Identified best environmental management practices to improve the energy performance of the retail trade sector in Europe

Energy Policy 63 (2013) 982–994

Contents lists available at ScienceDirect

Energy Policy journal homepage: www.elsevier.com/locate/enpol

Identified best environmental management practices to improve the energy performance of the retail trade sector in Europe$ Jose-Luis Galvez-Martos a,b,n, David Styles b, Harald Schoenberger b a

University of Aberdeen, School of Engineering, Fraser Noble Building, King's College, Aberdeen AB24 3UE, Scotland, United Kingdom European Commission, Joint Research Centre, Institute for Prospective Technological Studies, Sustainable Production and Consumption Unit, EXPO Building, 3 Inca Garcilaso, E-41092 Seville, Spain

b

H I G H L I G H T S







There is a high energy performance improvement potential of the retail trade sector. We propose techniques with a high performance level and applied by frontrunners. We identified main barriers. These barriers are mainly based on economic criteria. The improvement of food refrigeration processes is essential.

art ic l e i nf o

a b s t r a c t

Article history: Received 10 February 2012 Accepted 15 August 2013 Available online 20 September 2013

The retail trade sector has been identified as a target sector for the development of sectoral reference documents on best environmental management practices under the Eco-Management and Audit Scheme. This paper focuses on the important energy-related needs in retailers' stores such as for food refrigeration and lighting, as well as heating, ventilation and air conditioning of the building. For the definition of best environmental management practices in the European framework, frontrunner retailers have been identified as those retailers integrating energy minimization and saving measures as standard practice systematically across stores. These best performers also integrate a comprehensive monitoring system in the energy management of every store or building belonging to the company, enabling the rapid identification of energy saving opportunities. An integrative approach is needed to define how best practices should be implemented in combination to optimize energy management within stores: building aspects such as insulation of the building envelope or the heating, ventilation and air conditioning system, should be optimized in combination with best options for refrigeration in food retailers. Refrigeration systems are responsible for half of the final energy use in stores and of their carbon footprint. Natural refrigerants, heat recovery from the condensation stage and covering of display cases are measures with high environmental benefits to reduce the impact of refrigeration. Finally, practices for lighting, as optimal lighting strategies, and the integration of renewable energy sources in overall zero energy building concepts can save considerable amounts of fossil energy, reduce the carbon footprint and produce significant cost-savings in the long term. & 2013 Elsevier Ltd. All rights reserved.

Keywords: Retail trade Environmental management Energy performance

1. Introduction In Europe, resource depletion and climate change are two main environmental concerns, which are driving environmental policy.

☆ The views expressed are purely those of the writers and may not in any circumstances be regarded as stating an official position of the European Commission. n Corresponding author at: University of Aberdeen, School of Engineering, Fraser Noble Building, King's College, Aberdeen, Scotland AB24 3UE, United Kingdom. Tel.: þ 44 1224 274370. E-mail address: [email protected] (J.-L. Galvez-Martos).

0301-4215/$ - see front matter & 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.enpol.2013.08.061

For example, the Sustainable Development strategy of the European Union defined in 2006 “Climate change and Clean Energy” as one key challenge, which has been mainstreamed in several policy instruments (EC, 2006, 2009). In the same policy framework, the Sustainable Consumption and Production Action Plan (EC, 2008) identifies retailers as one of the most important actors in order to change consumption patterns. As a matter of fact, retailers are in direct contact with consumers, so their potential to influence the environmental behavior of customers is presumed to be important, not only to drive more awareness among consumers, but also to improve their environmental performance and the sustainability of the supply chain (Styles et al., 2012a, 2012b).

J.-L. Galvez-Martos et al. / Energy Policy 63 (2013) 982–994

Nomenclature As CEN CSR EC EMAS EP EPBD GHG HDDs

Building envelope area per square meter of sales area European Committee for Standardization Corporate Sustainability Report European Commission Eco-Management and Audit Scheme European Parliament Energy Performance of Buildings Directive Greenhouse Gas Heating Degree Days

In the framework of this Sustainable Consumption and Production Action plan, two new instruments were established. On the one hand, the Retail Forum, comprising the European Commission and the main European retailers, is focused on the promotion of sustainable consumption patterns but also environmental practices and best practice exchange among big players. On the other hand, the ‘Reference Document on Best Environmental Management Practice in the Retail Trade Sector’ (Schoenberger et al., 2013) has been developed under the new regulation 1221/2009 on EcoManagement and Audit Scheme (EMAS), which is identifying retail trade sector as one of the so-called priority sectors. These two schemes highlight the strategic importance of the retail trade sector and undoubtedly are connected to the Roadmap to a Resource Efficient Europe, published in 2011 (EC, 2011), where the main strategies for a better use of resources are drawn. In particular, the reference documents are intended to assess and benchmark the environmental performance of companies, comprehensively considering the full value chain of retailing organizations. All the environmental aspects of retailers' activities are covered by the sectoral reference document: direct aspects, if they are controlled by themselves; or indirect aspects, if they are not controlled by retailers but can be significantly influenced to produce a benefit for the environment. Best environmental management practices are understood as all the elements that retailers can implement, from single techniques to global policies, to achieve a better environmental performance in a certain economical framework. The most important identified direct aspects are energy performance, waste management, transport (which may be regarded as indirect, depending on the organizations' practice), materials consumption and water management. The most important indirect aspects are related to the supply chain and to the influence on the consumer behavior. The high specific energy consumption per square meter makes stores one of the building typologies with highest energy consumption. Tassou et al. (2010) studied the energy performance of several hundreds of stores in the UK (big hypermarkets, superstores, supermarkets and convenience stores) and determined that the average electricity consumption of UK retailers' buildings varies from 700 kWh per square meter and year in biggest buildings to 2000 kWh/m2yr in small convenience stores, while heating energy consumption varies up to 250 kWh/m2 yr. The average total energy consumption of a store is about 1000 kWh/m2 yr, which is significantly higher than the final energy demand of other commercial buildings, such as offices (100– 200 kWh/m2 yr) or hotels (100–300 kWh/m2 yr), and much higher than residential buildings (50–150 kWh/m2 yr). According to the issue paper from the European Retail Forum on the energy efficiency of stores (Retail Forum, 2010), the use of energy by non-food retailers is much lower than for food retailers, as preservation of food through refrigeration can consume up to 50% of the energy demand of a store, which can be lower for bigger hypermarkets (25–30%), as they cannot be considered only as food stores (Tassou et al., 2010). In non-food

HVAC IEA IPTS LED LT MT PV q Q TWG U

983

Heating Ventilation and Air Conditioning International Energy Agency Institute for Prospective Technological Studies Light-emitting diode Low temperature Medium temperature Photovoltaic Heat flux Specific heat consumption per square meter and year Technical Working Group U-value, heat transfer coefficient

retailers, lighting is a main concern, accounting for up to 50% of the total energy demand, and also has a strong marketing purpose. This paper presents the relevant scientific findings backing up the selection of best environmental management practices, which are basically identified taking into account the performance of frontrunners as the ‘benchmark of excellence’ for the sector. The main focus is made on the management of stores, owned or rented, commercial centers and distribution centers of retailers. Data collation and information exchange with retailers played a very significant role in the final identification of best environmental management practices. The analysis of the provided data, the scientific literature and information exchange with the relevant experts during the development of the study led to the identification of several best environmental management practices, which are described in nine energy-related subsections of the sectoral reference document. The information received was mainly unpublished data and, in many cases, confidential. The analysis of this information produced original findings regarding to both the performance results from technology implementation to the energy management policy at retailers, which are presented in this paper. In general, most of the new analysis is focused on the economic performance of the outstanding new approaches. Technologies achieving best performance are well known by retailers, but their decision-making process can be very different and highly dependent on the economic performance, so those taking higher risks and with long-term perspective are achieving best results.

