Term Lumen Maintenance of LED Light Sources
Installation IES LEM-3-13: Upgrading Lighting Systems in Commercial and Institutional Spaces
Design IES TM-15-11: Luminaire Classification System for Outdoor Luminaires
Design IES RP-29-06: Lighting for Hospitals and Health Care Facilities
Design IES RP-1-12: American National Standard Practice for Office Lighting
Installation IES-500-06: Installing Indoor Commercial Lighting Systems
Installation

IES-501-06: Installing Exterior Lighting Systems

Installation

IES-502-06: Installing Industrial Lighting Systems

Definitions/ Specifications IES RP-16-10: Nomenclature and Definitions for Illuminating Engineering
Definitions/ Specifications IES DG-3-00: Application of Luminare Symbols on Lighting Design Drawings
LEDs IES G-2-10: Guideline for the Application of General Illumination (“White”) Light-Emitting Diode (LED) Technologies
Measurement/ Testing IES LM-9-09: Electrical and Photometric Measurements of Fluorescent Lamps
Definitions/ Specifications IES LM-15-03: Guide for Reporting General Lighting Equipment Engineering Data for Indoor Luminaires
Measurement/ Testing IES LM-46-04: Photometric Testing of Indoor Luminaires Using High Intensity Discharge or Incandescent Filament Lamps
Design IES LM-61-06: Identifying Operating Factors for Installed Outdoor High Intensity Discharge (HID) Luminaires
Measurement/ Testing IES LM-62-06: Laboratory or Field Thermal Measurements of Fluorescent Lamps and Ballasts in Luminaires
Definitions/ Specifications IES LM-72-97: Directional Positioning of Photometric Data
Definitions/ Specifications IES LM-74-05: Standard File Format For the Electronic Transfer of Luminaire Component Data
Measurement/ Testing IES LM-78-07: Approved Method for Total Luminous Flux Measurement of Lamps Using an Integrating Sphere Photometer
Measurement/ Testing IES LM-45-09: The Electrical and Photometric Measurement of General Service Incandescent Filament Lamps
Measurement/ Testing IES LM-40-10: Life Testing of Fluorescent Lamps
Measurement/ Testing IES LM-65-10: Life Testing of Compact Fluorescent Lamps
Measurement/ Testing IES LM-66-11: Electrical and Photometric Measurements of Single-Ended Compact Fluorescent Lamps
 LEDs IES TM-16-05: Technical Memorandum on Light Emitting Diode (LED) Sources and Systems
 Illuminance Levels IES Lighting Handbook, 10th Edition

 

National Electrical Manufacturers Association
CategoryStandard
LEDs NEMA SSL-1-2010: Electronic Drivers for LED Devices, Arrays, or Systems
Luminaire NEMA LE 4-2012: Recessed Luminaires—Ceiling Compatibility
Luminaire NEMA LE 5-2001: Procedure for Determining Luminaire Efficacy Ratings for Fluorescent Luminaires
Specialty Lighting NEMA EM 1-2010: Exit Sign Visibility Testing Requirements for Safety and Energy Efficiency
Ballast NEMA BL 3-2013: Dimming Ballast Energy Performance
Ballast NEMA BL 2-2009: Energy Efficiency for Electronic Ballasts for T8 Fluorescent Lamps
Fluorescent Lamps NEMA LL 9-2011: Dimming of T8 Fluorescent Lighting Systems

 

