Open AccessArticle
Buildings Energy Performance in a Market Comparison Approach
Buildings 2017, 7(1), 16; doi:10.3390/buildings7010016 -
Abstract
The current regulations on the energy certification of buildings represent for the real estate market and the building sector a real cultural revolution. In recent years, the focus on the energy efficiency of buildings has grown exponentially. It is therefore necessary that the
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The current regulations on the energy certification of buildings represent for the real estate market and the building sector a real cultural revolution. In recent years, the focus on the energy efficiency of buildings has grown exponentially. It is therefore necessary that the property valuations and methodologies used for this purpose bear in mind the energy quality of buildings. This study aims to determine the contribution of an energy performance feature to the real estate property value. This information can help, on the one hand, to understand the energy savings and the corresponding savings income in the property management and, on the other, to control the air pollution from CO2 emission reduction. The energy performance hedonic price and the CO2 emission price are appraised in the Market Comparison Approach (MCA). Full article
Open AccessArticle
A Multi-Parametric Mathematical Approach on the Selection of Optimum Insulation Thicknesses in Buildings
Buildings 2017, 7(1), 15; doi:10.3390/buildings7010015 -
Abstract
Detailed simulations have indicated optimum insulation thicknesses of walls’ insulation for a variety of cases. Simplified analytical relations have also been proposed to the same aim, allowing the extraction of more general results, with limited accuracy however, as imposed by mathematical simplicity requirements.
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Detailed simulations have indicated optimum insulation thicknesses of walls’ insulation for a variety of cases. Simplified analytical relations have also been proposed to the same aim, allowing the extraction of more general results, with limited accuracy however, as imposed by mathematical simplicity requirements. In this sense, a variety of important parameters are ignored, such as: the existence of any glazing at the wall, the absorptance of the wall, the base temperature of the heated space which the referred to wall belongs to and its variation with insulation, the thermal characteristics (thermal capacitance, total heat losses coefficient) and the heat and solar gains of the heated space. An alternative analytical approach is consequently developed here, incorporating all above parameters and in this context accessing the wall as part of the whole heated space, instead of considering it solely as an isolated fabric element. The approach consists of a set of two implicit equations which are easily solved, and enables the investigation of the effects of all principal and secondary parameters on the optimum thickness. The ignorance even of the secondary of these parameters has proved to lead to significant errors. Full article
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Open AccessArticle
Experimental Study on Use of Sound Absorption Treatment for Reduction of Environmental Sound Propagation and Reverberation in Staircases: A Case Study in Housing
Buildings 2017, 7(1), 14; doi:10.3390/buildings7010014 -
Abstract
In recent years, many open-plan houses have been proposed not only for comfort reasons, but also as a place to engage in family life. However, in contrast to the fact that this kind of plan makes it easy for people to interact, the
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In recent years, many open-plan houses have been proposed not only for comfort reasons, but also as a place to engage in family life. However, in contrast to the fact that this kind of plan makes it easy for people to interact, the daily life household sounds that occur inside the home may be perceived as noise. It is especially difficult to suppress the propagation of sound and reverberation in staircase and stairwell areas due to the absence of sound-absorbing furniture. In this study, we focused on addressing sound management within the staircase area in open-plan housing where sound absorption is particularly difficult. In order to suppress sound propagation on the upper and lower floors and the reverberation of sound, we placed a thin sound absorption panel on the wall, ceiling, and riser of the staircase. As a result, we were able to confirm that the propagation of sound on upper and lower floors can be suppressed by carrying out the sound absorption treatment on the staircase. Furthermore, we found that in stairway landing areas, the suppression effect of the propagation of sound varies depending on the position of the sound source and the positioning of the sound absorption panel, and that there is a position for placing the sound absorption panel where the sound-absorbing effect is effective. Full article
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Open AccessArticle
The Effectiveness of Thermal Insulation in Lightweight Steel-Framed Walls with Respect to Its Position
Buildings 2017, 7(1), 13; doi:10.3390/buildings7010013 -
Abstract
Lightweight steel-framed (LSF) construction, given its advantages, has the potential to reach high standards in energy and environmental performance of buildings, such as nearly zero-energy buildings (nZEB). When compared with traditional construction, LSF system offers distinct benefits in such fields as sustainability, cost-effectiveness,
