Natural illumination of deep-plan office buildings : light pipe strategies

Abstract

Abstract – Deep plans are a common practice in middle and high-rise office building design, and large open plans have become the preferred office layout by modern businesses due to the flexibility of the space and economic benefits achieved from maximum plot to gross floor area ratios. Consequently, the deep core areas of these buildings cannot be naturally illuminated by side windows, and depend entirely on electricity for illumination. This paper describes the benefits of daylight piping technologies; in particular, hollow mirrored light pipes coupled with laser cut panel collectors to enhance natural illumination of deep plan office buildings. Light pipes are assessed by testing two scale models of buildings, one with horizontal and the other with vertical light pipes as daylight devices. Testing was carried out under sunny sky conditions and an artificial sky that closely simulates the CIE overcast sky. Results have shown that mirrored light pipes coupled with laser cut panels can achieve required values for ambient illumination in the core of buildings under sunny conditions, with an overall efficiency (input to output lumens) up to 32%, but their performance drops under overcast conditions.