Using integrated parametric control to achieve better daylighting uniformity in an office room: A multi-Step comparison study

Abstract

In addition to windows, louvers are the most common architectural elements widely used in office buildings to protect them from excessive daylight and improve daylight penetration as well. Advanced glazing, window blinds, other fenestration systems and their automation can further improve daylighting performance. However, the stability and uniformity of daylight distribution throughout a day inside a building remain a challenge. To explore a solution for this issue, this paper proposes an advanced integrated lighting system combining different architectural elements, which can be controlled parametrically. The suitable design of such integrated system is identified through a multi-step comparison study employing parametric design approach. The criteria is to keep a relatively uniform daylight distribution in the range of 300 -500 lux over 90% of the whole desktop area in a 7-meter-deep office room. An office building in New Cairo was chosen for a case study, where it is south oriented with a prevailing condition of clear sky. Hourly results on the 21 st of several chosen months are given to show the suitability of the proposed design throughout a year, aiming to explore the maximum use of daylight and hence reduce the energy consumption of electrical lighting. The comparison indicates that the combined use of the integrated system can achieve a satisfactory relatively uniform distribution of daylight over about 90% of the desktop area, within illuminance range of 300 -500 lux for most of the working hours throughout a year.

Evaluation of Suitability of a Parametrically Controlled Louvers for Various Orientations throughout a Year Comparing to an Existing Case

“…The proposed parametric system is using three main tools based on a previous study [8]. The first tool is the "mirrored louvers" with 75% reflectivity, which are used to redirect the sun light inside the deep room into specific targets over the ceiling, then the ceiling works as a source of light.…”

“…The louvers are located at the upper part of the window from the outside, with 2.2 m height from the floor. The second tool is the electrochromic window [22], located at the lower part of the window that is also controlled parametrically, based on the intensity of solar radiation [8] and used to provide the room with the needed diffuse light, valued between 300 and 500 lux. The diffuse light coming from the electrochromic window was amended by controlling the translucency value by using "Radiation Trans Material" as a component in Honeybee [23].…”

“…Such system was investigated previously in a South oriented room in Egypt [8], and succeeded in providing more than 80% of daylight during the working hours. The current study will examine the performance of such system by using different orientations, and then investigate the efficiency of this system throughout the year during the working hours in the UK territory.…”

“…Other systems were using mirrored tools, such as automated blinds, which also responding to the sun movement and redirecting the beams to specific targets over the ceiling [12,13], then the ceiling works as a source of light. Moreover, the automated blinds were investigated to optimize daylighting [8] and enhance thermal performance simultaneously, by controlling the rotation angles of the blinds with response to the sun movement [14]. Further researches investigated fenestration systems for the sake of providing diffuse light and redirection [15], for instance, perforated sheets were used for scattering the daylight, likewise, translucent materials [16] and prismatic panels [17].…”

“…Former studies and literatures investigated enhancing the daylight inside the buildings using static and automated tools [5,8]. These tools were dramatically based on redirecting sunlight inside the buildings, such as light-shelves [9] and Optical Louver System (OLS) [10], which is usually assembled in the clearstory windows and known as static systems.…”