In countries of the third world such as Lebanon (case of this paper), the organizations, schools, institutes, universities, etc. are searching to economize as possible the price of installation of electrical systems such as light sources, equipment and other electrical devices without taking into consideration the high impact of the electrical bill for such installations and without taking into consideration the environmental impact such as the emission of the CO2, toxic gases, mercury and the high fuel cost. This mentality is widely spread in Lebanon because the majority of owners and investors want to install the cheapest materials in order to reduce as possible the investment cost without taking into consideration the future impact of such installations even if they know that these installations have bad impact on the electrical bill and the environment. In this paper, the authors will discuss the installation of Fluorescent lamps particularly in schools and Original Research Article British Journal of Applied Science & Technology, 4(16): 2358-2381, 2014 2359 universities and how is it possible to replace these lamps by other lamps with high efficiency such as CFL and LED lamps. A comparative study is developed and the authors proposed solutions for such buildings and this study can be applied on a bigger scale for all building sectors in Lebanon. This study is the first study that compares different lighting technologies applied on a real building which is a school in Lebanon and it can be applied and generalized to all buildings in all sectors. Aims: The aim of this study is to compare different technologies used for lighting system such as fluorescent, Compact Fluorescent Lamp (CFL), and LED installed in schools and universities in the third world especially in Lebanon and their impact on the economy of the country and the environment. This study emphasizes the important of the installation of LED technology in such buildings and its positive impact on the economy of the country and for many reasons developed in this paper. Study Design: This study is developed using the software Dialux for lighting calculation and comparison between different technologies. Place and Duration of Study: This study was made by the first author in a technical school (public school) in Hammana in Lebanon during the year 2014 using real measurements on site and using lighting software “Dialux” in order to compare different types of technologies. Methodology: Real measurements were taken for the lighting load from private generator 60kVA and from power authority (EDL) for the existing lighting system (In the public school). The first author studied the distribution of lighting points for other technologies for the same lux level in each room. The calculation of the predicted load is done and a comparative table that shows different indicators for each technology and final the study is generalized for all schools and universities in Lebanon. The generalized study shows important results on the scale of the country in which the replacement of fluorescent lamps by LED lamps is enough to close 1.5 thermal power plants of the size 35MW in Tyre (south Lebanon) and to economize 2.16% of the total power consumption on the Lebanese scale. Results: The replacement of fluorescent lamps (2x36W) by LED lamps as indicated in this paper will reduce the total power consumption on the Lebanese scale of 48.81 MW (2.16% from total power generated in Lebanon), the saved Energy is 52712.85 MWh/year, saved emission of CO2 from Fuel Oil is 35317.71 Ton of CO2/year, saved fuel consumption from private generators is 36990 liters/day (6,658,200 liters/year), saved cost of maintenance is 767,181$/year, Reduced Cost of electricity and maintenance is 8,955,141$/year, etc. Conclusion: In this paper, the first author presents a comparative study between four different types of lamps (fluorescent 2x36W, CFL of type Philips, CFL of type Arcluce, LED of type ASTRA). This study emphasize the important of doing calculation using “DIALUX” software before selecting any type of lamps even if we consider this lamp is energy-saving. Moreover we have to take into consideration many indicators which are presented in this paper before buying any type of lamps. This study is a sample that helps all investors, owners, clients... to compare many types of lamps using indicators presented in this paper before buying them. We have to take also into consideration the impact on the environment such as the emission of the CO2, toxic gases, mercury... In conclusion, the best choice of lamps in these days is the LED and of course a good quality and not of bad quality.