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• Examination of a typical classroom in Greece and its installed power for an artificial lighting profile from 1970 until today (type and number of luminaires, installed power per classroom, consumed annual energy kWh/m2). • Calculation of potential energy savings for customizing installed power LED with AC and DC supply aiming for the illuminance target values from the European Norm 12464–1, 2011. • Measurements of dimming curves of LED luminaires with AC and DC supply (consumed energy versus lighting output) and measurements of power of typical photosensors. • Estimated energy savings, CO 2 reduction and cost optimal analysis due to various scenarios (different luminaire technologies and daylight harvesting techniques). • Calculation of the final energy consumption for potential power supply from renewable energy sources using DC LED luminaires and photosensors. The energy consumption for the artificial lighting in school buildings is one of the main consumers of electricity. In Greece, there is a large number of school buildings with quite old lighting systems using luminaires with T8 and sometimes T12 fluorescent lamps and degradated translucent diffusers. Due to the economic crisis, the public sector failed to invest in LEDs and although daylight is adequate during the year, the adoption of control technology is rather slow. The paper, using a typical classroom of a Greek public school, examines a number of lighting technologies (with AC and DC supply) together with two daylight harvesting systems. The first one uses one stand-alone photosensor per luminaire while the second one sensor per control zone, in an effort to calculate energy savings and light adequacy. The dimming curves of the DC LEDs were measured along with the installed power of the photosensors. The results show that the existing 90.5 kWh p /m2 of annual lighting primary energy consumption can be reduced to 0.55 kWh p /m2. The maximum annual reduction of CO 2 emissions was 32.44 kgr/m2 for classroom areas, which is translated to 201929 tn for the whole country. It is evident that the path to Zero Energy School Buildings goes through the mandatory use of daylight controls. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Highlights • The weighted average values of thermal energy consumption (oil and natural gas) for space heating, as of 2011, of the complete stock of buildings in Greece used as primary residences (insulated or not, single-dwellings or apartments), is estimated to 60.9 up to 130.1 KWh·m−2·year−1. • The mean actual thermal energy consumption for space heating of residential buildings is much lower than that evaluated based on HDHs or the method of Hellenic Building Energy Performance Regulation (REPB), according to European Directive 31/2010. • The implementation of the Hellenic regulation for building energy performance (REPB) imposed the improvement of thermal protection of the building envelope and the performance of the electrical and mechanical systems. • Applying the REPB minimum requirements on thermal protection reduce the space heating loads of residential buildings in all climate zones by 63% to 70%. The compliance of existing residential buildings to the minimum requirements of the REPB could result to about 24.4 TWh of savings in space heating energy annually. • The benefits of any National Regulation on Building Energy Performance should be examined on the basis of expected lower actual energy consumption. Abstract This paper presents the energy, the technical and the environmental characteristics of residential buildings in Greece, as well as their potential for energy conservation, based on their actual energy consumption data. The technical characteristics of residential buildings related to their energy performance (insulation, type of openings, system for space heating and cooling, etc.), the actual energy use (kWh.m−2.year−1) and the environmental factors (kgCO₂.m−2.year−1) related to energy consumption, are some of the parameters of this survey. The average annual specific energy consumption of residential buildings in Greece was 112 kWh·m−2·year−1 in 2014, the 6th lower consumption among the 28 European member states (EU-28) in which the average residential building energy consumption is of about 158.8 kWh·m−2·year−1. The potential of space heating energy conservation for Greek residential buildings was estimated, based on (i) the 2011 heating energy consumption data and (ii) the percentages of space heating energy conservation, calculated by analysing 144 different types of residential buildings, having various geometric and technical characteristics, such as the A/V ratio (envelope area to volume of building), the heating degree hours (HDHs) and various occupancy profiles. The resulting average actual energy consumption is much lower than that calculated using Heating Degree Hours (HDHs) or the method of Hellenic Building Energy Performance Regulation (REPB). Almost 45% of these buildings were built before 1980, without any thermal insulation or double glazing. The compliance of these buildings to the minimum requirements of the REPB (related to thermal insulation and the efficiency of their electromechanical systems), could result to about 24.4 TWh of savings in space heating energy annually, i.e. to about 32–175 kWh·m−2·year−1, depending on the climate zone that corresponds to 8.5–46.2 kgCO₂·m−2·year−1 reduction. [ABSTRACT FROM AUTHOR]