2. Methodology The formal process for the identification of a best environmental management practice is run by the European Commission and is quite similar to the identification of best available techniques for the European Directive on Industrial Emissions, formerly Integrated Pollution Prevention and Control (Schoenberger, 2009). A Technical Working Group (TWG) was established with relevant experts and stakeholders and two meetings were held: the kick-off meeting established the basis for the information exchange process and the structure for the description of identified best environmental management practices. Then, the Institute for Prospective Technological Studies (IPTS), one of the seven research institutes of the Joint Research Center of the European Commission, established a research group to gather the required information, assessing its suitability for the definition of ‘best environmental management practice’ and producing the final document. Data collation was performed through site visits, meetings with relevant experts, analysis of publicly available information, such as CSR reports or scientific publications as well as confidential and non-confidential technical information from retailers. A final meeting was held to conclude on best practices, indicators to measure their performance and the achievable ‘benchmarks of excellence’ as defined by Article 46.1 of the EMAS regulation. Frontrunner

984

J.-L. Galvez-Martos et al. / Energy Policy 63 (2013) 982–994

approaches were identified and their performance could be used to set benchmarks of excellence. These very ambitious performance levels represent the 10–20% best performing stores of the best performing retailers (i.e. frontrunners). In this way, the provisions of the EMAS regulation were materialised. The final document is published as a Joint Research Center Technical Report (Schoenberger et al., 2013). The energy management of retailers is a very important section in the study and mainly covers those scientific and engineering aspects of energy systems at retailers' buildings, oriented also to managers, in order to provide a sufficient background for decision-making regarding the environmental performance of companies. It excludes transport and logistics, which is usually covered through a different management system and, therefore, out of the scope of this paper. Many of the most important European retailers collaborated in the development of the document such as Lidl, Migros, Mercadona, Royal Ahold (Albert Heijn, ICA), Coop (Switzerland), Coop (Italy), Coop (Sweden), Marks&Spencer, Colruyt, Ikea, Rewe, Carrefour, C&A, H&M, Aldi, Metro and Sainsbury. Technical experts working from retailers, engineering companies and suppliers, retailers associations and NGOs also contributed to the reference document. The level of consensus on the conclusions drawn at the final meeting of the TWG was very high and there were not any split views in the final document conclusions.

3. Environmental improvement potential through better energy performance The energy performance of retailers is characterized by their high energy demand, especially of those selling food needing preservation (so-called food retailers). There, typically, 50% of the energy is consumed by the refrigeration process, mainly at the compression stage. For food retailers, lighting is usually consuming less than 30%, although it depends on the design concept and, especially, on the sales format. Heating, ventilation and air conditioning accounts for 15–20%, and the rest is usually consumed by secondary processes, such as appliances, ovens, water heaters, etc. To illustrate the improvement potential of retailers, initial information concerning the energy performance of several food retailers was gathered from their Corporate Sustainability Reports (CSR) and plotted in Fig. 1. This chart represents the specific energy consumption (final energy per year and sales area unit) of the whole company vs. the number of stores and total sales area (represented by bubble sizes). The comparability of the measured energy consumption cannot be fully assured, as the

Fig. 1. Specific energy consumption per number of stores and sales area (represented by bubble size) for sampled European food retailers.

monitoring system varies from one company to another. Nevertheless, it can be observed that the largest food retailers have larger total sales areas across a greater number of stores, represented at the right part of the graph, while smaller retailers are located at the left of the graph with smaller total sales areas (bubble sizes). The improvement potential implied by Fig. 1 is significant. Small retailers (for example, those working only at the regional or national level) usually have higher specific energy consumption than large retailers working at the international level and often with a higher degree of standardization across stores. Best performers can be identified in Fig. 1 as those with energy consumption less than 500 kWh/m2/yr. Thus, there is considerable scope for improvement in relation to the energy performance of retailers. As seen in Fig. 1, the biggest assessed retailer has an average final energy consumption of about 600 kWh/m2 yr. Improvement options implemented across all stores could therefore have a positive economic impact on the business performance. The amount of energy that could be saved is significant and it is responsible for a major part of the carbon footprint of the retailers' operations. Apart from the energy contribution, an important fraction of the carbon footprint comes from direct greenhouse gases (GHG) emissions caused by the leakage of refrigerants from refrigeration systems. Other processes, such as fuel burning for heating, transport and logistics, also account for direct carbon emissions from the sector. The biggest European food retailer, Carrefour, reported that around 60% of their total carbon footprint is caused by the refrigeration process: direct emissions come from refrigerants leakage (30%) and indirect emissions from electricity consumption (30%) (Carrefour Group, 2009). However, it is expected that indirect GHG emissions from the electricity consumption may be higher for other retailers, as Carrefour has 47% of its stores in France, where lower emissions from electricity generation are accounted. Non-food retailers are consuming less energy than food retailers and, usually, have a very different behavior in their energy performance due to differences in sales concepts. The percentage of energy consumption for lighting is higher than 50%, and can be up to 80%, for specialized stores. Measures to reduce energy consumption can affect sales, in which case they may be implemented cautiously or avoided. A good example for the whole sector is store lighting. Many retailers have implemented efficient devices and have reduced their consumption for basic store lighting. Some retailers are more reluctant to implement the use of natural light or to reduce the number of spotlights because product illumination is regarded as an important marketing issue. In fact, retailers usually have different management schemes for measures that may affect sales (reduce illumination needs, cover refrigeration display cases with glass lids, reduce opening hours, etc.) and are more keen on measures without any influence on sales (e.g. building heating system improvement, renewable energy sources, etc.). In general, retailers are concerned about their energy bill and many initiatives and measures have been implemented to save energy (Retail Forum, 2010). Good energy performance translates into lower costs, greater resilience against potential increases in energy prices, better business performance, extended knowledge of energy processes within stores and smaller carbon footprints. To develop further improvements, two main approaches have been identified, among current environmental management practices: – ‘lighthouse’ projects: the main investment on energy saving measures is performed over one or two stores, where the most innovative systems have been implemented even regardless of the cost. The final result is a really outstanding store, but with a very long payback time. There are cases where the main objective is to show publicly the environmental awareness of

