LED Energy Saving Studies

Gary Robinson, Area Projects Manager

How much energy will I save?

Using the correct lights can save high amounts of energy, this is why lighting is included in the government list of energy-efficient plant and machinery. The question of energy efficiency when comparing lighting systems is at face value is a simple one: How much energy will I save? The answer can be simple as a rule of thumb calculation, however demonstrating it can be far more complex. The quick answer when comparing Fluorescent to LED is approximately 60% without auto controls and 80% with auto control. But this is not the whole story, especially when the customer is looking for a payback time of installation costs.

What else do we need to know?

An important factor is the current running cost of the installed lighting.  This depends on a few different parameters. Total wattage value of all the lamps, type of ballast in the luminaire and approximate age of the installation. A fitting that has 4 x 18w T8 fluorescent lamps and an electronic ballast will be at installation 72w for the lamps plus 10% gear losses making 79.2W. If the installation is 3 or more years old the gear losses will be more than 10% and a wire wound ballast can be as much as 12% losses The only truly accurate way to measure is to meter the installation.  

What does an LED cost to run?

LED is far more simple because the driver losses are negligible, so low as to not need to be added into the calculation So a 32W Core Panel Light will be 32W against a fluorescent of 79.2W, a 40% saving on a one for one replacement. This can be far more when you look at larger fluorecent tubes or CFL. It is also almost certain that we can reduce the number of fittings in a space by as much as 25% reducing costs further.  

Other factors that should be considered

It is important to know what the current usage is or “burning hours”.  An office environment is never an 8 hour day, 10 hours is more typical and with late night cleaners can be more than that, especially when they leave the lights on overnight. How may days per week and weeks per year all come in to play. Can auto control be used to switch off luminaires when they are not needed? What has been the maintenance regime? Most offices will burn to fail, i.e they only change a lamp when it fails. Due to the nature of fluorescent this usually means that they will be running at 60% of the installed light levels. New LED fittings will be far brighter.    

Is electricity the only running cost to be considered?

Every fluorescent lighting scheme will have a cost for maintenance. Lamps will need to be replaced. The cost of an 18W tube is not very much but the cost of a man with a ladder per hour to change the tube can be as much as £25 per hour. If we factor in average life expectancy of the tube over a 5 year period it can be assumed that all the tubes will be changed twice. Add in the cost of the labour based on average time allowance per fitting you achieve a 5 year capital cost of the light installation.    

What can RICOMAN do for you

Our lighting managers are fully trained and equipped with a number of tools to conduct energy saving calculations for your projects. Get in touch now and we will work out the best solution for you.