Underwriters Laboratories
CategoryStandard
Luminaires UL 1598: Luminaires
LEDs UL 1598C: Light-Emitting Diode (LED) Retrofit Luminaire Conversion Kits
Lamps UL 1993: Self-ballasted Lamps and Lamp Adapters
LEDs UL 8750: Light Emitting Diode (LED) Equipment for Use in Lighting Products
LEDs UL 8752/ULC-S8752: Organic Light Emitting Diode Panels
LEDs UL 8753/ULC-8753: Standard for Field-Replaceable Light Emitting Diode (LED) Light Engines
Mounting UL 8754/ULC-8754: Holder, Bases, and Connectors for Solid-State (LED) Light Engines and Arrays
Ballasts UL 935: Standard for Fluorescent-Lamp Ballasts
Ballasts UL 1029: Standard for High-Intensity-Discharge Lamp Ballasts
Ballasts UL 542: Fluorescent Lamp Starters
Luminaires UL 153: Portable Electric Luminaires
Mounting UL 496: Lampholders
General Lighting UL 2108: Low Voltage Lighting System
Speciatly Lighting UL 924: Emergency Lighting and Power Equipment
Specialty Lighting UL 676: Underwater Luminaires and Submersible Junction Boxes
Specialty Lighting UL 48: Electric Signs
Specialty Lighting UL 1574: Track Lighting Systems

 

International Electrotechnical Commission (IEC)
CategoryStandard
Definitions/ Specifications IEC 60050-845 ed1.0 (1987-12): International Electrotechnical Vocabulary - Lighting
Incandescent Lamps IEC 60064 ed6.0 (1993-12): Tungsten filament lamps for domestic and similar general lighting purposes - Performance requirements
Fluorescent Lamps IEC 60081 ed5.0 (1997-12): Double-capped fluorescent lamps - Performance specifications
HID Lamps IEC 60188 ed3.0 (2001-05): High-pressure mercury vapour lamps - Performance specifications
Incandescent Lamps IEC 60357 ed3.0 (2002-11): Tungsten halogen lamps (non vehicle) - Performance specifications
Installation IEC 60364: Low-voltage electrical installations
Incandescent Lamps IEC 60432: Incandescent lamps - Safety specifications
Luminaires IEC 60598-2-2 ed3.0 (2011-11): Luminaires - Part 2-2: Particular requirements - Recessed luminaires
Luminaires IEC 60598-2-22 ed3.0 (1997-08): Luminaires - Part 2-22: Particular requirements - Luminaires for emergency lighting
HID Lamps IEC 60662 ed2.0 (2011-02): High-pressure sodium vapour lamps - Performance specifications
Mounting IEC 60838: Miscellaneous lampholders
Fluorescent Lamps IEC 60901 ed2.0 (1996-03): Single-capped fluorescent lamps - Performance specifications
Fluorescent Lamps IEC 60969 ed1.0 (1988-12): Self-ballasted lamps for general lighting services - Performance requirements
HID Lamps IEC 61167 ed2.0 (2011-03): Metal halide lamps - Performance specification
Ballasts IEC 61347: Lamp control gear
Specialty Lighting IEC 62034 ed2.0 (2012-02): Automatic test systems for battery powered emergency escape lighting
Rural Systems IEC/TS 62257-9-5 ed2.0 (2013-04): Recommendations for small renewable energy and hybrid systems for rural electrification - Part 9-5: Integrated system - Selection of stand-alone lighting kits for rural electrification
Rural Systems IEC/TS 62257-12-1 ed1.0 (2007-06): Recommendations for small renewable energy and hybrid systems for rural electrification - Part 12-1: Selection of self-ballasted lamps (CFL) for rural electrification systems and recommendations for household lighting equipment
Definitions/ Specifications IEC/TS 62504 ed1.0 (2011-03): General lighting - LEDs and LED modules - Terms and definitions
Fluorescent Lamps IEC 62639 ed1.0 (2012-02): Fluorescent induction lamps - Performance specification

LEDs

IEC/PAS 62717 ed1.0 (2011-04): LED modules for general lighting - Performance requirements
LEDs IEC/PAS 62722-2-1 ed1.0 (2011-06): Luminaire performance - Part 2-1: Particular requirements for LED luminaires

 

International Energy Conservation Code (IECC)
CategoryStandard
Lighting Power Densities IECC 2012

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