LIGHTING AUDIT GUIDE FOR TEACHERS & STUDENTS. By Clare Pries. April 2008

Transcription

1 LIGHTING AUDIT GUIDE FOR TEACHERS & STUDENTS By Clare Pries April 2008 Coolmob trading as Environment Centre Northern Territory, April 2008

2 LIGHTING AUDIT With lighting accounting for 15 to 25% of the energy consumed at your school any energy efficiency measures in this area will provide very good opportunities for savings. There are two primary reasons why more energy is consumed by lighting at schools than necessary. The first stems from the common perception that it is more economical to leave fluorescent lighting (the type of lights mainly used in schools) on than to turn on and off as needed. The second is that in the past lighting systems were designed to use older less efficient lamps and fittings, and due to the low costs of energy, over-lighting was common practice. This section deals with these issues, identifies how energy savings can be made, and provides the information required to effectively under-take a lighting audit at your school. TURN OFF LIGHTS! One reason why people believe it is more economical to leave fluorescent lights on is because the initial inrush of current to start lights is considerably higher than when they are operating, this is true, however, it is only for a very short time (much less than a second). The total energy used during the inrush current is equivalent to only a few seconds of normal operation. The other reason used to justify leaving these lights on is the effect that switching lights on and off has on the life-span of the lamps. Again the belief is correct, lamp-life is reduced with switching, however, as the lamp is not required to operate for as long each day the amount of time (in years) before the lamp needs to be replaced is longer and the amount of energy used is less. The economics of the impact of switching is complicated and depends on the type of fittings, and, the cost of lamps, labour, disposal and electricity. The results of an analysis taking all these factors into consideration for the use of fluorescent lamps in the average Northern Territory school, show, that it is economical to turn fluorescent lights off when leaving a room for around minutes. 1 TOO O MUCH LIGHT! New fluorescent tube lamps produce around 20% more light than older fluorescents, and have better colour rendering (good colour rendering make objects appear more natural and bright) 2. The provision in the past to over-light and the installation of new lamps as your older lamps fail are the primary factors that lead to unnecessary energy consumption by existing lighting systems. If your fluorescent lighting system is over 15yrs old it is likely that it is consuming more energy than it needs to. A very efficient fluorescent lighting system for classrooms has an energy consumption of 6 8 Watts per square metre, older less efficient systems can have an energy consumption of up to 30+ Watts per square metre. TOO LITTLE LIGHT! It is possible that your lighting system has a very high energy use per square metre and only provide the light needed. The causative factors for this generally involve the following: Old less efficient lamps still being used. Lamp reflective fittings and diffusers not being cleaned regularly. Light output from dirty fixtures can be reduced by as much as 35% 3. Light fixtures should be cleaned at least once every year. Dark coloured or dusty classroom surfaces The reflectance of wall surfaces plays an important part in your lighting design, up to 40% losses can result if wall surfaces are not regularly cleaned 14. The accumulative losses of all these factors can result in lighting levels 70% lower than could be achieved with your current lighting system. 1 The analysis has been based on a function developed by A. Carriere and M. Rae, published in: Economics of Switching Fluorescent Lamps, IEEE Transaction on Industry Applications, Vol. 24, No. 3, May/June Sustainable Energy Development Office Government of Western Australia, Technology Table 1, Section 5.1 Lighting in Commercial Buildings and Offices, Energy Saving Manual Energy Smart Toolbox, 3 Platts Research & Consulting, 2004, Boosting Lighting Efficiency with Reflectors and Maintenance and Light Output Declines With Time, available at

