Tennis court lighting, like most things in life, vary dramatically depending on the type of usage and personal preferences.  In principle, the ball is small and moves fast.  This usually requires a higher level of lighting than, say, a football.  The important thing to bear in mind is that it is always cheaper to do the job right the first time than to have to redo it in 2 years’ time.  Other factors will include how close are your neighbours and how much do you want to spend.

Lighting levels

This would be the first consideration as everything else will be based on the lux levels required.  For basic play and just to have enough light to see the ball a minimum of 100 lux is required.  This would be suitable for a late night fun game, however, if you are more serious and using the court for training you should really be working to 250 lux.  This will give you sufficient light for higher speeds of play and would be where many good clubs operate their lighting levels.  At the next tier up, competition courts operate at 500 lux.  These lux levels allow for high speed play and would be suitable for any class of player.  Any light levels are achievable, it just depends on where you see your style of play in relation to the budget you set.  To go from 100 lux to 500 lux would require approximately 2.5 times the poles and light modules.

Along with the overall lighting level, uniformity, or evenness of the spread of light is equally important.  It is not sufficient for a designer to quote an average lux level as this could vary from 500 lux directly under the fittings, to 100 lux in centre court.  The average may be 250 but the useableness of the light will be hampered by being patchy and uneven.  You therefore need to ensure that the uniformity factor is round 0.4.

Light Control

In order to make sure your friendly neighbours stay friendly, check the lighting plan provided by the supplier to ensure there is no spill light at ground level.  Also ensure the lights mount horizontally.  This will tend to be the more specialised lights as many of the cheaper modules will mount at an angle.  Whilst these angled units are less expensive, they can cost a lot in relationships as the glare from these lights can be literally seen for miles.

Pole Height

For domestic courts this is usually best to be kept as low as possible to minimise glare and over-spill light.  Depending on the light fitting used and the lighting levels required a height of 6m to 8m is usually feasible.  For public areas poles up to 20m are used, particularly when lighting a number of courts from a restricted number of poles.  This height make uniformity easier as the light spreads naturally when given more distance.

To compensate for the lower poles it is often necessary to use more poles.  For instance if using 10-15m poles, 4 would be sufficient to get 250 lux and good coverage.  If 6-8m is ideal then 6 poles may be required to get the same results or 8-10 poles to achieve competition lux levels.

The main problem with metal halides was that when bulbs needed to be changed, the higher the poles the bigger the hassle. With LED’s having now come into their own in terms of reliability and longevity, keeping pole height down to make servicing easier is no longer an issue.

Remember that often these poles, although galvanised to resist rusting, can be powder coated or painted to suit your environment.  Black or white are common but other options are often available on request.

Pole installation

Lighting poles are now available virtually off-the-shelf from a number of reputable suppliers.  They conform to relevant regulations and the manufacturers can provide drawings and specifications to help aid a council planning submission.  The poles are mostly supplied with a complete installation kit including a frame structure which gets concreted into the ground.  This, along with the installation instructions, makes it simple and safe for any good contractor to install the poles.

Electrical requirements

The typical current draw for a tennis court will be from 2.4kW (less than a kettle to boil water) for achieving 100+ lux up to 6kW which would provide competition level lighting with 10 poles.  The modules typically are supplied with an LED driver which can be mounted at the base of the pole or may be integrated into the design of the lamp.  Whilst the wiring up and installation is simple, ensure that a qualified electrician does the installation and that the modules are compliant with local regulations.

Conclusion

This planning work will put you in good stead to have a lot of fun for many years to come.  A cautionary note would be to use this guide to cross check what you are told by contractors.  Sometimes things that are simpler, easier and cheaper for them may not be best for you in the long term.

Good luck and enjoy the game!

We often get asked the question ‘Can I replace metal halide bulbs with LED bulbs in the same fitting?’ Whilst this would be nice and convenient it is unfortunately not possible at present.  That is not to say it will never be possible.  As most of us over-30-year-olds can testify, things that were totally impossible are suddenly and surprisingly ubiquitous the next minute.  For those under 30 nothing is any longer regarded as impossible, so watch this space!

