Sustainable Building Envelope Research Articles

Thermal insulation and flammability of composite waste polyurethane foam encapsulated in geopolymer for sustainable building envelope

Polyurethane foam (PUR) is a lightweight, thermally insulating, widely used, and highly flammable material that has after its use an adverse effect on the environment, i.e., PUR disposal is considered hazardous. Its flammability can be mitigated using various fire retardants, but they do not change the hazardous nature of waste PUR. Therefore, in the current study, waste PUR with and without flame retardants based on N and P was incorporated into a geopolymer, the alkali-activated material (AAM) based solely on metakaolin, to evaluate the potential recycling route of waste PUR while taking into account its flammability, so it can enter safely into the circular economy through the building industry. To enhance the mechanical properties of the composite, a fresh mixture was irradiated with microwaves. However, the irradiation of geopolymer containing PUR negatively influenced mechanical performance, which led to the evaluation of the behaviour of the complex dielectric constant of PUR and fire retardants. Materials and composites were evaluated regarding their chemistry, mineralogy, microstructure, and porosity to connect the structure with extrinsic properties like geometrical density, thermal conductivity, and fire properties. Nonetheless, positive influences of PUR being encapsulated in the geopolymer were lowered density (from 1.8 to 1.6 kg/l) and improved thermal insulation ability (from 940 to 860 mW/(m·K)) of the composites: with the inclusion of <5 % of PUR, thermal insulation improved by nearly 10 %. However, the contribution of PUR to the composite originated from its skeleton, which has more than 15 times bigger geometrical density (0.81 kg/l) compared to the density of the skeleton (0.047 kg/l). This offers an open field for further advancements of thermal properties, but would also lead to a decrease of the compressive strength, which was already lowered from 90 MPa for 30 % with <5 % of added grated PUR. Furthermore, the flammable nature of PUR and its other drawbacks can be controlled by permanent embedding in the noncombustible structure of geopolymer, making the envelope of sustainable buildings green and safer. Overall, including grated waste PUR in geopolymer represents a promising, easy, cost-effective recycling path with low energy consumption, where the composite cannot develop fire on a scale of pure PUR, even in the worst-case scenario, but only if the composite is designed in a way, that flammable materials cannot join flames during their combustion. This paper gives prospects to other flammable waste materials to be safely used in the circular economy, and to porous materials to shape properties of the composite by their intrinsic and/or extrinsic properties.

Investigation of thermophysical properties of Turkey oak particleboard for sustainable building envelopes

The article investigates the thermophysical parameters of Turkey oak particleboard with different densities and their response to varying heat pulse power to cover possible thermally dependent disturbance effects during the measurement. Samples were measured by the Pulse Transient Method using a Cuboid Model to estimate all basic thermophysical parameters. The aim was to assess the properties of the two different particleboard of high and medium density and compare them with published data. We also calculated uncertainties based on sensitivity coefficients analysis for the cuboid model. This methodology helps to assess how the input error propagates into the resulting parameter estimate and helps to optimize the experiment. The quality of oak particleboard holds significant importance in building construction. Additionally, the analysis results assess the suitability of different materials for improving energy efficiency in building construction. Interestingly even slight density differences and thickness can significantly impact the effectiveness of building insulation properties of materials.

A BAYESIAN DATA UPDATING MODEL FOR MANAGING BUILDING ENVELOPE INSPECTIONS

Building envelope management includes all activities, e.g., periodic inspections, condition assessment and maintenance, needed to preserve the integrity of the building exterior. In building envelope management, appropriate decision-making focuses on finding an optimum inspection interval and repair strategy. A Bayesian updating with rating method is presented for conducting planning and decision-making for building envelop inspections using data from previous inspections. The model applies to a zone (strip) of the envelope and uses the previous inspection records to predict the future condition. An artificial neural network (ANN) is used to improve the prediction for the envelope condition. The ANN uses historical data of an envelope condition to determine a correction factor, for the predicted condition, to account for the effect of factors that promote damage. The Bayesian updating will improve the capabilities of the model in predicting the future conditions as more data becomes available. Used along with a cost optimization and reserve analysis, the model will result in a more sustainable and cost-effective building envelope management process.

