What is DALI and why is it used in commercial buildings?

DALI (Digital Addressable Lighting Interface) is an open-protocol digital communication standard for lighting control defined in IEC 62386. Each DALI device (ballast, LED driver, sensor, or switch) has a unique digital address on a two-wire bus that carries both power and data. The DALI controller can individually address, dim, group, and monitor every device on the bus. Unlike analogue dimming (0–10V), DALI provides two-way communication — the controller can query a device's current level, fault status, and lamp hours. DALI is preferred for commercial buildings because it is open-protocol (not tied to a single manufacturer), scalable, and integrates easily with building management systems.

What is the difference between DALI and KNX?

DALI is a lighting-specific protocol. A DALI system controls luminaires, sensors, and switches within a lighting installation but does not natively integrate with HVAC, blinds, or access control. KNX is a whole-building automation protocol (ISO/IEC 14543) that integrates lighting alongside heating, ventilation, air conditioning, blind and shutter control, energy metering, and security systems on a single bus. A KNX system can control DALI lighting via a KNX-DALI gateway. For a pure lighting control project, DALI is simpler and more cost-effective. For a fully integrated building automation project, KNX (with DALI integration) is the preferred solution.

Is Lutron suitable for commercial buildings or just homes?

Lutron Caseta is designed for domestic and small commercial applications (up to about 75 devices). Lutron RadioRA 2 and the newer RA 3 are suitable for larger residential projects — hotels, high-end apartments, luxury retail — with up to 200 devices per system. For large commercial buildings, Lutron Vive is a scalable wireless lighting control platform designed for offices and commercial spaces. Lutron EcoSystem is Lutron's commercial DALI-compatible protocol used in larger installations. Lutron systems are proprietary but have an excellent reputation for reliability and support.

How does occupancy-based lighting control work?

Occupancy-based control uses PIR (Passive Infrared) or microwave sensors to detect the presence of people in a space and automatically switch or dim lights accordingly. When no occupancy is detected for a preset time-out period (typically 5–30 minutes), the system dims or switches off the lights. Some systems use a two-stage approach — dimming to 10–20% on no occupancy for a further timeout period before switching off completely. The sensors must be positioned to provide full coverage of the space, avoiding blind spots behind furniture or partitions. Occupancy control reduces lighting energy consumption in intermittently used spaces such as meeting rooms, toilets, and corridors.

What happens to emergency lighting when a smart control system switches off the lights?

Emergency lighting operates independently of the smart lighting control system. Under BS 5266-1, maintained emergency luminaires must remain illuminated whenever the building is occupied, and non-maintained emergency luminaires must operate automatically on mains failure regardless of the control system state. Smart lighting control must never be able to switch off emergency luminaires — these must be wired on a dedicated circuit that bypasses the control system entirely. A common installation error is connecting emergency luminaires to a DALI or relay-switched circuit — this is non-compliant and dangerous.

What is daylight harvesting and how is it commissioned?

Daylight harvesting is a control strategy that reduces artificial lighting output as natural daylight increases, maintaining a constant target illuminance level on the working plane. A photocell (daylight sensor) measures the combined natural and artificial light level. The control system calculates the artificial light required to maintain the target lux level (e.g., 500 lux for office work per BS EN 12464-1) and dims the luminaires accordingly. Commissioning requires setting the target lux level, calibrating the photocell position (it must measure the actual daylight contribution, not the direct artificial light output), and verifying the response across the dimming range. Re-commissioning may be needed seasonally as daylight angles change.

Can smart lighting be retrofitted to an existing building?

Yes, though the cost and complexity depend on the existing installation. Wireless systems (Lutron Caseta, Philips Hue for commercial, DALI wireless) can be retrofitted without new wiring — wireless controls replace existing switches and DALI LED drivers replace existing ballasts. Wired DALI systems require a two-wire DALI bus to each luminaire, which may mean significant rewiring in existing buildings. Relay-based scene control (replacing manual switches with smart relays in the distribution board) is a lower-cost retrofit option that allows basic on/off and scene control without replacing luminaires or running new data cables.

LIGHTING SYSTEMS GUIDE

Smart Lighting Control Systems UK: DALI, KNX & Lutron Guide

The complete UK guide to intelligent lighting control — DALI (IEC 62386), KNX, and Lutron systems explained. Scene setting, occupancy sensing, daylight harvesting, emergency lighting integration under BS 5266, retrofit vs new build options, and 2026 costs.