Although all lamps generate heat in some form or another, the way metal halide and other traditional forms of lighting work is very different to LED.  Metal halide lamps push their heat forward.  This means that they need a glass or high-temperature plastic cover to cope with the heat.  However, the body or frame holding the bulb itself can be light and thin, often mild steel or plastic as there is no heat coming out the back of the lamp.  By contrast LED’s generate a lot of heat but it flows out the back, with very little coming forward.  In this way a plastic lens can be used for the front, but requires an aluminium heatsink as the back part of the housing to help remove the heat build-up.  This simple contrast means that (for the moment) the way the 2 types of lamps operate is fundamentally too different to be able to make the change simply by replacing bulbs.

Whilst we are aware there are products on the market which claim to do this swap out, be very careful.  At this point a realistic wattage replacement is 1.2kW of LED for a 2kW of metal halide power.  As of mid-2018 this would be regarded as a highly efficient sports light.  This means that the heat generated is equivalent to 240 x 5W domestic lamps, but crammed into a light that is about 600 x 600mm.  If you were to further reduce this size to that of a 2kW bulb, it is technically, and practically, impossible to remove the heat.  As a build-up of heat would destroy the LED’s, this leaves the only other conclusion that it cannot therefore produce the right amount of energy. This is of course simple to prove.  Get lux readings of your existing lighting layout and then ask the supplier of the alternative bulbs to do the same.  If they don’t have the facility to produce lighting layouts it is very unlikely that the product will work.  If they can prove that it works then you know that science has again progressed and we need to do some catching up.

The response is often ‘Well it works at home!’  This is perfectly true and is only possible due to the low current draw of these lamps and, consequently, the low amounts of heat that will be generated.  The more that is expected out of a lamp in terms of light output, the more heat will be generated.  Domestic lamps are often only 3 or 5W but produce a good glow in their setting.  Compared to a high intensity lamp like a sports fitting, these domestic units are very large by comparison, giving a lot of surface area which also helps dissipate heat.  If a sports light was created that used domestic 5W bulbs it would likely measure more than about 2sqm.  Space in the ceiling of house is not really at a premium, hence light fittings don’t have to be very streamlined.  However, having a large and heavy light 25m in the air increases the cost and engineering challenges for the pole manufacturers.  Additionally, if clubs are wanting to replace metal halide fittings with LED, the modules have to be similar to the metal halides in dimensions and weight for the same reason.

The only viable solution currently is to have a module that is matched in size and weight as mentioned, but then also has optimised light output to compare with the metal halide.

So, proceed with caution if the option looks too simple and cheap.  As with most things in life, if it looks too good to be true, it may be just that!

A question we regularly get asked is ‘Do I need to replace all the lights at once or can I do it over time?’  The answer is definitely that if can be done in phased approach over time, but needs a touch more planning to make it successful.  Get it right and you’ll be everyone’s hero, get it wrong and no-one will remember to thank you for the money you’re saving them in the long run.

Legacy high powered LED lights have been designed to replace traditional metal halide fittings on a one-for-one basis.  This means that the weight and size have been optimised so that existing poles can be used, but also means that the beam pattern is very similar to what a standard narrow beam flood light would produce.  One of the key advantages therefore is that lights can be replaced as they fail, or as budgets permit, without causing big issues in the meanwhile.

Case Study

A city based recreational football ground had reasonable club attendance but only a small amount available annually for maintenance and repairs.  With replacements globes costing around $250-$300 each, the biggest expense was in the hiring of high lift equipment and the technicians time to do it.   The field had 4 poles with eight lamps on each.

The planning phase was the most important to ensure that all interested parties were getting what they needed:

The Players

Whatever decision was made it had to work all the time for the players.  Having a hotch-potch make-shift system was not going to cut it for players who were paying membership fees.  Being a city location ensured there were other clubs within easy reach if the facilities didn’t come up to scratch.

The Neighbours

The current metal halides, whilst old, were professionally designed and installed and the neighbours enjoyed glare-free lighting, being mounted horizontally.

The Treasurer

Whatever the solution the club had to pay for the installation and be able to live with the results.  Proving a reasonable return on investment (ROI) was important to get everyone on board with the increased capital requirement that new LED’s would require.  The fact that all expenses could be recouped within 10 years was enough to convince the money guys that it was a worthwhile investment.