Plasmonic aerogel window with structural coloration for energy-efficient and sustainable building envelopes

Renowned for superior thermal insulation properties, silica aerogel holds substantial promise for eco-friendly building construction. This study presents a novel colored transparent aerogel (CTA) window design that simultaneously achieves good light transmission, thermal insulation, and color modulation, which has not been reported before. The radiative properties of the core–shell plasmonic particle-doped aerogel were theoretically predicted by the combination of Mie theory and Monte Carlo methods. The results showed that the CTA window has high visible light transmittance (∼ 45%) and low thermal conductivity (∼ 0.018 W/m K), all while displaying an array of vivid colors. An energy consumption simulation of CTA windows in various climates in China showed potential energy savings of up to 90% compared to the single tinted window in severe cold regions. Moreover, a cost assessment of CTA windows is conducted to evaluate their economic feasibility and environmental benefits. This study introduces an innovative avenue to meet the escalating demand for both visually pleasing and energy-efficient materials, contributing profound insights into the realm of sustainable architectural design.

Towards development of sustainable lightweight 3D printed wall building envelopes – Experimental and numerical studies

3D printing technology can be of crucial importance in the design of sustainable and energy-efficient building envelopes. With this technology, there is the potential to mechanically and thermally optimise the topology of printed walls. Additionally, the printing and infill materials used can be insulating, and thus contributing to the overall reduction of heat loss. To date, limited examples of 3D printed envelopes and information about the thermal and mechanical performance of 3D printed walls are available. This study developed a 3D printable wall element with an insulating property for application in building envelopes. Seven wall topologies are studied through simulations of mechanical and thermal performance using two mixtures: a control mixture (normal-weight) and a lightweight mixture containing expanded thermoplastic microspheres (ETM) for thermal insulation. One wall topology is selected based on the performance of the simulation and printed using both mixtures. The 3D printed envelopes were tested under compressive strength and analysed with the ARAMIS system, a digital image correlation (DIC) technology. Computer simulations and the DIC analysis identified the main causes for failure, which are the inter-filament weakness and the imperfections of the geometry of the printed envelope.

Activity and efficiency of the building sector in Morocco: A review of status and measures in Ifrane

&lt;abstract&gt; &lt;p&gt;One-third of all greenhouse gas emissions come from the world's building stock while accounting for 40% of global energy use. There is no way to combat global warming or attain energy independence without addressing the inefficiency of the building sector. This sector is the second consumer of electricity after the industrial sector in Morocco and is ranked third emitter after the energy sector and transportation sector. Using Ifrane as a case study, this paper examines and reviews the city's energy use and the initiatives taken to improve building efficiency. The findings showed that, during the analyzed period, i.e., from 2014 to 2022, Ifrane's annual electricity consumption climbed steadily from 35 to 43 GWh. The government of Morocco has implemented effective laws, guidelines and regulations, as well as publicized ways to reduce energy consumption and increase energy efficiency. However, gathered data and survey results revealed opportunities and challenges for enhancing Ifrane's efficient energy use.&lt;/p&gt; &lt;p&gt;The study also evaluates government programs, codes/standards and related actions for the improvement of household energy efficiency. As part of the review, the available literature was analyzed to assess the effectiveness of energy behavior and awareness, the impact of an economical and sustainable building envelope, the impact of building retrofitting programs, the importance of energy-performing devices and appliances, the adoption of smart home energy management systems, the integration of renewable energies for on-site clean energy generation and the role of policies and governance in the building sector in Ifrane. A benchmark evaluation and potential ideas are offered to guide energy policies and improve energy efficiency in Ifrane and other cities within the same climate zone.&lt;/p&gt; &lt;/abstract&gt;

Life Cycle Assessment of Advanced Building Components towards NZEBs

The building sector accounts for 40% of the total energy consumed in Europe at annual basis, together with the relevant Greenhouse Gas (GHG) emissions. In order to mitigate these impacts, the concept and establishment of the Nearly Zero Energy Buildings (NZEBs) is under continuous and intensive research. In fact, as the energy used for buildings’ operation becomes more efficient, impacts resulting from the buildings’ embodied energy become of more importance. Therefore, the selection of building materials and components is of high significance, as these affect the energy performance and potential environmental impacts of the building envelopes. The objective of this study is to perform a preliminary Life Cycle Assessment (LCA) on advanced multifunctional building components, aiming to achieve lower embodied emissions in NZEBs. The advanced components analyzed are composite panels for facade elements of building envelopes, providing thermal efficiency. The design of sustainable building envelope systems is expected to upgrade the overall environmental performance of buildings, including the NZEBs. The findings of this study constitute unambiguous evidence on the need for further research on this topic, as substantial lack of data concerning embodied impacts is presented in literature, adding to the growing discussion on NZEBs at a whole life cycle perspective across Europe. This research has shown that the electricity required from the manufacturing phase of the examined building components is the main contributor to climate change impact and the other environmental categories assessed. Sensitivity analysis that has been performed indicated that the climate change impact is highly depended on the electricity grid energy mix across Europe. Taking into account the current green energy transition by the increase of the renewable energy sources in electricity production, as well as the future upgrade of the manufacturing processes, it is expected that this climate change impact will be mitigated. Finally, the comparison between the CLC thermal insulator and other foam concretes in literature showed that the materials of the building components examined do not present any diversions in terms of environmental impact.

