Hellenic Buildings Research Articles

Climate Change Scenarios and Their Implications on the Energy Performance of Hellenic Non-Residential Buildings

It is important to understand how the climate is changing in order to prepare for the future, adapt if necessary, and, most importantly, take proper precautionary measures to alleviate major negative impacts. This work investigates the potential impacts of climate change on the anticipated energy performance of the existing Hellenic building stock until the end of the century. The assessment considers average climatic projections for two future time periods, one for the near and one for the distant future, following two representative concentration pathways (RCPs). The first one is a baseline scenario (RCP8.5) representing the highest greenhouse gas emissions. The second is an intermediate stabilization scenario (RCP4.5), assuming the imposition of conservative emissions mitigation policies. The future climate data are generated for 62 cities throughout Greece. As a case study, the work focuses on Hellenic non-residential (NR) whole buildings, analyzing available data collected during about 2500 energy audits of real NR buildings. The available data are used to assess the buildings’ heating and cooling demand and energy use. The annual average air temperature for Greece in 2050 is projected to increase by 1.5 K for the RCP4.5 scenario and by 1.9 K for the RCP8.5 scenario. In 2090, the increase is estimated to reach 1.7 K and 4.2 K, respectively. Accordingly, if the existing NR buildings are not renovated, the average heating energy use is expected to decrease by 22–26% in 2050 and by 23–52% in 2090. On the other hand, the average cooling energy use is expected to increase by 24–30% in 2050 and by 28–66% in 2090.

Time evolution of energy use intensities and energy gap of existing Hellenic non-residential buildings

This work exploits data from the energy performance certificates (EPCs) of the national electronic repository, to characterize the energy use intensity (EUI) of non-residential (NR) buildings in Greece and investigate the gap between the nominal needs and the actual energy use. Over the past eight years, a total of about 1,500,000 EPCs have been issued for various building types, out of which 17.5% for NR buildings. As the national EPC database is progressively enriched with more data, the work considers the time evolution of the average EUI and analyse the available data in order to determine whether they can be regarded as typical and representative for the Hellenic building stock. When available, data on actual energy use of the buildings is used in an attempt to close the gap between calculated (asset) and actual (operational) energy use. The data is organized in terms of different end uses and used to generate empirical correction factors that relate the normative calculated heating energy consumption with the actual energy use. These factors can be used to make more realistic estimates of the energy performance of buildings that undergo different refurbishments at national level.

Energy performance of European residential buildings: Energy use, technical and environmental characteristics of the Greek residential sector – energy conservation and CO₂ reduction

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.

Modeling energy refurbishment scenarios for the Hellenic residential building stock towards the 2020 & 2030 targets

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 80s 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 CO2 emission targets.

Energy and other Key Performance Indicators for Buildings– Examples for Hellenic Buildings

Buildings are the leading energy consuming sector, representing about 40% of the final energy consumption in Europe. Different key performance indicators are available that can support the diverse needs and priorities of stakeholders in their efforts to improve the overall energy performance of buildings. The work first reviews the energy use and characteristics of European buildings, the main European legislation and technical developments that drive the efforts for lowering energy consumption. The main indicators that are used during the design, construction and operation of buildings are elaborated and when possible quantified, along with pertinent standards and regulations for guidance. Using common energy related indicators, a case study then focuses on Hellenic buildings and provides an insight on their performance, exploiting data from energy performance certificates. The contents document relevant work in information and communications technology for delivering simulation, modelling, analysis, monitoring and visualization tools, along with ongoing efforts to exploit building typologies for realistic assessment of energy use, during the design and operation of buildings. Future priorities are also outlined that support the ongoing European efforts to refurbish the existing building stock and the decision making process for setting effective policies towards nearly zero energy buildings.

Hellenic renewable energy policies and energy performance of residential buildings using solar collectors for domestic hot water production in Greece

Total final energy consumption in Hellenic buildings reached 6.5 × 106 tons of oil equivalent (Mtoe) or 34.2% of the total (2010), of which 4.6 Mtoe in residential buildings. National implementation of the European Directive on the energy performance of buildings (EPBD) in Greece since 2010 is the first coordinated attempt to improve the energy performance of Hellenic buildings. In this framework, as of 2011, new buildings have an annual solar fraction of 60% for sanitary hot water production from solar thermal systems. Efforts are currently underway to comply with the EPBD recast so that by the end of the decade, all new buildings are nearly zero-energy buildings and that the very low amount of energy required should be covered to a very significant extent by energy from renewable energy sources (RESs). At the same time, the unprecedented financial crisis and escalating energy costs in Greece have reemphasized the need to explore the opportunities of renewables and energy conservation measures (ECMs). This paper reviews the relevant RES policies and status, with an emphasis to the Hellenic buildings. Using Hellenic typical residential buildings, the national requirements, and methodologies, this work quantifies the benefits of using solar thermal collectors to cover 100% of the domestic hot water demand. The results illustrate that, even as a single action, this popular ECM can improve the energy class of existing residential buildings and in some cases even reach an energy class-B, which is the minimum requirement for new buildings. Combining with other cost effective ECMs and exploiting RES for space heating and cooling can help building owners to not simply comply with new regulations but most important reduce the operational cost of buildings while maintaining a comfortable indoor thermal environment.

