Energy saving potential and strategies for electric lighting in future North European, low energy office buildings: A literature review

This article presents key energy use figures and explores the energy saving potential for electric lighting in office buildings based on a review of relevant literature, with special emphasis on a North European context. The review reveals that theoretical calculations, measurements in full-scale rooms and simulations with validated lighting programs indicate that an energy intensity of around 10 kWh/m2 yr is a realistic target for office electric lighting in future low energy office buildings. This target would yield a significant reduction in energy intensity of at least 50% compared to the actual average electricity use for lighting (21 kWh/m2 yr in Sweden). Strategies for reducing energy use for electric lighting are presented and discussed, which include: improvements in lamp, ballast and luminaire technology, use of task/ambient lighting, improvement in maintenance and utilization factor, reduction of maintained illuminance levels and total switch-on time, use of manual dimming and switch-off occupancy sensors. Strategies based on daylight harvesting are also presented and the relevant design aspects such as effects of window characteristics, properties of shading devices, reflectance of inner surfaces, ceiling and partition height are discussed.

► Electricity saving potential for lighting in offices is examined based on literature.
► Feasible reduction of 50% in average electricity use for lighting is identified.
► Electric lighting reduction strategies are discussed including daylight harvesting.