Derry City & Strabane District Council has implemented some energy efficiency measures at its offices to reduce the energy consumption of their public building.
DCSDC wants to set an example within the goal of achieving an energy efficient city which leads to savings on the public building expenses.
In that context, they have upgraded the lighting system.

The Council was approached by the Technology Strategy Board (TSB) who were looking to install innovative lighting systems in public buildings to test the technology, gauge users experience and to ascertain if it could be replicated in other public buildings.

The retrofitting consists on the 'Redwood system', installed on one floor of one wing of the building, with an area of 472m2 lit by 116 light fittings. An almost identical area directly below served as a control space. Both areas were monitored to analyse the results. Energy savings were expected from two sources: from the improved efficiency of the lamps and from improved control of both lighting and HVAC.

This lighting system uses a CAT cable system to provide data connection with the control engine and for electrical power. The intelligence of the system ensures the control engine “learns” the occupancy patterns in each office and reacts to personal preferences. The benefits are: daylight harvesting, automatic dimming, remote book / time lights in specific area, demand management, lower energy consumption and customer comfort and satisfaction, among others.

Resources needed

The equipment was purchased by a subcontractor to the TSB who installed, commissioned and carried out the experimental work on their behalf.

Evidence of success

The estimated efficiency savings amount to 13,807 kWh/yr (44%), saving £1,933/yr and reducing carbon dioxide emissions by 7.60 t/yr. If these figures are scaled up from the test area to the building as a whole (all spaces except the basement, amounting to 4,469 m2 of floor-space) the savings become 130,728 kWh/yr, saving £18,302/yr and reducing carbon dioxide emissions by 71.96 t/yr.

Difficulties encountered

Project installation was very smooth, the contractor communicated on a regular basis with the office staff affected by the installation. Minor problems did arise after the commissioning phase and with the contractor based approximately 75 miles from the site, response times did present problems.

Potential for learning or transfer

The Redwood system was installed on one side of one floor, thus the savings here could be replicated on the remaining building areas of the building. Therefore, the estimated overall savings for the building in energy use, electricity cost and carbon emissions where calculated as at least 72% of the current figures. The evaluation/experimental process also included a series of customer surveys to gauge users’ perceptions of how effective the new lighting system was. Feedback from these surveys was very positive. The overall objective of the TSB’s project was to show the benefits of reducing energy consumption in an office environment, while maintaining customer expectations of adequate lighting levels and comfort.

This concept is easily transferred to other offices and buildings with similar occupancy levels and functions. The installation contractor has gone on to installing similar systems in office buildings for a local university and a local hospital.

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Main institution
Derry City and Strabane District Council
Northern Ireland, United Kingdom
Start Date
February 2014
End Date
October 2014


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