As lighting is estimated to account for 20-25% of the company’s energy consumption this was clearly an area to be investigated. “We were keen to evaluate the potential for LED lighting and decided to try out a relatively small project initially, with a view to measuring the savings and potentially rolling out LEDs throughout the building,” said Les Smith, Citi’s EMEA Critical Facilities Engineering Manager. “It also became apparent that improving the control of the lighting would help to reduce energy consumption even further, so the Philips LightMaster system was included in the project.”
The initial project focused on levels 6 and 7 in one tower and included several elements. Early on, existing fluorescent luminaires at the perimeters were replaced with dimmable LED luminaires, using a modified fitting for ease of installation into the existing ceiling grid.
These luminaires are dimmed in relation to natural daylight, maintaining desired illuminance levels with minimum energy consumption. “Daylight influences around a third of each floor so the impact on energy consumption is significant,” Les Smith continued. Further savings have been achieved with the introduction of new exterior LED lighting, which is projected to reduce energy usage by 50% in comparison to the sodium lighting system that it replaced. By selecting an LED system, a reduction in the number of fittings used in the balcony lighting at the four apexes of the CitiGroup Tower was possible.