The visual comfort, economic feasibility, and overall energy consumption of tubular daylighting device system configurations in deep plan office buildings in Saudi Arabia

Abstract

Despite the abundance of daylight in hot desert climates, deep-plan office buildings still lack the provision of sufficient daylight. Although tubular daylighting devices (TDDs) offer a potential solution, they may have visual and economic consequences. Therefore, the present study evaluated the visual comfort, overall energy consumption, and economic feasibility of multiple TDD configurations. Typical deep-plan office space has been simulated based on a field-validated simulation process to evaluate visual comfort and energy consumption. The WLCC method was used to assess the economic feasibility. The reference case was illuminated using LED and a dimming control system with photosensors placed in cardinal orientations. Supplementary daylight was provided using different configurations of vertical and horizontal TDDs. Window shading devices were used to enhance visual comfort. The study found that vertical TDDs perform better than horizontal TDDs in terms of illumination uniformity and economic feasibility. They reduced the electric lighting load by up to 21%. However, the utilization of the TDDs in the hot desert climate has the potential to significantly increase indoor heat gain, which, in turn, increases the cooling energy. It is found that the additional energy required for cooling far outweighs the energy-saving benefits gained by TDDs. Accordingly, thermal issues associated with the utilization of TDDs should be investigated to allow widespread use of them in arid regions where high solar radiation is available throughout the year. Moreover, other daylighting-associated benefits, such as users’ productivity enhancement and health and mood improvement, should be considered to promote the usage of TDDs and boost their economic returns.