Photovoltaic (PV) power system is a technology for producing electricity from renewable resources that is rapidly expanding thanks to its capability to save conventional fossil fuels and to decrease the emissions of greenhouse gases. However, as more attention is being focused globally on the development of building-integrated PV systems, the technical, the economic as well as the environmental assessment of these systems is crucial to ascertain their viability. The purpose of this paper is to present an economic and environmental analysis of relatively small rooftop PV-grid-interconnected energy systems of 2–10 kW p rated power, located in Athens, Greece. The techno-economic feasibility of the PV systems is conducted employing the computerized renewable energy technologies assessment tool ‘RETScreen’. The energy and environmental assessment of the systems is carried out employing SimaPro 7.1 software, which is a standard Life Cycle Assessment tool. The results of the economic analysis indicate that with the current prices, investment in PV-grid-interconnected systems with power capacity higher than 5 kW p is in general viable. However, an increase in energy sale prices and/or cost reductions in the production of PV systems are crucial for the successful development of small-scale residential size PV systems in the country. The environmental analysis reveals that the PV systems with higher rated power perform worse as far as the environmental impact is concerned. The critical phase of the life cycle of PV systems is the module manufacturing process, which is characterized by high electricity consumption, representing most of the environmental impact. Nevertheless, it is further shown that the application of PV technology presents important environmental benefits compared to conventional energy production systems. [ABSTRACT FROM AUTHOR]

Abstract: Hotels are a diverse building type with high normalized energy end-use because of its focus to provide best facilities for guests. There is scope, and in many countries legislative requirements, to reduce energy consumption without compromising facilities; case-studies from tourism intensive countries could be useful for demonstrating such possibilities. This paper presents a method of deriving energy benchmarks to enable classification of hotels in Greece based on operational energy use in terms of electricity and oil. The method of classification defines clusters of hotels using the k-means algorithm controlled with the silhouette plot after applying normalization factors for the operational energy data to correct for size, operation (seasonal or annual) and climatic conditions. Ninety hotels are analysed in the sample presented in this paper; and well separated clusters are defined for the whole sample and for the sample split in hotels with annual and seasonal operation. Energy consumption varies considerably between and within clusters indicating that a range of energy consumption targets might be more suitable than single value benchmarks for this type of building. [Copyright &y& Elsevier]

Residential buildings in Greece account for about 79% of the exclusive-use building stock and consume about a quarter of the total final energy consumption, with space heating and domestic hot water being the main energy end-uses. About 58% of the dwellings were constructed before the 80 s and the adoption of the first thermal insulation regulation. This paper presents the results from the Hellenic pilot action within EPISCOPE. The overall approach and analysis are based on the national TABULA residential building typology for single- and multi-family houses in order to estimate heating energy performance and savings. The work exploits Census and statistical data for defining the Hellenic building stock and empirical adaptation factors to make more realistic estimates from normative calculations. The analysis is supported by a detailed data disaggregation in terms of the number of dwellings and floor areas, based on envelope thermal characteristics, heat production units, energy carriers, use of renewables etc. The calculation results are adapted for the building types and then projected to the building stock. Numerous scenarios for different modernization rates are assessed for identifying the most promising refurbishment strategies in space heating and DHW for reaching the 2020 and 2030 national CO 2 emission targets. [ABSTRACT FROM AUTHOR]