J.-L. Galvez-Martos et al. / Energy Policy 63 (2013) 982–994

the company rather than to achieve a really good overall performance for the whole organization. However, this approach may be very useful if it is regarded as a ‘laboratory’ or ‘pilot’ store, where many measures are tested in order to design the best standard for new stores and in the retrofitting of existing ones. – ‘standardization’ projects, where, for example, a single measure is tested in several stores (with different climate, cultural and social conditions) in order to assess the technical suitability and the economical feasibility of the measure. The final assessment results may lead to the inclusion of the measure in company standards for all new stores and for the retrofitting of existing stores. As a matter of fact, identified best performers are using this approach, which requires greater commitment and higher initial investment but results in better overall environmental and economical performance in the short, medium and long term. It was observed that identified best performers follow the second approach whereas the first one is preferred by retailers that are not well advanced yet or are still beginners with respect to systematic implementation of energy efficiency measures in their stores. The influence of the sales concept is quite important for the overall energy performance of the store. The performance is usually dependent on the concept the store is designed for, as hypermarkets, supermarkets, convenience stores, carry and cash, etc. In general, this paper refers to energy consuming processes inside the store (heating, refrigeration, lighting, etc.) and proposes indicators for these processes. For example, convenience stores and small food stores have higher density of refrigerated display cases than bigger supermarkets or hypermarkets. This, of course, would affect to the overall consumption for refrigeration, usually higher in small stores, but does not affect to the energy consumption per meter of display case (called linear consumption), which is an indicator quite often used for the efficiency of refrigerated cabinets at food stores. Our research team at IPTS has used several criteria in the identification of best environmental management practice. The energy performance has been one of the main criteria, but not the only one. Applicability, cross-media effects, economics and the existence of commercially implemented examples are also essential factors to consider a technique as a ‘best environmental management practice’. The best environmentally-performing solution for a certain energy aspect may not be regarded as best practice if the initial investment is too high or the technique is still at laboratory or pilot scale (it is not ready for the market) or if the applicability is rather limited. Next sections of this paper describe the most important technical, environmental and economic characteristics of the identified practices for the energy management and monitoring, building aspects, refrigeration, lighting and other relevant aspects, which are summarized in Table 1. 3.1. Energy management and monitoring Although any environmental management system should consider energy management as one of the most important direct environmental aspects, energy management is usually performed separately because of its direct impact in the operating costs and in the business performance of the company. A good energy management system should be able to prioritize energy saving measures in order to first, reduce energy demand, especially the application of passive measures; second, improve the efficiency; and third, to increase the share of cleaner energy sources. Although highest attention should be paid to reducing the energy demand, other cost-efficient solutions may be regarded with priority if their environmental and economic benefit justifies its application. For instance, if the cost to retrofit building insulation is unaffordable when a store is refurbished, the use of electricity from cleaner sources may be implemented before other

985

actions to reduce the demand; efficient heaters may be installed. This approach should be regarded as an exception necessary in the shortterm, with long-term strategies oriented towards fundamental energy demand reductions – e.g. renting or specifying well-insulated buildings. One of the most important elements of the management system is the monitoring of energy consumption (CEN, 2009). It was observed that best performances are usually achieved in companies with comprehensive environmental monitoring. This systematic monitoring of all stores should facilitate the detection of significant deviations from the average energy consumption, the quantification of the benefits of implemented measures, the identification of hotspots and the development of in-house energy expertise within retail companies. Generally speaking, retailers are advanced in sales monitoring techniques but still have gaps in the environmental monitoring system, and energy performance is an example for that. A list of monitoring variables was developed for the reference document divided into three categories: energy sources (what is the retailer consuming), store operation processes (how and where are they consuming energy: refrigeration, lighting, space heating, space cooling, etc.) and energy influencing factors (what factors are influencing energy consumption: heating degree days, incidents, opening hours, etc.). In total, 35 parameters were detected that are of relevance to the energy performance and that can be represented in retail energy performance indicators. Commonly used indicators, and alternative indicators derived from them, are shown in Fig. 2. This figure also shows the connections between these indicators and internal processes, and across indicators. The most common indicator is the amount of final energy consumed per year and per sales area, which is called the specific energy consumption. One of the main characteristics of the indicators proposed in all sectoral reference documents is the process oriented approach, which may lead to the segregation of common indicators, such as the specific energy consumption of a store (e.g. in kWh/m2 yr) covering several processes (e.g. heating, lighting, refrigeration, etc.) or indicators which are specific to the process, such as the linear energy consumption for refrigerated display cases (kWh/ m yr). This last indicator is a very common parameter controlled by the technical managers of stores, but never reported in public documents dealing with the environmental performance. Then, benchmarks of excellence are also proposed at process level, where comparable indicators exist or may be developed. Both specific energy consumption and generation are common indicators publicly reported by companies in their corporate sustainability reports and in the environmental statement of their management system. Two other common indicators only used in the internal monitoring and reporting are lighting power density (measured in W/m2) and the amount of refrigerant leakages, as it can be assumed to be equal to refrigerant purchases in 1 year. Many retailers are currently publishing their carbon footprint, measured as the amount of GHG emissions per year (and, frequently, per m2). This footprint is the aggregated value of direct emissions (from fuel burnings or emissions of refrigerants with a high global warming potential) and indirect emissions (due to electricity consumption). In general, best performers in monitoring are also those with a good energy performance, as best management practice in energy monitoring commonly leads to the implementation of preventive or corrective measures to minimize energy consumption. 3.2. Building aspects Measures to improve the energy performance should start on reducing store energy demand, which is achieved by avoiding heat losses through the improvement of the building envelope and the integration of different building elements. In this respect, two

986

J.-L. Galvez-Martos et al. / Energy Policy 63 (2013) 982–994

Table 1 Summary of best environmental management practices to improve the energy performance of stores. Identified best environmental management practice

Benchmarks of excellence

Recommended indicators

To monitor the energy use

100% of stores and processes monitored

Implementation of a monitoring system (y/n) Percentage of stores controlled Number of controlled processes

Implemented benchmarking mechanisms To improve the envelope of existing retail buildings, to optimize the building envelope design and the HVAC system according to integrative approaches To recover the waste heat from the refrigeration cycle and to maximize its use

Specific energy consumption for heating, cooling and air conditioning less or equal to 0 kWh/m2 yr if waste heat from refrigeration can be integrated. Otherwise, less or equal to 40 kWh/m2 yr for new buildings and 55 kWh/m2 yr for existing buildings

Store specific energy consumption per m2 (sales area) and year Store primary energy consumption per m2 (sales area) and year

To implement energy saving measures in the refrigeration system of a food store, especially the covering of refrigeration display cases with glass lids.

100% covered LT cabinets 100% use of cooling zones (e.g. in cash and carry) or 100% covering of MT refrigeration where this can lead to an energy savings of more than 10% Specific (linear) consumption of refrigeration 3000 kWh/m yr

Specific energy consumption per m2 sales area and year

To use natural refrigerants

General use of natural refrigerants

Leakage control (% of refrigerant) Percentage of stores with natural refrigerants

To design smart lighting strategies with enhanced efficiency and reduced consumption, to use daylight without affecting the sales concept, if appropriate, and to use the most efficient lighting devices

Power consumption less than 12 W/m2 for supermarkets and 30 W/m2 for specialized stores

Specific energy consumption per m2 sales area and year Installed lighting power per m2

To integrate renewable energy sources in low energy demanding buildings

To have net zero energy buildings (store or distribution center) where local conditions allow the production of renewable energy on site, or investment in equivalent renewable energy generation at other locations

Specific energy generation per m2 of sales area Percentage of energy from alternative generation Percentage of alternative energy generation in excess of consumption

central European retailers have been identified as frontrunners, not only in the application to the design of new buildings, but also in the retrofitting of existing ones. The benefit of this depends on the initial situation: retrofitting a building with a bad performance will always have a shorter payback time when applying improvement measures. Nevertheless, this fact may not work for specific local circumstances. For instance, we obtained a real estimation from a retailer of the payback time for some retrofitting measures of a supermarket in France, shown in Fig. 3. Payback times for improving the building envelope are much longer than for other measures, like the installation of heat pumps, the use of renewable energy or changes in lighting devices. Lower electricity prices in France and other locally-influenced factors may have a strong influence on those results. According to the results obtained by Petersdorff (2006), for the retrofitting of generic buildings in several climates, built according to existing codes, the payback time differences in European countries are not really caused by differences in the climate, but by their different conventional building practices. Usually, cold climates have more demanding building codes, making their current stock of buildings more energy efficient than in moderate or in warmer zones. As a consequence, the building practice in warmer climates makes estimated payback times of insulation improvement short.

