Showing papers in "Buildings in 2018"

The Vertical Farm: A Review of Developments and Implications for the Vertical City

Abstract: This paper discusses the emerging need for vertical farms by examining issues related to food security, urban population growth, farmland shortages, “food miles”, and associated greenhouse gas (GHG) emissions. Urban planners and agricultural leaders have argued that cities will need to produce food internally to respond to demand by increasing population and to avoid paralyzing congestion, harmful pollution, and unaffordable food prices. The paper examines urban agriculture as a solution to these problems by merging food production and consumption in one place, with the vertical farm being suitable for urban areas where available land is limited and expensive. Luckily, recent advances in greenhouse technologies such as hydroponics, aeroponics, and aquaponics have provided a promising future to the vertical farm concept. These high-tech systems represent a paradigm shift in farming and food production and offer suitable and efficient methods for city farming by minimizing maintenance and maximizing yield. Upon reviewing these technologies and examining project prototypes, we find that these efforts may plant the seeds for the realization of the vertical farm. The paper, however, closes by speculating about the consequences, advantages, and disadvantages of the vertical farm’s implementation. Economic feasibility, codes, regulations, and a lack of expertise remain major obstacles in the path to implementing the vertical farm.

Life Cycle Assessment (LCA) of Different Kinds of Concrete Containing Waste for Sustainable Construction

Abstract: Concrete production causes significant environmental damage during its entire life cycle due to the large consumption of natural aggregate. The aim of this research was to use the Life Cycle Assessment (LCA) methodology to conduct a comparative analysis of four different concrete mixtures, i.e., construction and demolition waste (CDW), incinerator ashes, marble sludge, and blast furnace slag. The LCA study was implemented in the Campania Region of Italy. The main contribution of the study was that it proposed the use of “green” recycled aggregates in concrete production in order to assess the reduction of potential adverse impacts, from both environmental and energy perspectives. SimaPro© software was used to conduct the analysis. The main results of the research showed that the recycled aggregates that were analyzed were preferable to traditional concrete. In particular, the recycled aggregate that had the least adverse impact on the environment was blast furnace waste.

Strategies for Applying the Circular Economy to Prefabricated Buildings

Abstract: In this paper, a circular-economy framework is applied to the prefabricated building sector to explore the environmental advantages of prefabrication in terms of reduction, reusability, adaptability, and recyclability of its components. A qualitative approach is used to revisit the design, construction, and demolition stages of prefabricated buildings; in so doing, the circular-economy framework is applied to foster circular prefabricated modi operandi. Prefabrication of buildings can be divided into four entities: elements and components, panels (or non-volumetric elements), volumetric, and entire modules. Through an analysis of published research on how the circular economy can be applied to different industry sectors and production processes, seven strategies emerged, each of which revealed the potential of improving the circular economy of buildings. The first strategy is reduction of waste through a lean production chain. By reusing the waste, the second strategy investigates the use of by-products in the production of new components. The third strategy focuses on the reuse of replacement parts and components. The fourth strategy is based on design toward adaptability, respectively focusing on reusability of components and adapting components for a second use with a different purpose. Similarly, the fifth strategy considers the implications of designing for disassembly with Building Information Modeling so as to improve the end-of-life deconstruction phase. The sixth strategy focuses on design with attention to recyclability of used material. Finally, the seventh strategy considers the use of tracking technologies with embedded information on components’ geometric and mechanic characteristics as well as their location and life cycle to enable second use after deconstruction. It is demonstrated that prefabricated buildings are key to material savings, waste reduction, reuse of components, and various other forms of optimization for the construction sector. By adopting the identified strategies in prefabricated buildings, a circular economy could be implemented within the construction industry. Finally, seven guidelines were distilled from the review and linked to the identified strategies. Owing to their degree of adaptability and capacity of being disassembled, prefabricated buildings would allow waste reduction and facilitate a second life of components.

Recent Progress in Daytime Radiative Cooling: Is It the Air Conditioner of the Future?

