Low Energy Lighting (LEL)

At the time of writing the methodology for EPC assessments of existing dwellings is RDSAP 9.94. The much anticipated RDSAP 10 update is due in Q1 2025 and a significant methodology overhaul from RDSAP to the Home Energy Model (HEM) is proposed for 2026.

As a chid I remember the traditional tungsten filament bulbs and how hot they ran. They'd blow quite regularly, and we'd have to unscrew them with a double-folded tea towel before fitting a new bulb. Also, the light fittings and cables would brown over time becase of the long-term exposure to the heat.

Light fittings back then were rated to the maximum power of bulb they would accomodate, because of the amount of heat generated, and you'd have to be careful with that because some domestic bulbs ran at 150W. Imagine how much power would be drawn if you had 10 of those all powered up at the same time.

Things have changed since then, and as part of the drive to reduce CO2 emissions the sale of standard bayonet filament bulbs in the UK is prevented by legislation. Even fluorescent tubes in the UK are on their way out too.

For energy efficiency reasons the move for some time has been towards what is called 'Low Energy Lighting', with LED of particular interest.

Essentially, for a better EPC rating the goal is to have all of your light fittings populated with 'Low Energy Lighting' (LEL). We'll define what LEL is here, and how lighting is assessed.

For the EPC assessment, we count the number of lights in the property, and we count the number of those which are classed as 'Low Energy Lighting'.

Currently we count the number of light fittings rather than bulbs (lamps), so a chandallier would be counted as 1. Also, where 4 or more spot lights are in the same room, we count half the number of lights - so 6 spotlights would be counted as 3. In the near future, when the assessment methodology for existing dwellings is updated from version 9.94 to version 10 however, every individual bulb will be counted.

We only count light fittings inside the property. We don't count light fittings on the outside of the property or in areas that we don't consider for the EPC assessment - such as unheated garages or conservatories where they are separated from the main building by an external quality door. We do however include fixed lighting under kitchen wall cabinets and plinth lights etc.

Note, that the assessment procedure considers Low Energy Lighting to include:

• LED lights
• Fluorescent tubes (FT)
• Compact Fluorescent Lamps (CFL)

Importantly, it does not consider Halogen bulbs to be Low Energy Lighting, and of course 'traditional' filament bulbs aren't either.

Note also that empty fittings have to be considered non-LEL unless the fitting is so designed that it will only accept LEL bulbs.

When the assessment methodology for existing dwellings finally moves up from version 9.94 to version 10, the assessment procedure will change slightly and CFLs will be counted individually, separately from LEDs.

A recommendation will appear on your EPC in all cases if the percentage of low energy lighting is less than 100% and the gain is deemed enough to appear on the certificate.

The recommendation is to fit Low Energy Lighting into all fixed outlets.

Moving up to 100% 'Low Energy Lighting', from a lower percentage, will only make a small difference to your EPC rating.

For example if we take my 3 bed terraced house (covered in our Case Study 2 page), where I have 18 light fittings, moving from 0% to 100% LEL would take me from a 66D to a 68D rating. That's an improvement of only 2 SAP points. If I had moved up from 50% to 100% it would only have improved my rating by 1 SAP point.

Those one or two SAP points however could be the ones that take you up a band from say a D to a C rating, if you were currently on the threshold, so considering the ease of effort and low cost, this is the first step that most homeowners will complete.

In summary, before calling out a Domestic Energy Assessor, just run round your property, replace any non-LEL bulbs with LEL bulbs, and make sure all fttings are populated, as empty fitting will usually be counted as non-LEL. 

It's a really easy measure to implement and the cost is low. The rating gain is also low, but because it is so easy to accomplish it should be the first job on your list to implement.

Click here to return to our 'Improve Your EPC' main page, and see if there is another way you could improve your EPC rating.