A comparison analysis between Total Equivalent Warming Impact and Expanded Total Equivalent Warming Impact index in an Air Conditioning application for a real university building

Heating, Ventilation, Air Conditioning and Refrigeration sectors cause 7.8% of greenhouse gas emissions worldwide. The environmental impact of the energy conversion devices involved in these sectors have been analysed by considering both indirect and direct greenhouse gas emissions by using the well-known Total Equivalent Warming Impact index, TEWI. The direct effect is calculated by considering the refrigerant leakages into the system while the indirect emissions depend on electric energy consumption and emission factors associated to electricity power plants mix. Recently an innovative environmental index so called Extended Total Equivalent Warming Impact (ETEWI) method that represents and upgrade of TEWI, is proposed to scientific community with aim to improve the environmental emission of Heating, Ventilation, Air Conditioning and Refrigeration sectors. This index allows to revisit the traditional terms of TEWI and also to introduce innovative terms. The traditional direct term is detailed by considering the dynamic evaluation of refrigerant charge in the system while the indirect one is calculated by assuming the hourly variation of energy consumptions and emission factors. Four innovative terms are introduced in order to take into account Urban Heat Island effects, gas leakages on pipeline and fuel combustion-based devices. ETEWI is applied in this work to an electric air-toair heat pump that supply heating and cooling demand of a real university building in South of Italy. A comparison between traditional TEWI and innovative ETEWI have been proposed to evidence the possibility to energy policy update for environmental indexes. The results demonstrate that the electric device shows a reduction equal to 29.7% in emissions evaluation by using ETEWI method with respect to traditional TEWI evaluation.