Energy Conversion and Management 48 (2007) 1160–1175 www.elsevier.com/locate/enconman

Empirical assessment of the Hellenic non-residential building stock, energy consumption, emissions and potential energy savings Athina G. Gaglia a,*, Constantinos A. Balaras a, Sevastianos Mirasgedis b, Elena Georgopoulou b, Yiannis Sarafidis b, Dimitris P. Lalas b a

Group Energy Conservation, Institute for Environmental Research and Sustainable Development, National Observatory of Athens, I. Metaxa and Vas. Pavlou, GR 15236 P. Penteli, Greece b Group Energy Planning and Sustainable Development, Institute for Environmental Research and Sustainable Development, National Observatory of Athens, I. Metaxa and Vas. Pavlou, GR 15236 P. Penteli, Greece Received 4 October 2005; received in revised form 7 April 2006; accepted 8 October 2006 Available online 30 November 2006

Abstract Comprehensive information and detailed data for the non-residential (NR) building stock is rather limited, although it is the fastest growing energy demand sector. This paper elaborates the approach used to determine the potential energy conservation in the Hellenic NR building stock. A major obstacle that had to be overcome was the need to make suitable assumptions for missing detailed primary data. A qualitative and quantitative assessment of scattered national data resulted in a realistic assessment of the existing NR building stock and energy consumption. Different energy conservation scenarios and their impact on the reduction of CO2 emissions were evaluated. Accordingly, the most effective energy conservation measures are: addition of thermal insulation of exposed external walls, primarily in hotels and hospitals; installation of energy efficient lamps; installation of solar collectors for sanitary hot water production, primarily in hotels and health care; installation of building management systems in office/commercial and hotel buildings; replacement of old inefficient boilers; and regular maintenance of central heating boilers. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Non-residential building stock; Energy consumption; Energy conservation; CO2 emissions

1. Introduction The existing building stock in European countries accounts for over 40% of final energy consumption in the European Union (EU). In 2002, the gross inland consumption in the EU-25 member states was 1677 Mtoe, while the final energy consumption reached 1080 Mtoe [1]. Consequently, an increase of building energy performance can constitute an important instrument in the efforts to alleviate the EU energy import dependency (currently at about 48% and may reach two thirds by 2020 [2] unless some urgent additional measures and policies are adopted) and comply with the Kyoto Protocol that came into effect on

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Corresponding author. Tel.: +30 210 8109146; fax: +30 210 8103236. E-mail address: [email protected] (A.G. Gaglia).

0196-8904/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.enconman.2006.10.008

February 16, 2004 to reduce carbon dioxide emissions by an overall 8% in the EU compared with 1990 values by 2012. This is also in accordance with the European Directive (2002/91/EC) on the energy performance of buildings (EPBD) [3]. As of January 2006, EU-25 member states are mandated to set minimum requirements on the energy performance of new and existing buildings that are subject to major renovations and for energy performance certification of buildings. Additional requirements include regular inspection of building systems and installations, an assessment of the existing facilities and providing advice on possible improvements and on alternative solutions. Finally, the new European Directive on the promotion of cogeneration (2004/8/EC amending Directive 92/42/EEC) sets mandatory minimum efficiency standards for new hot water boilers fired with liquid or gaseous fuels. It encourages the use of combined heat and power (CHP) and creates a

