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Strategies for reducing the environmental impacts of room air conditioners in Europe Laurent Grignon Masse n Philippe Rivi ere 1 Je r ome Adnot2 Mines ParisTech Center for Energy and Processes 60 Boulevard Saint Michel 75272 Paris Cedex 06 France a r t i c l e i n f o Article history Received 29 January 2010 Accepted 1 February 2011 Available online 22 February 2011 Keywords Room air conditioners Energy effi ciency measures Life Cycle Analysis a b s t r a c t In Europe buildings tend to be equipped with individual air conditioners which constitute a fast growing electrical end use In this context this study aims to assess the environmental impacts of European individual air conditioners and to analyse policy strategies to reduce these impacts After analysing the European context concerning individual air conditioners the environmental impacts of European air conditioners are assessed using a Life Cycle Analysis approach The following step consists in studying both technically and economically different improvement options aiming at reducing the environmental impacts of these appliances These results obtained at the product level are then generalised at the European level and different policy measures are defi ned and analysed The main conclusion is that the implementation of a Minimum Energy Performance Standard based on Least Life Cycle Costs could save up to 49 TWh and 20 MtCO2 eq in 2020 and be economically benefi cial to the European end user fax 33 1 40 51 24 91 E mail addresses laurent grignon masse mines paristech fr L Grignon Masse philippe riviere mines paristech fr P Rivi ere jerome adnot mines paristech fr J Adnot 1 Tel 33 1 40 51 90 80 2 Tel 33 1 40 51 91 74 3 In 2006 room air conditioners were included in the 12 fi rst product families in the scope of the Energy using Products EuP directive CEC 2009a This directive aims at establishing a framework for setting ecodesign requirements for energy using products in the residential tertiary and industrial sectors Energy Policy 39 2011 2152 2164 There are different types of air conditioners Table 1 the single split type is by far the most common type in Europe The single split system is composed of two packages one indoor and one outdoor unit connected only by a pipe that transfers the refrigerant The indoor unit includes the evaporator and a fan while the outdoor unit contains a compressor and a condenser The multi split system is similar to the previous product but includes several indoor units each connected to the outdoor unit The single duct system is a movable packaged unit that contains the compressor the heat exchangers and the fans The condenser ejects hot air through a duct to the outside i e air used to cool the condenser is taken from inside the room and rejected outside by a duct Operating schemes of the single split and the single duct systems are given in Figs 1 and 2 All the systems can be designed as reversible operating then as heat pumps The percentage of reversible air conditioners is increasing in Europe and e g more than 80 of split air condi tioners sold nowadays are reversible in countries like France Portugal or Greece Pout and Hitchin 2009 2 1 2 The air conditioning market in Europe The European market is still growing substantially about 3 5 million units were sold in 2005 BSRIA 2005 compared with only 1 6 million in 1996 Adnot et al 1999 Most units are produced in China and surrounding Asian countries The installed stock is far from the saturation levels seen in other parts of the world e g 85 of households in Japan own at least one individual air conditioner Rivi ere et al 2009 and the sales fi gures show no sign of approaching market saturation Italy and Spain together account for more than half of all European sales BSRIA 2005 The annual additional cooling capacity is about 12 6 GW for both countries together that is about a 5 GW increase in electric peak demand with an energy effi ciency ratio of 2 5 According to Pout and Hitchin 2009 individual air condi tioners are primarily installed in non residential buildings e g offi ces retail units with this sector accounting for 63 of all sales expressed in cooling capacity About 30 of split and multi splits are installed in new buildings about 15 20 are used in existing buildings for replacement the remainder goes into existing buildings for fi rst time installation 2 1 3 Energy effi ciency of air conditioners The energy effi ciency of individual air conditioners is char acterised by the Energy Effi ciency Ratio EER defi ned as the ratio between the cooling power and the electric power input Simi larly in heating mode the Coeffi cient Of Performance COP is defi ned as the ratio between the heating power and electric power input The EER and COP depend on climatic conditions e g the EER decreases when the indoor temperature decreases or when the outdoor temperature increases and on the part load ratio the ratio between the required cooling load and the maximum cool ing load that can be extracted by the appliance Air conditioner standard performance is evaluated at full capacity with an outside air temperature of 35 1C in cooling mode and of 7 1C in heating mode ISO 1994 1995 2 1 4 Energy effi ciency of the European market Two main mechanisms have been implemented in Europe in order to improve the energy effi ciency of the whole market Since 2002 an energy label has been applied to individual air conditioners CEC 2002a It aims to guide potential buyers in their choice of effi cient products but does not contain any minimum effi ciency requirement The second mechanism consists in voluntary minimum energy effi ciency requirements By participating in the Eurovent Certifi cation scheme manufacturers are allowed to include their pro ducts in the annual Eurovent Certifi cation product directory which is widely used among consultants and installers However in return they have to certify all their equipments Certify All policy and