3 IS YOUR LIGHTING SYSTEM EFFICIENT? The first step in determining the efficiency of your fluorescent lighting system, is to calculate the energy used per square metre. This is achieved by dividing the classroom floor area by the total wattage of the lighting system. The second step is to measure the lighting lux levels. A lux is the lumens per square metre and a lumen is the measurement for light. Australian Standards are produced which recommend the minimum light lux levels required to provide the appropriate lighting requirements for a task. The following table lists the recommended lux levels for selected areas in a school. Source: AS (Interior lighting, Part 2.3: Educational and training facilities) Type of interior or activity Illuminance lux Classrooms: General use classrooms 240 Laboratories, Music Rooms 320 Libraries: Audio listening areas 160 Audio visual areas, Book Stacks 240 Circulation & Amenity Areas: 80 Toilets, change rooms, locker rooms, cleaners rooms Corridors, passage ways, ramps 40 Stairs Internal: 80 External: 20 Entrance halls, lobbies, foyers, waiting rooms 160 Enquiry desks 320 Administration areas: General tasks involving typing, reading, writing 320 Background/environment 160 Meeting rooms 320 Training rooms, seminar rooms 240 Photocopying Intermittent: 160 Sustained: 240 First Aid Centres Rest rooms: 40 Treatment rooms: 400 Cafeterias/ Kitchens General: 160 Counters, food preparation, cooking, washing up: 240 Indoor Sports Facilities Recreation & training: 300 Competition: 500 HOW TO MEASURE LUX LEVELS OF A ROOM An instrument designed to measure light levels is called a lux meter. These can be purchased (the cost of these devices can vary from $50 to $350), hired from instrument hire businesses or should be available to loan from the Infrastructure Sustainability Unit. Where to take measurements: At 5 or 6 different locations in the room being measured. At desk height for classrooms and offices, and at the floor level for general passage ways such as corridors. When to take measurements: The amount of light a room receives from its windows will vary at different times of the day and year. Lux readings should be taken when day lighting is at a minimum, that is, early in the morning or late in the afternoon depending on the location of windows, or, on an overcast day. Examples of lux meters How to take measurements: The meters are simple to use and read. Simply place the sensor where you wish to take measurement allow to settle then take note of reading. Lux readings can vary by as much as Lux within a distance of only a few centimetres, so it is good practice to take a couple of measurements in the same general position and note the lowest figure. Movement of people near the sensor will affect the reading so try to minimize movement at time of reading. Standing between light sources and sensor will lower Lux readings.

4 CALCULATE THE EFFICIENCY OF YOUR LIGHTING SYSTEMS Use a copy of the floor plans available for your school on PDF from the Infrastructure Sustainability Unit, or, use a tape measure to physically measure each room being assessed. 5m 5m 2.5m 4m 5m Floor plans will have the scale used, noted at the bottom. The area for area 3 & 4 in the example above would have a total floor area of 12.5mtrs x 9mtrs = 112.5m 2. Note the number of lamps in each fixture and the number of fixtures within the room. Find out what type of lamps are used. T5 (top), T8 (bottom) The most common type of lamp used for school classrooms and office buildings is the T8 linear fluorescent tube. These lamps have a diameter of 26mm and come in 600mm/18W, 1200mm/36W, and 1500mm/58W. Older lighting systems may still use less efficient 38mm T12 tubes which come in 600mm/20W, 1200mm/40W, 1500mm/64W. Very new systems may have 16mm T5 tubes installed, these come in 550mm/14W, 1150mm/28W, and 1450mm/35W. For other lamp types you will need to check with your maintenance staff on the type and wattage as most can not be determined through a visual inspection alone. You will also need to check with maintenance staff what type of ballasts 4 are used for your fluorescent lights (electronic or magnetic). The table below gives estimates on the total wattage of common lamp/ballast systems used within a school. 4 For an excellent description of how fluorescent lamps work and what ballasts do check out

5 LAMP Classrooms & Offices 18W - 600mm T8 Linear Fluorescent 36W mm T8 Linear Fluorescent BALLAST WATTS Magnetic 24 Electronic 21 Magnetic 43 Electronic 38 20W - 600mm T12 Linear Fluorescent Magnetic 26 40W mm T12 Linear Fluorescent Magnetic 47 14W - 550mm T5 Linear Fluorescent Electronic 18 28W mm T5 Linear Fluorescent Electronic 32 Magnetic 43 36W - 410mm Single U-Tube Laboratories, Passage ways & Toilets 28W 210mm Square Compact Fluorescent Electronic 38 Magnetic 35 Electronic W Mercury Vapour Gym / Assembly 400W Metal Halide High -Bay 150W Halogen 150 Flood light To calculate the Watts/m 2 divide the total Watts used by the lighting system by the total floor area. Example: No of lamps (A) No of fixtures in room (B) Type of lamp 2/Fixture 24 36W - T8 (magnetic) Total Watts per lamp (C) Total Watts (D) (AxBxC) Total floor area (E) Total Watts/m 2 (D/E) 112.5m W/m 2 5 To estimate the power used by other sized Mercury Vapour or Metal Halide lamps multiply the lamp watts by 110%.