Abstract: Radiative cooling is a well-researched area. For many years, surfaces relying on radiative cooling failed to exhibit a sub-ambient surface temperature under the sun because of the limited reflectance in the solar spectrum and the reduced absorptivity in the atmospheric window. The recent impressive developments in photonic nanoscience permitted to produce photonic structures exhibiting surface temperatures much below the ambient temperature. This paper aims to present and analyze the main recent achievements concerning daytime radiative cooling technologies. While the conventional radiative systems are briefly presented, the emphasis is given on the various photonic radiative structures and mainly the planar thin film radiators, metamaterials, 2 and 3D photonic structures, polymeric photonic technologies, and passive radiators under the form of a paint. The composition of each structure, as well as its experimental or simulated thermal performance, is reported in detail. The main limitations and constraints of the photonic radiative systems, the proposed technological solutions, and the prospects are presented and discussed.

Construction Technology Adoption Cube: An Investigation on Process, Factors, Barriers, Drivers and Decision Makers Using NVivo and AHP Analysis

Abstract: Due to the complexity, high-risk and conservative character of construction companies, advanced digital technologies do not become widely adopted in the short term, while vendors make determined efforts to overcome this and disseminate their technologies. This paper presents the methods of an investigation addressing the extremely complex issues related to the current practices of digital technology adoption in construction. It discusses how construction companies follow a specific logical process linked to need, project objectives, the characteristics of the adopting organization and the characteristics of the new technology to be adopted. The study aims to demonstrate a novel method of data collection and analysis, such as data and methodological triangulation techniques, including the use of NVivo and AHP to explore how companies make the decision to uptake new technology (e.g., advanced crane, tunnel boring machine or drones) by focusing on customer and vendor activities, their interactions, contributing factors and people involved in the process. The major original contribution of this paper is developing an innovative methodological cube for investigating the Construction Technology Adoption Process (CTAP) covering technology adoption, acceptance, diffusion and implementation concepts. CTAP is a framework that delineates the phases of the process that customer organizations use when deciding to adopt a new digital technology and the parallel vendor activities. The significance of these contributions is that they enable vendors to understand how to match their strategies with customer expectations in each phase of CTAP. It also provides a benchmark for new construction companies to use the current best practices of decision making. Future research is warranted to more clearly delineate any differences with respect to developing nations or related industries such as mining and property management.

HBIM and Virtual Tools: A New Chance to Preserve Architectural Heritage

Abstract: Nowadays, architectural heritage is increasingly exposed to dangers due to natural disasters or human invasive actions. However, management and conservation represent crucial phases within the life cycle of historical buildings. Unfortunately, the complexity of conservation practices and the lack of knowledge of historic buildings are the cause of an inefficient recovering process in case of emergencies. To overcome this problem, this research aims to ensure the preservation of relevant information through the use of building information modeling (BIM) methodology. By developing historic building information models (HBIMs), it is possible to enhance the architectural heritage. This represents an opportunity to incorporate digital media into the global heritage conservation field. To achieve this goal, a historical castle was selected as a case study; this unique piece of architecture is located in the Piedmont Region, close to city of Turin (Italy). The results show a direct relation between a historical digital model, finalized to the management of architectural and system components, and visualization tools. To conclude, the adoption of this strategy is an effective way to preserve and consult information using advanced visualization techniques based on augmented and virtual reality (AR and VR).

Advances in Structural Systems for Tall Buildings: Emerging Developments for Contemporary Urban Giants

Abstract: New developments of tall buildings of ever-growing heights have been continuously taking place worldwide. Consequently, many innovations in structural systems have emerged. This paper presents a retrospective survey of the main structural systems for tall buildings with emphasis on the advancements of recent, emerging, and potentially emerging systems. A structural systems chart that was previously developed by the authors has been updated in this paper to recognize, categorize and add the more recent structural systems. Recent trends of tubular structural systems in modified forms including the braced megatubes and diagrids are presented. Core-outrigger structural systems are discussed with emphasis on their adaptability. The potential of employing superframes for stand-alone and conjoined megatall buildings is predicted. As a means to solve today’s various project-specific complex design requirements, different mixed structural systems for supertall and megatall buildings are presented. This paper also discusses the widespread application of composite structural systems and recent trends of concrete cores for contemporary tall buildings. Finally, the future of tall buildings is predicted as the race for height continues.

