Smarter Lighting Design: how good lighting saves energy, cuts costs, and improves performance

Lighting is one of the biggest opportunities for businesses to reduce energy use, lower operating costs, and improve the quality of their spaces. Yet it’s often overlooked or treated as a simple “like-for-like” replacement exercise.

At DDP, we take a different approach. As an electrical design consultancy, we design lighting systems that align with best practice, support building users, and deliver real, measurable savings.

In this article, we explore the key principles of good lighting design, referencing the CIBSE SLL (Society of Light and Lighting) Guide, and show how smart lighting and controls can transform both energy performance and business outcomes.

What the CIBSE SLL Guide tells us about good lighting design

The CIBSE SLL Lighting Guides are widely regarded as the benchmark for lighting best practice in the UK. They go far beyond minimum compliance and focus on lighting quality, efficiency, and suitability for the task.

Key principles include:

1. Light for the task – not the space

One of the most important messages from the SLL Guide is that lighting should be designed around visual tasks, not just overall illuminance levels. Over-lighting entire spaces wastes energy and can cause discomfort.

Good design considers:

• Task illuminance

• Surround and background lighting

• Contrast and uniformity

• Glare control (UGR)

2. Visual comfort matters

Poor lighting leads to eye strain, headaches, and reduced productivity. The SLL Guide emphasises:

• Appropriate luminance ratios

• Controlled glare

• Suitable colour temperature and colour rendering (CRI)

Comfortable lighting isn’t a luxury — it directly affects performance and wellbeing.

3. Energy efficiency without compromise

The SLL Guide promotes efficient solutions that do not sacrifice lighting quality, including:

• High-efficacy LED luminaires

• Optimised lighting layouts

• Efficient optical control

• Intelligent controls and zoning

A practical example: saving energy with smarter lighting design

A common issue we see is offices lit uniformly at full output for 12–14 hours a day, regardless of occupancy or daylight availability.

A typical improvement strategy includes:

• Replacing legacy fluorescent fittings with high-efficiency LED luminaires

• Redesigning the layout to reduce excessive illuminance

• Introducing daylight and occupancy controls

• Zoning lighting to match how the space is actually used

Real-world case study (UK office environment)

In one UK commercial office refurbishment:

• Old T8 fluorescent lighting was replaced with LED panels and downlights

• Occupancy sensors and daylight dimming were installed

• Lighting levels were designed in line with SLL recommendations rather than historic over-lighting

Results:

• Lighting energy consumption reduced by over 55%

• Annual energy cost savings in the tens of thousands of pounds

• Improved lighting quality and occupant satisfaction

• Reduced maintenance due to longer lamp life

This kind of outcome is achievable in many existing buildings with the right design approach.

Why lighting controls are no longer optional

Lighting controls are one of the most powerful tools for reducing energy use — and they’re strongly supported by both the CIBSE SLL Guide and Part L of the Building Regulations.

Effective controls include:

Occupancy detection

Lights automatically switch off (or dim) when spaces are unoccupied — ideal for:

• Meeting rooms

• Toilets

• Store rooms

• Circulation spaces

Daylight harvesting

Sensors dim artificial lighting when sufficient daylight is available, maintaining comfort while minimising energy use.

Time scheduling

Ensures lighting isn’t left on outside operational hours — a simple but highly effective measure.

Scene setting

Allows users to select appropriate lighting scenes for different activities, improving usability and reducing unnecessary output.

When properly designed and commissioned, lighting controls can reduce lighting energy consumption by 30–60%, often with short payback periods.

Why good lighting design needs an electrical design consultant

Lighting is not just about fittings, it’s about:

• Understanding industry best practices 

• Coordinating lighting, controls, and power

• Designing for compliance, comfort, and efficiency

• Avoiding costly over-design or under-performance

As a specialist electrical design consultancy, we help clients:

• Optimise lighting designs from concept to construction

• Reduce capital and operational costs

• Improve building performance and user experience

• Future-proof systems with smart controls and flexibility

Thinking about upgrading your lighting?

If you’re planning a refurbishment, new fit-out, or energy upgrade, lighting is one of the fastest ways to see real returns on investment.

Get in touch with us to discuss how a well-designed lighting and controls strategy can save energy, cut costs, and improve your space.