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Volume 10
Issue 5
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Buildings, Volume 10, Issue 5 (May 2020) – 17 articles

Cover Story (view full-size image): One method for controlling damage to non-structural walls is to cast exterior non-structural concrete wall elements to be monolithic with frame elements, without anchoring the wall longitudinal bar. The non-anchorage of the wall’s longitudinal bar significantly increases the drift capacity of the wall and decreases damage. The non-anchorage of non-structural hanging walls, having boundary confinements, was found to exhibit a higher drift and strength capacity than similar walls with anchored detailing and no boundary confinements. The boundary confinements were observed to have a greater influence on the capability of the hanging wall when placed alongside non-anchored detailing reinforcement. View this paper.
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10 pages, 1378 KiB  
Article
Research for the Presence of Unmanned Aerial Vehicle inside Closed Environments with Acoustic Measurements
by Giuseppe Ciaburro, Gino Iannace and Amelia Trematerra
Buildings 2020, 10(5), 96; https://doi.org/10.3390/buildings10050096 - 23 May 2020
Cited by 16 | Viewed by 3464
Abstract
Small UAVs (unmanned aerial vehicle) can be used in many sectors such as the acquisition of images or the transport of objects. Small UAVs have also been used for terrorist activities or to disturb the flight of airplanes. Due to the small size [...] Read more.
Small UAVs (unmanned aerial vehicle) can be used in many sectors such as the acquisition of images or the transport of objects. Small UAVs have also been used for terrorist activities or to disturb the flight of airplanes. Due to the small size and the presence of only rotating parts, drones escape traditional controls and therefore represent a danger. This paper reports a methodology for identifying the presence of small UAVs inside a closed environment by measuring the noise emitted during the flight. Acoustic measurements of the noise emitted by a drone inside a large environment (12.0 × 30.0 × 12.0 m) were performed. The noise was measured with a sound level meter placed at different distances (5, 10, and 15 m), to characterize the noise in the absence of anthropic noise. In this configuration, a typical tonal component of drone noise is highlighted at the frequency of one-third of an octave at 5000 Hz due to the rotation of the blades. This component is also present 15 m away from the source point. Subsequent measurements were performed by introducing into the environment, through a loudspeaker, the anthropogenic noise produced by the buzz of people and background music. It is possible to distinguish the typical tonal component of UAV noise at the frequency of 5000 Hz even when the level of recording of anthropogenic noise emitted by the loudspeaker is at the maximum power tested. It is therefore possible to search for the presence of small UAVs inside a specific closed environment with only acoustic measurements, paying attention to the typical frequency of noise emission equal to 5000 Hz. Full article
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12 pages, 4105 KiB  
Article
Optimal Control Method for HVAC Systems in Offices with a Control Algorithm Based on Thermal Environment
by Sung-Kyung Kim, Won-Hwa Hong, Jung-Ha Hwang, Myung-Sup Jung and Yong-Seo Park
Buildings 2020, 10(5), 95; https://doi.org/10.3390/buildings10050095 - 21 May 2020
Cited by 9 | Viewed by 4566
Abstract
This study examined a method to reduce energy consumption in office buildings. Correspondingly, an optimal control method was proposed for heating, ventilation, and air conditioning (HVAC) systems via two control algorithms that considered the indoor thermal environment. The control algorithms were developed by [...] Read more.
This study examined a method to reduce energy consumption in office buildings. Correspondingly, an optimal control method was proposed for heating, ventilation, and air conditioning (HVAC) systems via two control algorithms that considered the indoor thermal environment. The control algorithms were developed by considering temperature and humidity as the factors of the indoor thermal environment that influence the control of HVAC systems and the predicted mean vote comfort ranges. Furthermore, an experiment was performed using office equipment that incorporated the two control algorithms for HVAC systems, and the correlation between changes in the thermal environment within the office and the occupant’s comfort levels was estimated via an actual survey. The results demonstrated that the proposed control method for HVAC systems, which considered the comfort ranges of temperature and humidity and the thermal adaptation capability, can efficiently maintain the occupant’s comfort with lower energy usage compared with conventional HVAC systems. Thus, the use of the control method contributes to the reduction of total energy consumption in buildings with HVAC systems. Full article
(This article belongs to the Section Building Energy, Physics, Environment, and Systems)
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16 pages, 4493 KiB  
Article
Simulation-Based Management of Construction Companies under the Circular Economy Concept—Case Study
by Pedro Núñez-Cacho Utrilla, Jarosław Górecki and Juan Manuel Maqueira
Buildings 2020, 10(5), 94; https://doi.org/10.3390/buildings10050094 - 16 May 2020
Cited by 22 | Viewed by 6146
Abstract
Society and the business world are paying more and more attention to the Circular Economy (CE) principles. The construction industry is no stranger to this issue, and the companies are transitioning towards sustainable production models. However, it is not easy to predict when [...] Read more.