This paper aims at implementing appropriate methodological approaches for a preliminary assessment of fuel poverty in Greece and analyzing in quantitative terms the potential impact of fuel poverty on public health. As regards the assessment of fuel poverty in Greece, both subjective and objective approaches have been implemented, utilizing primary data from existing surveys undertaken by National Statistical Authority, while the health impacts attributed to fuel poverty were quantified through statistical analysis. The implementation of objective approaches showed that around 20–25% of Greek households were in fuel poverty in 2013, while with subjective measures this percentage reaches to 29.5%, twice as in 2010. Furthermore, the regression models developed showed that the increased levels of fuel poverty observed after 2010 have had significant negative impacts on public health. Specifically, 1–2.7% of deaths recorded annually in Greece as well as the 2.7–7.4% of cardiovascular diseases and the 3.1–8.5% of respiratory infections treated by the Greek hospitals are attributed to fuel poverty. Taking into consideration that more than 60% of Greek households do not have adequate insulation, the development of ambitious energy saving programs for residential buildings could build synergies between climate change mitigation and fuel poverty alleviation. [ABSTRACT FROM AUTHOR]

Abstract: Adequate indoor illuminance is accepted as one important determinant of conditions for comfort and productivity in offices. This paper uses the results of field surveys in 26 offices in five European countries (France, Greece, Portugal, Sweden and the UK) to investigate what illuminance levels are actually achieved on office desks, what light level is considered ‘best’ by occupants, and how this is affected by outdoor sky conditions and illuminance. The paper also explores how blinds and lights are used by occupants to modify light levels at their desks. The office workers show a remarkable degree of adaptation to different light intensities. They use controls to modify the light level at their desks to almost the same mean level irrespective of the sky conditions outside. There is a small but significant effect of lighting on self-reported productivity which seems to be higher when offices are daylit. [Copyright &y& Elsevier]

Abstract: This paper describes an effort to estimate the impact of a cool roof (characterised by increased solar reflectance compared to the initial roof and high infrared emittance) on the energy performance and thermal behaviour of a non-cooled school building in Athens, Greece. An experimental monitoring campaign has been carried out before and after the application of a white elastomeric coating with a solar reflectance of 0.89 on the roof of the building. The air and surface temperature of the building have been measured and a set of meteorological parameters have been collected. An infrared camera has been used to depict the differences in the surface temperature before and after the cool roof application. The monitoring results are complemented and supported by building simulation. The building has been modelled into TRNSYS software and the model has been calibrated and validated using the experimental data. Simulation results show a decrease in the air temperature in the classes that reaches 2.8°C and a decrease in the annual cooling load by 40%. The corresponding heating penalty (i.e. the increase of heating load) is 10%. Additionally, the impact of the cool roof on thermal comfort, peak power and surface temperature has been assessed. [Copyright &y& Elsevier]

Abstract: Cool roofs are an emerging technique with a recent growing interest worldwide. The aim of the present paper is to present the application of cool roofs’ technology in a laboratory building located in Iraklion, Crete, Greece. The building is monitored towards its energy performance and indoor environment before and after the implementation of the cool roof technology. The specific case study is intended as a shining example of the cool roof capabilities in improving the thermal conditions in non-air conditioned and in reducing the energy consumption in air conditioned buildings. [Copyright &y& Elsevier]

Abstract: The paper presents a methodology that has been developed and implemented for the simulation of electricity use (kWh) as well as electricity pricing (c€/kWh) in buildings. In the simulation, electricity pricing has been treated as dependent on electricity use as energy pricing tariffs usually discriminate between specific electricity consumption zones, time periods, etc. Pricing and electricity use, together, may then provide an estimation of the building electric energy cost (€). The simulation runs on an hourly resolution allowing to highlight some potential wasteful and costly practices in energy use and management and providing insight to user behavior, which has been a key driver for its development. The key aspects of the simulation approach are presented and its use is demonstrated in two different buildings in Greece and Italy. The methodology is now adapted to allow for neural network based, real time training, which will also be briefly introduced. [Copyright &y& Elsevier]

