Abstract

Fully glazed buildings have increased in popularity throughout the world's building sector. Office buildings are often especially designed with a high glazing ratio to fulfil representative architectural tasks. However, a high glazing ratio is also likely to result in a high solar load and glare problems, which cause an unsatisfactory working environment that can reduce employee productivity severely. Furthermore, it creates high cooling loads resulting in immense maintenance costs. Solutions provide light direction to illuminate the space naturally and shading to avoid glare as well as to reduce cooling loads.

Many studies have been carried out on thermal comfort, others on lighting issues, but mostly under artificial lighting conditions or under the exclusion of sunny conditions. The performance of light directing elements under sunny conditions and the resulting lighting quality so far has not been investigated. Especially under sunny conditions, however, conflict between the use of daylight, the need for solar protection, and the view to the outside occur and have not been assessed.

To fill this gap an intensive monitoring program has been conducted at the University of Dortmund investigating different innovative shading and light directing devices (2001–2006). Simultaneously user acceptance studies have been carried out to evaluate lighting quality issues. This paper discusses some of the results on the subjective rating of the indoor lighting environment. Space and light perception often does neither correspond with the lighting levels set in regulations mostly for artificial lighting conditions nor the control strategies for shading devices. The objective of the work was to clarify the interdependencies between the conflicting needs and to point out user preferences which are important for a productive environment.

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