Society and the business world are paying more and more attention to the Circular Economy (CE) principles. The construction industry is no stranger to this issue, and the companies are transitioning towards sustainable production models. However, it is not easy to predict when and to what extent a company implements the CE. To measure this process, a scorecard, that includes the main Key Performance Indicators (KPIs) of the construction industry, related to the CE, was designed. Thus, the objective of this article is to design and test the CE-dashboard applicable to the construction industry. To do it, firstly, a literature review is performed. The next step is the selection of the KPIs collected in the literature, more suitable for reporting information about CE. Afterwards, a simulation based on the Monte Carlo technique performs. After multiple iterations, this method establishes the most probable KPI values as a result, which will be confronted with the limits used in the scorecard. With all this information, the dashboard emerges in Qlik software. Finally, a test of this dashboard takes place according to the information about KPIs from one of the leading Spanish companies (General Contractor (GC) building company). This step brings the validity of the created measurement instrument. Full article
(This article belongs to the Collection Construction Management – Future Innovations, Methods, Techniques and Technologies)
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13 pages, 1076 KiB  
Article
The Energy Cost of Cold Thermal Discomfort in the Global South
by Abdulla N. Alnuaimi and Sukumar Natarajan
Buildings 2020, 10(5), 93; https://doi.org/10.3390/buildings10050093 - 15 May 2020
Cited by 8 | Viewed by 3596
Abstract
The Global South, much of it in warm tropical latitudes, is expected to double its total energy demand by 2050. In addition to increased mean demand, greater demand for space cooling during external temperature peaks will exacerbate the strain on already fragile energy [...] Read more.
The Global South, much of it in warm tropical latitudes, is expected to double its total energy demand by 2050. In addition to increased mean demand, greater demand for space cooling during external temperature peaks will exacerbate the strain on already fragile energy networks. Recent anecdotal evidence that a proportion of the increase in cooling demand is driven by cold—rather than warm—indoor thermal discomfort, suggests the imposition of an unnecessary cooling energy cost. Here, we investigate the impact of this cost on the expanding Global South using field data from four cities in India, Philippines, and Thailand. We observe that mean cold discomfort across the four cities is roughly 45 percentage points higher than warm discomfort, suggesting warmer indoor temperatures would not only lower overall discomfort but also reduce cooling energy demand. Computer simulations using a calibrated building model reveal that average savings of 10%/Kelvin and peak reductions of 3%–19%, would be feasible across the expected external temperature range in these cities. This suggests that more climatically appropriate indoor thermal comfort standards in the Global South would not only significantly counteract the expected rise in energy demand, but also produce more comfortable indoor conditions and reduce peak demand. Full article
(This article belongs to the Section Building Energy, Physics, Environment, and Systems)
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9 pages, 1698 KiB  
Article
Deformability of Glued Laminated Beams with Combined Reinforcement
by Justyna Sobczak-Piąstka, Svyatoslav S. Gomon, Mykola Polishchuk, Sviatoslav Homon, Petro Gomon and Victor Karavan
Buildings 2020, 10(5), 92; https://doi.org/10.3390/buildings10050092 - 12 May 2020
Cited by 10 | Viewed by 4237
Abstract
Wood is one of the most popular renewable natural materials. Nowadays, raw wood is hardly ever used in the construction industry. It has been substituted by glued laminated wood that is processed with the use of high-tech methods, thus eliminating the principal flaws [...] Read more.
