JOURNAL OF ENGINEERING AND APPLIED SCIENCE, VOL. 67, NO. 6, DEC. 2020, PP. 1475-1494 FACULTY OF ENGINEERING, CAIRO UNIVERSITY FACULTY OF ENGINEERING, CAIRO UNIVERSITY THE IMPACT OF GREEN VEGETATED FACADES ON ENERGY EFFICIENCY FOR MULTISTORY RESIDENTIAL BUILDINGS A. H. MAHMOUD 1 , A. R. ABDIN 1 , AND R. A. T. ALOTHMAN 2 ABSTRACT The issue of energy consumption in various sectors of life, especially in the building sector and, reducing energy is considered a major challenge faced by construction industry. The building envelope can be improved to reduce the energy needed for cooling and heating the building, therefore there is an urgent need to make it more efficient. The research aims to study the impact of green vegetated facades in multistory residential buildings on the energy efficiency in cold semi-arid and hot arid climates, it investigates the parametrical design for using green vegetated facades. For this purpose, the energy consumption is evaluated using DesignBuilder tool. A vegetated layer is considered as an additional layer in the building, therefore, the comparison will be between non-vegetated, green vegetated and insulated facade of residential buildings in two different locations with two different climates, Duhok/ Iraq and Cairo/ Egypt. The study concluded that green vegetated facades reduce the energy demand in air conditioning devices, from 13.4% to 37.6% for cooling, and from 18.3% to 100% for heating except for some orientations, while simultaneously reducing the annual energy consumption from 18% to 51.4% according to building location and orientation. KEYWORDS: Energy consumption, Green vegetated facade, Multistory buildings. 1. INTRODUCTION Living walls and green facades play an important role in mitigating urban microclimate and improving buildings' energy performance [1]. These vertical systems have many environmental, economic, and social benefits [2]. Green facades such as other types of green infrastructure can decrease the internal temperature of the building leading to a reduction in energy consumption [3]. Using green vegetated facades in the building envelope will create an air layer that is considered as an insulating layer [4]. 1 Professor, Department of Architecture, Faculty of Engineering, Cairo University, Giza, Egypt, arch.ayman@yahoo.co.uk 2 Ph.D. Candidate, Department of Architecture, Faculty of Engineering, Cairo University, Giza, Egypt and Lecturer, Architectural Engineering Department, College of Engineering, University of Mosul, Iraq.