3.2.1. Building envelope improvement The building envelope has a key role in the heat loss and in the thermal balance of stores and other retailers' buildings. According to the Energy Performance of Buildings Directive (EPBD) (EP, 2010), the envelope of a building is integrated by the elements separating the indoor from the outdoor environment (wall, windows, doors, insulation, rood, basement, etc.). The heat loss through the envelope

Specific (linear) energy consumption per m of display case and year Percentage of stores with natural refrigerants

is characterized by the heat transfer coefficient, U, which is the amount of heat loss per m2 of envelope and per degree of temperature difference. Achievement of low heat transfer coefficients (e.g. 0.1 W/m2 K) has been observed in aforementioned European frontrunner retailers, which also achieve the lowest heat demand in their buildings. Nevertheless, the cost efficiency of this measure has to be assessed over the long term and taking into account future scarcity of resources and increases in energy prices. Insulation of existing buildings can be technically complex and have high installation costs. Measures to improve the building envelope always pay back, but often only in the long term. 3.2.2. HVAC optimization Space heating and cooling, ventilation and air conditioning are also of high importance in relation to the energy consumption of retail buildings. In relative terms, HVAC may not be as important as refrigeration for food retailers and lighting for non-food retailers. Nevertheless, the interaction of these processes with the HVAC system is a characterizing particularity of the retail trade sector. First, the refrigeration excess heat is usually wasted and its recovery can completely avoid the need for additional heating energy. Second, lighting produces significant internal heat gains, and changing to a low energy lighting system can reduce cooling demand or increase heating demand depending on the climate, season and building envelope thermal quality. Integration of heat gains, heat recovery and the optimization of the air change rate are key factors in the minimization of HVAC energy consumption. 3.2.3. Integrated approaches Best practitioners integrate building improvement with HVAC system optimization (air exchange rate optimization, internal

J.-L. Galvez-Martos et al. / Energy Policy 63 (2013) 982–994

987

Fig. 2. Energy performance indicators commonly used in the retail trade sector in Europe.

Fig. 3. Retailer estimations of payback times for several techniques, assessed for a supermarket to be retrofitted in France.

gains and heat recovery) to minimize their overall space heating and cooling energy demand. Some standards have been developed to address the need for integration of building elements to achieve better energy performance without huge investment costs. Two good and well introduced examples are Minergie and the PassivHaus standards (Swiss Energy, 2007; Feist and Schnieders,

2005). According to the Minergie standard, the energy demand of a building should be less than 40 kWh (primary) per square meter and year, or 55 kWh/m2/yr, if an existing building is retrofitted. The achievable benefits from optimized integration of building elements are remarkable. A few examples are shown in Table 2.

988

J.-L. Galvez-Martos et al. / Energy Policy 63 (2013) 982–994

Table 2 Examples of building improvements. Implemented measure

Achievable savings

Example stores or references

Costs

Retrofitting building envelope by increasing the thickness of insulation

Depend on climate and current situation of the building: average ranges from 60 to 150 kWh/m2 yr

Estimations for several scenarios (Boermans and Petersdorff, 2006; Schoenberger et al., 2013)

Depend on achievable savings and needed initial investment. Average total cost from EUR 0.02 to 0.12 per kWh saveda

Draught lobbies at entrances

11 kWh/m2 yr (  10% of energy consumption before retrofitting)

Main entrance of C&A Mainz store, Germany (C&A, 2010)

Payback time about 1 yr (authors' estimation)

Integration of heat recovery with retrofitting of building envelope and HVAC optimization with CO2 sensors

80% of initial heat demand (24 kWh of Migros Centre Brügg, Switzerland primary energy per m2 sales area and (Migros, 2010) year)

Payback time 1–2 yr

Integration of heat recovery with HVAC optimization and renewable sources (Geothermal Heat Pump)

115 kWh/m2/yr, about 80% of initial energy demand

Payback time 4–6 yr

a

Edeka Villingen Store, Germany

Depreciation time of 20 years.

In order to corroborate the influence of the climate in energy performance of retailers' buildings, a non-food retailer, operating all over Europe, provided the data for all its European stores. To control the influence of climate on heating demand in a quantitative manner, the Heating Degree Days (HDDs), concept was used. According to the definition of Eurostat, heating degreedays express the “severity of the cold in a specific time period taking into consideration outdoor temperature and room temperature” (Eurostat, 2010). The general expression for its calculation is HDD ¼(18 1C Tm)  d if Tm is lower than or equal to 15 1C (heating threshold) and nil if Tm is higher than 15 1C. Tm is defined as the mean outdoor temperature, calculated as (Tmin þTmax/2), over a period of d days. For the statistical reporting of HDD, calculations are to be done on a daily basis (d¼ 1). When heating demand vs. HDD is plotted, no relationship is observed (Fig. 4a). This reveals an important conclusion: codes and standard practices vary in Europe, even for the same country, and climate is not the main factor influencing the heat demand of a retailer's building, as the chart shows almost a random distribution of the heating demand. For warmer climates (less than 2500 HDD) it varies from 0 to 80 kWh/m2 yr, for moderate climates (from 2500 to 3500 HDD) stores are consuming from 0 to 120 kWh/m2 yr and for cold climates (higher than 3500 HDD), they are consuming in the range 20–60 kWh/m2 yr for heating. Fig. 4b shows the heat demand vs. the quotient heat demand/ heating degree days. This factor can be directly related to the Uvalue, as shown below. The U-value is defined by Eq. (1). U¼

q AΔT

ð1Þ

where U is measured in W/m2 K, q is the heat flux (J/m2 s) over a building envelope surface and ΔT is the temperature difference between building indoor and outdoor environments. The U-value is a technical parameter that represents how the building is losing or gaining heat through its envelope. The definition of Eq. (1) depends on many factors. The amount of energy to maintain a constant temperature has to be equal to the energy loss through the envelope and is directly proportional to the temperature difference. Temperature difference and time can be integrated in the heating degree days definition and a new expression is derived from Eq. (1) that can be useful to assess retailers' buildings: U¼k

Q As HDD

ð2Þ

where k is a constant conversion factor, Q is the specific heat consumption per square meter of sales area (kWh/m2 yr) and As is

Fig. 4. Heating demand vs. HDD (a) and vs. Q/HDD factor (b) for 180 European stores of the sampled retailer.