Technical, Financial, and Social Barriers and Challenges in Deep Building Renovation: Integration of Lessons Learned from the H2020 Cluster Projects

Abstract: With a low rate of new building construction and an insufficient rate of existing building renovation, there is the need to step up the pace of building renovation with ambitious performance targets to achieve European Union (EU) climate change policies for 2050. However, innovative technologies, including, but not limiting to, plug and play (PnP) prefabricated facades, information and communications technology (ICT)-support for building management systems (BMS), the integration of renewable energy systems (RES), building information model (BIM) and building performance simulation models (BPSM), advanced heating, ventilation, and air conditioning (HVAC), advanced geomatics, 3D-printing, and smart connectors, cannot alone solve the problem of low renovation rates of existing buildings in Europe that is hindering reaching of EU-wide targets. A workshop was held at the Sustainable Place Conference 2018 to present, with an integrative approach, the experiences from four H2020 innovation actions, i.e., 4RinEU, P2ENDURE, Pro-GET-OnE, and MORE-CONNECT, which were united by their central aims of improving building energy performance through deep renovation practices. This article presents the outcomes of the joint workshop and interactive discussion, by focusing on technical, financial, and social added values, barriers and challenges, in the context of the building renovation processes tackled by the four projects. Conclusive remarks converge on the identification of open questions to address future innovation opportunities, as well as some recommendations to be used at a policy level and/or in future implementation projects.

Life-Cycle Asset Management in Residential Developments Building on Transport System Critical Attributes via a Data-Mining Algorithm

Abstract: Public transport can discourage individual car usage as a life-cycle asset management strategy towards carbon neutrality. An effective public transport system contributes greatly to the wider goal of a sustainable built environment, provided the critical transit system attributes are measured and addressed to (continue to) improve commuter uptake of public systems by residents living and working in local communities. Travel data from intra-city travellers can advise discrete policy recommendations based on a residential area or development’s public transport demand. Commuter segments related to travelling frequency, satisfaction from service level, and its value for money are evaluated to extract econometric models/association rules. A data mining algorithm with minimum confidence, support, interest, syntactic constraints and meaningfulness measure as inputs is designed to exploit a large set of 31 variables collected for 1,520 respondents, generating 72 models. This methodology presents an alternative to multivariate analyses to find correlations in bigger databases of categorical variables. Results here augment literature by highlighting traveller perceptions related to frequency of buses, journey time, and capacity, as a net positive effect of frequent buses operating on rapid transit routes. Policymakers can address public transport uptake through service frequency variation during peak-hours with resultant reduced car dependence apt to reduce induced life-cycle environmental burdens of buildings by altering residents’ mode choices, and a potential design change of buildings towards a public transit-based, compact, and shared space urban built environment.

Design for deconstruction in the design process: State of the art

Abstract: Stricter building regulations have resulted in the construction of buildings with a low energy use during the operation phase. It has now become increasingly important to also look at the embodied energy, because it might, over the lifespan of the building, equal the energy used for operating the building. One way to decrease the embodied energy is to reuse building materials and components or to prepare the building for deconstruction; a term called design for deconstruction (DfD). While design for deconstruction has showed environmental, social, and economic benefits, hardly any building designed and built today is designed for deconstruction. The aim of this literature review is to understand the state-of-art of design for deconstruction and how it affects the design process. In most of the literature, general construction principles are specified that promote the design for deconstruction and focus on (a) the overall building design, (b) materials and connections, (c) construction and deconstruction phase, and (d) communication, competence, and knowledge. Furthermore, the reuse potential of specific building materials is discussed, as well as the available tools for DfD. Additionally, the current barriers for DfD as specified by the literature show lack of competence, regulations, and other related elements.

Barriers to Adoption of Sustainable Technologies for Energy-Efficient Building Upgrade—Semi-Structured Interviews

Abstract: Globally, only 2% of existing building stock is built yearly; the remaining 98% already exist. Energy consumption and indoor thermal comfort of the existing building stock are not encouraging. This is due to many challenges associated with existing buildings; the challenges range from cracks, leakages, poor insulation, heat losses and high rate of unsustainable technologies. This paper investigates possible barriers facing the adoption and application of sustainable technologies (STs) for sustainable or energy-efficient upgrade of existing buildings. New STs are manufactured on a regular basis to meet improved energy efficiency standards, yet there are minimal actions/attempts to adopt and apply improved technologies in existing buildings for energy efficiency. Indeed, there are limited studies focused on the use of qualitative approaches to identify barriers to adoption and use of STs. Thus, a semi-structured interview approach was adopted and applied using sustainability/energy efficiency professionals, building services engineers, project managers, architects, and facility managers in Australia. The results indicate that barriers to the adoption and application of sustainable technologies are perceived benefits in demolish-and-build, age of building, cost of STs, perceived poor payback time, unreliable energy-savings projections, existing design, hidden and overall cost of renovation, and cost of STs.