Energy certification of Hellenic buildings: First findings

Transposition of the European Directive on the energy performance of buildings (EPBD) in Greece was enacted in 2008. A follow-up regulation on the energy performance in the building sector – KENAK, four technical guidelines published and a national software for building energy audits and certification released in 2010, constitute the main instruments of EPBD implementation in Greece, following the European standards and in accordance to EPBD mandates. About 8500 temporary energy inspectors are already in place, while permanent accreditation is in progress. Energy performance design study has been set as a mandatory requirement for obtaining a building permit for new constructions since October 2010. Energy performance certificates (EPCs) are issued as of January 2011. By May 2013, over 355,000 energy performance certificates have been issued through the official national registry (www.buildingcert.gr). The vast majority has been issued for buildings or building units rented out (65%) or sold (17%), about 17% for the refurbishment of residential buildings under a national funding programme for the energy retrofitting of households and only 0.3% for new buildings. The EPC registry constitutes the first comprehensive national building database that reveals relevant information on buildings’ energy performance. This paper presents an analysis of the available EPCs aiming to provide an insight of the energy performance of buildings in Greece, towards better understanding the Hellenic building stock.

Building typologies as a tool for assessing the energy performance of residential buildings – A case study for the Hellenic building stock

Successful strategies towards minimizing the energy consumption and greenhouse gas emissions attributed to the building sector require knowledge on the energy-related characteristics of the existing building stock. Despite the numerous studies on energy conservation applications in buildings, current knowledge on the energy-related characteristics of the building stock still remains limited. Building typologies can be a useful instrument to facilitate the energy performance assessment of a building stock. This work is based on a harmonised structure for European building typologies (TABULA) developed for residential buildings, but the methodology may be extended to the tertiary sector as well. National typologies are sets of model buildings with characteristic energy-related properties representative of a country's building stock. The model buildings are used as a showcase for demonstrating the energy performance and the potential energy savings from typical and advanced energy conservation measures (ECMs) on the thermal envelope and the heat supply system. The proposed Hellenic residential building typology is presented for the first time along with an assessment of various ECMs that are used for an estimate of the energy performance of building stock in Greece in an effort to meet the 9% indicative national energy savings target by 2016.

Data collection and analysis of the building stock and its energy performance—An example for Hellenic buildings

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.

Energy efficiency in the Hellenic building sector: An assessment of the restrictions and perspectives of the market

The significance of bioclimatic architecture has become widely accepted since the 1970s and the implementation of its principles in practice is a key factor in order to achieve energy efficiency in the building sector. The way, however, from scientific acceptance to commercial utilization is not a straightforward one. This paper deals with the notion of bioclimatic architecture in buildings and investigates the aspects of this concept in Hellas. A sample of university researchers, building contractors and members of public organisations was interviewed using a standardised set of guidelines. The barriers to promoting bioclimatic design, role of the local government in the adoption process, level of environmental culture as well as perspectives of this concept in Hellas were the key areas of discussion in each of the interviews. The results from the data analysis reveal insufficient economic incentives, a lack in technical information as well as a lack in specific environmental policies that would foster the propagation of bioclimatic architecture.

European residential buildings and empirical assessment of the Hellenic building stock, energy consumption, emissions and potential energy savings

The existing building stock in European countries accounts for over 40% of final energy consumption in the European Union (EU) member states, of which residential use represents 63% of total energy consumption in the buildings sector. 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 comply with the Kyoto Protocol to reduce carbon dioxide emissions. This is also in accordance to the European Directive (EPBD 2002/91/EC) on the energy performance of buildings, which is currently under consideration in all EU member states. This paper presents an overview of the EU residential building stock and focuses on the Hellenic buildings. It elaborates the methodology used to determine the priorities for energy conservation measures (ECMs) in Hellenic residential buildings to reduce the environmental impact from CO 2 emissions, through the implementation of a realistic and effective national action plan. A major obstacle that had to overcome was the need to make suitable assumptions for missing detailed primary data. Accordingly, a qualitative and quantitative assessment of scattered national data resulted to a realistic assessment of the existing residential building stock and energy consumption. This is the first time that this kind of aggregate data is presented on a national level. Different energy conservation scenarios and their impact on the reduction of CO 2 emissions were evaluated. Accordingly, the most effective ECMs are the insulation of external walls (33–60% energy savings), weather proofing of openings (16–21%), the installation of double-glazed windows (14–20%), the regular maintenance of central heating boilers (10–12%), and the installation of solar collectors for sanitary hot water production (50–80%).

Proxeny Decrees from Megara

At the west end of the mediaeval castle on the Megarian Minoa the front surface of the west wall has fallen away. The foundations of the wall thus laid bare consist of large square blocks of poros and blue limestone from Hellenic buildings. The corner block is of blue limestone and is inscribed in three columns on its upper surface. On the face of the second and third columns are traces of mortar which show that there was originally a course above the stone. The block is 1·12 m. in breadth and ·55 m. in height. Its depth cannot be ascertained, as it is buried almost up to the surface. At the top is a margin 10 cm. in width, extending along the whole length of the stone. The inscription is below the margin, and the three columns are separated by vertical grooves. The first column is ·355 m. in breadth, the second ·32 m., and the third ·265 m.

Three Karian Sites: Telmissios, Karyanda, Taramptos

The inscription published below was discovered in June, 1893, built into a house in the small village of Pelen, which lies in the interior of the peninsula of Myndos, in the upper valley of a stream flowing southwards past Episkopi into the Gulf of Kos (Adm. Charts 1546, 1604); but which is not marked in any map hitherto. The stone is a block of the local grey limestone, and was much encrusted with whitewash; after a little cleaning, however, the reading became sufficiently clear. The inscription came from the ruins of a large church which stands about two miles east of Pelen, on the ridge between the valley of Pelen and that of Ghiöl to the east of it, at the point where the mountain road traverses the hills from Faréliah towards Budrum. The church is built upon the ruins of a Karian or Hellenic building, of large roughly squared stones, with the broad draft down the angles which is characteristic of the pre-Mausolean masonry of this neighbourhood. The site is much overgrown with thick shrubs, but enough can be made out to confirm the evidence of the inscription that this is the site of the temple of Apollo Telmisseus. We did not, however, find any other traces of inscriptions.