Wood is one of the most popular renewable natural materials. Nowadays, raw wood is hardly ever used in the construction industry. It has been substituted by glued laminated wood that is processed with the use of high-tech methods, thus eliminating the principal flaws and defects of the natural material. The deformability of glued laminated beams with combined reinforcement has been studied, under which the steel reinforcement of the periodic profile was placed in the dappings of the upper compressed zone, while ribbon-reinforced composite was glued to the bottom of the stretched zone. The graphical charts for the layer change of the deformations of wood, steel, and composite reinforcement from the beginning of the loading application to the moment of destruction are presented. Full article
(This article belongs to the Special Issue Recent Advancements and Trends on the Design of “Timber Composite” Solutions for Enhanced Buildings)
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23 pages, 9983 KiB  
Article
Predicting Maximum and Cumulative Response of A Base-isolated Building Using Pushover Analysis
by Kenji Fujii, Yoshiyuki Mogi and Takumi Noguchi
Buildings 2020, 10(5), 91; https://doi.org/10.3390/buildings10050091 - 11 May 2020
Cited by 4 | Viewed by 4085
Abstract
The evaluation of the maximum and cumulative response is an important issue for the seismic design of new base-isolated buildings. This study predicts the maximum and cumulative response of a 14-story reinforced concrete base-isolated building using a set of pushover analyses. In the [...] Read more.
The evaluation of the maximum and cumulative response is an important issue for the seismic design of new base-isolated buildings. This study predicts the maximum and cumulative response of a 14-story reinforced concrete base-isolated building using a set of pushover analyses. In the proposed pushover analysis method, the maximum and cumulative responses of the first and higher modes are evaluated from the nonlinear analysis of equivalent single-degree-of-freedom (SDOF) models. Then, the maximum local responses are predicted by enveloping the two pushover analysis results by referring to the contribution of the first and higher modal responses, while the cumulative strain energies of the lead-rubber bearings and steel dampers are predicted from the cumulative response of the first mode. The results reveal that the responses predicted by the proposed set of pushover analyses have satisfactory accuracy. Full article
(This article belongs to the Special Issue Seismic Analysis of Buildings)
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4 pages, 959 KiB  
Correction
Correction: Emami, N., et al. A Life Cycle Assessment of Two Residential Buildings Using Two Different LCA Database-Software Combinations: Recognizing Uniformities and Inconsistencies. Buildings, 2019, 9, 20
by Nargessadat Emami, Jukka Heinonen, Björn Marteinsson, Antti Säynäjoki, Juha-Matti Junnonen, Jani Laine and Seppo Junnila
Buildings 2020, 10(5), 90; https://doi.org/10.3390/buildings10050090 - 09 May 2020
Cited by 1 | Viewed by 2925
Abstract
We noticed that the Figures 2 and 3 have become the same in the final version of this paper [...] Full article
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18 pages, 3730 KiB  
Article
Impact of the Reinforcement Detailing on Seismic Performance of Isolated Non-structural Walls
by Walid Ahmad Safi, Yo Hibino, Koichi Kusunoki, Yasushi Sanada and Tomohisa Mukai
Buildings 2020, 10(5), 89; https://doi.org/10.3390/buildings10050089 - 07 May 2020
Cited by 1 | Viewed by 4795
Abstract
Following the observation of severe damage to structurally isolated non-structural reinforced concrete walls after major earthquakes, researchers began to reassess the effectiveness and connection detail of non-structural walls to moment-resisting frames. A method to control damages to the non-structural wall, is to cast [...] Read more.
