The magnitude of the harm caused by the emission of Green House Gases in the environment has been gaining quite some importance in the World scenario within the past years. Since Industrial Revolution took place, the World has been passing through an era of enormous population growth, great technological advances and an extraordinary utilization of the available resources. As collateral effects, there are the growth of the World’s pollution, the emission of toxic trash, the destruction of forests, and lastly, the climate change. Thus, as the World’s population grows, more important it is the Sustainable Development issue in the center of the global economy. By unifying the need to have a simple organizational structure with low costs with the sustainability issue, retail companies might be able to have a very successful formula to operate. Sustainability, despite asking for new investments, have the capacity of bringing positive financial results through the economy of operational and maintenance costs. Though, the objective of this study is to evaluate the option of changing the air conditioning system of a retail company. Assuming that the retail company is a free consumer of energy in the Brazilian market, and that the price of energy is a random variable, the Real Option Theory will be used to evaluate the managerial flexibilities of the project.