the building envelope area per m2 of sales area. The area of building envelope per m2 of sales area is related to the building shape, size and design. Retailers with a high standardization level have very similar shapes and the relationship between building envelope and sales area is almost constant or vary in a very narrow interval, as it is the case for the retailer of Fig. 4. Table 3 shows the

J.-L. Galvez-Martos et al. / Energy Policy 63 (2013) 982–994

Table 3 The regression model and regression coefficients for each climate category for the 180 European stores of a single retailer. Building location HDD

Regression

R2

HDD o 2500 2500o HDD o 3500 HDD 43500

Q ¼1.92 þ1704Q/HDD Q ¼ 2.54 þ2880Q/HDD Q¼ 4.22 þ 3670Q/HDD

0.7933 0.9614 0.8973

regression coefficients and the squared regression coefficient. Although the dispersion is higher for warmer climates, the Uvalue can be assumed to be proportional to the Q/HDD quotient. So, the figure representing heat demand vs. Q/HDD for very similar buildings can be considered equivalent to a figure representing how the heat demand varies with the U-value of a building with similar designs, as Fig. 4b shows real values from 180 stores from a European retailer with a high level of standardization (all the stores have very similar size and shape). Assuming the proportional relationship between Q/HDD and the U-value, it is deduced that the main energy saving in heating energy demand can be achieved only by reducing heat loss or the U-value. Trend lines of Fig. 4b prove that the heat demand is reduced to very low values when the envelope is well improved and avoids heat losses. Then, after this analysis, the climatic influence becomes evident and highest achievable benefits are observed for colder climates. One of the main conclusions from the chart is that – heating demand in warmer regions is in the same range of colder climates, so opportunities are identified to reduce the demand by improving the building envelope. This has to be done by reducing the U-value: highest thickness of insulation material, better materials for roofs, walls and façades, double or triple glazing, etc. This corroborates the findings of Schlenger (2009) for office buildings. – a huge improvement potential is detected and should be done through the integration of building efficient measures (see next sections). Although energy savings in warmer climates are less significant, the investment per kWh saved is typically much lower than for other climatic areas. This is due to the usual lower insulation level of the building practice for the thermal envelope in warmer climates.

3.3. Efficient refrigeration and heat recovery As already indicated, refrigeration in food retailers is responsible for more than 50% of the energy consumption and for more than 60% of the total carbon footprint due to direct emissions and indirect emissions. Nevertheless, refrigeration is an essential process for food preservation, to maintain food properties and to reduce food waste in the production chain. Effective refrigeration is therefore an environmental imperative. The vapor compression cycle is used to refrigerate goods and consists of 4 stages: evaporation, compression, condensation and expansion. Heat is withdrawn from products (in an indirect or direct way) and is released to the outdoor environment at the condensation stage. This excess heat can be recovered and used for other purposes, as space heating or hot water preparation. Usually, new installed systems are already taking advantage of the excess heat and heat recovery from refrigeration systems is seen more as a common practice than a best practice (Arias, 2005; IEA, 2005). Nevertheless, the integration of heat recovery processes by retrofitting existing supermarkets and the integration with other energy saving measures is not common practice. In the words of a retailer manager, the condensation stage of the refrigeration cycle

989

can produce twice the heat demand of a supermarket integrated in a well insulated building with an optimized HVAC system (Anonymous retailer, 2010). One of the best performers in Europe is able to recover heat from refrigeration and use it in such an efficient way that excess heat is left over. Usually, the excess heat is sold to neighboring companies by means of a district heating network or a distribution system within the same shopping center building. An energy flow diagram (Sankey diagram) of this approach is shown in Fig. 5. The conceptual approach of Fig. 5 achieves very important energy and costs savings and the produced heat can be commercialized, although a distribution infrastructure is required. The integration of this measure with other identified best practices related to the building envelope can significantly reduce the payback time of other technologies. In central Europe, one retailer has been applying this concept for many years and has achieved the best performance profiles of the assessed companies. This retailer corresponds to Retailer 1 of Fig. 6, where the final, specific heat demand for a number of stores is presented. This figure also presents the specific heat demand of retailer building in Germany, as published in a work from 2009 (Arge Benchmark, 2009), and another curve for a good performer, Retailer 2, located in the same region of Retailer 1. Cumulative frequency represents 240 German stores, 221 stores from Retailer 2 and 105 stores from Retailer 1. The climatic influence can be considered negligible for the interpretation of curves. More than a half of Retailer 1 stores produce net heat from their refrigeration cycle. This means that these stores do not need any extra heating system, only an intermediate heat exchanger installed in the refrigeration cycle. So, a benchmark for space heating of 0 kWh/m2 yr for food store heating demand is derived, which can be considered ambitious but achievable. Retailer 2 is also implementing heat recovery and is able to minimize store consumption to very low levels, but not as efficiently as Retailer 1. The average heat demand of stores in Germany is about 100 kWh/ m2 yr, which indicates a huge improvement potential. The integration of energy saving measures can therefore have a dramatic effect on the energy balance of the store. However, this technique can have very important restrictions or drawbacks for its implementation: – Usually, large supermarkets have a lower relative refrigeration load (about 2–5 m of display case per 100 m2 of sales area) than small ones (from 6 to 12 m per 100 m2 of sales area). Less display-case length reduces the demand for food refrigeration and reduces the amount of available excess heat. – Load of medium temperature (MT) cooling (0–6 1C) compared to the load for low temperature (LT) cooling (from  25 to  20 1C). The ratio varies a lot and depends in the store concept. It is usually 2:1 (MT:LT) in length of display cases but the ratio for energy consumption can be 1:1 (Rhiemeier et al., 2009). This ratio has a considerable influence on the available heat for recovery. – Other best practices may affect the energy balance inside a store, especially decreasing or increasing internal gains. Examples of this are covering of refrigerated display cases, change to a more efficient lighting system, change of refrigerant, food preservation improvements, use of cold rooms, optimization of the HVAC system, etc. Any subsequent change in design can make the integrated system less efficient (e.g. cause it to be oversized). – Use of compact systems: many suppliers of refrigeration equipment also integrate HVAC in the same compact module, with an optimized design. This can lead to very good performance results, but its retrofitting may not be possible or can have important limitations. The use of plug-in refrigerators does not allow heat recovery.

990

J.-L. Galvez-Martos et al. / Energy Policy 63 (2013) 982–994

Fig. 5. Energy flow diagram (Sankey diagram) of a supermarket with optimized building envelope and the HVAC system.

Fig. 6. Specific heat demand for a sample of German retailers and two European retailers (labeled as 1 and 2).