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13 min readUpdated 2026-05-18Andrew Moore, Founder of Elec-Mate

Written and reviewed by Andrew Moore, founder of Elec-Mate, against BS 7671:2018+A4:2026, IET Guidance Note 3 and the IET On-Site Guide.

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Key Takeaways

1DALI (Digital Addressable Lighting Interface, IEC 62386) is the open-protocol standard for intelligent lighting control in commercial buildings. Each DALI device has a unique address and can be individually dimmed, grouped, and monitored over a two-wire bus.
2KNX is a building automation standard (ISO/IEC 14543) that integrates lighting with HVAC, blind control, access control, and metering on a single bus. More complex to commission than DALI but provides whole-building integration.
3Lutron Caseta is the leading retrofit smart lighting system for domestic and small commercial applications; Lutron RadioRA 2 and RA 3 serve larger residential and boutique commercial projects where a proprietary but highly reliable system is preferred.
4Emergency lighting must not be controlled by scene or occupancy switching — BS 5266-1 requires maintained and non-maintained emergency luminaires to be independently wired and operational regardless of the smart lighting control system state.
5Daylight harvesting — reducing artificial light output as natural light increases — can reduce lighting energy consumption by 20–50% in buildings with good natural light. Requires a photocell (daylight sensor) correctly positioned to measure the relevant daylight contribution.

01 · Lighting Systems Guide

DALI — Digital Addressable Lighting Interface

DALI (Digital Addressable Lighting Interface) is the open international standard for intelligent lighting control in commercial buildings, defined in IEC 62386. It has largely replaced analogue 0–10V dimming in new commercial lighting installations and is the protocol of choice for offices, retail, education, and healthcare.

How DALI works — a two-wire DALI bus (non-polarised, typically running on existing lighting wiring) connects all DALI devices (LED drivers, ballasts, sensors, switches, and relays). The DALI controller addresses each device individually using a unique address (0–63 per bus segment). Commands can target individual devices, groups of devices (up to 16 groups per bus), or all devices simultaneously. Each DALI bus segment supports up to 64 devices.
DALI-2 (IEC 62386 Part 2) — the updated standard that introduces mandatory interoperability testing. DALI-2 devices from different manufacturers are certified to work together, eliminating the interoperability issues occasionally seen with first-generation DALI products. Specify DALI-2 certified products for all new installations.
Wiring and commissioning — the DALI bus can be wired in any topology (star, bus, ring, tree) up to a maximum cable length of approximately 300 metres total bus length at 1.5mm² cable. The DALI bus runs at 16V DC with a maximum current of 250mA — it is a safety extra low voltage (SELV) circuit. Commissioning involves addressing each device, assigning groups and scenes, and configuring sensor thresholds.
Integration with BMS — DALI controllers can be integrated with a Building Management System via BACnet, Modbus, or a gateway device. This allows lighting to be controlled as part of the overall building energy management strategy, with occupancy and lighting data visible in the BMS dashboard.

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02 · Lighting Systems Guide

KNX Building Automation

KNX is the international open standard for home and building automation (ISO/IEC 14543), originally developed as EIB (European Installation Bus) in the 1990s. It integrates lighting, HVAC, shading, metering, and security systems on a single two-wire bus or IP backbone.

KNX bus — a two-wire twisted pair bus (KNX TP) runs throughout the building, carrying both power (24V DC, 640mA per segment) and data. KNX devices (actuators, sensors, dimmers, switches) connect to the bus in any topology. A KNX installation can have up to 57,375 devices across multiple bus segments connected by line couplers.
ETS software — KNX systems are configured using ETS (Engineering Tool Software), a proprietary tool supplied by the KNX Association. ETS is used to program group addresses, define device parameters, and download configurations to devices. KNX programming requires specialist training — the KNX Association offers a certification programme (KNX Basic, KNX Advanced).
KNX IP — KNX over IP (KNXnet/IP) allows KNX devices to communicate over an Ethernet/IP backbone, which is useful for connecting KNX segments in different buildings or across large campuses. A KNX IP router bridges the TP bus to the IP network. Remote access and monitoring can be provided via a KNX IP interface and visualisation software.
When to specify KNX — KNX is most cost-effective on large projects where whole-building integration is required from the outset. For a lighting-only project, DALI is simpler and more cost-effective. KNX's strength is integrating lighting with heating, cooling, shading, and metering in a single programmable system.

