Dashpivot article page – Part L lighting

Part L lighting

Part L Lighting

Part L of the UK Building Regulations specifically addresses the conservation of fuel and power in buildings, including aspects related to lighting.

The aim is to improve energy efficiency and reduce carbon emissions.

In the context of lighting, Part L sets standards for both residential and commercial buildings, focusing on the use of energy-efficient lighting solutions.

What are the main considerations for Part L lighting compliance?

Residential Buildings

Part L encourages the use of energy-efficient lighting, such as LED lights, to reduce power usage. A certain percentage of fixed light fittings must be energy-efficient. Part L emphasises the use of controls like dimmers or occupancy sensors to reduce energy usage when rooms are unoccupied or have sufficient natural light.

Non-Residential Buildings

Luminaire efficacy dictates the minimum standards for the efficacy of lighting fixtures, encouraging the use of more efficient lighting technologies. Reduce energy consumption by using technology such as automated controls, motion detectors, daylight sensors and timers. Lights in different areas should be independently controllable to avoid unnecessary lighting in unoccupied spaces.

Design and Installation

Lighting design must be integrated with the building design to optimise natural light usage and reduce artificial lighting needs. You require detailed documentation to demonstrate compliance with the regulations.

Updates and Compliance

Part L is periodically updated to reflect advancements in lighting technology and energy efficiency standards.
Compliance with Part L is mandatory for new buildings and major renovations, with certification required to demonstrate adherence to the standards.


Part L aims to reduce energy consumption in buildings through efficient lighting design and technology.

It also contributes to the UK's overall efforts in reducing carbon emissions and promoting sustainable development.

What are Part L lighting calculations?

Calculating compliance with Part L of the UK Building Regulations for lighting involves several key factors. These calculations are designed to ensure that the lighting in a building is energy efficient, both in terms of the installed lighting fixtures and the way they are controlled.

Here's a general guide on how you need to be making these calculations:

Luminaire Efficacy

Luminaire Efficacy is a measure of how efficiently a light fixture produces visible light, expressed in lumens per watt (lm/W).

The calculation is:

total light output of the luminaire (in lumens)

the power consumption (in watts)

Part L sets minimum efficacy standards that luminaires must meet.

Lighting Controls

Includes daylight dimming, presence detection, and time-controlled switching.

To get the calculation, assess the expected reduction in lighting use due to these controls. This can be more complex and may require simulation or specific calculation methodologies.

Total Installed Lighting Power

To get the calculation, for each area of the building:

the power of each luminaire  *  the number of luminaires

Compare this with the maximum allowable lighting power for the building or space, which is determined based on the area and usage type.

Building Area Method (for Non-Dwellings)

A simplified method where total allowable lighting power is calculated based on the area of the building.

To calculate:

the area of the building (in m²) * the allowable lighting power density (watts per m²)

The allowable lighting power density varies depending on the type of space.

Room/Area Method

A detailed method where each room or area's lighting requirements are calculated based on its size and usage.

The calculation is similar to the Building Area Method but applied to individual rooms or areas.

Compliance Documentation

Detailed documentation of all calculations and design choices must be provided to demonstrate compliance. This can be accompanied by Photographic Evidence to show construction stages match the designs.

See how you can use Part L Photographic Evidence to document your compliance in the example below.

Part L Photographic Evidence

Keep your lighting Part L compliant with this digital Part L Photographic Evidence template

Use Photographic Evidence to show your Part L lighting compliance

Ensure you can show your compliance with Part L regulations by using this digital Part L Photographic Evidence template in case of an audit.

Your team can take photos on site to show that the different stages of work being done match the design stages.

Attach your photos to any other reports, such as progress reports, change requests, etc.

Photos have automatic timestamps, geotagging, smart tags and you can add markup to highlight important information, like how your work matches or doesn't match the design stage.

If you want to capture more information, you can add fields or sections to your report with the drag and drop form builder.

Ensure compliance with signoff approval by building signatures directly into your report.

Build digital workflows for Part L lighting to be compliant

Ensure you're meeting Part L regulations by building processes to request, record and sign off on Part L Photographic Evidence.

This Part L Photographic Evidence app enables your team to integrate Part L compliance into their daily work flow.

Workflows build stages for planning Part L checks, with automated notifications when it's time to collect Photographic Evidence, and when it's been submitted and is awaiting signoff approval.

Share completed reports in a single click from the app to your team or to 3rd parties as professionally formatted PDF or CSV.

Reduce double handling of your photographic evidence collecting by keeping on top of what's been submitted in the chronological Timeline view or a more detailed Register view.

Inspection and Test Plan (ITP) template

Inspection and Test Plan (ITP) template

No one plans to fail, they fail to plan. Ensure your projects are a success with this ITP.

Non-conformance report (NCR) template

Non-Conformance Report template

Document those painful non conformances with this powerful template.

Construction Punch List template

Construction Punch List template

Punch your way through those punch lists with this powerful template.

Sitemate builds best in class tools for built world companies.

Über Nick Chernih

Nick is the Senior Marketing Manager at Sitemate. He wants more people in the Built World to see the potential of doing things a different way - just because things are done one way doesn't mean it's the best way for you.

Hinterlassen Sie einen Kommentar