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Lightweight steel-framed (LSF) construction, given its advantages, has the potential to reach high standards in energy and environmental performance of buildings, such as nearly zero-energy buildings (nZEB). When compared with traditional construction, LSF system offers distinct benefits in such fields as sustainability, cost-effectiveness, constructive process, and safety at work. Despite the benefits of this constructive system, the effect of thermal bridges in LSF elements, caused by the high thermal conductivity of the steel structure, can be a disadvantage. The excessive heat losses or gains through these thermal bridges are more relevant in buildings’ exterior envelope, such as facade walls. These building components’ thermal performance is crucial in the buildings’ overall energetic behaviour, with a direct impact on energy consumption and resulting monetary costs during their operational stage. In this work the influence of the thermal insulation position on its effectiveness is evaluated in LSF facade walls. For this purpose, several LSF wall types are assessed, namely cold, warm, and hybrid construction. The influence of thermal bridges instigated by the steel studs in the LSF walls’ overall thermal performance is evaluated as well. The computations are performed using specialized finite element software (THERM). Full article
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Open AccessArticle
Rough Set Theory for Real Estate Appraisals: An Application to Directional District of Naples
Buildings 2017, 7(1), 12; doi:10.3390/buildings7010012 -
Abstract
This paper proposes an application of Rough Set Theory (RST) to the real estate field, in order to highlight its operational potentialities for mass appraisal purposes. RST allows one to solve the appraisal of real estate units regardless of the deterministic relationship between
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This paper proposes an application of Rough Set Theory (RST) to the real estate field, in order to highlight its operational potentialities for mass appraisal purposes. RST allows one to solve the appraisal of real estate units regardless of the deterministic relationship between characteristics that contribute to the formation of the property market price and the same real estate prices. RST was applied to a real estate sample (office units located in Directional District of Naples) and was also integrated with a functional extension so-called “Valued Tolerance Relation” (VTR) in order to improve its flexibility. A multiple regression analysis (MRA) was developed on the same real estate sample with the aim to compare RST and MRA results. The case study is followed by a brief discussion on basic theoretical connotations of this methodology. Full article
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Open AccessFeature PaperArticle
Thermal Conductivity of Straw Bales: Full Size Measurements Considering the Direction of the Heat Flow
Buildings 2017, 7(1), 11; doi:10.3390/buildings7010011 -
Abstract
The thermal conductivity of straw bales is an intensively discussed topic in the international straw bale community. Straw bales are, by nature, highly heterogeneous and porous. They can have a relatively large range of density and the baling process can influence the way
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The thermal conductivity of straw bales is an intensively discussed topic in the international straw bale community. Straw bales are, by nature, highly heterogeneous and porous. They can have a relatively large range of density and the baling process can influence the way the fibres are organised within the bale. In addition, straw bales have a larger thickness than most of the insulating materials that can be found in the building industry. Measurement apparatus is usually not designed for such thicknesses, and most of the thermal conductivity values that can be found in the literature are defined based on samples in which the straw bales are resized. During this operation, the orientation of the fibres and the density may not be preserved. This paper starts with a literature review of straw bale thermal conductivity measurements and presents a measuring campaign performed with a specific Guarded Hot Plate, designed to measure samples up to 50 cm thick. The influence of the density is discussed thoroughly. Representative values are proposed for a large range of straw bales to support straw-bale development in the building industry. Full article
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Open AccessArticle
Real-Time Monitoring of Occupants’ Thermal Comfort through Infrared Imaging: A Preliminary Study
Buildings 2017, 7(1), 10; doi:10.3390/buildings7010010 -
Abstract
Thermally comfortable indoor environments are of great importance, as modern lifestyles often require people to spend more than 20 h per day indoors. Since most of the thermal comfort models use a variety of different environmental and personal factors that need to be
