International Journal of Energy Science and Engineering Vol. 3, No. 3, 2017, pp. 29-36 http://www.aiscience.org/journal/ijese ISSN: 2381-7267 (Print); ISSN: 2381-7275 (Online) * Corresponding author E-mail address: tshennawy@yahoo.com (T. El Shennawy) Improving Energy Performance of Existing Office Buildings Lamiaa Abdallah 1 , Tarek El Shennawy 2, * 1 Alexandria Higher Institute of Engineering & Technology (AIET), Alexandria, Egypt 2 Alexandria National Refinery & Petrochemicals Co. (ANRPC), Alexandria, Egypt Abstract Egypt, as a developing country, suffers an energy crisis manifested by limited energy resources and increasing demand. This crisis is anticipated to worse in next few years due to the fast developments in major sectors of the country, including the building sector. The existing building stock in Egypt consumes more than 60% of the electrical energy. Improving the energy performance in buildings can be done by retrofitting the building envelope, using more efficient energy-using equipment such as lighting and air conditioners, using renewable energy sources, and altering the occupants’ behavior concerning energy usage. In this paper, a quick, easy-to-implement procedure is proposed for implementation in existing office buildings. The procedure combines both economic and environmental aspects of energy conservation methods and prioritize them, along with the solution economics, energy saving and environmental benefits. An office building in Alexandria, Egypt, is taken as a case study to illustrate the effectiveness of the procedure. The results are easily presented to the decision makers. The procedure can be applied to most non-residential buildings. A national action plan is required immediately to be implemented in Egypt seeking for energy conservation actions in the existing building sector, which can save energy, decrease fuel imports to operate power plants, decrease the need to build new power plants, decrease the associated carbon dioxide emissions and improve the overall economic situation of the country. Keywords Energy Conservation, Energy Efficiency, Office Buildings, Retrofitting, CO 2 Emissions Received: March 25, 2017 / Accepted: April 19, 2017 / Published online: August 1, 2017 @ 2017 The Authors. Published by American Institute of Science. This Open Access article is under the CC BY license. http://creativecommons.org/licenses/by/4.0/ 1. Introduction Energy is a key issue for development of any nation. However, using energy consumes finite fossil fuels; causes air pollution, environmental damage, global warming and costs money. Let us assume that we have a certain amount of natural gas (or methane CH 4 ). A common way to convert its chemical energy into work is to combine it with oxygen from the atmosphere and burn it to release its chemical energy in the form of heat. Accordingly, methane and oxygen undergo a chemical reaction and produce water and carbon dioxide, as shown in eq. (1): CH 4 + 2O 2 → CO 2 + 2H 2 O + heat (1) The amount of CO 2 released in order to generate 1 kWh of electric energy is shown in Table 1 [1]. Table 1. CO2 emissions (kg/kWh). Fuel Coal Oil Nat. Gas CO2 0.95 ~ 1 0.75 ~ 0.8 0.55 According to the United Nations Environment Programme (UNEP), buildings consume about 40% of global energy, 25% of global water, and 60% of global electricity. Buildings also emit more than 30% of global greenhouse gas (GHG)