Search

Development and use of preconstruction have been exhibited for several decades. Numerous modules, ranging from the simplest to the most advanced concepts, have been suggested to ameliorate the layout of building structures, with respect to a broad spectrum of needs. This study aims to unfold the fire defensiveness of an innovative precast concrete sandwich wall-system subjected to the ISO 834 fire, such as this is provided for in EN1991-1-2. In light of a rapidly evolving environment that should shield structures against fire, this investigation emphasises on the vulnerability of precast panels with a varying thickness of insulation by means of a numerical methodology and a versatile heat transfer-model. A finite-element analysis is carried out with COMSOL Multiphysics® simulation software. In a following step, as fire risk should be vigorously tackled, the research is extended to validate numerical predictions of the model by means of an experimental setup for wall specimens arranged in the laboratory. Therefore, an additional goal of this research is to assess temperature discrepancies for both addressed cases. Despite various approximations of the model, an excellent agreement between numerical and experimental results is shown, confirming the rationality of computational simulations in terms of temperatures’ precision. It has been revealed that for all examined cases, the insulation ability (I) has been maintained for more than 3 h regardless of the positioning of the insulation. Further evidence though suggested that is not the case for the loadbearing capacity (R), as the installation of a fire exposed insulation layer resulted in lower stability systems. Also, the effect of the insulation thickness is not that dominant as on average and maximum temperature deviations among marginal assemblies (d\ud \ud EPS\ud = 2 cm and d\ud \ud EPS\ud = 10 cm) did not exceed 5 °C and 10 °C at t\ud \ud fire\ud ≈ 100 min.

Subject of this study is the analysis of the Smart Readiness Indicator (SRI), as well as its application for a residential building in Greece. The indicator, which was firstly introduced in the revised EPBD in 2018, assesses the buildings’ smart readiness through the examination of the presence and the evaluation of the functionality level of smart services. Its goal is the promotion of buildings that are energy efficient, adaptive to their users’ needs, and flexible in respect of their electricity demand, according to the three key - functionalities, as stated by the Directive. A smart building is not only characterized by its sustainability but also by its adaptiveness to the environmental conditions and its users’ preferences. Smart buildings are a basic component of smart cities, which utilize a great range of smart technologies aiming at the improvement of their citizens’ lives. The Smart Readiness Indicator as well as the sub indicators evaluate the smart buildings using a multicriteria assessment method, which is thoroughly described in this paper. Finally, the indicators’ calculation is executed for a residential building in Greece leading to results, which are discussed along with identified methodology shortcomings and difficulties.

Construction and Demolition Waste (CDW) effective management is of vital importance, especially regarding the climate-neutral economy target set for 2050. The common practice of landfilling them during the past decades and ignoring the environmental impacts is now obsolete, with countries around the world adopting national regulations for their proper treatment. The lack of data on the CDW volume produced every year both in the European region and at the Greek national level is evident, in contrast with Asian or American regions, and introduces a great uncertainty in the field. This study aims at estimating the CDW quantities produced by a typical multi-storey residential building in Greece, built in the mid-20th century, made of reinforced concrete and filling masonry walls. The subsidized renovation programs by the European Union, which have a great impact on the Greek domain, are also considered, so two renovation procedures are considered during the building’s lifespan, resulting in an extended lifetime of the building along with additional CDW quantities produced on each renovation procedure. Challenges regarding the disposal, recycling and reuse potential and alternatives of the distinct CDW types produced are presented, based on the international literature available data.

Climate change has a major impact on the urban built environment, both with respect to the heating and cooling energy requirements, but also regarding the higher probability of confronting extreme events such as heatwaves. In parallel, the ongoing urbanization, the urban microclimate and the formation of the urban heat island effect, compounding the ongoing climate change, is also a considerable determinant of the building’s energy behavior and the outdoor thermal environment. To evaluate the magnitude of the complex phenomenon, the current research investigates the effect of climate change and urban heat island on heating and cooling energy needs of an urban building unit in Thessaloniki, Greece. The study comparatively evaluates different tools for the generation of future weather datasets, considering both statistical and dynamical downscaling methods, with the latter involving the use of a regional climate model. Based on the output of the regional climate model, another future weather dataset is created, considering not only the general climatic conditions, but also the microclimatic parameters of the examined case study area, under the future climate projections. The generated future weather datasets are then used as an input parameter in the dynamic energy performance simulations with EnergyPlus. For all examined weather datasets, the simulation results show a decrease of the heating energy use, an effect that is strongly counterbalanced by the rise of the cooling energy demand. The obtained simulation results also reveal the contribution of the urban warming of the ongoing climate change, demonstrating the need to perform a holistic analysis for the buildings’ energy needs under future climate conditions.