The Facilities Team & Volunteers

With much of the work being done at the club by volunteers, using maintenance free lighting would free up the volunteers to do other tasks, or give them the day off!

With some targeted fund raising activity is was found that they could afford to replace the lamps on one pole each year, thereby taking 4 years to complete the project.

The facilities team used lighting simulations from 3 manufacturers to decide which lamp would be the best in the ‘phased approach’ by seeing which would give the best, most-even light distribution when used in conjunction with the old metal halides.  It was decided to replace one pole at a time and if lamps on other poles failed in the meanwhile, the working units from the swapped out modules were used until that poles turn came around.  In this way the expense was budgeted and easy to predict. Using a Return on Investment calculator it was estimated the pay-back period to be 10 years which gave the club confidence that they were making the right long-term decision.  This was over against the instinctive thought to rather just constantly carry on paying out a smaller amount annually for maintenance.

A 5 year, 50 000 hour warranty went a long way to convincing the board that the lamps would be for benefit of the club well into the future.  Delaying the decision to move to digital lighting only postpones the end date of having an efficient and effective lighting system, like which is not possible apart from LED.

So if you’re looking to do a phased approach ensure some key points:

1)      Will the light pattern of the new lamp blend with the old in terms of light distribution and colour temperature

2)      Can I replace my existing units one-for-one in terms of size and weight so that the current poles can be used?

3)      Have points 1 and 2 been backed up by an accurate simulated lighting plan and been compared to existing light levels?

Once you’ve gone through this whole exercise you will be far more likely of a successful change-over and more able to maximise the benefits into the future.

Getting enough light on the ground without bothering the neighbours is a great start to a good game of evening football.  When evaluating what will, or won’t, work there is a number of parameters that will affect the results.  Lumens and Lux are 2 of the most common to be looked into so let’s explain a bit more about both terms and then the answer becomes more clear.

Lumens is a measurement of the volume of light being emitted by the lamp.  This is controlled by how the manufacturer of the LED chip (Cree, Lumiled etc.) has designed it and the value will vary depending on how much current is put through it.  For instance, a 5W chip operating at 5W may produce 90 lumens/watt.  That is, for every watt of power put in, it will generate 90 lumens out.  However, if you run the same LED at 3W you will get a big increase in the efficiency and generate perhaps 120 lumens/watt.  The lamp manufacturer therefore specifies a gross lumens value in two ways – raw lumens and effective lumens.  The raw lumens is what the LED manufacturer has put as the value at a given temperature and wattage.  This does not take into account the lamp as a system and doesn’t reflect any calculation for losses from optics, temperature etc.  The effective lumens is what is calculated once the lamp has been built into a system.  This is tested over a period of hours and so allows the lamp time to heat up and is testing the actual light output rather than the theoretical light produced in a laboratory by the LED itself.  If the lighting manufacturer doesn’t specify if the values stated are raw or effective, you can safely assume they are raw.  Losses from raw to effective may be as much as 30% and is specific to the system i.e. cannot be estimated without knowing more details about the lamp as a whole.

Lux, on the other hand is a practical, field measurement of real light on the ground or at a specified height.  This test can be done physically or simulated using software and the IES (digital light pattern) file. Once the lamps have been set up on their poles (or simulated) and the field is illuminated, then you can measure the actual light on the ground.  This takes into account the same losses as the effective lumens test but also shows how the light is controlled.  This is very important for big-field sports like football, cricket, baseball and rugby.  Having a huge mass of bright light that only shines 50m isn’t very helpful on a rugby field.  Additionally, the mass of light tends to have a lot of stray light which can tend to annoy spectators and neighbours.

So, whilst you have to have the right lumen values being emitted from the lamp, the way it is controlled is of utmost importance.  Just because a light has high power and lots of lumens doesn’t mean the light will go where you want it to go.  A proper lighting plan is therefore essential.  If you are not sure what lighting levels you need there are a number of sources of this info – a handy quick reference being is the Legacy guide but there are numerous more detailed sources available.  Once you know what the standard is, check out your lighting levels with a lux meter.  Again there are some helpful app downloads to give you an idea of where your illumination is up to.  If this is sufficient, use it as the base for your design.  If it isn’t sufficient, work with the lighting guidelines and the designer to come up with a system that works.

