Lighting Case Study: PwC Office with the Highest BREEAM Rating Ever

　　The Building Research Establishment Environmental Assessment Method (BREEAM - Building Research Establishment Environmental Assessment Method) is commonly known as the Building Research Establishment Green Building Rating System. Founded in 1990, BREEAM is the world's first and most widely used green building assessment method. It serves as both a set of green building evaluation standards and a best practice approach for green building design, and as such has become the most authoritative international standard for describing building environmental performance. Numerous globally renowned landmark buildings, including HSBC Global Headquarters, PwC UK Headquarters, Unilever UK Headquarters, the Strata Tower in London, Place de l'Hémicycle in Paris, and the Central Art Gallery Shopping Center in Germany, have all adopted the BREEAM assessment system for green building evaluation and certification.

　　The green building assessment under the BREEAM system covers nine aspects: Management, Health and Wellbeing, Energy, Transport, Water, Materials, Land Use and Ecology, Waste, and Pollution. Among these, lighting accounts for at least 20% of the total building energy consumption, and greater use of natural light is required. Clearly, to meet this requirement, it is necessary to use as much as possible: T5S and LED, as well as control systems. Therefore, how to design the lighting to help PwC's 1 Embankment Place become the most efficient BREEAM building was the question pondered by its lighting designers.

　　The BREEAM excellent requirement for ceiling lighting is 8W/m². The entire building has 33,500 square meters of open-space office areas, client areas, conference rooms, restaurants, and similar non-office spaces. Control aspects include DALI dimming and scene settings, presence/absence detection, and daylight control. People work long hours at PwC and there are late-night overtime situations, which means segregating lighting zones for groups of 400-500 people. However, to avoid surrounding darkness, one-third of illumination must be retained, switched in adjacent zones, with all circulation areas maintained at 50% light output. To avoid affecting control and running overloaded equipment with specific requirements, this adjustment is set with a very tight bandwidth — occupants can control, or indoor temperature within ±1°C, with each lighting level incremented by a maximum of 20%.

PwC is located in one of the busiest spots in London, along Charing Cross station, where handling the lighting for some of the infrastructure was a significant challenge, such as how to approach the construction of the main entrance. Linear LED luminaires run continuously along each side, using existing cable trays and control forms, interspersed with additional fixtures, illuminating the ribs across the suspended ceiling. ArcPad Extreme twin-head linear LED luminaires are mounted on the lower beams spanning the underside of the atrium. No harsh light is produced.