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Thermally comfortable indoor environments are of great importance, as modern lifestyles often require people to spend more than 20 h per day indoors. Since most of the thermal comfort models use a variety of different environmental and personal factors that need to be measured or estimated, real-time and continuous assessment of thermal comfort is often not practically feasible. This work presents a cheap and non-invasive approach based on infrared imaging for monitoring the occupants’ thermal sensation and comfort in real time. Thanks to a mechatronic device developed by the authors, the imaging is performed on the forehead skin, selected because it is always exposed to the environment and, thus, facilitating the monitoring activity in a non-invasive manner. Tests have been performed in controlled conditions on ten subjects to assess the hypothesis that the forehead temperature is correlated with subjects’ thermal sensation. This allows the exploitation of this quantity as a base for a simple monitoring of thermal comfort, which could later be tuned with an extensive experimental campaign. Full article
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Open AccessFeature PaperArticle
Energy Saving Assessment of Semi-Transparent Photovoltaic Modules Integrated into NZEB
Buildings 2017, 7(1), 9; doi:10.3390/buildings7010009 -
Abstract
Photovoltaic semi-transparent materials (STPV) integrated into glazing systems can offer good potential for energy saving to buildings, influencing heating loads, cooling loads, and lighting, as well as electricity production. Moreover, with the new stringent regulations issued by various European countries, following the Energy
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Photovoltaic semi-transparent materials (STPV) integrated into glazing systems can offer good potential for energy saving to buildings, influencing heating loads, cooling loads, and lighting, as well as electricity production. Moreover, with the new stringent regulations issued by various European countries, following the Energy Performance of Buildings Directive (EPBD, 2010/31/EC), the building envelope, including the glazing elements, needs to have high thermal performance to guarantee Nearly Zero Energy Building (NZEB) behavior. This work presents an assessment of energy saving potential of 4 different types of STPV with respect to conventional double pane glass. Dye sensitized solar modules (DSM) and thin film modules were considered in the study. Simulations based on an IEA reference office building (STD) and on reference buildings prescribed by the new Italian building energy performance regulation (NZEB) were carried out. All the glazing peculiarities could be simulated using only one simulation tool, namely IDA ICE 4.7.1. Dye sensitized solar modules resulted as the best performing devices for all orientations and climate zones. The work also evidenced how the requirements of NZEB seem to be too stringent for insulation properties, especially for the climate zone of Rome. Full article
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Open AccessFeature PaperArticle
High Energy-Efficient Windows with Silica Aerogel for Building Refurbishment: Experimental Characterization and Preliminary Simulations in Different Climate Conditions
Buildings 2017, 7(1), 8; doi:10.3390/buildings7010008 -
Abstract
The paper deals with the potential of high energy-efficient windows with granular silica aerogel for energy saving in building refurbishment. Different glazing systems were investigated considering two kinds of granular silica aerogel and different glass layers. Thermal transmittance and optical properties of the
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The paper deals with the potential of high energy-efficient windows with granular silica aerogel for energy saving in building refurbishment. Different glazing systems were investigated considering two kinds of granular silica aerogel and different glass layers. Thermal transmittance and optical properties of the samples were measured and used in building simulations. The aerogel impact on heat transfer is remarkable, allowing a thermal transmittance of 1.0–1.1 W/(m2·K) with granular aerogel in interspace only 15 mm in thickness. A 63% reduction in U-value was achieved when compared to the corresponding conventional windows, together with a significant reduction (30%) in light transmittance. When assembled with a low-e glass, the U-value reduction was lower (31%), but a moderate reduction in light transmittance (about 10%) was observed for larger granules. Energy simulations for a case study in different climate conditions (hot, moderate, and cold) showed a reduction in energy demand both for heating and cooling for silica aerogel glazing systems, when compared to the conventional ones. The new glazings are a suitable solution for building refurbishment, thanks to low U-values and total solar transmittance, also in warm climate conditions. Full article
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Open AccessEditorial
Acknowledgement to Reviewers of Buildings in 2016
Buildings 2017, 7(1), 7; doi:10.3390/buildings7010007 -
Abstract The editors of Buildings would like to express their sincere gratitude to the following reviewers  for assessing manuscripts in 2016.[...] Full article
Open AccessArticle
Performance Evaluation of Well-Insulated Versions of Contemporary Wall Systems—A Case Study of London for a Warmer Climate
Buildings 2017, 7(1), 6; doi:10.3390/buildings7010006 -
Abstract
Climate change and its consequences are of a great concern and the likely increasing temperature would add more dilemmas for the choice of passive design options. The performance of building envelopes is one of the key determinants of energy use and thermal comfort.