A critical review for formulation and conceptualization of an ideal building envelope and novel sustainability framework for building applications

Energy use in the building is responsible for one-third of total carbon dioxide (CO 2 ) emissions globally. Nearly half of the energy loss occurs through the building envelope due to heat transfer to/for the surroundings. Therefore, there is a need to design an optimum building envelope to reduce energy use in buildings that depend on several parameters. This study aims to review different building parameters and provide a conceptual framework to optimize the building envelope. In total, 260 papers were reviewed, and the building envelope design consideration was categorized into: 1) Design Parameters (design and geometry), 2) environmental conditions (indoor and outdoor) and 3) performance criteria (energy, environment, economic, comfort). Energy use and CO 2 -emission in buildings increase with high thermal conductivity, low thermal mass, and low solar absorption of its envelope. Geometrically, building orientation impacts energy use more than the building shape factor. Changing set point temperature according to surrounding conditions has reduced energy use and CO 2 -emission by 30% and 56%, respectively. However, indoor air quality, velocity, and occupancy have meagerly affected building energy use. Energy and emission optimization criteria are directly related, but the emission-based optimized envelope is thicker than the energy one. Other criteria such as economy and comfort (thermal and visual) are inversely proportional to the energy-efficient building envelope. Based on the comprehensive review, this study proposed a conceptual framework to design a sustainable building envelope that includes life cycle assessment, occupant's satisfaction, and social benefits. Several future research recommendations were made, including 1) the use of switchable reflective materials to minimize heat transfer, 2) dynamic insulation material to control insulation value as needed, and 3) smart windows with tunable optical properties.

Simulation on Building Envelope Design using Biomimicry Conceptual of Palm Leaf Pattern for Self Cleaning Maintenance

Contemporary architectural designs acting to increase the aesthetic value of the building’s overall perspective. The complexity of the maintenance works for the building envelope cleanliness becomes challenging in maintenance operations. Biomimicry – innovation inspired by nature, reveals an opportunity to simplify the cleaning process mentioned by infusing the self-cleaning characteristic of palm tree species on the design of building envelope. This research is intentionally to determine of the most ideal building envelope form that utilize the effect of the biomimicry conceptual as self-cleaning maintenance properties by finding the wind velocity to assess the dust flow behaviour. The basic architectural forms that commonly applied by the architects is used as a model to create the building forms in a way to find the physical self-cleaning characteristic by using the palm leaf pattern. By using the Autodesk Computational Fluid Dynamics (CFD) software, this tool is used to simulate the environmental situation and examine the efficiency of the self-cleaning function on different building models. The results are compared among the different models to identify the best building model that fully employ the self-cleaning function using the palm leaf pattern. The finding on self-cleaning properties of architectural forms is potentially developed the solution of sustainable building envelope design for a better functional and free maintenance.

Recycled agricultural plastic waste as green roof drainage layer within the perspective of ecological transition for the built environment

Although green roofs are considered among the most sustainable building envelopes, an expanding tendency is the use of recycled or reused materials and low-cost products to improve their environmental and economic sustainability. This article evaluated the use of polyethylene granules, derived from the recycling of agricultural plastic waste coming from greenhouse covering, as drainage layer in green roofs. To this end, the physical properties (i.e. particle size, specific weight, minimum and maximum density and permeability) of five different recycled plastic granules were determined. Moreover, the thermal conductivity of one of these recycled products was assessed through a customized testing methodology varying the water content. Thermal conductivity measurements were conducted by using two pieces of equipment to cross-referencing the measurements. The same surveys were carried out on other granular drainage materials (i.e. perlite, expanded clay) to validate the proposed methodology as well as to compare the thermal performance of the examined materials. The results of the thermo-physical tests showed that the recycled plastic granules have features within the range requested for green roof drainage layer, very similar to those of perlite and, therefore, they may be used as an alternative to natural drainage materials. In addition, recycled polyethylene had mechanical and environmental performances better than commercial products, indeed it has the lowest weight increase in saturated conditions, about 80 kg/m3, so reducing the extra load applied on existing building rooftops, as well it produces very low Global Warming Potential (GWP) impact, that is 2–4 kgCO2eq/FU. These outcomes could have wide dissemination considering that Europe is one of the major consumers of agricultural plastic products and their reuse/recycling comply with the ecological transition objectives.