Why Not Wood? Benefits and Barriers of Wood as a Multistory Construction Material: Perceptions of Municipal Civil Servants from Finland

Abstract: As the construction sector continues to be associated with highly energy-intensive practices leading to excessive carbon emissions, governments in many countries are promoting a shift towards greener building practices, like the use of wood in multistory construction (WMC). Meanwhile, local-government actors (e.g., municipalities) often act as important gatekeepers of urban development given their authority to oversee or approve zoning and land-use plans. Despite this fact, they are not much focused on in existing WMC research. This qualitative interview study serves to fill a gap by studying municipal civil servant perceptions regarding WMC, using Finland as a case study. Civil servants were asked to elicit their personal opinions on WMC, and what they perceived as favorable or unfavorable about using wood as a multistory construction material. Results show increasing support for WMC, and that this is due to key benefits made possible by the technical qualities of engineered wood products in emerging WMC projects. These products permit both the adoption of rapid construction practices that enhance citizens’ quality of living, and also the sourcing of local renewable building materials that support local industries. On the other hand, barriers to the use of wood were identified, such as inadequate information distribution, a limited number of WMC industry actors, and inefficient policy measures.

Feasibility Study of Mass-Timber Cores for the UBC Tall Wood Building

Abstract: The UBC Brock Commons building in Vancouver, which comprises of 18 stories and stands 53 m in height, was at the time of completion in 2016 the world’s tallest hybrid wood-based building. The building’s 17 stories of mass-timber superstructure, carrying all gravity loads, rest on a concrete podium with two concrete cores that act as both the wind and seismic lateral load-resisting systems. Whereas the construction of the concrete cores took fourteen weeks in time, the mass-timber superstructure took only ten weeks from initiation to completion. A substantial reduction in the project timeline could have been achieved if mass-timber had been used for the cores, leading to a further reduction of the building’s environmental footprint and potential cost savings. The objective of this research was to evaluate the possibility of designing the UBC Brock Commons building using mass-timber cores. The results from a validated numerical structural model indicate that applying a series of structural adjustments, that is, configuration and thickness of cores, solutions with mass-timber cores can meet the seismic and wind performance criteria as per the current National Building Code of Canada. Specifically, the findings suggest the adoption of laminated-veneer lumber cores with supplementary ‘C-shaped’ walls to reduce torsion and optimize section’s mechanical properties. Furthermore, a life cycle analysis showed the environmental benefit of these all-wood solutions.

The Sustainability of Tall Building Developments: A Conceptual Framework

Abstract: As cities cope with rapid population growth—adding 2.5 billion dwellers by 2050—and grapple with expansive sprawl, politicians, planners, and architects have become increasingly interested in the vertical city paradigm. This paper reviews and examines shortfalls of tall buildings found in the literature to inform future developments. The paper gathers a vast amount of fragmented criticism and concerns, and organizes them around the three pillars of sustainability: social, economic, and environmental. Mapping out the “unsustainable” aspects forms the foundation for addressing them in future research and tall building developments.

Strategies to Improve the Energy Performance of Buildings: A Review of Their Life Cycle Impact

Abstract: Globally, the building sector is responsible for more than 40% of energy use and it contributes approximately 30% of the global Greenhouse Gas (GHG) emissions. This high contribution stimulates research and policies to reduce the operational energy use and related GHG emissions of buildings. However, the environmental impacts of buildings can extend wide beyond the operational phase, and the portion of impacts related to the embodied energy of the building becomes relatively more important in low energy buildings. Therefore, the goal of the research is gaining insights into the environmental impacts of various building strategies for energy efficiency requirements compared to the life cycle environmental impacts of the whole building. The goal is to detect and investigate existing trade-offs in current approaches and solutions proposed by the research community. A literature review is driven by six fundamental and specific research questions (RQs), and performed based on two main tasks: (i) selection of literature studies, and (ii) critical analysis of the selected studies in line with the RQs. A final sample of 59 papers and 178 case studies has been collected, and key criteria are systematically analysed in a matrix. The study reveals that the high heterogeneity of the case studies makes it difficult to compare these in a straightforward way, but it allows to provide an overview of current methodological challenges and research gaps. Furthermore, the most complete studies provide valuable insights in the environmental benefits of the identified energy performance strategies over the building life cycle, but also shows the risk of burden shifting if only operational energy use is focused on, or when a limited number of environmental impact categories are assessed.