these products can be independently tested Further more a minimum EER for air conditioners is required in order to be certifi ed Thus since 2004 products rated G according to the Labelling Directive were eliminated from the Eurovent Certifi ca tion air conditioner programme which prevents Eurovent certi fi ed manufacturers more than 75 of the market from selling such products An analysis was carried out in order to compare current effi ciency levels in Europe to Minimum Energy Performance Standards MEPS existing in other countries COP and EER values come from the Eurovent Certifi cation public database Eurovent 2006 4 In Fig 3 each point represents the EER value of a split system air conditioner reversible or cooling only sold in 2006 in Europe Chinese and South Korean MEPS which are based on the same rating standards as in Europe ISO 1994 are also plotted The analysis shows that a signifi cant number of the products sold in Europe would not comply with the legislation of these countries To illustrate the gap 80 90 of the cooling only air conditioners i e non reversible air conditioners in the Eurovent database do not reach South Korean MEPS and even some products rated A in Europe would not be allowed in South Korea Similar conclusions were obtained for other countries Australia Japan and for the heating mode Rivi ere et al 2009 Table 1 Shares of air conditioners sold in Europe by type Hitchin and Pout 2008 Types of air conditionersMarket shares in Europe Single split78 Multi split10 Single duct6 Other package window wall 6 Total100 Fig 1 Operating schemes of a single split system Orphelin 1999 Fig 2 Operating schemes of a single duct system Orphelin 1999 4 As effi ciency values come from the Eurovent Certifi cation database pro ducts are at least rated F according to the Labelling Directive Nevertheless less effi cient air conditioners can be found on the market since several manufacturers do not participate in the Eurovent voluntary MEPS requirement L Grignon Masse et al Energy Policy 39 2011 2152 21642153 Therefore despite energy effi ciency measures implemented in Europe the European market is signifi cantly less effi cient than in other zones This suggests on one hand that the European energy labelling is somewhat outdated and on the other hand that there is an important potential for improvement in air conditioner energy effi ciency 2 1 5 Seasonal performance metrics to rate air conditioners in Europe The present European standard EN14511 CEN 2004 uses the same testing conditions as the ISO 5151 standard ISO 1994 This testing is carried out in design cooling conditions maximum cooling capacity and maximum summer outdoor temperature However over a cooling season it represents only a few hours of use Most of the time the air conditioner is working at part load and lower outdoor air temperature Hence in order to rate the effi ciency of air conditioners the USA and Japan have defi ned seasonal performance indicators they combine several test conditions different cooling loads and different outdoor tem peratures and their respective hours of occurrence in a typical climate for a given load curve The fi nal seasonal EER is the ratio between the seasonal cooling needs or heating for SCOP and the seasonalelectricityconsumption Rivi ereetGrignon Masse 2008 In order to update the European rating standard CEN 2004 two seasonal effi ciency metrics were developed for air condi tioners the Seasonal Coeffi cient Of Performance SCOP in heat ing mode and the Seasonal Energy Effi ciency Ratio SEER in cooling mode A comprehensive calculation method described in CEC 2009c allows the assessment of these effi ciency metrics which takes into account the effects of temperature and energy load variations on performance In both cooling and heating modes auxiliary power consumption oil heater thermostat off standby and off mode is also included European seasonal effi ciencies are used to evaluate the aver age energy effi ciency of air conditioners In view of the variations in typical climates used in the USA Japan and Europe it is unfortunately not possible to compare the effi ciency of air conditioners sold in these three regions 3 Life Cycle Analysis of European room air conditioners An LCA of European air conditioners is undertaken to assess the environmental impacts and to determine improvement paths The fi rst step consists in characterizing reference cases which are representative of the European market in terms of technical features Based on these products the LCA tool developed by VHK 2005 in the framework of the Ecodesign directive is used to perform the LCA This tool takes into account the different phases of the product s life cycle production distribution use and end of life to calculate the following environmental impacts materials consumption energy consumption air and water emissions 3 1 Technical descriptions of representative products 3 1 1 Types of air conditioners considered in the present study The European market for individual air conditioners is mainly composed of three main product types single split systems multi split systems and single duct systems Research has shown that there were important differences between split air condi tioners whose capacity is lower than 6 kW and those whose capacity is between 6 and 12 kW e g in terms of energy effi ciency In addition while cooling only air conditioners and reversible ones are very similar in terms of components their operating conditions largely differ and it is important to make a distinction between them Finally fi ve different reference cases were analysed a cooling only air conditioner in the less than 6 kW range a reversible air conditioner in the less than 6 kW range a cooling only air conditioner in the 6 12 kW range a reversible air conditioner in the 6 12 kW range a single duct air conditioner 3 1 2 Determination of technical characteristics of the reference cases The specifi cation of the reference cases is based on databases developed by