6 HOW YOU CAN INCREASE THE ENERGY EFFICIENCY OF YOUR LIGHTING SYSTEM OPTIONS A - REDUCE TIME LIGHTS ARE TURNED O REDUCE TIME LIGHTS ARE TURNED ON MANUALLY TURN OFF LIGHTS IF LEAVING A ROOM FOR MORE THAN MINUTES. $ Use awareness raising campaigns on the costs and myths of leaving lights on when not needed, use student light monitors to check lights are turned off at recess & lunch, get teachers to turn off lights when they leave rather than leaving for cleaners to turn off, use posters on exit doors or near light switches to remind people to turn off lights. Note: Lights produce heat which must be removed by the air-conditioning system. Less light power used = less heat = less air-conditioning costs USE SENSORS, PUSH BUTTON OR DIAL UP TIMERS ON LIGHT SWITCHES TO TURN LIGHTS OFF AUTOMATICALLY IN ROOMS USED INTERMITTENTLY (toilets, staff/meeting rooms, withdrawal rooms). $$ Contact the Infrastructure Sustainability Unit to discuss which type would be suitable for your school. USE LIGHT SENSITIVE PHOTO ACTIVATION SWITCHES ON SECURITY LIGHTS TO ENSURE ONLY ON WHEN NEEDED. $$ IDENTIFY LIGHT SWITCHES WITH LABELS This will ensure only those lights needed will be turned on. $ INSTALL LIGHT SENSITIVE PHOTO ACTIVATION SWITCHES TO LIGHTING CIRCUITS NEAR WINDOWS. $$$ A photocell sensor detects the levels of natural light and turns lights off or down when sufficient day-lighting is available. This option will generally involve re-wiring of circuits and replacement of existing control gear. Source: Advanced Building technologies & properties, (Lighting and Daylighting,

7 USE TASK LIGHTS FOR TEACHERS DURING AFTER CLASS HOURS $ - $$ The type of lamps best used will depend on whether it is likely if teachers work stations are moved from one year to the next. Ceiling or wall mounted lights will have higher costs and are fixed. A trial could be undertaken to assess if desk lamps are suitable. Remember 1 lamp using 100W will use a lot less energy than a classroom of 40W lamps, select a lamp with sufficient light output. DAY LIGHTING $ Use natural light wherever possible. Posters on windows reduce light levels in rooms, find alternative areas to display posters if possible. OPTIONS B - REDUCE THE TOTAL ENERGY USED IN EXISTING LIGHT FIXTURES REMOVE A LAMP FROM TWIN FIXTURES WHERE LIGHT LUX LEVELS ARE AT LEAST TWICE THE RECOMMENDED LEVEL AND FROM TRIPLE FIXTURES WHERE LIGHT LUX LEVELS ARE AT LEAST 50% HIGHER THAN RECOMMENDED LEVEL. $ - $$ Note: The remaining lamp in a twin fixture may need to be repositioned to centre of fixture by an electrician. When removing lamps, remove starter and use a sticker stating that lamp should not be replaced. (Stickers can be obtained from the Infrastructure Sustainability Unit). Starter INSTALL LAMP REFLECTORS WHERE LIGHT FIXTURES HAVE POOR REFLECTIVE QUALITIES. $$ Reflectors can be retrofitted to existing fluorescent tubes to increase the amount of light directed downward from the fitting. These can be used to reduce the need to increase lighting energy consumption where light levels are too low, or, to reduce energy consumption through de-lamping where room lighting levels are at least 80% higher than standards prior to lamp removal and reflector fitting. An example of a inefficient lighting fixture. Some of the light is being absorbed by the dark surfaces and some is being diffused into the ceiling cavity. INSTALL A VOLTAGE REDUCTION DEVICE. $$ After start-up the voltage supply to fluorescent lights can be reduced with only a small effect on light output (~10-15%), the subsequent lower current produces savings of around 30% in energy consumption. Voltage reduction control should be considered where light lux levels are at least 40% higher than that recommended by the Australian Standards. Voltage reduction is only suitable for lighting systems controlled by magnetic ballasts.