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Climate change and its consequences are of a great concern and the likely increasing temperature would add more dilemmas for the choice of passive design options. The performance of building envelopes is one of the key determinants of energy use and thermal comfort. This research presents an evaluation of commonly used construction systems (lightweight and heavyweight) with different levels of thermal mass. The performance of different construction combinations is quantified on the basis of their impact on thermal comfort and energy consumption for current and future time slices in London, UK where climate change impact is expected to be extreme. A flat model is examined as a case study to model the performance of the construction systems with low, medium and high level of thermal mass. The dynamic thermal simulation software used was DesignBuilder, which employs EnergyPlus as its calculation engine. In essence, this study establishes a new approach for assessing the performance of well-insulated contemporary construction systems on the basis of overall annual thermal comfort hours and energy consumption. Results indicate limited advantage of heavyweight construction systems in a changing climate. Full article
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Open AccessReview
Estimation and Minimization of Embodied Carbon of Buildings: A Review
Buildings 2017, 7(1), 5; doi:10.3390/buildings7010005 -
Abstract
Building and construction is responsible for up to 30% of annual global greenhouse gas (GHG) emissions, commonly reported in carbon equivalent unit. Carbon emissions are incurred in all stages of a building’s life cycle and are generally categorised into operating carbon and embodied
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Building and construction is responsible for up to 30% of annual global greenhouse gas (GHG) emissions, commonly reported in carbon equivalent unit. Carbon emissions are incurred in all stages of a building’s life cycle and are generally categorised into operating carbon and embodied carbon, each making varying contributions to the life cycle carbon depending on the building’s characteristics. With recent advances in reducing the operating carbon of buildings, the available literature indicates a clear shift in attention towards investigating strategies to minimize embodied carbon. However, minimizing the embodied carbon of buildings is challenging and requires evaluating the effects of embodied carbon reduction strategies on the emissions incurred in different life cycle phases, as well as the operating carbon of the building. In this paper, the available literature on strategies for reducing the embodied carbon of buildings, as well as methods for estimating the embodied carbon of buildings, is reviewed and the strengths and weaknesses of each method are highlighted. Full article
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Open AccessArticle
Rethinking of Critical Regionalism in High-Rise Buildings
Buildings 2017, 7(1), 4; doi:10.3390/buildings7010004 -
Abstract
The character of height and density of newly high-rise cities, along with the force of globalization, have jeopardized the character of dwellings once entailing a regional flavor. The critical regionalism which serves as a resistant medium against placelessness and lack of identity in
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The character of height and density of newly high-rise cities, along with the force of globalization, have jeopardized the character of dwellings once entailing a regional flavor. The critical regionalism which serves as a resistant medium against placelessness and lack of identity in the International Style has focused more on mid-rise or low-rise solutions rather than providing direct high-rise resolutions. Additionally, high-rise endeavors are not compatible with critical regionalism theories. This has happened partly due to critical regionalism theories multi-facet character inherent in its dialectic structure. Thus, to remedy the inadvertency of texts in the discourse of architectural regionalism, the present study seeks rethinking of critical regionalism by focusing on the pathology of high-rise buildings in the issues pertaining to place and identity. Finally, the architectonic articulation to place-making and identity-giving is discussed. Full article
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Open AccessFeature PaperReview
Thermochromic Oxide-Based Thin Films and Nanoparticle Composites for Energy-Efficient Glazings
Buildings 2017, 7(1), 3; doi:10.3390/buildings7010003 -
Abstract
Today’s advances in materials science and technology can lead to better buildings with improved energy efficiency and indoor conditions. Particular attention should be directed towards windows and glass facades—jointly known as “glazings”—since current practices often lead to huge energy expenditures related to excessive
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Today’s advances in materials science and technology can lead to better buildings with improved energy efficiency and indoor conditions. Particular attention should be directed towards windows and glass facades—jointly known as “glazings”—since current practices often lead to huge energy expenditures related to excessive inflow or outflow of energy which need to be balanced by energy-intensive cooling or heating. This review article outlines recent progress in thermochromics, i.e., it deals with materials whose optical properties are strongly dependent on temperature. In particular, we discuss oxide-based thin surface coatings (thin films) and nanoparticle composites which can be deposited onto glass and are able to regulate the throughput of solar energy while the luminous (visible) properties remain more or less unaltered. Another implementation embodies lamination materials incorporating thermochromic (TC) nanoparticles. The thin films and nanocomposites are based on vanadium dioxide (VO2), which is able to change its properties within a narrow temperature range in the vicinity of room temperature and either reflects or absorbs infrared light at elevated temperatures, whereas the reflectance or absorptance is much smaller at lower temperatures. The review outlines the state of the art for these thin films and nanocomposites with particular attention to recent developments that have taken place in laboratories worldwide. Specifically, we first set the scene by discussing environmental challenges and their relationship with TC glazings. Then enters VO2 and we present its key properties in thin-film form and as nanoparticles. The next part of the article gives perspectives on the manufacturing of these films and particles. We point out that the properties of pure VO2 may not be fully adequate for buildings and we elaborate how additives, antireflection layers, nanostructuring and protective over-coatings can be employed to yield improved performance and durability that make TC glazings of considerable interest for building-related applications. Finally, we briefly describe recent developments towards TC light scattering and draw some final conclusions. Full article
