The Egyptian Society of Energy in Buildings and Environmental Design Journal of Sustainble Building and Environment. Volume no. (xx). Issue no.(xx), p(xx-xx). Journal Theme: Environmental performance of buildings and urban spaces Evaluation of Office Spaces Ventilation using Simulation software El-Dakahlia Governmental Headquarter as a Pilot Renovation Mohamed M. ElDabosy 1,* , Mahmoud M. AbdElrahman 2 1 Teaching Assistant, Faculty of Engineering, Mansoura University, Mansoura, Egypt 2 Teaching Assistant, Faculty of Engineering, KafrElShiek University, KafrElShiek, Egypt * Tel: +20 106 914 1822, E-mail: m.aldabosy@gmail.com Abstract: El-Dakahlia Governmental Headquarter is the central office building serving 5.5 million citizens in El-Dakahlia governorate in Egypt, and The public plaza around the building is the focus of Mansoura city urbanism. Despite The building importance, it faces many problems on its indoor environment and has a poor thermal performance. Natural ventilation is an effective method for enhancing indoor environmental quality in hot-arid climates with zero energy consumption. So, the building requires redesigning the entire spaces and façades according to the environmental aspects. This research evaluates different passive façade designs within a new special architectural design, by using digital simulation tools - CFD software and Ecotect - to reach affordable natural ventilation and hence thermal comfort. The evaluation method depends upon the perfect natural ventilation occurred and perfect solar gain control. It was found that, a double layer west, east and south- east façade, single one in north-west also creating indoor open space will achieve adequate natural ventilation and comfort spaces. This research aims to produce a concept of pilot renovation stands up on simulation process and green architecture standers to be generalized on other office and governmental buildings in Egypt. Keywords: Natural Ventilation, Office Buildings, Pilot project and Green Renovation. 1. Introduction Enhancing indoor environmental quality in the office buildings with energy efficient ways may have a high priority for architects and researchers. Health of Employees and public and working performance levels is badly affected by bad indoor environment [1]. Office buildings in Egypt face problems of high energy consumption for mechanical cooling systems, besides a poor indoor environmental quality in the traditional constructions. The existing buildings are important issue in the environmental design because the modifications and involving environmental techniques are limited. If the old buildings have been wrongly oriented, this would make the problem more complicated. So, old office buildings in Egypt are a good case towards green renovation using simulation strategies. In searching for a pilot project for green renovation, governmental building is one of the most suitable start point which needs to be compatible with sustainable design standards not only for its high energy consumption [2], but also for some important reasons such as; • Closely linked to public. • A lot of beneficiaries. • Slackness in operation and maintenance. • Usually, It's located in the cities centers and represented an important part of "the image of the city" • Its Affiliation to the government Stimulates to be a green policy applied on other buildings.