It’s a good idea to get a couple of lighting companies so you can compare the lighting plans from different manufacturers.  Once done you should be well on the way to making a better, more informed decision, achieving efficiency and low maintenance for many years to come.

 

If you have looked into LED lighting at all you will have noticed there is dozens, if not hundreds, of options.  So, as you can imagine, there a dozens, if not hundreds, of variations to the answer of this question. They range from 100W to 1500W, big fins, small fins, fan assisted, metal pressed, die cast, white powder coat, black powder coat, COB’s, small chip LED’s, high efficiency LED’s and so on and so on.  Your head begins to spin at the options, but one thing you can be sure of is that LED is the most efficient – right?  Wrong.  Or more correctly – potentially wrong.

Let’s just confirm that point quickly as it is really important – just because it is LED does not mean that it is energy efficient.  Or, conversely, just because it is old technology metal halide does not make it inefficient.  A number of factors need to be assessed to decide if LED is going to work for you.  How often are the lights used, and for how long etc. etc.

So let’s look at some of these factors in a bit more detail…

How often are the lights used and for how long?

A while back we had a client insisting on looking at LED.  They ran a rodeo once a year for one night and he felt LED was going to give him the best return on investment because if ‘was the best’ and ‘the latest technology’.  Needless to say we were dubious.  The LED fittings he wanted cost 4 times that of metal halide and the amount of electricity used in the year would have only been 10’s of dollars because of only being used once a year.  In this case there was no way of justifying the purchase.  On the other hand, making a 40% energy saving on 100’s of hours of use per year can make it very viable.

How many lights will I need to use?

The only way to conclusively check if there is a gross energy saving is to get a lighting plan done.  If you are using the existing poles then you can figure out what lighting levels you already have and get a comparative study done using LED.  You can immediately see if you will require more or less fittings and energy by the layout results.  Don’t take this as a given that LED will reduce your energy consumption.  Most systems are less efficient than their traditional alternatives.

Optics and field size

The larger the field, the more difficult it is for LED to improve on power consumption.  This is because many of the LED optics are not optimised for big field sports and are therefore very inefficient at distributing the light, particularly at a distance.  The critical factor is the control of the light with optics or reflectors as this determines ultimately how many LED watts will be required.  Again, a lighting plan using the IES file for the specified light is the only way to know if it will work or not.  Don’t baulk at this step.  It may cost a few hundred dollars at worst, and at best could save you hundreds of thousands in wasted investment.

To conclude then, efficiency is relative to the size of the investment vs the usage of the lights.  Assuming you get a really good optic and can replace your metal halide fittings and get a 40% saving in electricity, make sure you get a sensible return on investment by looking at the whole lifetime cost, rather than just focusing on the isolated factor of energy consumption.

A key difference between traditional metal halide fittings and LED fittings is the maintenance costs.  The basic housing for the metal halide fittings can last for 10’s of years but the bulbs need to be replaced regularly as they lose 20-25% of their efficiency within the first 250 hours of operation.  By contrast LED fittings should last 50000 hours as a system without the need for maintenance other than occasional cleaning.

Whilst this is all perfectly true, the flip side is that if the metal halide fails, you only have to replace the bulb.  By contrast, if the LED fails, you have to replace the whole unit.

A number of factors influence how long the LED’s last.  Key elements are the driver, the LED’s, waterproofing, condensation control and the control of heat.

The Driver or Power supply

This is a critical component and is one of the most common causes of failure in LED’s.  The power supply in a mains AC powered system is essentially the brains of the lamp.  The PC Board in an AC system is a ‘dumb’ board loaded with LED’s.  All control, dimming etc are controlled by the power supply, except for the temperature control on the board.  There are a number of specialist manufacturers who offer very good warranties and have proved themselves in the field. Ensure your supplier is not economising on this component as it is likely to be where issues will come from and can be expensive to replace.

