How to Build a Lighting Specification for Commercial Projects

Define the project objectives

A lighting specification is not a product list. It is a performance brief — stating the illuminance targets, the control requirements, the compliance standards the installation must meet, and the criteria by which products will be selected and accepted.

Before selecting any products, establish for each zone or space type:

• What activities will the space support?
• What atmosphere or character is the lighting expected to create?
• What hours will the lighting be in use, and is the pattern predictable or variable?
• Are there different requirements at different times of day or for different uses?
• Is there significant natural light, and does the artificial lighting need to respond to it?

Set performance requirements

For each zone, specify:

• Maintained illuminance (lux) — the average lux level at the working plane after the maintenance factor has been applied. CIBSE-referenced values by space type are covered in the Lumily LED commercial lighting guide.
• Uniformity ratio (Uo) — the ratio of minimum to average illuminance. CIBSE SLL guidance recommends Uo ≥ 0.7 for most working environments.
• Colour rendering index (CRI) — Ra ≥ 80 for most commercial applications; Ra ≥ 90 for colour-critical retail, healthcare, and high-quality hospitality.
• Colour temperature (CCT) — 2700–3000K for hospitality; 3500–4000K for offices and retail; 5000K+ for technical or industrial environments.
• Unified Glare Rating (UGR) — UGR ≤ 19 recommended for offices and most commercial work environments.

Identify compliance requirements

• Building Regulations Part L — minimum energy efficiency and control requirements for new and substantially refurbished commercial buildings.
• CIBSE Lighting Guide LG7 — the UK standard reference for office lighting.
• BS EN 12464-1 — European standard covering illuminance, uniformity, glare and colour rendering for indoor work places.
• BS 5266 — emergency escape lighting requirements for commercial premises.
• BREEAM / LEED — specific lighting credits for energy efficiency, occupancy controls, and daylighting.
• IP ratings — wet or outdoor spaces must specify fittings with appropriate IP ratings.

Specify the control system

• Control zones — define the boundaries and what can be operated independently within each zone.
• Dimming protocol — specify 0-10V, DALI, DMX, Casambi, or on/off, with reasons.
• Scene requirements — list the scenes required in each zone with approximate target levels for each luminaire group.
• Occupancy sensing — specify sensor types, mounting locations, and hold times.
• Daylight linking — specify whether automatic dimming linked to natural light levels is required and the setpoint.
• Emergency integration — define how emergency fittings integrate with the general control system.
• BMS integration — if applicable, specify the interface protocol and the signals to be exchanged.

Select and specify products

For each product type in the specification, record:

• Product name, manufacturer, and full model reference
• Rated lumen output (initial and maintained at L80 or L70)
• CRI, CCT, and CCT tolerance
• Input power and efficacy (lumens per watt)
• Dimming protocol and compatibility
• IP rating and certification standard (IEC 60529)
• Photometric data file (IES or LDT) for lighting calculation software
• Warranty period and terms

Write the sustainability section

• Energy consumption target — maximum watts per square metre for each zone category.
• Control strategy — occupancy sensors, daylight dimming, scheduled off modes.
• Product lifespan — minimum L70 rating at 50,000 hours; recyclability of driver and strip components.
• Light pollution — for exterior lighting, specify curfew dimming, directional control, and compliance with CIBSE Guidance Note 8 on obtrusive light.
• Responsible sourcing — products must comply with RoHS and WEEE regulations.

Budget and procurement

• Product schedule — a complete schedule of all luminaire types, quantities, unit prices, and total supply cost.
• Lead times — specify earliest required on-site date, particularly for custom-length profiles or bespoke driver configurations.
• Approved manufacturers — specify whether equal products from alternative manufacturers will be considered, and what approval process applies.
• Commissioning — specify the acceptance testing process and what documentation is required at practical completion.