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Open AccessArticle
Investigating the Physical Characteristics of Non-Structural Lightweight Aggregate Blocks of Built with Region Materials
Buildings 2017, 7(1), 2; doi:10.3390/buildings7010002 -
Abstract
Given the importance of light construction in terms of better performance of structure, in case of earthquake, reduction of life and financial casualties, as well as shortage of studies in this field, the present research studied building non-structural lightweight blocks using lightweight aggregates
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Given the importance of light construction in terms of better performance of structure, in case of earthquake, reduction of life and financial casualties, as well as shortage of studies in this field, the present research studied building non-structural lightweight blocks using lightweight aggregates of Scoria, Pumice and Leca. On the other hand, density, compressive strength, and water absorption volume of these blocks have been investigated in this research in order to replace traditional materials with them. The experiments’ results show that, due to hardness and strong texture, high mechanical resistance of their lightweight aggregate Scoria blocks have higher compressive strength and density but lower water absorption volume compared to Pumice and Leca lightweight aggregate blocks. Despite desirable compressive strength and lower density compared to the other two blocks, pumice blocks have higher water absorption volume, and they do not meet standards. This makes them less interesting. Among these Leca blocks with density of 1151.94 (kg/m3) below 2000 kg/m3 of Iran density standard of 7782 (28-day compressive strength of 2.57 MPa), higher than 2.5 MPa of Iran compressive strength standard of 7782 (and water absorption volume of 282.92 kg/m3) and below 288 kg/m3 of Iran water absorption volume standard of 7782 (as a non-load-bearing lightweight block), has been recognized desirable. Full article
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Open AccessArticle
Monitoring a Pre-Normative Multi-Family Housing Case-Study in a Mediterranean Climate
Buildings 2017, 7(1), 1; doi:10.3390/buildings7010001 -
Abstract
In Spain, a significant percentage of the residential building stock presents deficient indoor conditions regarding current energy standards, due to having been constructed before the Norma Básica de la Edificación in 1979 (NBE CT 79) regarding thermal conditions in buildings. Current environmental policies
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In Spain, a significant percentage of the residential building stock presents deficient indoor conditions regarding current energy standards, due to having been constructed before the Norma Básica de la Edificación in 1979 (NBE CT 79) regarding thermal conditions in buildings. Current environmental policies pursue a cut in energy consumption and seek improvements in indoor conditions by refurbishing current stock, mainly that constructed between 1950 and 1980. Before any retrofitting action, housing monitoring has become essential for a better understanding of real and passive environmental behavior. This paper aims to present the monitoring in hourly intervals, real-time and post-occupancy conditions of a residential building in Seville, built in the 1950s and belonging to national heritage. The results obtained show major discrepancies between thermal indoor data collected and comfort conditions, both in summer and winter, which are solved by the sporadic use of cooling and heating devices present in the dwellings, thus leading to less energy consumption than expected. This is a common occurrence in multi-family housing units from the Mediterranean arc: there are many periods of the year in which a vast number of the population lives in poor energy conditions. Full article
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Open AccessArticle
Side-View Atmospheres under Outdoor Midday High Luminance
Buildings 2016, 6(4), 53; doi:10.3390/buildings6040053 -
Abstract
This work deals with daylighting for indoor quality atmospheres, considering building skins and side-views. We also tested the vision perception provided by highly glazed façades. Several Spanish restaurants were analyzed, and two were assessed and measured under outside midday high luminance. The selected
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This work deals with daylighting for indoor quality atmospheres, considering building skins and side-views. We also tested the vision perception provided by highly glazed façades. Several Spanish restaurants were analyzed, and two were assessed and measured under outside midday high luminance. The selected pictures can be identified as restaurants via MIT Scene Recognition software and are used to demonstrate working, stressful, and socializing atmospheres. Light and vision detailed analysis was performed defining three workplanes—“table”, “person”, and “outside”—from the viewpoint of the user. The obtained DGP (daylight glare probability) for the first case (facing southeast) shows a higher glare probability than the second (facing north). In both restaurants, there is notable spatial contrast and high information content. If, in the overall perception, the adaptation from the intermediate workplane is considered, the DGP is lower than if only one workplane is considered. The conducted indicative survey shows that there is a high light contrast, and there are some undesirable visual elements. The studied fully glazed façades tend to provide fraught atmospheres. These would be useful for some stimulating activities; however, for calm restaurants that offer tasting menus with quality food, it seems that the studied fully glazed façades may not be suitable. Full article