Seismic Strengthening and Energy Efficiency: Towards an Integrated Approach for the Rehabilitation of Existing RC Buildings

Abstract: In Italy, most of the residential buildings (77%) were constructed before 1981, when only 25% of the national territory was classified as seismic. Further, the first provisions addressing thermal performance criteria were introduced in 1991, when about 88% of the existing Italian buildings had already been realized. Therefore, the Italian building stock is characterized by a large deficit in terms of both seismic capacity and thermal insulation. The large number of buildings having inadequate performance, both seismic and thermal, calls for rehabilitation interventions that are based on an integrated and sustainability-oriented approach. In the paper, the influence on seismic performance deriving from some retrofitting techniques, generally adopted to enhance the thermal performance of infill walls, has been evaluated. A common residential RC building representative of existing buildings designed only for vertical loads has been studied. The seismic performances have been evaluated through Incremental Dynamic Analyses (IDA). A first comparison is related to a thermal retrofitting intervention made by replacing the existing masonry infill walls with new elements that are able to ensure an adequate thermal protection. Further, a retrofitting intervention based on the “double skin” technique, where new infilled RC frames are added and connected to the existing ones, has been investigated in terms of seismic and thermal performance.

An Investigation of Thermal Comfort and Adaptive Behaviors in Naturally Ventilated Residential Buildings in Tropical Climates: A Pilot Study

Abstract: This article presents a pilot study of thermal comfort and adaptive behaviors of occupants who live in naturally ventilated dormitories at the campus of the National University of Singapore. A longitudinal survey and field measurement were conducted to measure thermal comfort, adaptive behaviors and indoor environment qualities. This study revealed that occupants living in naturally ventilated buildings in tropics were exposed to higher operative temperatures than what American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) comfort standards recommend for naturally conditioned spaces. However, they still felt that such conditions were acceptable. Two behavioral adjustments were found to have profound impacts on occupants’ acceptance of the imposed heat stresses: (1) increasing the indoor air velocity by turning on mechanical fans and opening the door/windows for cross ventilation, and (2) reducing clothing insulation by changing clothes and dressing in fewer clothes. Higher indoor air velocities were also associated with greater satisfaction with indoor air quality. The future study should develop a statistical model to correlate adaptive behaviors with temperature variations for tropical climates.

Thermal comfort analyses of secondary school students in the tropics

Abstract: This study aims to analyze the thermal comfort level of students in secondary schools in the tropical city of Makassar. The analysis is carried out based on data surveyed from eight selected high schools. The study involved 1594 students in 48 classrooms. The recorded data includes personal data and measured environmental parameters. At the same time, students were asked to fill out questionnaires related to their thermal comfort levels. The surveyed classrooms showed high air temperatures. The air temperatures ranged from 28.2 °C in the morning to 33.6 °C in the midday. The radiant temperatures were similar to the air temperature, which indicated that the airflow speed was low. The only parameter that could meet the Indonesian national standard was relative humidity. However, many students still feel comfortable (−1 to +1) based on TSV (thermal sensation vote) and TCV (thermal comfort vote). Even though about 80% of respondents accepted this hot temperature, most of them preferred to have a decrease in the air temperature. Regarding the PMV (predicted mean vote), only about 23% respondents were predicted to feel slightly warm (+1). The regression analyses show that the neutral temperatures were 29.0 °C and 28.5 °C for TSV and TCV, respectively.

Phase Change Materials for Building Applications: A Thorough Review and New Perspectives

Abstract: The purpose of this paper is to provide a comprehensive report on the state of the art on the technologies used in the modeling of energy storage systems by latent heat in buildings, and draw lines on perspectives on the technology evolution in this sector. In the first part, the emphasis is put mainly on the two main lines of research: experimental and numerical. In the second part, the main trends of research in this sector have been followed. An anatomical operation of more than 100 documents (published between 2006 and 2016), on the behavior of storage systems integrating Phase Change Materials (PCM), covering a large number of configurations treatment and their applications in thermal comfort of buildings area, has shown that the information published in this topic are very diverse and enormous, but in many cases are insufficient. The results show that, with suitable design, the PCM can contribute to the reduction of costs and achieve energy reductions in buildings, guaranteeing a comfortable interior environment. The evaluation of this multitude of documents gave the following remark: The effectiveness of any proposed approach to a numerical study is a concept with ambiguities, depending upon the method used, its precision, the problem to be modeled, the convergence criteria and the input parameters choice. The diversity of experimental conditions and the variety of results revealed that the published works are not directly comparable.