– For winter periods, heating demand may require the compressor to work more hours than required for refrigeration alone, shortening its lifetime. – Condensation temperature should be high to have a good heat recovery performance. This would increase the energy consumption of compressors and the coefficient of performance can be reduced, even if the overall energy consumption is reduced. The use of other alternatives, as integrated heat pumps and other technologies should be considered for the design (Arias, 2005). – Climatic conditions affect the total energy balance: in cold climates, the load for refrigeration is lower and the energy consumption for space heating is higher, while in warm climates, cooling demand is high and internal gains are more important for tightened buildings. The carbon footprint of refrigeration is caused also from refrigerant leakages, which can be considered to be unavoidable and may be even more important than those indirect emissions from electrical energy consumption. Tightened refrigeration installations require a huge investment and other more realistic environmentally-friendly options should be considered. In general, the use of natural refrigerants constitutes a best practice, since they have much lower global warming potential than conventional hydrofluorocarbons, such as R404A, R134A, etc. Ammonia is an

example of frequently used refrigerant for indirect systems for big, large-scale systems. Hydrocarbons, as propane, are frequently used in small, independent plug-in units, showing a great efficiency, but not allowing heat recovery. Bigger sizes for hydrocarbon vapor compression units are possible, but safety is usually seen as a main drawback for commercial applications. The main trend, in moderate climates, is the use of CO2 as natural refrigerant, labeled as R744, for more frequent stores sizes. Leakages of CO2 from refrigeration installations are not significant and the efficiency of the system may be higher than conventional refrigeration cycles. For LT refrigeration, many retailers in Europe have decided to shift all their installations to CO2 because of its high performance and environmentally friendly character. Less mass of refrigerant is needed, as CO2 volumetric refrigeration capacity is high, so smaller compressors and pressure ratios are required. The main drawbacks of CO2 refrigeration is that the critical temperature is 31 1C, so, for ambient temperatures higher than 25 1C, the COP is reduced significantly. In addition, when working at MT, the saturation pressure is quite high (over 100 bar), which requires special equipment and specialized training and maintenance. This issue is not reflected in the energy consumption of refrigeration in supermarkets, which is reduced due to the higher efficiency of CO2 systems. Fig. 7 shows the energy performance of 103 refrigeration plants and 11 CO2 plants (including MT and LT) in the same region and for the same retailer, which provided the data. As shown, the energy consumption (measured per meter of display case and year) is usually higher for conventional plants than for CO2. However, when interpreting this chart, it has to be considered that the good performance of CO2 plants is also a consequence of newer and better-optimized installations. The applicability of CO2 for MT refrigeration depends on the ambient temperature, especially if condensation occurs at ambient outdoor air temperature. Novel solutions, as water spray systems, are proposed to overcome these disadvantages, although these require additional investment. As well, the integration of natural refrigerants in MT and LT is necessary to achieve a good economic balance. Rhiemeier et al. (2009) and EC (2011) show that the economic balance and the carbon footprint balance do not improve significantly using a cascade of R404a refrigerant combined in a cascade system with CO2. In other reference, Sinclair Knight Merz (SKM (2010), a benefit from a combined optimized system is observed but still far from the reduction of the carbon footprint if only CO2 is used, where a 47% reduction of the carbon footprint is observed.

J.-L. Galvez-Martos et al. / Energy Policy 63 (2013) 982–994

991

Fig. 7. Total linear energy consumption of refrigeration systems for 103 stores with conventional refrigeration systems and 11 stores with CO2 plants.

Fig. 8. Energy savings vs. minimum retrofitting cost per meter of display case when the payback time is 3 years or less.

Many single measures are also identified as best practice in order to save energy in the refrigeration system. The most important one is the covering of display cases with glass lids. This is already a standard practice being implemented for freezers and LT refrigeration, as potential costs savings is high. Nevertheless, it is still not implemented universally since some retailers consider it to be a sensitive marketing issue, as a barrier is placed between the consumer and the product. Identified energy saving potentials are higher than 20% of refrigeration energy consumption, although it depends on many factors (frequency of opening, load of products, air flow, store occupancy, etc). Exemplary retailers have identified the opportunity to reduce their energy bill and they are covering all the display cases in every store. These retailers have identified that, after an adaptation period, sales are back to normal. If sales are not affected, retrofitting costs would be the main decision criteria and driver for existing stores. Real costs vary from EUR 300 to EUR 600, depending on the glass lid design. Fig. 8 shows three straight lines, which are our own estimations of the retrofitting cost and energy savings, plotted for three energy price scenarios, and based on an acceptable payback time of 3 years (a typical commercial payback threshold). Acceptable costs are at the left of the curves, and the line is displaced to the right if the energy price increases. For example, if the retrofitting cost is EUR 300 per meter of display case, energy savings of at least 26% would

be required at a current energy price to justify investment costs, but only 22% if the energy price increased by 20%. Covering display cases avoids the release of cold air to the store, avoiding an uncomfortable store environment and/or unnecessary heating. On the other hand, covered display cases may lead to higher indoor air temperature in summer time, and higher HVAC cooling demand. The same happens to the humidity, which may increase in the store; if the HVAC system does not have an appropriate humidity control, because open refrigeration cabinets work as the store humidity sink. Also, when covering display cases, the refrigeration system will also become oversized, as compression needs will be reduced and also the available heat for recovery will be reduced. Then, an integrative approach with respect to store refrigeration and HVAC systems is essential to achieve the optimal thermal and refrigeration performance, and the best indoor air quality. 3.4. Other relevant aspects of energy at retailers: lighting and the integration of renewable energy Retailers demand an important amount of electricity for other uses, apart from refrigeration, ventilation and space heating or cooling: lighting, demonstrations of electric and electronic equipment (e.g. lamps department), elevators, escalators, cooking at restaurants,

992

J.-L. Galvez-Martos et al. / Energy Policy 63 (2013) 982–994

Fig. 9. Example of lighting power density profile over 24 h, including the expected impact of a daylight control system.

food preparation (cutting operation, bakery, etc.), specific appliances for offices (computers, copiers, etc.), etc. Lighting is a very sensitive aspect of marketing in a supermarket. A non-food retailer may consume half of their total energy bill for lighting purposes, and energy consumption for lighting in retailers can be higher than 100 kWh/m2 yr. There are two types of lighting devices: natural and artificial. Natural lighting comes from the store glazing and building skylights. Artificial lighting is used for basic lighting, i.e., for corridors, parking, accesses and general lighting, and for effect lighting, which is designed to produce a desired effect on products (spotlights, colorful effects, etc.). Best environmental management practice for lighting starts in the definition of lighting strategies in the energy management system of stores. A correct lighting strategy is able to produce energy savings if it is focused on the real illumination needs and it is combined with efficient lighting systems (efficient devices, daylight integration, and intelligent control). For this, several steps should be taken: – First, illumination requirements should be defined in every zone of the store. This is achieved with reference to the luminous flux, perceived by the human eye and measured in lumens, lm, per unit of sales area (e.g. lm/m2 or lux). – Second, to define lighting devices to be used in order to supply the illumination requirements. The most important parameter to control is the amount of light per unit of power, i.e. lm/W. Large savings can be achieved in this way since many efficient types of equipment can be used (efficient T5 fluorescents, LEDs, daylight control systems, etc.). Although the lighting strategy should be defined regarding customer needs, i.e. illumination needs, from the energy manager perspective, the specific lighting power density, in W/m2, is an important indicator to assess the efficiency of lighting and its impact on energy consumption, energy saving opportunities, and energy implications for the HVAC system. In addition, this is a practical process indicator, based on easy accessible data and does not require sub-metering. Therefore, a lighting strategy may be defined in specific lighting power density, W/m2, in every zone of the store. – Third, depending on the occupancy level of the store, sales concept, timetable of specialties, daylight availability, etc., the lighting profile should be defined (LRC, 2006). An example of the 24-hour lighting profile of a store is defined in Fig. 9. The example of Fig. 9 is a store with a relatively low lighting power density, 22.5 W/m2. If the store manager turns on all the