The LED’s

There is a large number of proven manufacturers of LED’s.  While a brand is no guarantee of high performance and longevity, there is credibility with some of these companies who have consistently produced excellent products for many years.  Amongst these are Cree, LG and Lumiled although lighting manufacturers constantly need to experiment with other products to ensure they keep in the forefront of the industry.  However, it is worth checking the credibility of the brand of LED’s to give you some idea of what your warranty is worth.

Waterproofing

As sports lights are generally installed outside a level of waterproofing is essential.  This would usually involve a seal around the lens and a waterproof cable gland. Once moisture gets into the lights it quickly damages the PC Board and will result in failures within days.

Condensation

When a lamp has been working hard and getting hot, a sudden change in temperature (like from rain) can cause the air in the lamp to condense.  This results in fogging in the lamp which will very quickly can deterioration in the electronics, and ultimately, failure.  Most lights are now designed with a breather valve.  This means that if there is a build-up of condensation in the lamp the moisture can go out, but not back in.  This method is virtually fool-proof and is essential for all lamps that are not made in a moisture free environment – which is the majority of lamps in the world.

Control of heat

One of the principle causes of LED failure is overheating.  The 2 main ways to control this is by having sufficient heat sinking and by moderating the temperature of the PC Board electronically.  As the housing is static and airflow is unpredictable, the surface area and fin size influences how well it will control the heat.  The other aspect is to control how hard the LED’s run.  The more current they draw the hotter they will be.  Control mechanisms are therefore put into place to throttle the current draw which in turn allows the LED’s time to cool down.  This method is only successful when used in conjunction with an effective heat sink and is not an alternative to a good heatsink.

So, lots to look into but once you’ve explored all the options and you’re confident of your decision, you will have a system that will last for many years to come.

High powered LED sports lights come in a myriad of shapes and sizes, beam patterns and CRI’s.  With the benefits of being digital there is amazing things that can be done with them to create effects, dim, flash etc. and are all features that can enhance the user experience and make your sports field much more multi-functional.  This increases the options for revenue streams and makes better use of the facility.

So, how much do these digital luminaires cost?

Well, as you’ve probably guessed, that depends on how far you want to go.  As the sky is literally the limit for what you can spend with all special effects, we have tried to just deal with conventional lighting for sport applications. Each sport has very different and specific requirements with relation to CRI, lux levels and pole heights and so we have not attempted to make this an exhaustive guide.

Many companies will do lighting layouts and IES files free of charge, or for small charge, so you to prove more accurately what the costs will be, but this should put you in the right ball-park so there’s no dramatic surprises.

There will be two main scenario’s:  Brand new build and replacement of metal halide fittings.

Brand New Build

This is the most difficult to guesstimate as you have nothing to work on to begin with.  However, let’s make a start.  Broadly speaking there are generally three levels of play – Class 1, 2 and 3.  This guide does not attempt to estimate a facility that will be have televised matches as the lighting required for this is significantly higher and is much more complex.  Also for a new installation bear in the mind the cost of the light fittings themselves is likely to be only about 20% of the cost of the poles, provision of power, control gear and installation.

Due to there being many different regulations in different countries we have broadly grouped them into 3 groups which reflect the lighting level required.

Group 1 – Involves large capacity crowds who are situated quite far from the action

Assumptions:

  • Lighting level of 500 lux
  • Pole height of 20-25m
  • Pricing range allows for CRI of 70-90
  • Estimated luminaire cost US$15-US$20/m2

Group 2 – This could be regional club matches with medium sized crowds and also include high-level training

Assumptions:

  • Lighting level of 200 lux
  • Pole height of 20-25m
  • Pricing range allows for CRI of 70-90
  • Estimated luminaire cost US7-US10/m2

Group 3 – Local matches or recreation grounds with very few spectators and also training

  • Lighting level of 75-100 lux
  • Pole height of 20-25m
  • Pricing range assumes CRI of 70
  • Estimated luminaire cost US4-6/m2

Replacement of metal halide fittings:

This scenario is simpler to estimate assuming you are happy with the lighting levels you currently have.  If you are unsure what they are or want to check they are near what you assumed, there are a few apps such as Lux Meter (Light Meter) for android or Lux Light Meter Pro for iOS which give a good indication.