Double-skin facades (DSFs) are a technology that lies behind innovative energy efficient facade systems. While it provides a potential for high energy efficient buildings, other important parameters, like point thermal bridge problems, are in most cases overlooked. The aim of this study is to investigate the magnitude of this approach and the effect it might has on the overall heat flow estimation in buildings. The study performs a numerical analysis of heat flow through the points where such effects are found, in order to analyse their nature under different design parameters selection like the use of thermal breaks, the substrate wall material, the thermal insulation thickness and the type of anchors used to securely connect both facade skins. The results are then applied to a case-study office building aiming at quantifying the overall contribution of point thermal bridges to heat flows through the building envelope. As the analysis shows, point thermal bridges in well-insulated envelopes have a heat-loss similar to the one from 1 m2 of facade’s wall. The overall effect at DSFs can surpass 25% of total envelope heat flow, leading to a large underestimation of actual heat flows through the building envelope. Overlooking their contribution, as many European national energy efficiency regulations currently do for the shake of simplicity, has a significant effect in widening the gap between predicted and actual energy efficiency of buildings.

Several studies underline the dramatic changes that are expected to take place in nature and environment due to climate change. The latter is also expected to affect the built environment. Particular emphasis is currently given to the impact of climate change on historical structures. Within this context, it is important to use simple methods and novel tools in order to investigate pecific case studies. In this study, the climate change impact on the hygrothermal performance of the log walls in a historic timber building is presented. The building under investigation is the Fadum storehouse, also known as ‘the coated house’, located in Tønsberg, Norway. The storehouse dates to the late 18th century. It has a particular design with the main features of stumps or piles up to which it stands and the ‘coating’ that covers its outer walls. The main damage of the construction is related to the biological degradation of the wood. The hygrothermal performance of the log walls, as well as the exterior and interior climate, have been monitored and the results have been used to validate a Heat, Air and Moisture transport (HAM) model. The validated HAM model is then used to examine the performance of the log walls for both current and potential future climate conditions. The transient hygrothermal boundary conditions serve as the input parameters to a biohygrothermal model that is used to investigate the biological deterioration of the building components. The findings reveal that currently there is no mould risk for the main body of the construction, which is in accordance with the visual inspection. The passive systems of the building are highly conducive to these results, since they protect it from driving rain and other sources of moisture and eliminate the potential impact of future climate change risk scenarios. This work is a part of the HYPERION project. HYPERION has received funding from the European Union’s Framework Programme for Research and Innovation (Horizon 2020) under grant agreement No 821054.

The increased rates of urbanization and industrialization of the 20th and 21st centuries have dramatically changed the land use and cover of modern cities, contributing to the degradation of the urban microclimate and the rise of the ambient urban air temperatures. Given the multiple negative energy, environmental and social consequences of urban warming, the present paper summarizes the findings of previous studies, assessing the main causes of the phenomenon along with the key investigation methods involving experimental and computational approaches. There follows a description of the most common mitigations, and adaption strategies towards the attenuation of urban warming are described. The analyzed elements include the addition of green spaces such as trees, grass and green roofs; changes on the albedo of the urban surfaces and water-based techniques, as well as a combination of them. The discussion of the reported findings in the existing literature clearly reflects the impact of urban morphology on the outdoor thermal environment, providing also useful information for professionals and urban planners involved at the phase of decision-making.

Although modern prefabricated buildings may offer many advantages, such as a significant reduction in cost and time, improved quality and accuracy in manufacture, easy dismantle and reuse of its components, etc., they have not gained the attention they deserve in the construction market yet. In this paper, a holistic approach for the formation of prefabricated buildings of advanced performance is presented. Within this context, a new, innovative prefabricated building element is developed, designed to exhibit optimized structural, hygrothermal, energy, acoustic, fire and environmental performance. The improved properties of the building element are ensured by the proper configuration of the layers that compose it with respect to the design objectives; for example, in order to support the heat storage and the control of indoor temperatures, the integration of PCMs in the element's layers is investigated. Furthermore, in order to indicate the contribution of the new building element to the sustainability of the overall construction, the performance of a building formulated with the new element is analyzed in terms of energy and environmental behaviour. The new building element and construction system are expected to systemize the prefabricated element's production, leading eventually to the improvement of the building quality, as well as to the reduction of time and cost of building's erection. In parallel, the new certified and optimized building performance will increase the share of prefabricated buildings in the Mediterranean countries, where housing needs are gradually growing, while at the same time, energy efficient and environmentally friendly construction will be promoted.