lights during opening hours, e.g. 13 h, and keeps a security lighting system consuming 1 W/m2, the energy consumption of the store during a whole year would be about 120 kWh/m2 yr. By using a control strategy, as shown in Fig. 9, the consumption would be 100 kWh/m2 yr, which is 17% less. If a daylight control system is used, 10% energy savings can be achieved (for this example). However, the use of daylight should be applied cautiously; in northern European countries it may not be an advantage as the energy savings for lighting may not compensate the heat loss through glazing. The use of efficient lighting devices, such as LED or T5 fluorescents, is leading many retailers to have lighting concepts with installed lighting capacity of less than 18 W/m2 (including basic and effect lighting) in food stores. There are economic barriers for the implementation of innovative lighting techniques, as payback times higher than 3 years (maybe the case for LEDs implementation in existing stores) may be not acceptable for retailers. The use of renewable energy sources at retailers is widespread throughout Europe. Many stores are installing PV-panels on roofs, with electricity generation values varying from 5 to 80 kWh/m2 yr (sales area). Also, many retailers have made important efforts on the use of renewable energy sources, as wind turbines. Other innovative techniques, such as ground source heat pumps, solar heat collectors or biomass boilers are also being implemented. Nevertheless, retailers rarely install renewable energy facilities in an integrative manner, i.e. combined with measures to reduce the energy demand and increase the efficiency of current systems. Although almost all retailers in Europe have invested in zero energy or carbon stores applied in one or two stores as lighthouse projects, the systematic implementation of integrative concepts to achieve zero energy building as standard practice is still some way off. Then, the production of renewable energy on site is not considered as a best environmental management practice per se: it should be combined in an integrative approach, e.g. improving the building envelope, reducing the demand of space heating and cooling, improving air tightness, energy monitoring, etc (Kolokotsa et al., 2011). Then, a benchmark can be identified in the zero energy building approach or to identify renewable energy investment opportunities installed outside the store.

4. Discussion A rough estimation of the potential of energy-saving measures has been calculated, taking the achievable savings described in this paper. In Europe, an average store, consuming about 700 kWh/m2 yr

J.-L. Galvez-Martos et al. / Energy Policy 63 (2013) 982–994

of final energy, would need 100 kWh/m2 yr for heating, 350 kWh/ m2 yr for refrigeration (this is about 4300 kWh per meter of display case and year), 145 kWh/m2 yr for lighting and 105 kWh/m2 yr for other purposes. The reduction potential of this average store is 36% (from 700 kWh/m2 yr to 450 kWh/m2 yr) if it is assumed that the following measures are implemented: – for a standard value of 12 m of refrigerated display cases per 100 m2, heating energy consumption can be substantially reduced to 0 kWh/m2 yr with the proper heat recovery from the refrigeration cycle (in a well insulated building and with and optimized HVAC system), – the consumption of energy for refrigeration can be reduced by 30% if the refrigerant is replaced by natural refrigerants and the display cases are covered with glass lids, – a reduction of lighting energy consumption to 100 kWh/m2 yr is achievable with the measures described in Section 3.4. Although an average has been considered for the calculation, energy consumption patterns vary from region to region, especially for heating and refrigeration. These results have to be considered as an example, as a process-oriented approach is preferred over a site-oriented one. Then, if an average reduction of 36% of the energy consumption in retailers' stores at EU-27 is possible, a reduction potential of 22.6–31.2 TWh per year could be explored, according to our estimation. To give a rough idea of this potentiality, these savings are equivalent to the electricity produced by 3.2 to 4.5 nuclear reactors (average production of 7 TWh per year and per reactor). The savings from covering refrigerated display cases alone would reduce the energy consumption by 9.4–13.1 TWh per year in Europe, equivalent to the output of 1.4–2 average European nuclear reactors. In general, energy-saving measures always produce cost savings, but the relatively low importance of energy costs, from 1% to 5% of total operating costs, is possibly the main drawback for its application. Table 4 shows some data on the potential energy savings of several big retailers (same ones as those shown in Fig. 1) when the same assumptions as explained in the previous calculation are made (0 kWh for heating, 100 kWh/m2 yr for lighting and 30% of savings in refrigeration). As observed, even for bad performers (where 38% savings are achievable) economic savings only represent less than 1% of total sales. When compared to profit, higher percentages are obtained but the payback times for the measures achieving greater savings are usually longer than the acceptability criterion of many companies (around 3 years). According to these results, implementation of best environmental management practice is mainly a matter of motivation and environmental awareness, apart from its economic performance. As already described in the methodology, the frontrunner approach has been used to detect best practices. In the field of energy management, two food retailers from central Europe were identified as best performers and their approach, if applied to the rest of Europe, would produce a huge benefit. These retailers are cooperatives, where a different business approach may be in place involving a longer economic perspective. The effective management of other environmental aspects by these retailers also indicates a different business ethic. For example, these same retailers implement many exemplary measures in relation to supply chain sustainability (Styles et al., 2012b). The retailer who provided the data for Fig. 4 is also considered to be a frontrunner in the energy management of stores, especially for monitoring, building envelope and HVAC optimization. It is a non-food retailer, with stores in all over Europe, and it is not a cooperative. In this case, retailer's origin is a Nordic country, so the building practice is likely to be oriented to the achievable lowest energy consumption. This happens even for warmer climates,

993

Table 4 Data on the potential savings and the economic implications for energy saving measures at stores. Retailer Turnover/ sales area (EUR/m2)

Average energy consumption (kWh/m2 yr)

Energy savings (%)

Saving potential (EUR/m2)

Savings/ turnover (%)

1 2 3 4 5 6 7 8

609 640 480 550 410 570 750 700

31 33 22 28 15 29 38 36

21.0 23.2 11.8 16.8 6.5 18.2 31.1 27.5

0.47 0.26 0.08 0.21 0.23 0.33 0.63 0.16

4492 8884 14,691 7966 2791 5525 4920 16,885

where buildings from this retailer achieve also good performances. The performance of this retailer in other environmental aspects, where it can be considered a best practitioner, reflects also a strong commitment and awareness, regardless of the profitability of implemented measures. For the remaining major European retailers, different commitment levels have been observed. The sector seems to be moving in the right direction. For instance, the Retail Forum was created in 2009 to exchange best practice and the implementation of certain measures has sped up in recent years (e.g. the banning of free plastic bags, covering low temperature display cases with glass lids of, use of renewable energy). In general, the measures identified in this paper lead to the reduction of greenhouse gases emissions and to an increase in energy efficiency, and their implementation may be driven by – better public image, although it requires a good communication strategy; – reduced exposure to price volatility in the energy market and to increasing energy tariffs; – significant long-term cost savings; – enhanced knowledge of retail activities, gathering momentum to implement innovations and also for research and development. Main barriers for the adoption of the described practices can be summarized as follows: – as described above, the relatively low importance of energy costs within the total operational costs of retailers reduces the economic attractiveness of energy saving measures. The most effective measures have the best performance in the long-term. Then, payback time policy (e.g. only to implement projects with payback times shorter than 3 years) can make them unaffordable. As well, subsidies received for the implementation and use of renewable energy sources can make some measures, such as the installation of PV panels on roof, much more economically attractive than other measures reducing the overall energy demand of the building. This effectively leads to the offsetting of excess primary energy consumption, rather than the optimum two step approach of (i) reducing demand by increasing efficiency; (ii) increasing the share of cleaner energy sources. – building characteristics are only partially under the control of retailers. Several chains in Europe have a high percentage of rented stores and they are limited in the changes to the building envelope and installations by lease agreements. – for some techniques, like natural refrigerants, two barriers are relevant: first, the lack of suppliers seriously constrains the uptake of novel technologies in some European regions; and second, the demand for technical skills and training associated with innovative applications can reduce the rate of uptake of techniques.