Following the observation of severe damage to structurally isolated non-structural reinforced concrete walls after major earthquakes, researchers began to reassess the effectiveness and connection detail of non-structural walls to moment-resisting frames. A method to control damages to the non-structural wall, is to cast exterior non-structural concrete wall elements to be monolithic with frame elements, without anchoring the wall longitudinal bar. The non-anchorage of the wall longitudinal bar significantly increases the drift capacity of the wall and decreases damage. Using an experimental approach, this study assesses the influence of reinforcement detailing and quantity of the transverse reinforcements on the strength and drift capacity of the non-structural hanging wall. This study further evaluates the workability mechanism of the transverse reinforcements and reinforcement detailing with concrete. The non-anchorage of hanging walls, having boundary confinements, was found to exhibit a higher drift and strength capacity than similar walls with the anchored detailing without boundary confinements. The strength capacity of the anchored detailing hanging walls with minimum amounts of reinforcements was higher than that of the non-anchored specimen. The boundary confinements were found to be more influential on the capability of the hanging wall when placed along with non-anchored detailing reinforcement. Full article
(This article belongs to the Section Building Structures)
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18 pages, 4751 KiB  
Article
Multi-objective Building Design Optimization under Operational Uncertainties Using the NSGA II Algorithm
by Shobhit Chaturvedi, Elangovan Rajasekar and Sukumar Natarajan
Buildings 2020, 10(5), 88; https://doi.org/10.3390/buildings10050088 - 07 May 2020
Cited by 24 | Viewed by 6061
Abstract
Operational uncertainties play a critical role in determining potential pathways to reduce the building energy footprint in the Global South. This paper presents the application of a non-dominated sorting genetic (NSGA II) algorithm for multi-objective building design optimization under operational uncertainties. A residential [...] Read more.
Operational uncertainties play a critical role in determining potential pathways to reduce the building energy footprint in the Global South. This paper presents the application of a non-dominated sorting genetic (NSGA II) algorithm for multi-objective building design optimization under operational uncertainties. A residential building situated in a mid-latitude steppe and desert region (Köppen climate classification: BSh) in the Global South has been selected for our investigation. The annual building energy consumption and the total number of cooling setpoint unmet hours (h) were assessed over 13,122 different energy efficiency measures. Six Pareto optimal solutions were identified by the NSGA II algorithm. Robustness of Pareto solutions was evaluated by comparing their performance sensitivity over 162 uncertain operational scenarios. The final selection for the most optimal energy efficiency measure was achieved by formulating a robust multi-criteria decision function by incorporating performance, user preference, and reliability criteria. Results from this robust approach were compared with those obtained using a deterministic approach. The most optimal energy efficiency measure resulted in 9.24% lower annual energy consumption and a 45% lower number of cooling setpoint unmet h as compared to the base case. Full article
(This article belongs to the Section Building Energy, Physics, Environment, and Systems)
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19 pages, 6913 KiB  
Article
The Structural Performance of Reinforced Concrete Members with Monolithic Non-Structural Walls under Static and Dynamic Loads
by Walid Ahmad Safi, Yo Hibino, Koichi Kusunoki, Tomohisa Mukai, Yasushi Sanada, Izumi Nakamura and Satoru Fukai
Buildings 2020, 10(5), 87; https://doi.org/10.3390/buildings10050087 - 06 May 2020
Cited by 1 | Viewed by 4890
Abstract
The required base shear and drift limit for post-disaster management buildings have increased in the Japanese Building Code following major seismic events. One method to satisfy these requirements for reinforced concrete frame buildings is to cast exterior non-structural concrete wall elements to be [...] Read more.
The required base shear and drift limit for post-disaster management buildings have increased in the Japanese Building Code following major seismic events. One method to satisfy these requirements for reinforced concrete frame buildings is to cast exterior non-structural concrete wall elements to be monolithic with frame elements, but without anchoring the longitudinal wall reinforcing. This provides additional stiffness and strength while limiting significant damage in the non-structural wall. In this study, the structural performances of such elements were evaluated using static and dynamic experimental tests. The result indicates that non-structural walls that were neither isolated by seismic slits nor anchored to the adjacent walls with longitudinal reinforcements experienced less damage and higher deformability compared with walls having seismic slits. The confinement reinforcing impact was not observed on the strength and drift capacity of the beam member, owing to the large number of transverse reinforcements. However, the confinements limited the damage and nearly prevented concrete crushing. The maximum horizontal load of the specimen could be predicted using cross-sectional analysis, and the authors propose a simple equation to predict it with sufficient accuracy. Full article
(This article belongs to the Special Issue Advanced Seismic Protection Technologies for New and Existing Structures)
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13 pages, 5277 KiB  
Article
A New Proposal for the Shear Strength Prediction of Beams Longitudinally Reinforced with Fiber-Reinforced Polymer Bars
by Czesław Bywalski, Michał Drzazga, Mieczysław Kamiński and Maciej Kaźmierowski
Buildings 2020, 10(5), 86; https://doi.org/10.3390/buildings10050086 - 03 May 2020
Cited by 8 | Viewed by 3293
Abstract
This paper investigates composite reinforcement with regard to its use as longitudinal reinforcement. The methods used to calculate the shear strength of concrete members reinforced with fibre-reinforced polymer (FRP) bars are analysed. The main parameters having a bearing on the shear strength of [...] Read more.