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framework for the development of cogeneration in order to increase energy efficiency and the security of energy supply. Buildings are also a major pollution source, contributing to greenhouse gas (GHG) emissions and the production of construction wastes that have a major impact on landfills. The most important GHG, by far, is carbon dioxide (CO2), accounting for 82% of total EU emissions in 2002. The main contributor to the total annual 775 Mt CO2 emissions from the EU-15 building stock in 2002 was the residential sector (77%), while the remaining 23% originates from non-residential buildings [4]. Considering the aggregate electrical and thermal energy consumption, buildings account for about a third of the total energy related CO2 emissions and even higher in some countries, depending on their electrical energy consumption and type of fuel used for power production [5]. Significant potential exists to reduce the rate of future emissions in the building sector by promoting more rapid uptake of energy efficiency in buildings [6]. On average, between 1980 and 1990, CO2 emissions from buildings have grown by 1.7% per annum (pa) with growth rates about four times greater in developing countries. The estimated technical potential of the overall emission savings for space heating, if all retrofit measures covered by the EPBD were realized for all EU-15 building stock of 2002 at the same time, could reach 398 Mt per year, although this may be difficult to implement practically [4]. The work reported in this paper was part of a study to quantify the potential benefits and to determine the priorities of building energy conservation strategies to reduce CO2 emissions from Hellenic buildings. This paper presents the results for non-residential (NR) buildings. The main goals were to: collect and adapt available data for the existing building stock and energy consumption; estimate the normalized thermal and electrical energy consumption for heating, cooling and lighting for existing buildings and predict growth for new buildings; estimate the aggregate energy savings as a result of implementing well established renovation measures and technologies for energy conservation in the entire building stock at different climatic zones; estimate the relevant costs for implementing these measures and propose supporting policies and an action plan. This is the first time that this kind of aggregate data is presented on a national level. The greatest obstacle encountered during this work was the lack of detailed data for the existing building stock and its characteristics and actual energy consumption. However, the overall approach may be applicable to other countries facing similar problems. 2. European buildings Comprehensive information and detailed data for the non-residential (NR) building stock is rather limited. A recent investigation has revealed the lack of available data in many countries, format inconsistencies of available data and the overall difficulty in collecting necessary informa-

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tion for the NR building stock in the EU-25 [7]. This is also in agreement with other similar studies reported in the literature [8]. The floor area of NR buildings is projected to increase by 1.7% pa in 2000–2030 at the EU level [9]. However, this growth is not uniform across the different services sectors. Floor spaces in market services (including offices, hotels, telecommunications etc.) is projected to increase about 2.0% pa between 2000–2030 and about 1.9% pa for the trade sector, whereas the increase in the non-market sector (including health, education, public sector etc.) will be limited to 0.8% pa. Greece and Portugal will exhibit the highest growth rates of NR floor area (+2.8% pa and 2.9% pa, respectively) in 2000–2030 as a result of the expected development of their tourist industry. 2.1. Energy consumption The tertiary sector (non-residential buildings and agriculture) is the fastest growing energy demand sector and is expected to increase by 1.2% pa in 2000–2030 [1,9]. The growth of energy needs in the tertiary sector, or more than 90% of the additional energy requirements, is driven by the evolution of NR buildings. Final energy demand by NR buildings in the EU-25 countries reached 125.1 Mtoe in 2000, while, by 2010, it is expected to reach 143.4 Mtoe with an annual growth of 1.4% pa. The breakdown of energy consumption by end use in European NR buildings for 2001 was: 52% for space heating, 9% water heating, 5% cooking, 14% lighting, 4% cooling and 16% other uses [10]. Electrical energy peak demand and consumption in NR buildings have been constantly increasing over the past decades and are thought to increase further, in particular due to the extensive use of HVAC and office equipment (i.e. information and communication technologies). Some countries exhibit a strong growth of electricity intensity, including three southern European countries (Greece, Spain and Portugal) and Ireland, which entered the EU at a lower level of development. The annual electrical energy consumption in the EU per employee was about 4700 kWh/emp in 1990 and grew to 5050 kWh/emp in 2001 [11]. The average specific annual thermal energy consumption for space heating was about 192 kWh/m2 in 1990 and decreased to 152 kWh/m2 in 2001. This is mainly attributed to the fact that some countries, like Norway, substituted fuel heating with electricity for space heating [11]. 2.2. The Hellenic situation In Greece, the final energy demand increased by 27.4% during the 1990’s, reaching 19.5 Mtoe in 2002 [1]. Even during the previous energy crises, energy demand exhibited the sharpest increase among all European countries [12]. As a result, there was a significant increase in the production of electricity using lignite, which, despite its low calorific value and high polluting potential, is primarily used