Durability of ETICS with Rendering in Norway—Experimental and Field Investigations

Abstract: External Thermal Insulation Composite Systems (ETICS) with Rendering are widely used in both rehabilitation and new building projects, even in areas with harsh climates such as the western regions of Norway. However, we have seen extensive cases of defects involving such systems. This paper presents a comprehensive review of Norwegian experiences regarding the durability of ETICS on walls. The presented results are based on building research conducted by SINTEF 61 as well as 30 accelerated climatic laboratory experiments over the last 25 years on similar facade systems. These systems generally perform satisfactorily if thoroughly designed and carefully erected. However, according to the survey, the systems are not very robust. Even minor errors in design techniques and/or craftsmanship can lead to rendering defects. The investigations clearly show that ETICS is particularly vulnerable when exposed to severe driving rain conditions. ETICS provides only a single-stage protection against wind and precipitation and do not dry effectively after being wetted. Hence, the resultant cracks and other rendering weaknesses could be disastrous, enabling moisture to penetrate into the thermal insulation and the wall behind. In areas with heavy driving rain, we recommend facade solutions erected in accordance with the principle of two-stage tightening rather than ETICS.

Investigation of Waste Paper Cellulosic Fibers Utilization into Cement Based Building Materials

Abstract: Recently, the utilization of renewable natural cellulosic materials, such as wood, plants, and waste paper in the preparation of building materials has attracted significant interest. This is due to their advantageous properties, low environmental impact and low cost. The objective of this paper is to investigate the influence of recycled cellulosic fibers (in the amount 0.5 wt % of the filler and binder weight) and superplasticizer (in the amount 0.5 wt % of the cement weight) on the resulting properties of cement composites (consistency of fresh mixture, density, thermal conductivity, and compressive and flexural strength) for hardening times of 1, 3, 7, 28, and 90 days. Plasticizer use improved the workability of fresh cement mixture. In comparison to the reference sample, the results revealed a decrease in density of 6.8% and in the thermal conductivity of composites with cellulosic fibers of 34%. The highest values of compressive (48.4 MPa) and flexural (up to 7 MPa) strength were achieved for hardened fiber cement specimens with plasticizer due to their significantly better dispersion of cement particles and improved bond strength between fibers and matrix.

A Lean Approach for Real-Time Planning and Monitoring in Engineer-to-Order Construction Projects

Abstract: Engineer-to-order (ETO) construction companies are characterized by an off-site and on-site production. Often, budget deviations for installation works on-site are identified in a late stage when improvement actions cannot be applied anymore. Consequently, installation tasks are often affected by significant delays and/or reworks. This work proposes a “real-time” capable approach for planning and monitoring in construction and a corresponding information technology (IT) framework. The core is represented by the so-called “pitching” concept known from lean management, which breaks down large job orders into smaller controllable parts. It can be considered as the main enabler for gathering management information in real-time and to identify problems and their causes on time. The most noticeable consequence lies in smaller jobs and a software-aided punctual control that allows a better rescheduling capability and, thus reduced, delays. A case study is provided, showing how the model was applied and validated in an ETO facade supplier company.

Post-Occupancy Evaluation and IEQ Measurements from 64 Office Buildings: Critical Factors and Thresholds for User Satisfaction on Thermal Quality