This paper investigates composite reinforcement with regard to its use as longitudinal reinforcement. The methods used to calculate the shear strength of concrete members reinforced with fibre-reinforced polymer (FRP) bars are analysed. The main parameters having a bearing on the shear strength of beams reinforced with composite bars are defined. A comparative analysis of the shear strength calculating algorithms provided in the available design recommendations concerning FRP reinforcement and formulas derived by others researchers is carried out. A synthesis of the research to date on sheared concrete members reinforced longitudinally with FRP bars is made. The results of the studies relating to shear strength are compared with the theoretical results yielded by the considered algorithms. A new approach for estimating the shear capacity of support zones reinforced longitudinally with FRP bars without shear reinforcement was proposed and verified. A satisfactory level of model fit was obtained—the best among the available proposals. Taking into account the extended base of destructive testing results, the estimation of the shear strength in accordance with the proposed model can be used as an accompanying (non-destructive) method for the empirical determination of shear resistance of longitudinally reinforced FRP bars. Full article
(This article belongs to the Special Issue Non-destructive Testing for Building Evaluation)
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21 pages, 972 KiB  
Article
Investigating U.S. Industry Practitioners’ Perspectives towards the Adoption of Emerging Technologies in Industrialized Construction
by Bing Qi, Mohamad Razkenari, Jiaxuan Li, Aaron Costin, Charles Kibert and Shuyu Qian
Buildings 2020, 10(5), 85; https://doi.org/10.3390/buildings10050085 - 30 Apr 2020
Cited by 26 | Viewed by 5219
Abstract
In recent years, a growing amount of research has focused on improving the performance of industrialized construction using emerging technologies. It is still necessary to have an in-depth understanding of the industry practitioners’ perspectives on the application of emerging technologies. Thus, a well-designed [...] Read more.
In recent years, a growing amount of research has focused on improving the performance of industrialized construction using emerging technologies. It is still necessary to have an in-depth understanding of the industry practitioners’ perspectives on the application of emerging technologies. Thus, a well-designed survey was distributed to industry practitioners who have been involved in industrialized construction projects. Then, a set of data analysis methods were utilized on the collected data to address the proposed four specific research questions. Results indicate that 3D and nD models, sensing techniques, and business information models are the technologies with the highest current utilization level. Extended reality, additive manufacturing, and advanced data analytics are the technologies with the highest development potential. Project inputs (e.g., cost, time, and labor), as well as implementation cost and software constraints (e.g., capital costs, software upgrading, and compatibility), are the main factors that affect practitioners’ decisions to adopt emerging technologies in industrialized projects. Inter-group comparison results indicate that company background has little significant influence on practitioners’ perspectives, while personal career profiles can significantly affect practitioners’ perspectives. Significantly, by uncovering the suggestions and viewpoints of practitioners, this paper aligns academic research with industry needs, ultimately providing guidance on future research directions and applications. Full article
(This article belongs to the Special Issue Construction 4.0)
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18 pages, 4034 KiB  
Article
Modulus of Elasticity and Compressive Strength of Tuff Masonry: Results of a Wide Set of Flat-Jack Tests
by Mariateresa Guadagnuolo, Marianna Aurilio, Andrea Basile and Giuseppe Faella
Buildings 2020, 10(5), 84; https://doi.org/10.3390/buildings10050084 - 28 Apr 2020
Cited by 30 | Viewed by 8883
Abstract
The assessment of the modulus of elasticity and compressive strength of masonry is a fundamental step in the seismic analysis of existing structures. In this paper, the representativeness of the values provided by flat-jack tests for tuff masonry is investigated through the analysis [...] Read more.