Abstract: This paper investigates the indoor thermal conditions in fifty low income non air conditioned houses in Athens, Greece, during the extremely hot summer of 2007. Hourly indoor temperature data have been analysed during three extended heat waves. Indoor temperatures as high as 40°C were recorded and the average indoor minimum temperature was always above 28°C. Mean indoor temperatures during the hot season were up to 4.2K above the normal climatic period, while the daily increase rate varied from 0.2K/day during the first up to 0.8K/day for the peak days of the heat wave. The exposure of inhabitants to high temperatures is very important because for almost 85% of the hot period, indoor temperature exceeded 30°C. Periods of about 216 continuous hours above 30°C, and six days above 33°C were recorded in many buildings. The dynamics and the evolution of indoor temperatures as a function of the outdoor climatic characteristics and the thermal capacitance of the buildings are analysed. Possible techniques to improve the indoor environmental quality in low income housing during extremely hot periods are discussed. [Copyright &y& Elsevier]

Abstract: This paper examines the behaviour in energy consumption of buildings that have polygonal and prismatic envelopes and are located in Mediterranean climates. More specifically, it aims at studying the differences in energy consumption of these kinds of buildings compared to orthogonal building envelopes. For this purpose a contemporary building was chosen and modelled in two different versions, one being the original prismatic form and the other a model of the same building with right angles, however retaining all area and volume data of the original prismatic building. Calculations reveal that the prismatic formed building has lower solar gains compared to its orthogonal counterpart and consumes less energy in an annual cycle. The results show a mean annual energy consumption difference of 7.88% in favour of the prismatic building envelope. Also, depending on the orientation, the difference in annual energy needs has a range between 2.51% and 16.01%. [Copyright &y& Elsevier]

Abstract: The urbanization and the deficiencies in proper development control have as consequence the environment''s degradation in urban centres and the change of microclimatic conditions. So, the urban microclimate of densely built areas is characterized by higher temperatures than the temperature of the suburbs and surrounding areas. Heating of the atmosphere and surfaces in urban areas compared to their surroundings is the phenomenon which is called urban heat island (UHI). The effect of building''s volume is considered as one of the main reasons for the urban heat island effect. Buildings, roads and paved surfaces, store the heat during the day and then release it slowly during the evening keeping the air temperature of the city hotter than surrounding areas. In other words, urban heat island cause thermal discomfort and it is responsible for the increase of energy demand in the buildings. This paper presents a study that aims at investigating the influence of urban morphology in microclimatic conditions. The investigation is carried out in Thessaloniki, Greece. The purpose of the research project is to measure how the temperature of building''s surfaces vary and interact during the day and according to the microclimatic parameters. There is a daily measurement of the examinated factors. Street orientation and configuration of the building blocks (height of buildings, width of road) are also important factors for the analysis of the measurements. [Copyright &y& Elsevier]

Abstract: The latest developments in the field of energy supply, along with the major issue of the environment protection, set new priorities and yardsticks concerning the energy policies implemented worldwide. The development and implementation of effective energy conservation policies has been a target of the European Union ever since the days when it was still called European Economic Community. In this framework, and despite the successes already monitored, the need for further energy conservation in the building sector is a both an aim and a tool. Emphasis is being placed on the residential building stock and the improvement of its energy performance. Greece has been one of the last countries to adopt the Directive on the Energy Performance of Buildings. A thorough research regarding the nature of the Greek residential building stock helps in highlighting the problems associated with this delay, but also the perspectives for catching up with the other EU member states and achieving the aims set for the coming years. This paper aims at providing detailed information on the residential urban building stock, as determined in a field study in typical big and smaller Greek cities. [Copyright &y& Elsevier]