03 · Lighting Systems Guide

Lutron Caseta and RadioRA 2

Lutron is a US-based manufacturer with a strong reputation in the UK market for reliable, aesthetically refined lighting control systems. Unlike DALI and KNX (which are open protocols), Lutron systems are proprietary — all devices must be Lutron.

Lutron Caseta — a wireless system for domestic and small commercial applications. Caseta uses Lutron's Clear Connect RF protocol for reliable wireless communication between dimmers, switches, sensors, and the SmartBridge hub. Caseta integrates with Amazon Alexa, Google Home, and Apple HomeKit. Maximum 75 devices per SmartBridge. Simple to install — retrofit existing switch positions without new wiring.
Lutron RadioRA 2 — a larger residential and boutique commercial system supporting up to 200 devices per main repeater. Used in high-end residential, hotels, restaurants, and boutique retail. Supports complex scene programming, motorised shade integration, and third-party integration via IP/RS-232. Programming is carried out using Lutron's Designer software. Requires Lutron-authorised installer training.
Lutron Vive — Lutron's commercial wireless lighting control platform for offices, education, and healthcare. Vive uses wireless area controllers and plug-load controllers to provide occupancy sensing, daylight harvesting, and scene control without new wiring. Suitable for open-plan offices and retrofits where wired control is not cost-effective.

04 · Lighting Systems Guide

Scene Setting

Scene setting (or preset control) allows multiple luminaires to be set to predetermined levels with a single button press. Scenes transform a space for different activities without manual adjustment of individual luminaires.

Common scene presets — meeting (full brightness on all zones), presentation (ambient low, projector screen area off), after-hours (perimeter security lighting only), cleaning (full brightness all zones), and off. Each scene stores a dimming level (0–100%) for each luminaire or group. DALI stores up to 16 scenes per bus segment.
Fade time — scenes transition with a fade time (typically 0.7–5 seconds) to avoid harsh switching. A slow fade to a warmer evening scene improves occupant comfort. Most DALI and KNX controllers allow individual fade times per scene per group.
Time-based scene scheduling — scenes can be triggered automatically at preset times via the controller's internal clock — for example, full morning brightness at 07:00, daylight harvesting mode at 09:00, evening mode at 18:00, and security mode at 22:00. Scheduling reduces reliance on occupants operating the system correctly.

05 · Lighting Systems Guide

Occupancy Sensors and Daylight Harvesting

Occupancy sensing and daylight harvesting are the two most impactful energy-saving strategies in a smart lighting installation. Together they can reduce lighting energy consumption by 30–60% in typical commercial buildings.

PIR sensors — detect movement via changes in infrared radiation from body heat. Suitable for spaces where occupants move frequently (open offices, corridors, toilets). Coverage range: 6–12 metres diameter for ceiling-mounted sensors at 2.4 metres height. Avoid mounting near heat sources or air vents.
Microwave/ultrasonic sensors — detect minor movements (typing, reading) that PIR sensors may miss. Better for spaces where occupants are stationary for long periods (private offices, meeting rooms). Higher false-alarm rate in spaces with HVAC air movement — adjust sensitivity accordingly.
Daylight harvesting setup — position the photocell to measure the daylight contribution to the working plane, not the luminaire output directly above the sensor. In open-plan offices, position the photocell on the ceiling mid-zone between the perimeter (high daylight) and core (low daylight) areas. Set the target illuminance per BS EN 12464-1 (500 lux for general office work, 750 lux for technical drawing, 300 lux for corridors).

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06 · Lighting Systems Guide

Emergency Lighting Integration

Emergency lighting is a life-safety system governed by BS 5266-1 and must operate independently of the smart lighting control system. Understanding the boundary between the systems is critical for both compliance and commissioning.

