When replacing aged lighting installations with the intention of maximising energy efficiency and gaining the best possible return on investment there are a multitude of lighting systems to choose from. Two of the most commonly proposed lighting systems are a DALI (Digital Addressable Lighting Interface)addressable system allowing luminaires to be centrally controlled and turned on and off or dimmed at predetermined times, or a Sensor controlled lighting system where each luminaire has an integral presence detection and daylight regulation sensor. As a general rule integral sensor controls and sensor controlled lighting tend to give optimum energy saving and return on investment for the following reasons:
- 1) When replacing a non dimmable lighting installation with a DALI system the external lighting wiring is unlikely to include the additional D1 and D2 wires required to allow the DALI controls to communicate with the luminaire. Where the luminaires have integral lighting or motion sensors there is no need for additional BUS wiring, they can simply use the existing live, neutral and earth connections. Integral sensor controlled lighting therefore often incurs significantly lower installation cost.
- 2) DALI control systems require routers and lighting control systems to allow the user to override and scene set the luminaires. This results in additional cost in the addressable lighting system which is avoided by using integral sensor controls in each luminaire.
- 3) DALI lighting control systems also require commissioning often sold as an extra cost on each project. Whilst internal lighting sensors also require programming this is usually a relatively simple process that can be carried out by the lighting installer or end user at little or no additional cost. In the event of luminaire failure on a DALI (Digital Addressable Lighting Interface) installation the replacement luminaire installed will require recommissioning, often carried out at the cost of a full days commissioning, making site lighting maintenance an extremely expensive process. These costs are avoided by the use of integral sensor controlled lighting in each luminaire.
- 4) Whilst a DALI (Digital Addressable Lighting Interface) system allows luminaires to be scene set or overridden from a central location, luminaires with integral sensors will only ever activate when a person is present in the area. As a result energy savings are often far greater with integral sensor controls. Although DALI addressable sensors can be used in DALI installations this incurs additional cost and also further exacerbates the issues raised in points 1-3.
- 5) As a general rule the cost of having an employee monitor the lighting and override luminaires that have been left switched on accidentally can only be justified in very large DALI (Digital Addressable Lighting Interface) controlled lighting installations, often over multiple locations.
