UK Business Lighting Guide: 15 Must-Know Terms Explained
Choosing the right lighting for UK commercial spaces (offices, retail stores, hospitality venues, or warehouses) can feel overwhelming. Understanding core lighting concepts like lumens, colour temperature, CRI, and efficacy is essential to create energy-efficient, visually appealing, and compliant lighting schemes. This guide explains these terms and shows how to apply them in real-world projects.
Lumens (lm) - How Bright Is Your Light?
Lumens measure the total visible light a fixture produces. The higher the lumens, the brighter the illumination. In commercial environments, correct lumen levels ensure functional lighting without over lighting:
Office workstations: ~300-500 lumens per square metre (suggested)
Warehouse aisles: Higher lumen output required
Choosing the right lumens improves energy efficiency, avoids over lighting, and helps meet UK Part L building regulations.
Watts (W) - Power Consumption vs Brightness
Watts measure energy use, not light output. Modern LED lights deliver bright illumination with significantly lower wattage compared to halogen or fluorescent lamps. For example, swapping a 50W halogen downlight for a 9W LED can reduce energy use by over 80%, cutting costs and supporting sustainability initiatives.
Efficacy (lm/W) – Light Output Per Watt
Efficacy shows how efficiently a light source converts power into visible light. High-efficacy LEDs (100-150 lm/W) produce more light for less energy, compared with older fluorescents at 60-80 lm/W. For large commercial projects, selecting high-efficacy fixtures can save thousands in annual energy bills.
Colour Temperature (K) - Warm, Neutral, or Cool
Colour temperature affects the mood and appearance of a space:
2700–3000K (Warm White): Cosy, welcoming. Ideal for hotels, restaurants, and high-end retail.
3500–4000K (Neutral/Cool White): Supports focus and alertness. Perfect for offices, classrooms, and medical facilities.
5000K+ (Daylight): Crisp and energising. Suitable for warehouses, workshops, and display areas requiring high contrast.
Selecting the right Kelvin value ensures your space feels right for staff and visitors. For more information, see our light temperature guide here.
Colour Rendering Index (CRI) - True Colours Matter
CRI measures how accurately a light source displays colours compared with natural daylight. Most commercial interiors are fine with CRI 80+, but high-end retail, galleries, and food displays benefit from CRI 90+ to ensure vibrant, true-to-life colours.
Beam Angle - Direct vs Wide Spread Light
Beam angle determines how a light spreads:
Narrow (15-30°): Accent lighting, display cases, feature walls
Wide (60°+): Open-plan offices, corridors, retail floors
Choosing the correct beam angle prevents dark spots and ensures balanced illumination. Many of our downlights are available in different beam angles.
Lux (lx) - Lighting Intensity on Surfaces
Lux measures the light falling on a surface. Recommended levels for UK commercial spaces:
150-200 lx: Circulation areas, warehouses
300-500 lx: Offices, general retail
750+ lx: Detailed tasks like quality control or assembly
Measuring lux helps confirm your lighting meets functional and legal standards.
Luminaire - The Complete Light Fixture
A luminaire includes the lamp, housing, lens, reflectors, and control gear. In commercial projects, it must combine aesthetics, efficiency, and ease of maintenance. Quality luminaires like our Flow range deliver all three.
LED - Efficient, Long-Lasting Lighting
LEDs are highly efficient semiconductors producing light without heating filaments or gases. They last 50,000+ hours, switch on instantly, perform well in cold conditions, and are mercury-free which is ideal for sustainable UK commercial projects.
Ballast and Driver - Power Regulation Essentials
Ballasts (for fluorescent lights) and drivers (for LEDs) regulate electricity to lamps. High-quality components prevent flicker, noise, and early failure, ensuring reliable lighting performance.
IP Rating - Protection Against Dust and Water
The Ingress Protection (IP) rating indicates resistance to solids and liquids:
IP20: Dry indoor spaces (offices)
IP44: Bathrooms or covered outdoor areas
IP65: Dust-tight and water-resistant, suitable for car parks, kitchens, and external walkways
Correct IP ratings ensure safety and durability. One of our most popular IP65 downlights are our Core downlights which is also fire rated.
Dimmable Lighting - Flexibility and Energy Savings
Dimmable fixtures let you adjust brightness for meetings, ambience, or displays. Properly paired dimmable drivers reduce energy use and extend lamp life.
Emergency Lighting - Compliance and Safety
Emergency lighting is legally required under the Regulatory Reform (Fire Safety) Order 2005. Two types:
Maintained: Always on, including during outages
Non-maintained: Only activates in an emergency
Regular testing and adherence to BS 5266 ensure compliance for UK commercial buildings.
Unified Glare Rating (UGR) - Comfortable Lighting
UGR measures glare in a space:
<19: Offices
<22: General commercial areas
Lower values reduce eye strain and improve comfort for staff and visitors.
Tunable White - Customisable Colour Temperature
Tunable white lighting allows adjustment from warm to cool tones, enhancing wellbeing, focus, and ambience. Options like our R3 downlight provide this flexibility.
Understanding lumens, Kelvin, CRI, beam angles, and IP ratings is just the first step. Combining these elements thoughtfully ensures your lighting supports functionality, energy efficiency, and visual appeal.
Whether you’re designing a new office, refreshing a retail store, or fitting a care facility, every lighting decision affects cost, comfort, and compliance.
Our UK lighting specialists offer complimentary lighting design service to help our clients implement effective, sustainable, and visually compelling lighting solutions.
