A presentation at the ‘International Workshop on Next Generation Technologies for Mobile Vehicles’ Air Conditioning’ in China pointed out the higher-than-thought real life HFC134a emissions due to system leakage and during servicing. On another note, a new Swiss study suggests that two thirds of the fuel used for Mobile Air Conditioning (MAC) could be saved by switching it off below 18°C.
Around 150 Chinese industry representatives and policy makers gathered this month in Nanjing, China, for the ‘International Workshop on Next Generation Technologies for Mobile Vehicles’ Air Conditioning’ organised by UNEP as part of its HCFC Phase-out and Mobile Air Conditioning project.
A presentation by French research institute École de Mines presented test results to reveal that:
These real life observations regarding refrigerant leakage are typically not accounted for in tools assessing the overall environmental benefits of different MAC systems, such as the MAC LCCP (life cycle climate performance) tool run until last year. The proposed tool had assumed low leakage rates for R134a MAC systems throughout all countries listed. As a result, the direct emissions for R134a had been assumed to be at an idealised low level for some countries, lowering the environmental benefits from switching to natural refrigerant MACs, including hydrocarbons.
2/3 of the fuel used for MAC could be saved by switching it off below 18°C
A new study undertaken by Empa on behalf of the Swiss Federal Office for the Environment (FOEN) looked into the impact of mobile air conditioning on fuel consumption. Using the standard climate model defined by the Swiss Society of Engineers and Architects (SIA, Bern1) they found that the average annual extra consumption of a petrol-engined car amounts to 5.4%. Differentiating between urban, suburban and motorway driving gives additional fuel usage values of 10%, 2.8% and 1.3% respectively.
The researchers also noted that the air conditioning systems in cars with automatic transmissions – today’s most widely sold models - only switch themselves off when the external temperature drops below 5 degrees, when the cooling system could ice-up. They developed a new model, the EEMAC, to predict emissions from air conditioning. The measurements showed that the MAC is still active at temperatures below the desired interior temperature. They applied the model to the average meteorological year of a central European region and compared this to the US EPA MOBILE6 model. The estimated average annual CO2 output according to EEMAC is six times higher than that of MOBILE6. Around two-thirds of the fuel used for air conditioning could be saved by switching the MAC system off below 18°C, the study concludes. The authors suggest that discussions should be set up with manufacturers to ensure air conditioning units turn off completely if no cooling is needed and turn on only when the windscreen mists.
A presentation by French research institute École de Mines presented test results to reveal that:
- The average leak flow rate from new R134a MAC systems amounts to 10g/yr
- The compressor is the main source of HFC134a emissions, with a 50 – 60%
- Leak tightness degradation of MAC systems has been confirmed by tests
- Only 2/3 of the refrigerant is charged to the MAC system, while 1/3 is emitted directly to the atmosphere when Do-it-yourself servicing is carried out
These real life observations regarding refrigerant leakage are typically not accounted for in tools assessing the overall environmental benefits of different MAC systems, such as the MAC LCCP (life cycle climate performance) tool run until last year. The proposed tool had assumed low leakage rates for R134a MAC systems throughout all countries listed. As a result, the direct emissions for R134a had been assumed to be at an idealised low level for some countries, lowering the environmental benefits from switching to natural refrigerant MACs, including hydrocarbons.
2/3 of the fuel used for MAC could be saved by switching it off below 18°C
A new study undertaken by Empa on behalf of the Swiss Federal Office for the Environment (FOEN) looked into the impact of mobile air conditioning on fuel consumption. Using the standard climate model defined by the Swiss Society of Engineers and Architects (SIA, Bern1) they found that the average annual extra consumption of a petrol-engined car amounts to 5.4%. Differentiating between urban, suburban and motorway driving gives additional fuel usage values of 10%, 2.8% and 1.3% respectively.
The researchers also noted that the air conditioning systems in cars with automatic transmissions – today’s most widely sold models - only switch themselves off when the external temperature drops below 5 degrees, when the cooling system could ice-up. They developed a new model, the EEMAC, to predict emissions from air conditioning. The measurements showed that the MAC is still active at temperatures below the desired interior temperature. They applied the model to the average meteorological year of a central European region and compared this to the US EPA MOBILE6 model. The estimated average annual CO2 output according to EEMAC is six times higher than that of MOBILE6. Around two-thirds of the fuel used for air conditioning could be saved by switching the MAC system off below 18°C, the study concludes. The authors suggest that discussions should be set up with manufacturers to ensure air conditioning units turn off completely if no cooling is needed and turn on only when the windscreen mists.
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Jun 24, 2010, 10:07
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