A hierarchical reference-based know-why model for design support of sustainable building envelopes

In current complex building designs, sustainability assessments are often performed after project completion, with limited impact on building performance which results in missed goals in terms of quality, cost, and time. We address this problem by proposing a hierarchical reference-based know-why model to answer the research question “what is a suitable decision support model to successfully integrate the sustainability requirements in the early design phase of buildings?”. The model presents a process that incorporates a life-cycle perspective and calculates design alternatives based on a defined reference and the DGNB building certification system. The results show that criteria synergies and trade-offs can be identified, leading to improved design by engineers and better building performance. Our findings pave the way for full integration of the model into building information modeling, combined with artificial intelligence. This can help manage the complexity of the sustainable design process on the path to carbon-neutral buildings.

Carbon-neutral building renovation potential with passive house-certified components: Applications for an exemplary apartment building in the Republic of Korea

Building energy consumption for heating and cooling and the comparatively short building lifecycle help account for the increasing ratio of the building sector's greenhouse gas (GHG) emissions. To counteract this increase, sustainable building envelope renovations can minimize GHG emissions through the extension of building lifecycle, saving of construction material, increased energy efficiency, and reduced heating and cooling energy demands. To reduce the GHG emissions of energy efficient building envelope renovation systems, this article compares the Life Cycle Assessment (LCA) results of different Passive House (PH) certified building envelope components regarding their GHG emissions per area unit. Based on PH-certified components, different building envelope renovation components were developed. The LCA facilitated the identification of components with the lowest carbon emissions, which were applied in the PH-conforming renovation model of an exemplary apartment building in Seoul, Republic of Korea. The LCA results over a service life of 50 years illustrate that the highest GHG emissions are associated with the renovated building's primary service energy demand, followed by windows, and the transport of materials. These research findings facilitate the environmental impact determination of multiple PH-standard building renovation systems, and support the planning of building renovations with minimized carbon footprints and service energy demands.

Verification of the Structural Performance of Textile Reinforced Reactive Powder Concrete Sandwich Facade Elements

As a part of the SESBE (Smart Elements for Sustainable Building Envelopes) project, non-load bearing sandwich elements were developed with Textile Reinforced Reactive Powder Concrete (TRRPC) for outer and inner facings, Foam Concrete (FC) for the insulating core and Glass Fiber Reinforced Polymer (GFRP) continuous connectors. The structural performance of the developed elements was verified at various levels by means of a thorough experimental program coupled with numerical analysis. Experiments were conducted on individual materials (i.e., tensile and compressive tests), composites (i.e., uniaxial tensile, flexural and pull-out tests), as well as components (i.e., local anchorage failure, shear, flexural and wind loading tests). The experimentally yielded material properties were used as input for the developed models to verify the findings of various component tests and to allow for further material development. In this paper, the component tests related to local anchorage failure and wind loading are presented and coupled to a structural model of the sandwich element. The validated structural model provided a greater understanding of the physical mechanisms governing the element’s structural behavior and its structural performance under various dead and wind load cases. Lastly, the performance of the sandwich elements, in terms of composite action, was shown to be greatly correlated to the properties of the GFRP connectors, such as stiffness and strength.

Composite Behaviour of Textile Reinforced Reactive Powder Concrete Sandwich Fa\xe7ade Elements

Within the EC funded project smart elements for sustainable building envelopes, carbon textile reinforcement was incorporated into reactive powder concrete, namely textile reinforced reactive powder concrete (TRRPC), to additionally improve the post-cracking behaviour of the cementitious matrix. This high-performance composite material was included as outer and inner façade panels in prefabricated and non-load bearing sandwich elements along with low density foamed concrete (FC) and glass fibre reinforced polymer continuous connecting devices. Experiments and finite element analysis (FEA) were applied to characterize the structural performance of the developed sandwich elements. The mechanical behaviour of the individual materials, components and large-scale elements were quantified. Four-point bending tests were performed on large-scale TRRPC-FC sandwich element beams to quantify the flexural capacity, level of composite action, resulting deformation, crack propagation and failure mechanisms. Optical measurements based on digital image correlation were taken simultaneously to enable a detailed analysis of the underlying composite action. The structural behaviour of the developed elements was found to be highly dependent on the stiffness and strength of the connectors to ensure composite action between the two TRRPC panels. As for the FEA, the applied modelling approach was found to accurately describe the stiffness of the sandwich elements at lower load levels, while describing the stiffness in a conservative manner after the occurrence of connector failure mechanisms.