 

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Assuming that you find the existing levels are what you need, then the calculation is simply a one-for-one replacement in most situations.  As an approximation the replacement of a 1kW metal halide fitting would be US$1500 and the replacement of a 2kW metal halide fitting would be US$2500, for a 70 CRI and about 10-15% more for a 90 CRI module.

If you are not happy with your existing lighting levels use the guide above for ‘New Build’ which gives a lux level and is based on square meter averages.

As you will appreciate there are a huge amount of variables in a calculation of this nature and we would always recommend getting a lighting plan done by a professional company.  However, this will hopefully put you in ball-park and give you something to work on.

Need a more accurate quote?  Try using our Sports Lighting Cost Calculator or contact Legacy Lighting for a personalised quote.

Sport lighting is a specialised and complex science.  The lighting level, evenness, glare, CRI, heights and spill-light control are all aspects the designer has to take into account and all these parameters vary depending on the application.  For a game where the ball is small and fast moving, like tennis, high lighting levels are required with a very good CRI.  If the game is being videoed or televised the lighting levels and pitch uniformity have to be of a very high standard.

Over the years we have taken a lot of this for granted with metal halide systems.  Although an old technology, metal halide naturally produces a very high CRI, flicker-free light with a very good colour temperature. The development of the reflectors over the years has resulted in a very efficient system that was relatively simple for designers to specify.  With only two main beam patterns, almost any big-field sport was catered for and increasing the number of lights brought up the lux readings to the desired level.

The introduction of LED a decade ago was thought to signal the death of 2kW metal halide fittings as they are ‘old and outdated’.  However, while all other forms of lighting were changing rapidly, sport lighting remained surprisingly static. Early adopters burned their fingers with very heavy lights that gave bad light and failed regularly. As a result designers have shied away from these digital fittings that could potentially give them a bad name.  From our attempts, even as recently as 2015, it needed nearly 3000W of LED power to get a similar beam to a 2000W metal halide. Considering the extra weight and necessary pole thickness upgrade and the 100% increase in unit cost LED, was not looking very favourable.

However, LED manufacturers like Cree and LG have continued to improve light output and efficiencies. Optic designers have carried on working away and now there are some systems that can truly replace metal halide one for one.

However, when looking at doing a swap out there are a number of points to consider.

Weight and sail area (surface area)

The poles you currently use have been designed for a specific weight and sail area.  Increasing either, or both of these could have quite dramatic effects in high wind.  Make sure that neither of them exceeds what is currently used or obtain the original poles drawings to make sure the increase can be accommodated in the existing design.  This should be carried out by a qualified structural engineer.

Lux levels

Assess accurately what the current lux levels are of your field, decide what you need.  Just because you had it designed to 500 lux 20 years ago by no means guarantees that is what it is at present. Be realistic and don’t over-specify unless power consumption and capital budget are not an issue.

Power consumption

Once the layout design has been completed, ensure that the power consumption is within the tolerances of what you have available for peak demand. This might sound obvious but many systems have been implemented without taking this into account.

  • CRI requirement will depend on what level of sport is being played. For most training and club applications 70 CRI is sufficient.  If the games are to be televised or it is amateur level with a small ball i.e. cricket, then 90 CRI may be needed.  This is not something that can be changed later so needs consideration early on as the price is affected by up to 20%.
  • If you’re not sure about the company making the lights, or can’t find out much about them, the two most important parts of the light are the driver and the LED’s. Ask for make and model and research these thoroughly.  If both these components are from a reliable source, it is likely the lamp will stay the pace.
  • Some manufacturers have now used the metal halide beam patterns to model their LED optic. This makes is simpler for the designer so but essentially the beam pattern, uniformity etc should be dealt with by them (or the manufacturer if they offer this service) and you should be able to rely on them for this.

If you can satisfy all these requirements then, when added to the benefits of digital lighting, you will have made a good decision that will last a long time.

There are currently three main forms of lighting used in sport applications.  Filament (halogen), discharge (metal halide and HID) and LED.  All have benefits and disadvantages in certain circumstances and it’s important to understand these when considering an upgrade or changing lights.

