Study on technical and economical solutions for improving air-conditioning efficiency in building sector

Climate change is an increasingly important global concern at this moment. Fossil fuels meet a majority of world energy needs and because buildings are large energy consumers, they are also a major contributor to global carbon emissions and greenhouse gas (GHG) production. It's important for the European Union, including Romania to avoid these problems. Buildings are responsible for 40% of energy consumption and 36% of CO2 emissions in the EU, according to United Nations Environment Programme (UNEP). The construction sector is developing since 2013 so in the future the energy consumption will increase very fast. As a result, renewable energy sources represent one of the main directions in reducing conventional energy consumption in buildings. In this paper the authors analyze solutions for decreasing the energy consumption required by the airconditioning system in an office building of 6466 m(2), located in Bucharest. The current air conditioning solutions are the classical ones, based on either fan coils, supplied with chilled water of 12/7 degrees C, or air-coolers, as part of an Air Handling Unit (AHU). In the latter case, the cooled water is prepared by a vapor compression refrigeration unit chiller of 190kW cooling capacity, working with R22. The solutions analyzed in this paper consider each of the following alternatives: a. Heat recovery from the exhausted air by using a heat exchanger integrated in the AHU; b. Replacement of the vapor compression refrigeration unit chiller with an one stage lithium bromide/water absorption refrigeration unit driven by solar energy; c. Coupling the above mentioned solutions. All these solutions are discussed and analyzed from both technical and economical points of view. (C) 2017 The Authors. Published Ltd.