A study into energy saving and visual comfort of lighting system in an open area office

Justification of the paper Globally office buildings use a significant amount of energy and electrical lighting accounts for a large proportion of total energy use in these buildings. Furthermore lighting is an important... [ view full abstract ]

Justification of the paper
Globally office buildings use a significant amount of energy and electrical lighting accounts for a large proportion of total energy use in these buildings. Furthermore lighting is an important parameter for workplace environment in the field of occupant satisfaction and increase productivity.
Improve environmental sustainability and reduce energy consumption in existing building in one hand and improve quality of indoor environments and user comfort on the other hand, have become a critical agenda for architects, designers and engineers.
This paper presents a qualitative and quantitative approach, focusing on energy consumption and user satisfaction, in order to optimising lighting system for an open area office in Tokyo.

Purpose
The objective of this study is to optimise lighting of workplace areas in terms of energy efficiency, visual comforts and performances.
Theoretical framework
An experimental test was conducted in four case studies regarding to sky conditions, internal illuminance and daylighting availability.
During the test indoor illuminance level and electric lighting energy were systematically measured and analysed. 118 office workers were requested to fill out a questionnaire based on workplace productivity after each test in order to assess the level of visual comfort.
Results and conclusions

Results reveal that in working place environment, there are close relationships between illuminance levels and visual comfort in one hand and the level of energy consumption in other hand. The resulting key directions for sustainable modification of existing building highlight issues for which a better understanding is required for the development of strategies that are both energy efficient and suitable for the office occupants.
Implications for Tipping Points
This study presents an experience into more effective utilization of existing building in terms of more energy efficient and environmental sustainability and more occupant friendly.

Key words
Energy consumption, visual comfort, illuminance