8 OPTIONS C - USE MORE ENERGY EFFICIENT LAMPS AND FITTINGS REPLACE OLD T8 HALOPHOSHUR FLUORESCENT TUBES WITH NEW TRIPHOSPHUR T8 FLUORESCENT LAMPS. $ Triphosphor lamps use less mercury and have 15-20% greater light output for the same energy use as older lamps. As the triphosphor are 15-20% brighter, in theory you can remove 15-20% of the lamps and achieve the same light levels for 15-20% less energy and emissions. REPLACE T8 FLUORESCENT TUBES WITH PROPRIETARY BRAND, T5 ADAPTORS AND LAMPS, OR LIGHT EMITTING DIODES (LED S). $$ - $$$ These lamps will produce the same amount of light but require less power to operate. T5 fluorescent lamps are 23% more efficient than T8 Triphosphor and 38% more efficient than T8 standard fluorescent lamps 18, requiring less energy to produce the same amount of light output. T5 lamps normally require a new fitting and an electronic ballast to operate and are therefore most economical when installing new light fixtures. An alternative to fixture replacement is the use of proprietary brand T5 adaptors which can be installed into the existing fittings providing equivalent light output with reduced energy input. New to the market LED s can replace existing fluorescent lamps maintaining light levels whilst reducing lighting energy consumption by around 70%. The lamps contain no mercury, have a lifecycle of 50, ,000hrs (fluorescent lamps have a lamp life of around 16,000hrs), produce negligible heat, and do not need ballasts or starters to operate. LED s are relatively expensive compared to fluorescent lamps however they have shorter pay-back periods if installed into lighting fixtures that operate for at least 2700 hours per year. LED s should be considered for security lighting at your school. The supply of energy efficient light fittings is developing rapidly, when looking to purchase T5 adaptors or LED s check with the Infrastructure Sustainability Unit for the latest improvements in this technology. REPLACE STANDARD INCANDESCENT GLOBES WITH COMPACT FLUORESCENT GLOBES. $ 20Watt Compact Fluorescent 100W Standard Incandescent 15W 75W 12W 60W 9W 40W (When purchasing compact fluorescent globes be sure to check the colour temperature of the lamp. Values of 4500K and above will provide a bright bluish day-light coloured light, values of around 2700K will provide a warm yellowish coloured light.) REPLACE EXISTING LIGHT FIXTURES WITH NEW HIGH OUTPUT LIGHT FIXTURES. $$$ Fixtures are now available that have almost double the light output to a standard fixture, reducing the number of lamps required to service a given area.

9 INSTALL ELECTRONIC OR LOW LOSS MAGNETIC BALLASTS. $$$ Ballasts are a type of transformer and are required to regulate the current going to a fluorescent lamp. The cheapest and least efficient type of ballast is standard magnetic. Though these can no longer be manufactured or imported into Australia, most older lighting systems will still have these installed. Low-loss magnetic ballasts are now available which use 15% to 45% less energy than a standard magnetic ballast (2-4W saving per lamp) 6. Electronic ballasts are the most efficient ballast available, eliminate flicker, and reduce the amount of power drawn by lamps by around 10%. 7 REPLACE MERCURY VAPOUR LAMPS WITH METAL HALIDE OR SODIUM LAMPS. $$$ For indoor lighting applications use metal halide lamps, these lamps provide almost double the light output for the same energy input as mercury vapour and have good colour rendering. For outdoor applications, such as car park and security lighting where colour rendering is not as important use high or low pressure sodium lamps. High pressure sodium lamps have similar efficiency to metal halides and low pressure around three times more efficient than mercury vapour. The low pressure sodium lamps have a very distinctive yellow glow. Example: a 125W mercury vapour lamp could be replaced with a 70W metal halide or high pressure sodium, or a 40-50W low pressure sodium. The ballasts/control gear for these lamps differ and need to be replaced as well. REPLACE OLD STYLE EXIT LIGHTS WITH NEW LED EXIT LIGHTS. $$$ The economy style exit lights used for most schools in Darwin consume around 10W. New LED exit lamps (as shown in the photos on the left) will consume only around 2-3W. 6 Based on maximum corrected input power Energy Efficiency Index classifications B1 & B2 stated in Australian MEPS for Fluorescent Ballasts. 7 Sustainable Energy Development Office Government of Western Australia, Technology Table 1, Section 5.1 Lighting in Commercial Buildings and Offices, Energy Saving Manual Energy Smart Toolbox,