Eurovent 2006 Distributions and regressions have been extracted from these databases to determine the character istics of average models in cooperation with the manufacturers Rivi ere et al 2009 The performance characteristics of the fi ve reference cases are presented in Table 2 In order to assess the technical improvements it is necessary to know accurately the technical solutions usually implemented in current products Some of the main technical features are shown in Table 3 for the fi ve reference cases detailed descrip tions are available in Rivi ere et al 2009 The evolution of performances according to outdoor climatic conditions and energy loads were also characterised which enabled an assess ment of the seasonal effi ciencies of the reference cases Table 3 2 3 4 5 6 0 EER W W Cooling Capacity kW EU Energy Class A EU Energy Class G South Korea MEPS 2004 China MEPS 2005 24681012 Fig 3 Comparison of the energy effi ciency of European split systems in cooling mode to South Korean and Chinese MEPS Source Eurovent directory of certifi ed products of March 2007 Table 2 Performance characteristics of reference cases Performance characteristics Cooling only 0 6 kW Reversible 0 6 kW Cooling only 6 12 kW Reversible 6 12 kW Single duct air conditioner Cooling capacity 3 5 kW3 5 kW7 1 kW7 1 kW2 2 kW EER2 93 12 52 82 3 Heating capacity 4 kW 8 1 kW COP 3 4 3 3 L Grignon Masse et al Energy Policy 39 2011 2152 21642154 3 2 Collection of data required to perform the LCA 3 2 1 Production phases The environmental impacts of the production phase mainly depend on materials type and weight that compose the product This information was supplied by manufacturers Table 4 presents the composition of three reference cases The only difference between reversible and cooling only split systems is the addition of a 4 way valve a second expansion valve and copper for tubing these elements to enable reverse mode operation For the two 7 1 kW reference split systems the composition is the same but the total mass ratio of the product is equal to 14 kg kW of cooling capacity instead of 13 kg kW This ratio is lower for the single duct air conditioner with 10 kg kW 3 2 2 Distribution phase Product volumes of reference cases are required in order to assess transportation impacts An analysis of available products leads to the following volumes 0 25 m3for the two split systems of 3 5 kW capacity 0 5 m3for the two split systems of 7 1 kW capacity and 0 25 m3for the single duct It is assumed that products are manu factured in Asia and transported to European countries by boat 3 2 3 Use phase It is essential to quantify the energy and the working fl uid used by every reference case They are the only resources consumed during the use phase since in the fi eld components are not replaced Detailed computer building simulations were performed on an hourly basis over a year with the TRNSYS 16 software to estimate energy consumption due to cooling and heating for six different building types existing and new offi ces existing and new fl ats existing and new retail units and for every EU 27 member state Rivi ere et al 2009 The systems were size based on peak cooling and heating loads determined by the simulations they are assumed to guarantee the required setpoint temperature over the whole season The energy consumption fi gures obtained by simulation are consistent with the rare European studies on the actual air conditioner consumptions e g Dunn and Knight 2005 Given the very limited number of studies on this topic the measure ment of in situ energy consumption would be of particular interest to improve decision making Energy consumption values obtained for each country and every type of building were then weighted with 2005 sales fi gures BSRIA 2005 which enabled a calculation of energy consumption per reference case as shown in Table 5 A distinction was made between electricity consumption in active mode and additional consumption e g standby which represents between 10 and 15 of the total consumption Consumption is not null when the compressor is not working because some devices remote con trols screens timers and oil heaters are still running Concerning this issue the only surveys available on products similar to the split and single duct in the European market were performed in Australia and New Zealand MCE 2006 this reference was used in the study Individual air conditioners can consume up to 100 W when the compressor is off depending on the available functions higher values do include improperly controlled and low effi cient crankcase heaters that enable heating of the compressor oil to prevent compressor damage at startup Regarding refrigerant fl uids the leakage rate represents the amount of lost fl uid related to the initial charge Based on the literature Barrault et al 2004 CETIM 2004 IPCC 2005 we assumed a yearly leak rate of 3 for split systems and 1 for single duct air conditioners which are more compact It is assumed that the systems are not supplied with new fl uids during the use phase which corresponds to the common fi eld practise 3 2 4 End of life phase There are two main issues to be dealt with regarding the end of life phase the treatment of the working fl uid and the treat ment of materials Since the focus is on new products in this paper it is assumed that the Directives WEEE CEC 2002b and F GAS CEC 2006 will be respected at the time the products are disposed of This implies that all the working fl uid is recovered and that the rate of material recovery is of at least of 80 of the total weight of the appliance Also the rates of re use and recycling of components materials and other substances are of at least 75 of the total weight of the appliance However a sensitivity study is carried out in Section 3 3 2 to evaluate to what extent different end of life scenarios would have changed the environmental impacts Table 3 Main technical features of reference cases Cooling only 0 6 kW Reversible 0 6 kW Cooling only 6 12 kW Reversible