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for power generation (currently about 63%) since it is the only national fossil fuel resource. The primary energy consumption per capita in Greece increased from 25,470 kWh/cap in 1990 to 29,890 kWh/ cap in 2000 and reached 37,634 kWh/cap in 2002, which is still well below the EU-25 average of 42,800 kWh/cap [1]. However, CO2 emissions per capita in Greece have climbed from 6998 kg/cap in 1990 to 8559 kg/cap in 2002, although the EU-25 average dropped from 8566 kg/cap in 1990 to 8233 kg/cap in 2002. Energy related activities including extraction, distribution and combustion of fossil fuels are responsible for about 76% of the total national annual GHG emissions, while during the period 1990–1995 the CO2 emissions from the energy sector accounted for about 90% of the total CO2 emissions in Greece [13]. In relation to building construction, the existing Hellenic Building Thermal Insulation Regulation (HBTIR) (Official Hellenic Journal – OHJ 362/4-7-79) has been in use since 1980 and sets the minimum requirements for thermal conductivity of the building envelope for different climatic zones. As a result, the great majority of the Hellenic building stock is not thermally insulated, despite the fact that the heating degree days reach over 2600 HDD in northern Greece. A few additional national laws and regulations have also been introduced in Greece in accordance with the EU directives for the rational use of energy and the abatement of emissions, like the annual maintenance of central heating boilers (OHJ 143/A/2-9-93) that mandates annual flue gas analysis and performance testing of boilers and the energy labeling of electrical appliances (OHJ A114/7-794). In accordance with the General Building Regulation and the common Ministerial Decision (OHJ 880/B/19-898), there is a new energy code under development (initially referred to as ‘‘Regulation on Rational Use and Energy Conservation in buildings’’ (RRUEC)) in compliance with the EPBD (2002/91/EC). The climatic zones defined in accordance with the proposed RRUEC are based on the heating degree days: Zone A (601–1100 HDD), Zone B (1101–1600), Zone C (1601–2200) and Zone D (2201– 2620). The following sections present an overview of the relevant data for the Hellenic NR building stock and 1991-2001 8%

energy consumption in order to extract the necessary data used in the follow up analysis on the assessment of energy conservation measures and CO2 reduction. 3. Hellenic non-residential building stock The breakdown of the total Hellenic building stock for different periods of construction is illustrated in Fig. 1. The buildings constructed before 1980 (pre-1980) correspond to 74.6% of the total building stock. These buildings are not thermally insulated and exhibit poor energy performance, while the vast majority of them are equipped with old electromechanical installations [14]. The percent of buildings that have been constructed during the 1990s is estimated based on the building construction activity for this period [15,16]. Non-residential buildings represent about 25% of the total number of Hellenic buildings for 1990 [14]. The main categories of the Hellenic NR building stock according to their end use are: offices/commercial (2.74% of the total number of buildings), schools (0.41%), hotels (0.26%) and hospitals (0.05%). Other uses of NR buildings include churches, factories, athletic facilities, storage areas, closed parking spaces etc, which account for 21.9% of the total stock, the majority of which have periodic use and a limited overall contribution to the total energy consumption. In this work, we focus on the four main categories of the Hellenic NR building stock, namely: office/commercial, hotels, schools and health care. The NR building stock was grouped in three temporal classes according to the year of building construction, which provides insight information with regard to the type of envelope construction in accordance with the national building standards in force at that time and, in particular, the use of thermal insulation and materials used for the building envelope or even the type of electromechanical installations. The first class includes the buildings constructed before 1980 (pre-1980), which is considered the boarder line for buildings without thermal insulation, since they were constructed before the implementation of the national thermal insulation regulation. The second class includes the buildings that have been constructed during the period 1980–2001 and are considered to be partially