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Open AccessArticle
Assessment of the Impact of Cool Roofs in Temperate Climates through a Comparative Experimental Campaign in Outdoor Test Cells
Buildings 2016, 6(4), 52; doi:10.3390/buildings6040052 -
Abstract
Over the last few decades many bibliographical studies have been conducted on cool roofs, by analyzing both the energy performance during summer and winter seasons and their contribution in mitigating the urban heat island effect. This paper describes the experimentation carried out in
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Over the last few decades many bibliographical studies have been conducted on cool roofs, by analyzing both the energy performance during summer and winter seasons and their contribution in mitigating the urban heat island effect. This paper describes the experimentation carried out in three outdoor test cells to comparatively assess the behavior of a cool roof solution with respect to a ventilated-roof and a warm-roof. The monitored data have confirmed that in summer cool roofs are the best solution, with respect to traditional tile roofing, sensibly reducing surface temperatures as a function of the solar direct radiation level (15–25 °C for I > 600 W/m2 and 5–15 °C for I < 300 W/m2, independently of the season). Furthermore, cool roofs involve an energy saving related to summer cooling by about 20% as to a warm-roof and 15%–20% as to a vented-roof. During winter, cool roofs improve the heating energy performance of a vented-roof by about 12%, against a slightly increased consumption (<5%) if compared to a warm-roof. These data confirm that, in temperate climates, cool roofs are appropriate solutions to sensibly improve summer energy performances with a negligible negative impact during winter, and to positively contribute to the mitigation of the heat island effect. Full article
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Open AccessFeature PaperArticle
History as an Instrument in the Development of Historical Danish Villages
Buildings 2016, 6(4), 51; doi:10.3390/buildings6040051 -
Abstract
A central contemporary societal discussion in Denmark concerns settlements that have poor connectivity and are geographically distant to main towns and cities. These settlements are called “outskirts.” Historically significant villages in these outskirts are being transformed in order to counteract a general destitution
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A central contemporary societal discussion in Denmark concerns settlements that have poor connectivity and are geographically distant to main towns and cities. These settlements are called “outskirts.” Historically significant villages in these outskirts are being transformed in order to counteract a general destitution of decrepit houses and public spaces. This research article explains the relationship between spatial alterations and the inherent historical structures these villages contain. The article analyses three student projects and examines how they relate to and gain from history in the development plans for a concrete exemplary case village in Denmark. The projects represent various ways in which the past is conceived and applied to the suggested concepts. The different approaches to history found in the student projects call for an open-minded position towards the assessment of historical structures worthy of preservation when operating in a generic context such as the Danish villages. Further, the students’ prioritisation of preservation of historical structures and phenomena alters from the analysis phase to the project development phase. This observation questions the traditional practice of developing plans based on a predefined analysis of heritage and suggests that heritage assessment be separated from project development. Full article
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Open AccessArticle
Optimized Load Shedding Approach for Grid-Connected DC Microgrid Systems under Realistic Constraints
Buildings 2016, 6(4), 50; doi:10.3390/buildings6040050 -
Abstract
The microgrid system is an answer to the necessity of increasing renewable energy penetration and also works as a bridge for the future smart grid. Considering the microgrid system applied to commercial building equipped with photovoltaic sources, the usage of a DC microgrid
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The microgrid system is an answer to the necessity of increasing renewable energy penetration and also works as a bridge for the future smart grid. Considering the microgrid system applied to commercial building equipped with photovoltaic sources, the usage of a DC microgrid architecture can improve the efficiency of the system, while ensuring robustness and reducing the overall energy cost. Given the power grid stress and the intermittency of the DC microgrid power production, backup power provision and load shedding operations may occur to stabilize the DC bus voltage. Based on the knapsack problem formulation, this paper presents a realistic optimization approach to shedding a building’s appliances, considering the priority of each appliance, and also considering a minimum amount of load that must be attended. The problem is solved by mixed integer linear programming and the CPLEX solver. The proposed architecture ensures critical load supply and voltage stabilization through the real-time operation of the operational algorithm allowing the load shedding optimization approach to be applied without compromising the robustness of the system. The results obtained by simulation prove that the DC microgrid is able to supply the building power network by applying the load shedding optimization program to overcome, mainly, the renewable energy intermittency. Full article
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