In the history, architecture was exploited to the human being to protect him from unsteady environmental conditions. In the past centuries, architecture was pioneer art which has special features such as; simplicity, organization, clear style, accurate decoration, material assembly, and so on. However, modern buildings become complex products that have so many parts which have to fulfil different functions. Therefore, new computational ways and techniques have been developed to facilitate the design of modern complicated buildings and to create a convenient quantitative relationship between the environment and the envelope, putting into consideration the obstacles which influence on the building design. This has therefore formed the concept of parametric design in architecture, in order to deal with complex designs and gain more accurate results. Modern architects claim that parametric design is the most creative way to understand the development and complexity of the new era of architectural trends [1]. Meanwhile, it is really hard to deal with sophisticated details in buildings using our brains to imagine, or conventional ways to design [2]. In addition, building technologies nowadays are integrated and containing many disciplines in the same time, and each discipline is dependent on the other disciplines in a very complex vast connections. Hence, they should be organized in a database container, and this container could be managed parametrically using parametric design as an advanced way to explore and understand these sophisticated relations [3]. This paper hence presents a literature review on parametric design in architecture practice and put a focus on its applications in daylighting and solar radiation, which can have an essential impact on improving daylight availability and energy saving.

Please cite this article as: Ahmad Eltaweel, Yuehong Su, Controlling venetian blinds based on parametric design; via implementing Grasshopper's plugins: a case study of an office building in Cairo, Energy and Buildings http://dx

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.

Nowadays, daylighting systems and shading devices are controlled automatically to achieve their optimum benefits. For more comprehensive accuracy, parametric control was recently used to manage complex parameters with more accuracy. Such a system was proposed and investigated in a previous research to provide steadier and more uniform daylight illuminance during the day and reduce more than 80% of the electricity consumption. This study is examining the daylighting performance by using the parametric system in different orientations and comparing with the conventional ones. Furthermore, the study will evaluate the suitability of the parametric system throughout the year during the working hours in a typical office room.

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