Making energy savings worth £0.02 per hour on a light fitting doesn’t sound very impressive. But if, like Windsor Life Assurance, your building has around 450 light fittings which are in use for a substantial part of the working day, the overall savings amount to tens of thousands of pounds a year. And, these savings are just one of the many benefits that are being provided by a new lighting control system designed and installed by MESL using equipment from the Clipsal brand of Schneider Electric.


Background:
In recent years, maintaining the 600 or so ageing fluorescent light fittings at the Windsor Life Assurance headquarters in Telford had become something of a headache, with at least one tube needing to be replaced every day. The company, a subsidiary of Swiss Re which is well known for its green credentials, therefore decided that the time had come for the lighting installation to be completely refurbished.

New fittings were to be installed throughout phase one of the building and, by careful planning, the number required was reduced from 600 to 450, with no adverse effects on lighting levels. The new fittings selected were fluorescent HF ballast types which, in addition to being more energy efficient and offering longer tube life, are also suitable for electronic dimming.

Solution:
Working in conjunction with Schneider Electric, Windsor Life Assurance and Mick Hatch of MESL, who is also the maintenance manager at Windsor Life Assurance, decided to make full use of this dimming capability to realise further energy savings, and to provide flexible control over the lighting in every part of the building.

To achieve this, products from the Clipsal C-bus range were chosen. The principal factors that influenced this decision were the versatility of the range, its suitability for large scale installations, its proven track record, value for money and the backing of the Schneider Electric organisation to ensure long-term product availability and support.

Other factors that weighed in favour of C-Bus were the attractive appearance of the accessories in the range – an important consideration for such a prestigious building – and the powerful yet intuitive tool-kit software used for configuring and controlling C-Bus systems.

The final installation includes 37 marshalling boxes covering the five floors of the building, and providing control for the 450 new light fittings. For lighting control purposes, each floor is divided into several zones, so that the lighting levels can be set on an area-by-area basis. Sensors to monitor ambient light levels are provided throughout the installation and most rooms are also fitted with PIR motion detectors.

Benefits:
“To avoid disrupting the work that goes on in the building, we had to do all of the installation outside normal office hours,” said Mick Hatch, “which meant that the whole project took almost a year to complete. Such is the flexibility of the C-Bus system, however, that putting the system to work stage-by-stage presented no problems. Integrating the new stages as they were completed was equally straightforward.”

Now that it is fully implemented, the C-Bus installation offers a high level of automation. For example, if the PIR sensors show that a room has been unoccupied for more than a preset time, the lights are dimmed to save energy. Further, as the ambient light rises and falls during the day, the lights are controlled so that light levels throughout the building are always maintained at an optimum level.

Finally, at 10:30 pm, all lighting is reduced to a minimal level, ensuring that energy is never wasted by lights being left on when the building is not in use.

In spite of the high levels of automation, which help to guarantee the substantial energy savings achieved by the installation, full provision is also made for manual intervention. Light levels can be set on an area-by-area basis, for example, in response to feedback from the occupants of each individual area. This feature has allowed typical lighting levels to be reduced to 80% of the maximum, which again translates into valuable energy savings.

“Windsor Life Assurance is delighted, of course, with the cost and energy savings produced by the new system,” said Mick Hatch, “but that’s not all – having effective control over the lighting installation is also an important benefit, as it helps to maintain a comfortable working environment which boosts productivity. From my point of view as the installer, I’m equally delighted. The C-Bus system is easy to configure, reliable and flexible.”

As Windsor Life Assurance discovered, flexible lighting control implemented with C-Bus products from the Clipsal brand of Schneider Electric offers a true win-win opportunity. The system makes the building more comfortable while also reducing energy usage and delivering savings that very quickly repay the cost of installation.

Email: peter@houston-associates.com