Using energy in heating and cooling has become increasingly important
worldwide to gain thermal comfort inside buildings, as rising temperatures in hot 
countries can cause discomfort to individuals, and impact their productivity 
negatively, causing increased dependence on AC, which raises up the energy quirements for buildings due to increasing AC hours of operation. In nonresidential buildings, AC systems consume majority of the buildings' energy 
budget to meet required thermal comfort (1)
. Consequently, simulations became an 
important tool to improve buildings' environmental performance, where designers 
use dynamic simulation operations to improve non-renewable energy use and 
minimize harmful environmental impacting factors like greenhouse gases, mainly 
CO2 which represents a 66% ratio (1)
, This study's focus is proving the positive 
role of energy simulations in conserving energy and improving eco-friendliness of 
buildings, through retrofitting to the envelope of an existing educational building 
residing in Cairo-Egypt, using a (Building Energy Modelling) tool, By 
considering: the building's geographical location, surrounding climate conditions, 
building orientation, envelope materials, window to wall ratio, yearly building 
occupancy schedule, interior space use, and used equipment, and by measuring 
energy consumption of AC, lighting, and equipment, which represent the 
building's total energy consumption for the year 2021, A comparison was made 
between the actual building's energy consumption and electric bills of year 2021, 
and the estimated total consumption according to the simulation, to guarantee the 
accuracy of simulation results in the future, And by comparison, a 96% match in 
consumption rates was found throughout the year. Based on the above, a retrofit 
solution is proposed to maximize eco-friendliness and minimize carbon footprint, 
this study depends on two main treatments to improve the building envelope, 
hence increasing energy efficiency, One: is adding climate appropriate thermal
insulation which resulted in 18% decrease in AC power consumption and 8.1% 
decrease in total building energy consumption. And Two: is replacing the 
building's glazing material with a more climate appropriate one, which resulted in 
a 21% decrease in AC power consumption, and a 9.7% decrease in total building 
energy consumption.