How much can I save by upgrading to LEDs?
We often get asked by school leaders and estates teams how much they could save by upgrading their lighting to LEDs and if there’s a way to tell from their Energy Sparks account how much of their electricity use is down to lighting.
We’ve asked school energy expert and founder of Inspired Efficiency, Matt Fulford for his take on this and here’s what he has to say:
Rule of thumb savings
Replacing old inefficient lighting for LED lighting is usually an excellent energy saving measure but trying to accurately assess the amount of energy that will be saved is important to have the confidence to invest. Different light fittings will save different amounts. For example, a single 5ft fluorescent tube will be 58W and an LED replacement will be around 25W saving 57%. A square light fitting in a suspended ceiling is typically made up of four 18W tubes totalling 72W but is replaced with a single LED panel light of around 23W saving 68%.
If a school has mostly older, inefficient lighting then typically around 40% of the school’s annual electricity consumption will be for lighting – the lighting load. For a whole school lighting upgrade, it is normal to save around 40% to 60% of this lighting load. So as a quick rule of thumb, the likely saving from installing LED lighting is around half of that lighting load (40%), so about 20% of the school’s total electricity use.
How can we calculate potential savings?
LED lighting companies will usually work out the savings but it’s good to be able to check that these have not been incorrectly presented. Using the initial rule of thumb above will be a suitable quick check. If the savings presented are a long way apart from this, it is worth doing your own calculations.
The most accurate way to calculate the energy saving from lighting is to survey each type of fitting to review what lamps (bulbs) are within each fitting, the wattage of the lamps, how many lamps are in the fittings and how many fittings there are of each type. Then find out what a suitable replacement lamp would be for each fitting and the wattage of the replacement.
In order to work out how much electricity is being used, you will also need to know how long the lights are on over a year. Working on the basis of the lights being on from 7am to 5pm, Monday to Friday for 40 weeks of the year, a school will have its lights on for 2000 hours a year. In reality the lights may be off some times during the day but on for cleaning, parents evenings etc so 2,000 hours is typically fairly accurate for primary schools and 2,200 is fairly typical for secondary schools.
So multiplying the wattage of all of the current lights by the number of hours they will be used will give you the number of kWh (remember to divide by 1,000 to go from W to kW). Compare that with the same for the new lights and you will be able to see the savings.
If the savings presented by the company are still very different, it is worth checking what hours have been used and that these are realistic and also that the rate of the cost of electricity is the same as the rate that is currently charged on the electricity bills.
Energy Sparks has a pupil activity to conduct a lighting audit as part of our Lower your Lighting Impact Programme. Staff and students could use this to estimate potential savings from a lighting upgrade.
How can we make the most savings?
Savings can be maximised by ensuring that the specification of the new LED lighting is as good as it can be with the lowest wattage LED fittings being selected. LED lights tend to provide more light output than older fluorescent fittings so making sure that any new installation avoids the room being over lit will maximise savings. It is also good to check whether it is necessary to use the same amount of light fittings as are currently installed as it is not always necessary to replace lighting on a 1:1 basis. As a basic rule of thumb, LED panel lights in a suspended ceiling can have three solid square ceiling tiles between each light fitting in both directions.
And don’t forget that you can use your Energy Sparks account to gain a better understanding of the cost of your lighting before embarking on a lighting project.
How can Energy Sparks help us assess the cost of our lighting?
Use the energy efficiency advice pages, accessed by clicking on the “Explore energy data” button on the Adult dashboard to inspect your electricity consumption in more detail.
The chart below comes from the Intraday analysis page, and shows the electricity consumption through an average day at a school with inefficient lighting. As soon as people start arriving at the school and switching lights on, consumption is high and remains high until the end of the day. This school has since upgraded the lighting and reduced electricity consumption by over 30%
The following chart is from the Baseload analysis page shows a school’s electricity consumption on a Sunday when the school is empty. The dip in consumption in the middle of the day shows that the school’s security lighting that is on overnight is using a lot of energy. We estimated that this school is spending £4,000 a year on electricity for their security lighting. Replacing with LEDs and adding motion sensors could save them money, alert people to intruders and keep their neighbours happier.
Finally, we have an example of a school with inefficient flood lighting on their playing field. We have estimated that lighting their pitch costs them approximately £6,000 a year. The school have had similar estimates from a lighting company and are expecting to save £4,000 a year once their upgrade project is complete. The project will include dimmable lights in accordance with Football Association guidance which will also save them money.
About Matt and Inspired Efficiency
Inspired Efficiency (IE) was founded and is run by Matt Fulford in 2013. IE has extensive experience in delivering energy advice and carbon reduction advice in the historic buildings (largely churches) and the public sector (especially schools). Matt advises the Church of England nationally on decarbonisation and has also advised the DfE. He works with Teach the Future and has previously been the chair of governors of a small rural primary school.
Inspired Efficiency have delivered a huge number of energy and decarbonisation reports for over 1,000 schools. Inspired Efficiency have undertaken initial heat decarbonisation plans , detailed decarbonisation design development, PSDS bids and have managed the roll out of LED lighting replacement and other programmes across multiple school estates.
Matt personally led the delivery of the conversion of St Andrews Primary School, Chedworth into a net zero carbon school using PSDS1 funding and has since been part of teams leading successful PSDS applications for several other schools, the Met Police and the University of Cambridge. IE have also shared the analysis from their experience and the results of all the heat decarbonisation audits they have undertaken with the Department for Education and this has been used in obtaining further energy efficiency funding.
Inspired Efficiency is as passionate about delivery its services sustainable as it is about delivering energy and carbon reduction of its clients. As such Inspired Efficiency has a environmental policy which is far more than words on a page, it commits to:
- Never using air travel for business
- Only using fully electric cars
- Only ever using 100% recycled paper products
- Only ever purchasing 100% renewable energy
- Never paying business expenses for single use plastic or meat products
- Only banking with ethical banks and pension providers
- Donating at least 5% of our profits to local sustainable solutions.
