The recent revision of Part L of the Building Regulations means that electrical contractors and installers of electrical systems are actively seeking better solutions for monitoring and reducing energy consumption in buildings. A number of specialised relays and related products have become available in recent years, and when used intelligently in combination with building management systems (BMS) can help the designer to address these requirements.
One of the simplest ways to conserve energy is to ensure that lights are not left on when personnel are not around. Staircases, corridors and other public access areas are prime examples of places where lights are often left on, either for convenience or because people forget to turn them off. Depending on the location, the use of movement detectors and/or timers can help considerably with this problem.

Timer

A versatile electronic staircase timer such as Finder’s 14.01 series conserves energy in lighting applications as diverse as office and factory property, residential flats and recreational areas, simplifying wiring and installation in the process. Any number of push button switches can be located along the length of a corridor or on a landing, and used to trigger the timer, which itself can be set to one of four different functions that are appropriate to a different lighting requirement.

1. Step function – the output relay ‘toggles’ or ‘steps’ between on and off with each successive operation of any of the triggering push buttons
2. Constantly on – overrides push button operation when permanent lighting is required for maintenance or similar longer-term occupancy.
3. Staircase function – the output relay will turn on immediately the push button is pressed and remain on for a preset time, with further pushes extending the period
4. Timing step – provides a combination of timed and on/off control. If the push button is momentarily pressed the output relay will switch on for the preset time, before reverting to the off position.  However, if the push button is depressed again within the timing period, the time period is terminated early.

The unit has a user-adjustable delay time range of 0.5 to 20 minutes. It is suitable for DIN rail mounting, and is protected to IP20.

Likewise PIR detectors can either perform the function of turning lights on when personnel approach, or of extinguishing them when there is no-one present. Finder’s 18 series of intelligent PIR movement detectors (Figure 1) detect body heat to control the lighting in a room or in an outdoor area and can reduce energy consumption by automatically switching off lighting when it is not required. The interior models are particularly useful within buildings that are not permanently occupied, such as offices, washrooms, corridors, stairwells and stores, while the exterior models find uses in outside loading bays, access ramps, etc. where constant lighting is not required.
An integral adjustable threshold light sensor further ensures that energy is not wasted by preventing the lights from being switched on in conditions of high ambient light.  To avoid accidentally switching off lights when personnel are still in the lighting zone, the units feature an extended ‘on time’, enabling the length of time the lights remain on after movement detection ceases to be extended by a preset delay time, which can be adjusted to anywhere in the range 10 seconds and 12 minutes. Designed and manufactured at Finder’s European facility near Turin in Italy, the design includes custom embedded system programming, CAD evolved optics, custom designed electronics, tooling and test equipment.

The new Part L guidelines stipulate that all new buildings should have the capability for 90% of the energy consumed to be monitored, and individual single phase and three-phase meters are available to address this. The Finder 7E Series single phase and the three-phase 7E.36 Series kWh totalising meters have been designed for the measurement, recording and display of energy consumption in individual sub-circuits, for loads drawing up to a maximum of 65A. The 7E.36 Series additionally includes both single and dual-tariff models.
All the meters are suitable for DIN rail mounting, and can easily be installed in a standard consumer unit. A high resolution pulsed open-collector output to DIN 43864 provides a link to BMS or other types of remote monitoring system. A variable rate pulsed red LED indicator offers a rapid visual indication when abnormal operation is occurring, for example due to phase loss or inversion. 
The meters are particularly applicable where there is a statutory need for compliance with the EU

Measuring Instrument Directive (MID) 2004/22/EG which comes into force in October 2006.
The 7E.36 Series is compliant with EN 62053-21 and prEN 50470 as well as with the EU MID 2004/22/EG, and is certified by PTB (Physikalisch-Technischen Bundesanstalt). Accuracy is specified to Class B and protection to Class II.

Intelligent use of energy-saving devices provides a useful addition to the management of any building, and is more predictable than relying on simply educating staff to conserve energy. The addition of individual energy consumption meters allows the monitoring and active management of the resources in a building, and helps supervisors to identify where excessive consumption is occurring.