Abstract: The indoor environmental quality (IEQ) of buildings can have a strong influence on occupants’ comfort, productivity, and health. Post-occupancy evaluation (POE) is necessary in assessing the IEQ of the built environment, and it typically relies on the subjective surveys of thermal quality, air quality, visual quality, and acoustic quality. In this research, we expanded POE to include both objective IEQ measurements and the technical attributes of building systems (TABS) that may affect indoor environment and user satisfaction. The suite of three tools, including user satisfaction survey, workstation IEQ measurements, and TABS in the National Environmental Assessment Toolkit (NEAT) has been deployed in 1601 workstations in 64 office buildings, generating a rich database for statistical evaluation of possible correlations between the physical attributes of workstations, environmental conditions, and user satisfaction. Multivariate regression and multiple correlation coefficient statistical analysis revealed the relationship between measured and perceived IEQ indices, interdependencies between IEQ indices, and other satisfaction variables of significance. The results showed that overall, 55% of occupants responded as “satisfied” or “neutral”, and 45% reported being “dissatisfied” in their thermal quality. Given the dataset, air temperature in work area, size of thermal zone, window quality, level of temperature control, and radiant temperature asymmetry with facade are the critical factors for thermal quality satisfaction in the field. As a result, the outcome of this research contributes to identifying correlations between occupant satisfaction, measured data, and technical attributes of building systems. The presented integrated IEQ assessment method can further afford robust predictions of building performance against metrics and guidelines for IEQ standards to capture revised IEQ thresholds that impact building occupants’ satisfaction.

Potential of Thermal Energy Storage Using Coconut Oil for Air Temperature Control

Abstract: The role of thermal mass in indoor air-cooling during the day is a common area of study, which is particularly relevant for an era characterized by energy crises Thermal energy storage (TES) technologies for application in rooms and buildings are not well developed This study focuses on the use of coconut oil (co_oil) as a temperature control agent for room air conditioning systems in tropical countries such as Indonesia, given its capability to store large amounts of heat at temperatures around its melting point Heat exchange studies between co_oil and the air environment were performed by considering three factors: Temperature difference between co_oil and the air environment, the heat absorption behavior and the release of co_oil, and the mass of co_oil required to have a significant effect The co_oil cell sizes were formulated as responses to natural day and night air temperature profiles, while the performance of the co_oil mass for decreasing room air temperature was predicted using a thermal chamber

Critical Delaying Factors: Public Sector Building Projects in Gilgit-Baltistan, Pakistan

Abstract: Project delays are a large and prevalent problem in the Gilgit-Baltistan construction industry, and delays can distinctly affect project duration, budget, and also community needs. The purpose of this study is to highlight and rank delaying factors in the Annual Development Programme public sector building infrastructure projects and examine them through a relative importance index. A total of 52 delaying factors were identified through a detailed literature review and categorized into eight major groups, and a pilot study with 16 experienced construction experts was conducted. A questionnaire survey was conducted to collect the importance of each factor from public construction experts. In total, 102 respondents participated in the survey. The study determined that difficulties in financing projects by contractors, delays in progress payments, dispute on land usage, improper project feasibility studies, award project to the lowest bid price, extreme weather conditions, inadequate contractor experience, and insufficient data collection and survey before design were among the top eight critical delaying factors. In addition, Spearman’s rank correlation tests revealed that there was no difference in perception between owners and contractors. A comparison of the top five delay factors was done with eight preferred construction industries in Asia to validate the results of this study. The findings are likely to be a solid contribution to the Gilgit-Baltistan construction industry in mitigating future construction delays.

Experimental Study of Self-Compacting Mortar Incorporating Recycled Glass Aggregate

Abstract: This experimental research is focused on the development of self-compacting mortar incorporating recycled glass aggregate (SCM-RGA) as partial substitution of fine aggregate (wt 0%, 10%, 20%, 30%, 40% and 50%). The fresh and hardened mechanical properties as well as durability of SCM-RGA mixes were investigated. Limestone powder (LP) was used as filler that constitutes 20% of the powder volume to reduce the amount of cement. The SCM-RGA mixtures were designed based on Japanese mix design method. The experimental test results showed that the slump flow of SCM-RGA mixes decreased and V-funnel flow time increased when the content of recycled glass aggregate (RGA) increased. The bulk density, compressive strength, flexural strength, water absorption and sorptivity of SCM-RGA mixes were decreased as RGA content increased. Moreover, the accelerated mortar bar test results showed that the expansion due to alkali–silica reaction (ASR) of SCM-RGA mixes increased as the content of RGA increased although the expansion of all mixes were within acceptable limit and potentially innocuous. In conclusion, up to 30% of RGA can be successfully integrated in SCM mixes that offers comparable strength performance, sorptivity enhancement and without long term detrimental ASR effect, and thus, contributes towards sustainable solid waste management, conservation of natural resources and environmental protection.