Predicting buildings’ heating and cooling needs through dynamic simulation methods requires the input of hourly weather data, so as to represent the typical meteorological characteristics of a specific location. Hence, the so called ‘typical weather years’ (TWY), mainly deduced from multi-year records of meteorological stations outside the urban centres, cannot account of the complex interactions between solar radiation, wind speed and high urban densities which lead to the formation of the urban heat island effect and to higher ambient air temperatures. As the assumption that climatic parameters at a reference location of a meteo station are similar for a densely built up area can lead to miscalculations of the heating and cooling needs, the aim of this study is to present a computational method for assessing the urban climate's effect during the generation of typical weather data for dynamic energy calculations. In this vein, a typical ‘urban specific weather dataset’ (USWD), reflecting the microclimatic conditions in front of a building unit inside an urban district in the city of Thessaloniki, Greece is created based on microclimate simulations with the Envi-met model; it is then compared with a typical reference weather dataset (RWD), representing climatic conditions at a reference location of a meteo station. The results indicate that the proposed method can capture microclimate characteristics; higher dry bulb temperatures were reported during the year inside the urban canyon, compared to the corresponding values at the reference location, with indicative mean daily deviations up to 1.0 °C and 0.75 °C in February and July respectively. Wind speed, near the building facade is generally found lower than the corresponding values at the reference location, due to wind sheltering by neighbouring constructions. Given that climatic parameters strongly influence the output of energy simulations the proposed computational method provide a contribution for higher accuracy of building energy simulation in the urban context. Future work will involve energy performance simulations of a typical building unit with the generated USWD file so as to evaluate the urban climate's influence on energy needs.

Electricity generation on site is a design challenge aiming at supporting the concept of energy-autonomous building. Many projects worldwide have promoted the installation of photovoltaic panels on urban buildings, aiming at utilizing a large area to produce electricity. In most cases, photovoltaics are considered strictly as electricity generators, neglecting their effect to the efficiency and to the thermal behaviour of the building envelope. The integrated performance of photovoltaic ventilated fa?ades, where the photovoltaics are regarded as part of a complicated envelope system, provides design challenges and problems that cannot be overlooked within the framework of the Nearly Zero Energy Building concept. In this study, a finite volume model for photovoltaic ventilated fa?ades is developed, experimentally validated and found to have a significant convergence to measured data.

The present study investigates the impact of different intervention scenarios regarding morphological characteristics of an urban district of Thessaloniki on microclimatic parameters such as surface, air and mean radiant temperature distribution during a typical summer day. The proposed intervention scenarios include the total replacement of concrete pavement and asphalt streets with similar cool materials, increase of the amount of trees and a combination of the above strategies. The three-dimensional non-hydrostatic climate model ENVI-met v.4 is used for the microclimate simulation. The analysis reveals a significant reduction of surface temperatures due to the replacement of conventional coatings with cool materials of higher albedo and emissivity, while changes in air temperature are of lower importance. However, the combined use of cool materials and additional tree planting can contribute to lower air temperatures through shading and leaves’ evapotranspiration.

This paper aims to analyse the changes that the new Hellenic Regulation on the Energy Performance of Buildings (REPB) has brought to the Hellenic residential buildings, which is in line with the European Directive 2010/31/EC. These changes refer to construction techniques, construction costs and energy performance. Our assessment is based on the numerical analysis of two typical residential buildings, a single and a multi-one. Both buildings were studied according to the requirements set before and after the application of the REPB for all (four in total) climate zones of Greece. The cost for implementing the two regulations was evaluated, as was also the energy consumption cost. Based on these costs we estimated the operating costs for heating, cooling and domestic hot water of the two buildings of this study. The implementation of the REPB significantly reduced the required heating loads for space heating in all climate zones by 37%–48% for both building types; this is mainly attributed to the improvement of the thermal properties of the building envelope and the improved energy performance of the electromechanical systems. The required cooling load was low and the implementation of the REPB did not change it significantly. Significant energy savings, in the range of 51%–58% were also achieved by installing flat plate solar collectors for Domestic Hot Water heating.