Traditional halogen lamps use a filament which heats up as the electricity passes through.  This glows, producing light and a lot of heat.  As a large part of the energy goes into the heat side of the equation, the halogen light is not very efficient from an energy perspective and is generally only able to be used for small court type sports like tennis.  However, the heat is all out the front of the lamp so the housing can be made from any material (metal, aluminium, plastic etc) and the front lens (typically glass) manages the heat.  This means the lamps can be quite small and mounted easily.  The main advantage of halogen is that they are cheap to buy but are really only suitable for small club or personal use due to their short life span and inefficiencies.

Metal Halide and Sodium Vapour are discharge lamps, much like a fluorescent tube, where the gas is the lamp is glowing, rather than a filament like with halogen. These types of lighting are more efficient than halogen but their useful life peaks very quickly, and their performance deteriorates after a few hundred hours.  In fact, a metal halide lamp will lose 25% of its original performance within the first 250 hours of use.  Like halogens, the heat comes out the front, allowing for light weight, typically metal pressed bodies or housings and glass fronts.  A frustrating fact of metal halides is that once they turn off they have a significant re-start time of about 10 minutes.  Metal Halide has been the main-stay of high powered sports lighting for decades and provides very good light economically.  The units are cheap to buy and are very proven in the field.  On-going maintenance can be expensive as the bulbs have to be replaced regularly.  This can be a nuisance, particularly when mounted 25m in the air.

LED’s are the latest innovation and have been in the market for about 10 years.  They have replaced other forms of lighting in most applications but have struggled with delivering value in the big field sports. One of the reasons is that unlike halogens and metal halides, LED’s generate heat behind them.  The LED’s are mounted to a flat pc board (electronic circuit board) and all facing in the same direction.  When turned on the pc board will heat up very quickly but very little heat radiates from the front. This means that the front lens can be plastic but the back-end, or housing, needs to be aluminium or some other type of heat-sinking material to remove the heat from the pc board.  For static lamps, like in a warehouse or fixed pole application, like sports fields, the manufacture has to account for high ambient (room) temperatures and low, or no, airflow. This is a critical part of the lamp as LED’s will fail if they get too hot. This important design aspect makes the lamps very heavy and often larger in surface area than other forms of lighting, like Metal Halide, Sodium Vapour and HID.  As an example, a car spotlight 100W halogen lamp will weigh 700g compared to an LED of equivalent wattage which would weigh about 4kg.  A well designed LED system is likely to provide the best long-term investment.  However, look into it carefully as there are many levels of quality and performance and just because it is LED is no guarantee that you will automatically improve on an older, metal halide system.  Also, when considering upgrading your metal halide fittings with LED, ensure that the poles are capable of supporting the extra weight and sail area.

When we (those of us over 40) think of an LED we tend to think of a little glowing diode on a pc board or electronic toy and register the fact the LED draws very little power.  While this may be correct for a single diode, when we ramp things up 10W of power is the same whether you’re powering a halogen bulb or LED.

OK so where is this power-consumption advantage of LED then?  And will I not get any benefit from changing over my old 2kW Metal Halide sports lights?

The answers lies in a number of factors which have to work together to make LED effective.  The key elements that the manufacturer has to blend are the following:

  1. Identifying the application
  2. Selecting an LED
  3. Designing an optic
  4. Designing the heat sink or housing
  5. Control of usage and dimming

The first point to consider when designing a lamp is what the application is.

Designing for the application

In a warehouse, the size of the lamp is not an issue as the roof space is generally a void.  Because the lights are running constantly, the user is more concerned about the power usage or efficiency.  For this user a high lumens/watt ratio is ideal as it means using less electricity.  Lights are therefore designed to have a large surface area and use lots of LED’s. Although this costs a bit more initially, the pay-back in power consumption easily justifies it.

Whilst this is good for warehouse lighting, it is not necessarily so for sports lighting or vehicle lighting.  Having a large and heavy light at the top of a 25m sports pole causes problems with ‘sail area’.  Much like a ships sails, these lights will cause resistance to the wind and put a lot of strain on the pole.  For instance, if you’re wanting to change from Metal Halide to LED, the poles at your club may have been designed for holding 10 lights weighing 20kg/each with a sail area of 0.8m2.  These are then replaced with 10 LED lights weighing 30kg/each and a sail area of 1m2.  We don’t have to be mathematicians to realise that we could well have an issue on a windy day!  Likewise having a very ‘energy efficient’ 350mm-diameter driving light on your 4WD is not going to look very cool or be very fuel efficient.