The assessment of the modulus of elasticity and compressive strength of masonry is a fundamental step in the seismic analysis of existing structures. In this paper, the representativeness of the values provided by flat-jack tests for tuff masonry is investigated through the analysis of a very large and homogeneous number of tests (635 double flat-jack tests). Data relate to existing buildings belonging to different historical and/or construction periods, located throughout the Campania region (Italy) in areas with different peculiarities. Results are compared with the values provided by Italian Building Code, containing ranges of the elastic modulus and compressive strength for different types of masonry. The values of flat-jack tests are then compared with laboratory tests available in the literature. Finally, comparisons with code equations are performed. It is shown that equations correlating the masonry compressive strength with the modulus of elasticity provide values larger than the mean of experimental data, whereas the equations correlating the masonry compressive strength with the strength of components provide lower values, if block and mortar strengths are varied within a probable and wide range. Full article
(This article belongs to the Section Building Structures)
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35 pages, 3734 KiB  
Review
Front End Projects Benefits Realisation from a Requirements Management Perspective—A Systematic Literature Review
by Joas Serugga, Mike Kagioglou and Patricia Tzortzopoulos
Buildings 2020, 10(5), 83; https://doi.org/10.3390/buildings10050083 - 28 Apr 2020
Cited by 5 | Viewed by 5867
Abstract
The recent notable emergence of a body of research in requirements management on one hand and benefits realisation has contributed to addressing a growing need for improved performance in Architecture, Engineering and Construction (AEC) projects. However, front end design (FED) as one of [...] Read more.
The recent notable emergence of a body of research in requirements management on one hand and benefits realisation has contributed to addressing a growing need for improved performance in Architecture, Engineering and Construction (AEC) projects. However, front end design (FED) as one of the vital processes in the project life cycle and delivery has attracted limited research to date within this understanding. This paper aims to map current evidence on requirements management in facilitating benefits realisation from an FED perspective. This is to bring about an updated and unified position on requirements management for its impact on design decision making. A systematic review of the literature covering the last ten years (2008–2018) aims first to build understanding and support identification of these emergent conceptual positions and secondly underscore essential requirements and their categorisations that impact on design discourse in FED. One hundred sixty-one peer-reviewed journal papers in the areas of benefits realisation and/or requirements management and/or FED based are identified on a pre-determined inclusion and exclusion criteria. Thirty-six requirements are identified as important in influencing use case changes important in design decision making broadly grouped into nine major categories. Following analysis, this research finds little evidence supporting an integrated requirements management practice and understanding to support design decision making. The research further finds bias in current research discourse towards four requirements categories (technical, economics, governance and environment); and 14 requirements, dominated by three strategic values, collaboration and project governance, with over 80% share of literature. The least 14 requirements such as “flow of spaces, social status/aspiration, mobility and integrated design” among others only account for less than 10% of literature. The authors argue for new research to bridge this gap, highlight the essential role of requirements management and broaden understanding to improve benefits realisation, particularly for FED processes. Full article
(This article belongs to the Section Construction Management, and Computers & Digitization)
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20 pages, 3262 KiB  
Article
Perceived Control in an Office Test Cell, a Case Study
by Nicola Lolli, Alessandro Nocente and Steinar Grynning
Buildings 2020, 10(5), 82; https://doi.org/10.3390/buildings10050082 - 27 Apr 2020
Cited by 5 | Viewed by 2932
Abstract
The influence of different control strategies on the user’s satisfaction in cell offices was studied in a full-scale facility in Trondheim, Norway. Eleven participants used two test cells as a workspace and answered a computer-based questionnaire for reporting their perceived thermal and visual [...] Read more.