In this study, three different Typical Weather Years (TWYs) generated in Meteonorm using different techniques are compared with each other and with an actual hourly climate dataset of a calendar year. The impact of different hourly weather files on building's annual energy needs is then assessed via dynamic simulations of a typical building. The analysis revealed that Typical Meteorological Months and the corresponding TWYs may vary significantly as different statistical processes have been followed for their development. Comparing the actual monthly average values with the corresponding values of the TWYs revealed peakdifferences up to 45% during the heating period. Regarding the performance of the three stochastically generated TWYs, differences on annual energy use for heating and cooling purposes were found up to 9.3% and 13%, while the mild actual winter conditions resulted in lower heating energy needs, varying by 42%-47%, depending on the TWY.

In this paper, some well-known buildings’ environmental performance assessment tools and methods are reviewed with regard to the consideration of visual comfort in their structure and assessment process. Specifically, the parameters used for visual comfort's assessment in widely used tools (BREEAM, LEED, SBTool and CASBEE - versions for office buildings) are examined; the type and the kind of criteria used for the assessment, the weightings applied and references to relative standards are reviewed and comparatively assessed. Although the presented results cover the issue of visual comfort as a whole, emphasis is given on daylighting–related factors.

The paper presents the ventilated facades as an intervention for efficient energy upgrade of new and, mainly, existing buildings. It focuses on the requirements that this specific building element should fulfill, with regard to legal, technical, social and financial aspects. More specifically, legal aspects concern mainly the regulations that determine the element's behaviour with respect to the hygrothermal, energy, sound and fire performance, as well as other legal restrictions (i.e. urbanism/planning rules or listed buildings). The technical aspects involve structural issues, architectural concerns and aesthetics, as well as functional matters. Finally, the social aspects refer to the acceptance of the element by building users and architects/engineers, while the financial aspects interrelate the ownership with the economic incentives and the investment feasibility. All the above are presented and discussed in the paper in order to highlight the applicability of ventilated facade systems in residential buildings.

Resent developments on the requirements regarding the thermal efficiency of buildings and building envelopes, have increased the need for energy retrofit of building envelopes. Cladding systems and ventilated facades are among the most attractive solutions to these problems due to a variety of reasons, including aesthetics, moisture control, serviceability and resistance to environmental factors. Despite all the benefits of these structures, their actual thermal efficiency has not been studied extensively yet. In many countries, the thermal performance of these structures is treated in the same way as more simple structures like ETICS. Within the framework of the European project E2VENT, an thorough study of the nature of thermal bridges has been performed – among others- in order to reveal the nature and the magnitude of thermal bridge effects in such structures, to investigate the design parameters that can assist in minimising their contribution in overall heat flows and to improve the overall thermal efficiency of the building envelope. Results shows that thermal bridges in metal cladding systems can be a significantly weak point in thermal insulation protection if no special care is given during the design and the construction process. By simply neglecting point thermal bridges due the lack of specific requirements, to the insufficient knowledge or by considering that only the use of thermal-break products can efficiently treat it, can significantly decrease the thermal insulation quality of the facade, leading to undesirable results.

Replacing conventional pavements with the corresponding high albedo ones constitutes a well-known technique to improve outdoor thermal environment of modern cites. Since most of the existing studies assess the impact of the high albedo pavements at the pedestrian&rsquo, s height and with respect to thermal comfort, this study aims to examine the effect of the application of highly reflective pavements on the heating and cooling energy needs of a building unit, located inside a dense urban area. Aiming at a higher accuracy of the energy performance simulations, an integrated computational method between ENVI-met model, Meteonorm weather data generator and Energy Plus software is established, to consider the site-specific microclimatic characteristics of the urban areas. The analysis is performed both for the design and the aged albedo values as significant changes may occur due to aging process. The analysis revealed that the application of cool materials on the ground surfaces only marginally affects the energy performance of the examined building unit, both for the design and the aged albedo value, changes on the annual heating and cooling energy demand, for both albedo scenarios did not exceed 1.5% revealing the limited potential of cool pavements regarding the improvement of the energy performance of urban building units.

The paper concerns the development of an innovative building module with advanced thermophysical and mechanical properties that will be used in constructing sustainable prefabricated buildings with high structural, hygrothermal, energy, acoustic, fire and environmental performance at the minimum possible time and cost. In this paper, the configuration of the new building element, as well as its hygrothermal, energy, acoustic and environmental performances are presented. In addition, its contribution to forming a sustainable, energy efficient, affordable building is investigated.