So as we said, the application is very important when designing a light and there is no best-fit for all industries.

Selecting the LED

Selecting the LED for a specific application is a complex problem.  There are hundreds of options on the market from dozens of manufacturers, covering the spectrum from 0.2W up to COB’s which can be over 50W.  As a rule of thumb, the less hard you drive an LED the brighter it glows relative to the wattage you put in.  This efficiency factor is called lumens/watt. So for instance a 5W LED may be producing 100 lumens/watt at 5W but if you run it at 2W it will produce 130 lumens/watt (Lumens being the measurement of light output against how many watts are put in).  Although the overall lumen value is less, the actual efficiency (or light output to current-draw) is much higher. Therefore if you run 5W LED’s at 2W you will get a high efficiency (lumens/watt).

The LED however just produces an intense glow of light and in itself has no control. For this we need an optic or reflector which will guide the light where we want it to go.

Designing an optic

This step is done in conjunction with the choice of the LED as they have to work together and is the most critical aspect.  Each optic or reflector is therefore optimised for a specific LED and this combination will determine the energy efficiency and light control.

As mentioned above LED’s themselves just produce a ball of light.  Harnessing this and guiding it exactly we it needs to go is the work of the optic.  There is three main ways to do this a) Total Internal Reflection optic b) Chrome reflector c) Combination of both.  There are pro’s and con’s for all three and we won’t go into that in any depth here.  Sufficient to say this control of the light decides whether to beam is going to be 5° wide and go 1km down the road, or 100° wide for a wide flood etc.  Sports lighting uses a combination of beam patterns for different applications.  The most difficult has proved to be the asymmetric narrow beam needed for large, field based sports like baseball, football, soccer and cricket.  Most manufacturers have taken the easy route of having a round beam pattern in a set number of angles.  However in big-field sports this proves to be very inefficient and can require up to 50% more power to achieve the same result as using a 2kW metal halide fitting.  Given that LED’s tend to be more expensive than metal halide, this can result in the project costing a lot more than you perhaps budgeted.

So, when you’re looking into this, be sure to get an IES lighting plan done before committing to purchase.  Many manufacturers will do this for a nominal sum, or even free, and is very important to make sure that you can achieve the right lighting levels without overloading your existing poles or ending up using twice the amount of electricity.

Designing the housing

Essentially this should be the simplest part of the design but is still very important.  The LED’s are working away and the optics are putting the light where we need it but unless we remove the heat effectively, the light isn’t going to last for very long.  On the other hand if we space the LED’s out and make large cooling fins, it will run very cool but will be too heavy to replace metal halide fittings one for one.

Designers use special software to model heat build-up and ensure that there is a balance between too much aluminium and sail area (like a ships sail) and being too small and risk overheating. Many high-powered LED sports lights weigh 2-3 times that of 2kW metal halides but are no more efficient.  Care needs to be taken to ensure that the poles have been designed to cope with the extra weight and sail area.

Control of usage and dimming

With digital LED lighting more options are available to us to save energy.  App based controllers are now available to interface with almost any lamp and can be used for pay-as-you-play, dim for training, get energy usage reports and much more.  These systems can have a rapid pay-back and take a lot of hassle out of managing the day to day problems of responsibility and maintenance.  Your lighting supplier would either have their own bespoke system or will have alliances with third party providers to offer a range of packages from simple to very complex.

Conclusion

So, in conclusion if you are wanting to install digital LED lighting for the energy efficiency, make sure that you are able to achieve this as it cannot be taken for granted.  If you are unsure we would recommend investing a few hundred dollars in getting a third party to cross-check that the lighting layout provided is accurate, as once the lights are up it could be an expensive mistake.  Suppliers should be willing to provide the IES files so this can be done.  Also use a lux meter to test what lighting you currently achieve and ensure that you have come-back on the supplier if minimum standards are not met.