Abstract: The process of building labeling and certification in accordance to the provisions of the European Directive on the Energy Performance of Buildings (EPBD) constitutes a unique opportunity for collecting information on the characteristics of the building stock and its energy performance on a national and European level. Thus, there is a need to handle data from a large stock of buildings and to be able to analyse information and extract practical trends and benchmarks. Stakeholders and technical managers who oversee a number of buildings experience similar needs in order to collect, organize and monitor the energy performance of a large pool of buildings. To facilitate these efforts, a common evaluation database and complimentary software for its exploitation have been developed in the frame of a European project. This paper presents an overview of the database and its available tools, and the main results from a case study on Hellenic buildings that reveals relevant characteristics. The Hellenic database included a sample of 250 buildings from different regions in Greece, with a breakdown that is representative of the national building stock. The main results focus on the buildings’ energy performance, thermal envelope characteristics and the exploitation of solar thermal energy. [Copyright &y& Elsevier]

Abstract: The knowledge of building stock energy data of a country is a very significant tool for energy benchmarks establishment, energy rating procedures and building classification boundaries determination, according to the Directive 2002/91/EC and its implementation in EU Member States. The lack of building energy databases in many EU Countries, including Greece, and the difficulties of collecting them lead to the investigation of other potential solutions. The aim of this paper is to present a method of a Virtual Building Dataset (VBD) creation for office buildings in Greece. The philosophy of VBD is based on the creation and simulation of random office buildings that could be found or built in Greece, taking into account the Greek constructional and operational characteristics of office buildings and Greek legislation. The VBD consists of 30,000 buildings (10,000 in each climatic zone) with their detailed constructional and operational data and of their simulation outputs: the annual specific energy consumption for heating, cooling, artificial lighting, office equipment and an indoor thermal comfort indicator. Based on VBD results the energy and indoor thermal comfort benchmarks for office building sector in Greece are assessed and presented. [Copyright &y& Elsevier]

Abstract: Energy consumption in buildings vary significantly, depending on factors as the use of the building, the construction type, maintenance, existing heating, cooling and lighting systems and other types of services. Hotel buildings have high energy consumption rate, as a result of their unique operational characteristics. Energy consumption in hotels is among the highest in the non-residential building sector in absolute values. Available specific information on the energy characteristics, thermal performance, energy losses, electric loads, and comfort conditions play significant role for the sustainable development of hotel''s systems. These data can also be used to identify whether there is space for improvement in new or existing hotels by comparing them against predicted or actual building energy performance. The aim of the present paper is to analyze the energy and exergy utilization in four hotels in Rethimno, Crete (Southern Greece) and in Kassandra, Halkidiki (Northern Greece). [Copyright &y& Elsevier]

Abstract: The purpose of this paper is to estimate the main determinants of households’ residential consumption for space heating in Greece employing cross-section data for 2003. In the empirical analysis household space heating consumption models are employed, using OLS, probit, tobit and quantile regression techniques. The results show that demographic and economic variables such as age of the respondent, family size and households’ annual income are suitable to explain differences towards oil consumption for space heating. In addition, the results suggest that dwelling''s size and rate of occupancy are positively associated with the amount of oil that Greek households consumed in order to achieve a significant level of heat comfort for their house. By evaluating household''s decision-making process with regard to space heating consumption we are able to propose an effective energy policy framework. [Copyright &y& Elsevier]

The aim of this paper is to present the architecture, the algorithms and the performance results of an integrated indoor environment energy management system (IEEMS) for buildings. The buildings’ users comfort requirements are fulfilled and regulated using a fuzzy controller. The fuzzy controller’s structure is adjusted to the users’ requirements that are monitored via a smart card system. The IEEMS is installed in two buildings in Athens and in Crete, both in Greece. The energy conservation achieved by the IEEMS operation is more than 30% compared to the existing control system. [Copyright &y& Elsevier]

This paper describes the installation, technical characteristics, operation and economic evaluation of a grid-connected building-integrated photovoltaic system (BIPV) installed in Northern Greece, and in particular in the city of Kastoria. The technical and economical factors are examined using a computerized renewable energy technologies (RETs) assessment tool. A number of different economic and financial feasibility indices are calculated for different financing scenarios in order to assess the gross return of the investment. Useful conclusions were drawn regarding the feasibility of BIPV systems and their potential for increased energy market penetration. [Copyright &y& Elsevier]