Emergency luminaires — independent wiring — emergency luminaires (maintained or non-maintained) must be wired on a dedicated circuit that is not controlled by any smart lighting system relay, DALI driver, or scene controller. The circuit must be live whenever the building is occupied (for maintained luminaires) and operational on mains failure (for non-maintained).
DALI emergency (IEC 62386 Part 202) — DALI Part 202 provides a framework for emergency luminaires within a DALI system. DALI emergency drivers include an integral battery, self-test capability, and can report their status (battery health, test result) to the DALI controller. The DALI emergency driver operates independently on mains failure — the DALI bus command cannot override emergency operation. This is the only compliant way to include emergency luminaires within a DALI system.
Central battery systems — larger buildings may use a central battery system (CBS) to power emergency luminaires. The CBS is completely independent of the normal lighting distribution. Where DALI is used for normal lighting, the emergency luminaires on the CBS circuit must not be connected to any DALI control output.

Always include emergency luminaire wiring in the design at the start of the project — retrofitting emergency lighting into a completed smart lighting installation is costly and disruptive.

07 · Lighting Systems Guide

Retrofit vs New Build — System Selection

The choice of smart lighting system depends significantly on whether the building is new construction or a retrofit of an existing installation. Each scenario has different constraints and cost profiles.

New build — wired DALI or KNX — new construction allows wired systems to be installed before plastering and finishing. DALI is the standard choice for commercial lighting control. KNX is specified where whole-building automation is required. Run the DALI bus cable alongside the lighting circuit cable in the same containment. Budget for commissioning time — DALI and KNX commissioning is a significant element of the project programme.
Retrofit — wireless systems or relay-based control — in occupied buildings, wireless systems (Lutron Vive, DALI wireless, Casambi) avoid the disruption of running new cables. Wireless DALI sensors replace wired sensors and communicate with DALI bus-connected wireless receivers. Relay-based scene control replaces existing switches with smart relays in the distribution board for basic on/off and scene control without replacing luminaires.
Luminaire replacement — retrofitting smart control often provides the opportunity to replace existing luminaires with LED equivalents incorporating DALI drivers. Combining a LED retrofit with smart control delivers the highest energy savings — LED reduces consumption by 60–80% over fluorescent, and smart control delivers a further 20–50% reduction on the reduced LED baseline.

08 · Lighting Systems Guide

Smart Lighting Control Costs (2026)

Smart lighting control costs vary widely with protocol choice, number of devices, commissioning complexity, and whether the project is new build or retrofit.

Basic scene control (relay-based) — £500–£2,000 for a small commercial space with push-button scene selection and time scheduling. Does not require DALI-compatible luminaires. Suitable for meeting rooms, reception areas, and small offices.
DALI system — £50–£150 per luminaire for DALI driver, DALI bus cable, sensors, and commissioning. A 50-luminaire open-plan office system typically costs £5,000–£12,000 for a complete DALI installation including commissioning. Software and ongoing support may carry an annual licence fee.
KNX system — £80–£200 per device plus £2,000–£5,000 for engineering and commissioning on a typical project. KNX is more expensive than DALI for lighting-only projects but provides whole-building integration value on larger commercial projects.
Lutron Caseta (domestic/small commercial) — £60–£120 per dimmer or switch, plus £100–£300 for the SmartBridge hub. A four-room domestic system with 12 devices typically costs £800–£1,500 supplied and installed.

09 · Lighting Systems Guide

For Electricians: Smart Lighting Control Work

Smart lighting control is a growth area for UK electricians. Clients — commercial building owners, property developers, and facilities managers — are increasingly specifying intelligent lighting to meet energy efficiency targets and improve occupant experience.

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Smart Lighting Control Systems UK: DALI, KNX & Lutron Guide

Key Takeaways

DALI — Digital Addressable Lighting Interface

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KNX Building Automation

Lutron Caseta and RadioRA 2

Scene Setting

Occupancy Sensors and Daylight Harvesting

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Emergency Lighting Integration

Retrofit vs New Build — System Selection

Smart Lighting Control Costs (2026)

For Electricians: Smart Lighting Control Work

Quote Smart Lighting Projects Accurately

Upsell BMS Integration

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Frequently Asked Questions About Smart Lighting Control Systems

What is DALI and why is it used in commercial buildings?

What is the difference between DALI and KNX?

Is Lutron suitable for commercial buildings or just homes?

How does occupancy-based lighting control work?

What happens to emergency lighting when a smart control system switches off the lights?

What is daylight harvesting and how is it commissioned?

Can smart lighting be retrofitted to an existing building?

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