Lighting Lingo Decoded: Top 15 Lighting Terms Every UK Business Needs to Know

Brightness and Efficiency

Lumens (lm)

Lumens measure the total amount of visible light emitted by a source. The higher the lumens, the brighter the light. For commercial spaces, selecting the correct lumen output is about more than just brightness. It is about delivering the right amount of light where it is needed. An office workstation may require around 300 to 500 lumens per square metre, while a warehouse aisle may need higher outputs. Choosing appropriate lumens reduces overlighting, cuts energy waste, and helps meet Part L building regulations. See more about lux vs lumens here. 

Watts (W)

Watts measure the power a light fitting consumes, not how bright it is. Older halogen or fluorescent fittings used high wattage to produce modest light. Modern LEDs deliver the same or higher brightness using significantly fewer watts. Swapping a 50W halogen downlight for a 9W LED can save over 80 percent on energy costs. For UK businesses, lower wattage means reduced electricity bills and a smaller carbon footprint, supporting both compliance and corporate sustainability targets. All of our Linear Lights products are LEDs. 

Efficacy (lm/W)

Efficacy is the ratio of light output to power input, expressed as lumens per watt. A high efficacy fitting delivers more light for less energy. Typical LED efficacy now ranges from 100 to 150 lm/W, compared to older fluorescent tubes at around 60 to 80 lm/W. For large scale commercial installations, choosing high efficacy fittings can reduce annual energy costs by thousands of pounds and shorten payback periods significantly. 

Light Quality and Ambience

Colour Temperature (K)

Measured in Kelvin, colour temperature defines whether light appears warm, neutral, or cool. This is not about brightness but atmosphere.

2700K to 3000K is warm white. It creates a relaxed, welcoming feel. Best for hotel lobbies, restaurants, and premium retail.

3500K to 4000K is neutral or cool white. It supports concentration and alertness. Ideal for offices, medical practices, and classrooms.

5000K and above is daylight. It is crisp, high contrast, and energising. Suited to warehouses, automotive workshops, and jewellery displays where fine detail matters.

Choosing the right Kelvin helps define the character of your space and influences how customers and staff feel. See our light temperature guide here for more information on choosing the right colour temperature for your space. 

Colour Rendering Index (CRI)

CRI measures how accurately a light source reveals the true colours of objects compared to natural daylight. The scale runs from 0 to 100. For most commercial interiors, a CRI of 80 or above is adequate. For high end retail, art galleries, or food displays, a CRI of 90 or above is recommended. Poor CRI can make products look dull, fabric appear faded, or skin tones look unnatural. Investing in high CRI lighting improves visual appeal and supports brand presentation.

Beam Angle

Beam angle describes how light spreads from a source. Narrow beam angles, typically 15 to 30 degrees, concentrate light on a specific point. They are ideal for accent lighting, display cases, or feature walls. Wide beam angles, 60 degrees or more, disperse light evenly across larger areas. They suit open plan offices, corridors, and general retail floors. Selecting the right beam angle prevents dark spots and ensures lighting is both functional and dramatic where needed.

Measurement and Hardware

Lux (lx)

Lux measures the intensity of light falling on a surface, with one lux equal to one lumen per square metre. Different tasks require different lux levels. The UK Health and Safety Executive recommends:

150 to 200 lux for circulation areas and warehouses.

300 to 500 lux for general office work and retail floor space.

750 lux or more for detailed tasks such as drawing, quality control, or precision assembly.

Measuring lux on site helps validate that your lighting design meets legal standards and provides a comfortable visual environment.

Luminaire

A luminaire is the complete lighting unit. This includes the lamp, housing, reflectors, lens, and control gear. The luminaire determines how light is distributed, how efficient the system is, and how the fitting looks. In commercial environments, luminaires must balance aesthetics with performance and ease of maintenance. Our Flow range delivers both beautifully.

LED (Light Emitting Diode)

LEDs are semiconductor devices that produce light when electricity passes through them. Unlike traditional lamps, they do not rely on heating a filament or ionising gas. This makes them highly efficient, durable, and long lasting. A quality LED can operate for 50,000 hours or more. That is equivalent to over 17 years of typical office use. LEDs also switch on instantly, perform well in cold conditions, and contain no hazardous mercury. They are the preferred choice for sustainable commercial projects.

Ballast and Driver

Ballasts and drivers regulate the electrical supply to lamps. Fluorescent tubes require ballasts to control starting and operating current. LEDs require drivers to convert mains power to low voltage direct current. The quality of these components directly affects performance. Poor drivers can cause flicker, audible hum, or premature failure. Specifying reputable control gear ensures reliable operation, consistent light output, and longer luminaire life.

Durability and Control

IP Rating

The Ingress Protection rating classifies the degree of protection against solids and liquids. The first digit indicates dust resistance on a scale of 0 to 6. The second digit indicates moisture resistance on a scale of 0 to 9K. For example:

IP20 is suitable for indoor dry areas such as offices.

IP44 is appropriate for bathrooms or sheltered canopies.

IP65 is dust tight and protected against water jets. Ideal for commercial kitchens, car parks, and external walkways.

Selecting the correct IP rating prevents premature failure and ensures safety in challenging environments. 

Dimmable Lighting

Dimmable lighting allows users to adjust brightness levels according to need. In meeting rooms, dimming supports presentations and screen visibility. In restaurants, it enables mood shifts from daytime service to evening ambience. In retail, it can draw focus to seasonal displays. Beyond flexibility, dimming reduces energy consumption and extends lamp life. For best results, ensure dimmable drivers are paired with compatible controls and that the system is commissioned correctly.

Emergency Lighting

Emergency lighting is a legal requirement under the Regulatory Reform (Fire Safety) Order 2005. It activates automatically when mains power fails, illuminating escape routes and safety equipment. Two common types are:

Maintained fittings, which operate as normal lighting and stay on during a power cut.

Non maintained fittings, which remain off until an emergency occurs.

Regular testing and compliance with BS 5266 are mandatory for UK commercial premises.

Unified Glare Rating (UGR)

UGR measures how much glare a lighting installation produces. In commercial spaces, excessive glare can cause eye strain and reduce productivity, especially in screen-based environments. UGR is rated on a scale typically between 10 and 30. The lower the number, the lower the glare.

UGR < 19 is recommended for offices.

UGR < 22 suits general commercial areas.

Tunable White

Tunable white lighting lets you adjust the colour temperature of a space - from warm to cool white - using controls or smart systems.  It supports staff wellbeing, improves focus, and allows businesses to create the right ambience for different tasks or times of day. Our R3 downlight has an option for tunable white or fixed colour temperatures. 

 

Bringing It All Together

Navigating lumens, Kelvin, beam angles, and IP ratings is only the beginning. The real skill lies in combining these elements to create a lighting scheme that supports the way people actually use a space. Whether you are fitting out a Grade A office, refreshing a high street store, or specifying lighting for a new care home, every decision affects energy performance, visual comfort, and long term costs.

If you are looking to translate these concepts into a tailored, efficient, and visually compelling lighting scheme, our team offers complimentary lighting design consultations to bring your vision to life.