Performance of Blue-Green Roofs in Cold Climates: A Scoping Review

Abstract: Green and blue-green roofs are emerging as an increasingly popular feature of rooftops, particularly in urban areas. Particular problematic conditions render their usage complex in the Nordic countries. In order to ensure that green roofs are built durable and with the service life expected of them, it is important to know all the relevant factors surrounding their construction and operation. A scoping study was conducted in order to gain an overview on green roof research and available scientific literature. One hundred articles of particular interest for Nordic climates were retrieved and their findings summarized. It is found that the vast majority of green roof research has been conducted on a theoretical basis, or with practical measurements on green roof test beds or isolated components. There is scarcely any literature on the operation of full-scale, building-implemented green roofs, and no articles were found on the building technical performance of aged green roofs. These knowledge gaps indicate a major risk factor in green roof operation, as their performance and integrity over time has not been documented. This despite the fact that green roofs have been implemented and in operation worldwide for decades.

In-Plane Strength and Stiffness of Cross-Laminated Timber Shear Walls

Abstract: The research presented herein investigated the in-plane performance of cross-laminated timber (CLT) shear walls for platform-type buildings under lateral loading. Finite element models of CLT connections (i.e., brackets, hold-downs and self-tapping screws) were developed in OpenSees and calibrated against experimental tests to represent the connections’ hysteresis behaviour under cyclic tension and shear loading. The results were incorporated into models of CLT single and coupled shear walls. The results in terms of peak displacement, peak load and energy dissipation were in good agreement when compared to full-scale shear wall tests. Subsequently, a parametric study of 56 single and 40 coupled CLT shear walls was conducted with varying numbers and types of connectors (wall-to-floor and wall-to-wall) for evaluating their seismic performance. It was found that the strength, stiffness and energy dissipation of the single and coupled CLT shear walls increased with an increase in the number of connectors. Single shear walls with hold-downs and brackets performed better under seismic loading compared to walls with brackets only. Similarly, coupled shear walls with four hold-downs performed better compared to walls with two hold-downs. Finally, ductility of coupled shear walls was found to be 31% higher compared to that of single shear walls. The findings from this research are useful for engineers to efficiently design CLT shear walls in platform-type construction.

Energy and Economic Performance of Solar Cooling Systems in the Hot-Summer and Cold-Winter Zone

Abstract: Building energy consumption has distinctly increased in the hot-summer and cold-winter zone in China. Solar cooling technology has been developed to reduce the increasing electricity consumption for air conditioning and to shift the peak load during hot summer days. This paper presents a performance simulation and economic analysis for both photovoltaic (PV) and thermal solar cooling systems compared to a reference system, which is composed of two electric heat pumps. The results show that 30.7% and 30.2% of primary energy can be saved by using the PV and the thermal system, respectively. The payback time is 6–7 years for the PV system, but more than 20 years for the thermal system based on current conditions in China. Therefore, the PV system is more suitable for practical application in the hot-summer and cold-winter zone. The thermal system could be an alternative when middle- and high-temperature solar thermal collector technology has been further developed, as well as following mass production of small- and middle-sized chillers.

Balanced Evaluation of Structural and Environmental Performances in Building Design

Abstract: The design of new buildings, and even more the rehabilitation of existing ones, needs to satisfy modern criteria in terms of energy efficiency and environmental performance, within the context of adequate safety requirements. Tackling all these needs at the same time is cumbersome, as demonstrated by several experiences during recent earthquakes, where the improvement of energy performance vanished by seismic-induced damages. The costs of energy retrofitting must be added to the normal losses caused by the earthquake. Even though the minimum safety requirements are met (no collapse), the damage due to earthquake might be enough to waste the investment made to improve energy efficiency. Since these measures are often facilitated by corresponding incentives, the use of public funding is not cost effective. The application of the existing impact assessment methods is typically performed at the end of the architectural and structural design process. Thus, no real optimisation can be achieved, because a good structural solution could correspond to a poor environmental performance and vice versa. The proposed Sustainable Structural Design method (SSD) considers both environmental and structural parameters in the life cycle perspective. The integration of environmental data in the structural performance is the focus of the method. Structural performances are considered in a probabilistic approach, through the introduction of a simplified Performance Based Assessment method. Finally, the SSD method is implemented with a case-study of an office-occupancy building, both for precast and cast-in-situ structural systems, with the aim to find the best solution in terms of sustainability and structural performance for the case at hand.