10 STEP 1 COLLECT INFORMATION FIND OUT WHAT TYPE AND HOW MANY LIGHTS ARE USED IN YOUR SCHOOL MEASURE OR USE FLOOR PLANS TO CALCULATE FLOOR AREA SURVEY STAFF/TEACHERS AND ROOMS TO FIND OUT HOW LIGHTS ARE USED AND IF OPERATIONAL TIMES CAN BE REDUCED LOOK AT OPTIONS A FOR OPPORTUNITIES TO REDUCE TIME LIGHTS ARE LEFT ON STEP 2 CALCULATE THE ENERGY EFFICIENCY USE THE INFORMATION FROM STEP 1 TO DETERMINE THE WATTS PER SQUARE METRE FOR EACH ROOM HIGH WATTS/m 2 LOW WATTS/m 2 > 12W/m 2 < 12W/m 2 MEASURE LUX LEVELS AVERAGE LUX READINGS < 40% ABOVE STANDARDS USE OPTIONS C TO INCREASE ENERGY EFFICIENCY OF LIGHTING SYSTEM Old halo-phosphor lamps, dirty fixtures and room surfaces, dark wall colours, and inefficient reflections from fittings could be reducing the amount of light available. Replace lamps with tri-phosphor tubes, clean classroom and light fixtures, and if necessary/possible lighten room surfaces, then re-measure lux levels. LUX < 40% ABOVE STDS AVERAGE LUX READINGS > 40% ABOVE STANDARDS Option B recommendations can be considered. Note on de-lamping: Factors such as glare, colour rendering, and uniformity of illumination (absence of shadows), all impact on the quality of light, therefore an aggressive de-lamping strategy should be undertaken with care. A de-lamping trial of a single room with sufficiently high light levels should provide a good indication of the impact on occupants and visual quality. If de-lamping will require the installation of reflectors and/or the repositioning of lamps in fixtures, advice should be obtained from a lighting specialist or the Infrastructure Sustainability Unit. In addition, an operations & maintenance plan should be established which includes group lamp replacement and regular cleaning of lamp fixtures and room surfaces to maximize efficiency and maintain savings.

11 STUDENT ACTIVITIES 1. Undertake light audit of your classroom. (Example shown below) ROOM: YEAR 4-5 CLASSROOM 2 TIME OF AUDIT: 8.00AM TYPE OF LAMPS AND USE eg s 28W T5 FLURO, 36W T8 FLUORO, 60W INCANDESCENT 36W T8 FLOURO TUBES MAIN CLASSROOM LIGHTS 75W INCANDESCENT BLACKBOARD LIGHTS 18W T8 FLOURO TUBES STOREROOM LIGHTS GENERAL OBSERVATIONS NUMBER OF FIXTURES AND LAMPS 12 X 2LAMPS = 24 LAMPS 6 X 1LAMP = 6 LAMPS 1 X 2LAMP = 2 LAMPS NOTES (STYLE & CONDITION OF DIFFUSERS, CONTROL SWITCHES USED, ARE ALL GLOBES WORKING) 2 LAMPS NOT WORKING DIFFUSERS APPEAR CLEAN LIGHTS OPERATED BY 2 LOCAL ON/OFF SWITCHS LIGHTS OPERATED BY 1 LOCAL ON/OFF SWITCH TIMER CONTROL ON LIGHT SWITCH ROOM COLOUR USE OF DAYLIGHTING HAVE LIGHTS BEEN LEFT ON WHEN NO-ONE IN CLASSROOM? LIGHT COLOURED WALLS AND CEILING POSTERS AND PICTURES ON WINDOWS BLOCKING SOME OF THE AVAILABLE DAYLIGHT SURVEY QUESTIONS ARE LIGHTS TURNED OFF AT: LUCHTIME? RECESS? ARE LIGHTS TURNED OFF WHEN TEACHERS FINISH FOR THE DAY? DO STUDENTS & TEACHER THINK THERE ARE ENOUGH LIGHTS? DO TEACHERS ONLY TURN ON LIGHTS THAT NEED TO BE TURNED ON BASED ON TASK TO BE PERFORMED AND/OR AVAILABLE NATURAL DAYLIGHT? RESPONSE LUNCHTIME YES RECESS - NO NO - LIGHTS ARE LEFT FOR CLEANERS TO TURN OFF GENERALLY EVERYONE THINKS OK STUDENTS NEAR WESTERN WINDOWS THINK LIGHTS COULD BE TURNED OFF AFTER LUNCH SOMETIMES - NOT OFTEN LUX READINGS N 7Mtrs TOTAL AREA = 35 M 2 24 X 43W = 1032W W/35M 2 = 29.5 W/M 2 DOORS 5Mtrs WINDOWS

12 2. Investigate what lighting efficiency improvements could be made in your classroom. 3. Discuss what lighting efficiency improvements could be made at home. 4. Conduct lighting audit of school. The audit could be undertaken by a single group of students or areas of lighting could be assigned to different groups. GROUP AREA CLASSROOM LIGHTING EXIT & EMERGENCY LIGHTING SECURITY LIGHTING OFFICES & ADMINISTRATION GYM/ASSEMBLY AREA PASSAGE WAYS & TOILETS CANTEEN & LIBRARY 5. Calculate the energy and green house gas savings from the options using the information in the section Estimating Energy Consumption and Savings Potentials.