SA-12-C028 -- Decision Making for HVAC

Demands for thermal comfort, better indoor air quality together with lower environmental impacts have had ascending trends in the last decade. Inmany circumstances, these demands could not be fully covered through the soft approach of bioclimatic design like optimization of the buildingorientation and internal layout. This is mostly because of the dense urban environment and the internal energy loads of the building. In such cases,heating, ventilation, air-conditioning and refrigeration (HVAC) systems make a key contribution to fulfilling the requirements of the indoorenvironment. Therefore, the most appropriate HVAC system must be selected. In this study, a robust decision making approach forHVAC system selection is proposed. Technical performance, economic and environmental impacts of 36 permutations of primary andsecondary systems are taken into account to choose the most appropriate HVAC system for a case study office building. The building is arepresentative of the dominant form of office buildings in the UK. Dynamic performance evaluation of HVAC alternatives using theTRNSYS package together with life-cycle energy cost analysis is undertaken to provide a reliable basis for decision making. The six scenariosconsidered in this paper broadly cover the decision makers attitudes on HVAC system selection. These scenarios are analyzed through anAnalytical Hierarchy Process (AHP), and sensitivity analyses which prove the robustness of the final decision for each scenario. One of thesignificant outcomes of this study reveals that the compound heating, cooling and power system (CCHP), despite the high level of energy demandand also a higher initial investment, is one of the top-ranked alternatives due to the lower energy cost and C02 emissions. The proposed approachand the results of this study could be used by researchers and designers, especially in the early stages of a design process where all the involved bodiescommonly face a lack of time, information and the tools necessary for the evaluation of a variety of HVAC systems.