994

J.-L. Galvez-Martos et al. / Energy Policy 63 (2013) 982–994

5. Conclusions Retailers' energy use is characterized by significant specific needs, for food refrigeration and lighting in relation to marketing display concepts. There is a huge improvement potential for the energy performance of European retailers (the equivalent energy production of 3–4 nuclear reactors). The most important energy saving measures and opportunities are described in this paper, with reference to best practice commercial application and achieved savings. Best environmental management practices identified for the energy performance of the sector are – to have an integrative energy management system, with a comprehensive monitoring system, that enables the identification of energy saving opportunities, the control of store performance, and the development of best practice standards for application across stores; – to improve the building envelope and to integrate heating, ventilation and air conditioning with energy recovery opportunities from exhaust air and from refrigeration processes; – to reduce the impact of the refrigeration installations of food retailers by using efficient natural refrigerants, such as CO2, and to cover display cases. This can also produce significant costsavings; – to reduce the impact of lighting by defining lighting strategies based on use of efficient lamps, intelligent control, and use of daylight where appropriate. – To establish and operate zero energy buildings or stores by using renewable energy sources or investing in off-site renewable energy generation facilities, with the integration of energy efficient measures for the building as a whole.

References Anonymous retailer, 2010. Personal Communication – May 2010. Arge Benchmark, 2009. Benchmarks für die Energieeffizienz von Nichtwohngebäuden – Referenzwerte für Energieausweise. Available from: 〈http://www. arge-benchmark.de〉 (accessed on September 2011). Arias, J., 2005. Energy Usage in Supermarkets – Modelling and Field Measurements (Ph.D. dissertation). Royal Institute of Technology Stockholm. Boermans, T., Petersdorff, C. 2006. U-values for Better Performance of Buildings, EURIMA Research report. Available from: 〈http://www.eurima.org〉 (accessed on October 2011). Carrefour Group, 2010. Sustainable Development at Carrefour. Expert Report 2009. 〈http://www.carrefour.com〉 (accessed on October 2011). C&A, 2010. Personal Communication. CEN, 16001:2009, 2009. Energy Management System – Requirements with Guidance to Use. European Standard. European Commission, EC, 2006. Review of the EU Sustainable Development Strategy, 10917/06. Available from: 〈ec.europa.eu/environment〉 (accessed on October 2011). European Commission, EC, 2008. Communication from the Commission to the European Parliament, the Council, the European Economic and Social

Committee and the Committee of the Regions on the Sustainable Consumption and Production and Sustainable Industrial Policy Action Plan. Available from: 〈ec.europa.eu/environment〉 (accessed 29.10.11.). European Commission, EC, 2009. Communication from the Commission to the European Parliament, the Council, the European Economic and Social Committee and the Committee of the Regions – Mainstreaming Sustainable Development into EU policies: 2009 Review of the European Union Strategy for Sustainable Development. Available from: 〈ec.europa.eu/environment〉 (accessed 29.10.11.). European Commission, EC, 2011. Communication from the Commission to the European Parliament, the Council, the European Economic and Social Committee and the Committee of the Regions: Roadmap to a Resource Efficient Europe. Available from: 〈ec.europa.eu〉 (accessed 30.11.11.). European Parliament, EP, 2010. Energy Performance of Buildings Directive. Available from: 〈http://europa.eu/legislation_summaries/energy/energy_efficiency/ en0021_en.htm〉 (accessed on October 2011). Eurostat, 2010. Energy statistics – heating degree days metadata. Available from: 〈app.eurostat.ec.europa.eu〉 (accessed 27.12.11.). Feist, W., Schnieders, J., 2005. Re-inventing air heating: convenient and comfortable within the frame of the passive house concept. Energy and Buildings 37, 1186–1203. International Energy Agency (IEA), 2005. Advanced Supermarket Refrigeration/ Heat Recovery Systems (annex 26). Available from: 〈http://www.ornl.gov〉 (accessed on September 2011). Kolokotsa, D., Rovas, D., Kosmatopoulos, E., Kalaitzakis, K., 2011. A roadmap towards intelligent net zero- and positive-energy buildings. Solar Energy 85 (12), 3067– 3084. Light Research Center (LRC), 2006. LED lighting in Freezer Cases, Field Test Delta Snapshots, Issue 2. Available from: 〈http://www.lrc.rpi.edu〉 (accessed on October 2011). Migros, 2010. Personal Communication. Petersdorff, C., 2006. Cost-Effective Climate Protection, Eurima, Research report. Available from: 〈http://www.eurima.org〉 (accessed on October 2011). Retail Forum, 2010. Energy Efficiency of Stores. Issue Paper. Available from: 〈http:// ec.europa.eu/environment/industry/retail/issue_papers.htm〉 (accessed on October 2011). Rhiemeier, J.M., Harnisch, J., Ters, C., Kauffelld, M., Leisewitz, A., 2009. Comparative Assessment of the Climate Relevance of Supermarket Refrigeration Systems and Equipment, Research Report 20644.00 UBA-FB 001180/e. Available from: 〈http://www.umweltbundesamt.de〉 (accessed on October 2011). Schlenger, J., 2009. Climatic Influences on the Energy Demand of European Office Buildings (Ph.D. dissertation). University of Dortmund, Dortmund. Schoenberger, H., 2009. Integrated pollution prevention and control in large industrial installations on the basis of best available techniques – The Sevilla Process. Journal of Cleaner Production 17 (16), 1526–1529. Schoenberger, H., Galvez-Martos, J.L., Styles, D., 2013. Reference Document on Best Environmental Management Practice in the Retail Trade Sector. JRC Technical Report EUR 25998. Available from: 〈http://susproc.jrc.ec.europa.eu/activities/ emas/documents/RetailTradeSector.pdf〉 (accessed on July 2013). Sinclair Knight Merz, SKM, Enviros, 2010. Eco-Efficiency Study of Supermarket Refrigeration for the European Partnership for Energy and the Environment (EPEE), Internal Report. Styles, D., Schoenberger, H., Galvez-Martos, J.L., 2012a. Environmental improvement of product supply chains: a review of European retailers' performance. Resources, Conservation and Recycling 65, 57–78. Styles, D., Schoenberger, H., Galvez-Martos, J.L., 2012b. Environmental improvement of product supply chains: proposed best practice techniques, quantitative indicators and benchmarks of excellence for retailers. Journal of Environmental Management 110, 135–150. Swiss Energie, 2007. The Minergie Standard for Buildings, Report. Available from: 〈http://www.minergie.ch〉 (accessed on October 2011). Tassou, S.A., Ge, Y., Hadawey, A., Marriott, D., 2010. Energy consumption and conservation in food retailing. Applied Thermal Engineering 31 (2–3), 147–156.