The complicated nature of indoor environmental quality (IEQ) (thermal, visual, acoustic comfort, etc.) dictates a multi-fold approach for desirable IEQ levels to be achieved. The improvement of building shells&rsquo, thermal performance, imposed by the constantly revised buildings&rsquo, energy performance regulations, does not necessarily guarantee the upgrade of all IEQ-related aspects, such as the construction&rsquo, s acoustic quality, as most of the commonly used insulation materials are characterized by their low acoustic performance properties. From this perspective the SUstainable PReconstructed Innovative Module (SU.PR.I.M.) research project investigates a new, innovative preconstructed building module with advanced characteristics, which can, among other features, provide a high quality of acoustic performance in the indoor space. The module consists of two reinforced concrete vertical panels, between which the load bearing steel profiles are positioned. In the cavity and at the exterior surface of the panel there is a layer of thermal insulation. For the scope of the analysis, different external finishing surfaces are considered, including cladding with slate and brick, and different cavity insulation materials are examined. The addition of Phase Change Materials (PCM) in different mix proportions in the interior concrete panel is also examined. For the calculation of the sound insulation performance of the building module the INSUL 9.0 software is used. The results were validated through an experimental measurement in the laboratory in order to test the consistency of the values obtained. The results indicate that the examined preconstructed module can cover the sound insulation national regulation&rsquo, s performance limits, but the implementation of such panels in building constructions should be carefully considered in case of lower frequency noise environments.

Towards the zero energy and emission future, near Zero Energy Buildings (nZEBs) lead the path for the building construction sector. European legislation provides normative provisions for the definition of nZEBs and their cost-optimal levels within the context of EPBD recast and Delegated Regulation No.244 (2012). However, that same framework unilaterally assesses the building's impact and considers only the emissions from the operational phase. The present study is a first approach of integrating embodied impact into the context of EPBD recast for the cost-optimal levels of nZEBs, an option provided by its accompanying guidelines. The proposed two-step assessment combines the LCA, LCCA and Energy analysis on the Greek nZEB case study. An extended sensitivity analysis regarding climatic, design and monetary parameters, correlates the effect of embodied impact with the transposition of the cost-optimal levels to building variants with lower material intensity. That same transposition highlights an increase in the primary energy of the cost-optimal level between 0.00 kWh/m2·year and 3.57 kWh/m2·year and a decrease in the share of embodied to the total life cycle emissions and energy between 0.61% and 2.36% and 0.78% and 2.82%% respectively. The effect fades in the total sensitivity analysis scale, where it is located only within the range of results that follow the current energy efficiency regulations’ calculations. Results validate the outcome of a previous companion case study, while both indicate the need for further analysis in order to assess the aspects of nZEBs which are subject of variable definitions across the EU member states.

This study evaluates the effect of the morphological characteristics of 4 urban districts in Thessaloniki, Greece on the vertical profile of the Tair inside the various urban canyons under different meteorological conditions. ENVI-met v.4 microclimate simulations are conducted for the 4 selected case study areas, while different meteorological boundary conditions are also considered. The obtained simulation results generally suggest significant differentiations on the local climatic conditions throughout the year, due to the diverse morphological characteristics. The analysis of the vertical Tair profile, revealed low deviations during night-time and peak deviations at noon. The maximum Tair discrepancies among all areas have been mainly attributed to the different amounts of solar radiation, received by the canyons’ surfaces and the respective sensible heat release. However, in all cases, the estimated Tair differences among the study areas decreased as the distance from the ground increased.

This paper presents the primary findings of a research project, aiming to introduce an innovative building module with improved thermophysical and mechanical properties that will serve as a bearing element and/or as an internal partition wall in prefabricated residential buildings. This new building module will comply with current requirements as regards its operation and performance. For the purposes of this investigation, the overall performance of the considered building elements is ensured by the proper configuration and assembly of the involved layers and is verified through analytical and experimental analyses, as well as through measurements at accredited laboratories. The objective of this innovative building element is to establish a building envelope with a high structural, hygrothermal, energy, acoustic, fire and environmental performance, while reducing both the time and cost required to complete its construction. Evidently, the accomplishment of this objective suggests various benefits on both the business sector and the research community. Moreover, the utilization of this building module is influential in terms of social impact, as it promotes the construction of buildings with advanced energy and environmental performance that can furthermore mitigate and adapt to the climate change impacts.