The influence of different control strategies on the user’s satisfaction in cell offices was studied in a full-scale facility in Trondheim, Norway. Eleven participants used two test cells as a workspace and answered a computer-based questionnaire for reporting their perceived thermal and visual comfort, and any desired changes in the cell environment. Concurrently, the indoor operative temperature and illuminance were registered. Two different strategies for controlling the indoor environment were used in the case study. In Cell A, the ceiling-mounted lights, the window blind, and a water-based radiator were controlled by the main acquisition and control system, whereas in Cell B, these were manually controlled by the users. In both cells, the window opening was user-controlled, except for a small motorised window, which was automated in Cell A, and user-controlled in Cell B. The results show that the occupants of Cell B first tended to open the window, then to adjust their clothing level, and finally to lower the blind when the operative temperature increased. The recorded Thermal Sensation Votes (TSVs) and Illuminance Ratings (IRs) show that the limitation of control opportunities in Cell A increases the level of thermal and visual dissatisfaction. Full article
(This article belongs to the Section Architectural Design, Urban Science, and Real Estate)
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13 pages, 1767 KiB  
Article
Technical Performance Overview of Bio-Based Insulation Materials Compared to Expanded Polystyrene
by Cassandra Lafond and Pierre Blanchet
Buildings 2020, 10(5), 81; https://doi.org/10.3390/buildings10050081 - 26 Apr 2020
Cited by 23 | Viewed by 6755
Abstract
The energy efficiency of buildings is well documented. However, to improve standards of energy efficiency, the embodied energy of materials included in the envelope is also increasing. Natural fibers like wood and hemp are used to make low environmental impact insulation products. Technical [...] Read more.
The energy efficiency of buildings is well documented. However, to improve standards of energy efficiency, the embodied energy of materials included in the envelope is also increasing. Natural fibers like wood and hemp are used to make low environmental impact insulation products. Technical characterizations of five bio-based materials are described and compared to a common, traditional, synthetic-based insulation material, i.e., expanded polystyrene. The study tests the thermal conductivity and the vapor transmission performance, as well as the combustibility of the material. Achieving densities below 60 kg/m3, wood and hemp batt insulation products show thermal conductivity in the same range as expanded polystyrene (0.036 kW/mK). The vapor permeability depends on the geometry of the internal structure of the material. With long fibers are intertwined with interstices, vapor can diffuse and flow through the natural insulation up to three times more than with cellular synthetic (polymer) -based insulation. Having a short ignition times, natural insulation materials are highly combustible. On the other hand, they release a significantly lower amount of smoke and heat during combustion, making them safer than the expanded polystyrene. The behavior of a bio-based building envelopes needs to be assessed to understand the hygrothermal characteristics of these nontraditional materials which are currently being used in building systems. Full article
(This article belongs to the Section Building Materials, and Repair & Renovation)
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16 pages, 3795 KiB  
Article
Early-Stage Temperature Gradients in Glazed Spandrels Due to Aesthetical Features to Support Design for Thermal Shock
by Jacopo Montali, Luciano Laffranchini and Carlo Micono
Buildings 2020, 10(5), 80; https://doi.org/10.3390/buildings10050080 - 26 Apr 2020
Cited by 2 | Viewed by 3199
Abstract
Investigating thermal breakage of glass panes requires careful analysis of the environmental boundary conditions to determine the expected thermal gradient between the sunlit and shaded parts of the glass. This is particularly critical for glazed spandrels, where an opaque posterior insulation layer normally [...] Read more.
Investigating thermal breakage of glass panes requires careful analysis of the environmental boundary conditions to determine the expected thermal gradient between the sunlit and shaded parts of the glass. This is particularly critical for glazed spandrels, where an opaque posterior insulation layer normally increases the system’s temperatures. The choice of the spandrel system should also be evaluated against the aesthetical impression that it conveys. The aim of this study is to understand how early design factors, such as aesthetical features like color, are driving temperature gradients in the glazed pane to design for thermal shock. Multiple finite-differences analyses in a quasi-static regime for non-ventilated, single glazed spandrels were conducted in three locations (London, New York and Mumbai). Results were then analyzed via a general linear model in SAS 9.4 and Tuckey post hoc analysis. It was shown that a low absorptance of the back insulation (e.g., light color) can lead to a wide range of possible temperature gradients depending on the glass transparency, with higher values of the thermally induced temperature gradients for more opaque glasses. Conversely, a high absorptance of the insulation layer leads to moderate values of glass temperature gradients, which are not substantially sensitive to the effect of the glass transparency. Full article
(This article belongs to the Section Building Materials, and Repair & Renovation)
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