Escolhas sustentáveis em sistemas de vedação: construção de uma métrica de avaliação relativa

A escolha de soluções eficientes para um sistema de vedação sustentável é um desafio exigente. Nesse sentido, esta pesquisa propõe desenvolver uma métrica de avaliação relativa que pondere, qualitativamente, o grau de sustentabilidade dos sistemas de vedação em projetos de habitação compacta e que sirva como método de escolha de tais tecnologias na etapa de projeto. O objeto de pesquisa justifica-se baseado na escassez de métodos simplificados a respeito e na iniciativa Casa Nordeste 1.0 de participação de uma competição internacional de projeto e execução de protótipos de casas sustentáveis operadas a energia solar, por parte da equipe do Laboratório de Modelos e Prototipagem (LM+P) da Universidade Federal da Paraíba (UFPB), no qual está inserido este plano de trabalho. O método proposto contempla a revisão bibliográfica sistematizada na busca de procedimentos, técnicas de avaliação/ seleção existentes, assim como na adoção de categorias, critérios e variáveis de avaliação de materiais e sistemas de vedação. Foram realizados estudos pilotos para desenvolver e testar a confiabilidade da construção preliminar da métrica proposta. Os resultados apontam que é possível diminuir parcialmente a complexidade de avaliar, de maneira simultânea, questões sociais, econômicas e ambientais, próprias da visão holística que orienta o paradigma adotado por esta pesquisa. Desse modo, por meio das estimativas comparativa e qualitativa de tecnologias construtivas, é possível obter subsídios para uma escolha mais criteriosa na etapa de projeto.

BIM and genetic algorithm optimisation for sustainable building envelope design

Decision-making (DM) at the early building design stages is essential to optimise sustainability performances. Nevertheless, the current methods of optimising building sustainability are complex as they involve multiple design variables and performance objectives. With the development of building information modelling (BIM), complicated buildings can be digitally constructed with precise geometry and accurate information for design optimisation in the early stages of project. Thus, this study explores the use of BIM and Genetic Algorithm (GA) to support DM and optimisation for sustainable building envelope design. To develop a BIM-GA optimisation method, Autodesk Revit template was created to extract data of building envelope from a Base Model (BM). Then, the data were employed to compute overall thermal transfer value (OTTV) and construction cost for BM evaluation and GA optimisation. A hypothetical building was modelled and then analysed using the proposed method as a test case. The BIM-GA optimisation method can address the difficulties of DM on building sustainability in the early design process.

Innovative, Translucent and Multi-functional Components for the Building Envelope: technological and performance optimization

The paper describes the actions aimed at the technology and performance optimization of an innovative, multi-functional building component made of precast and pre-stressed glass blocks useful for the construction of sustainable building envelopes able to reduce the energy consumption and to produce clean energy from the sun. The design optimization of different sub-components and the choice of the right materials for guaranteeing their good response in terms of mechanical resistance, thermal and acoustic insulation, light transmission, electricity production, integration with other components, dimensional coordination, are particularly described.

Vacuum insulation panels (VIPS) in building envelope constructions: An overview

Driven by updated building energy codes and green building initiatives across the world, vacuum insulation panel, also known as VIP, has become a desired insulation product for building envelope constructions. VIP has initial center-of-panel thermal conductivity of 0.004 W/mK or lower, and integration of VIP in building envelopes can reduce CO2 emissions and contribute towards ‘net-zero’ or ‘near-net-zero’ building constructions. Although VIPs have been applied in real-world constructions across the world, primarily in Asia, Europe and North America, it is still a novel building product under investigation. This overview paper is a summary of fundamentals, constituents, constructions and performances of VIPs. The paper shows there exists many advantages and challenges associated with the integration of VIPs in building envelope constructions. The speed at which VIPs will be integrated in building envelope construction in the coming years remains unclear; nevertheless, it is evident that vacuum technology is the promising way forward for sustainable building envelope constructions in the 21st century.

Sustainable building envelope design by considering energy cost and occupant satisfaction

The built environment is a major contributor to the world's carbon dioxide emissions, with a considerable amount of energy being consumed in buildings due to heating, ventilation and air-conditioning, space illumination, use of electrical appliances, etc., to facilitate various anthropogenic activities. The development of sustainable buildings seeks to ameliorate this situation mainly by reducing energy consumption. Sustainable building design, however, is a complicated process involving a large number of design variables, each with a range of feasible values. There are also multiple, often conflicting, objectives involved such as the life cycle costs and occupant satisfaction. One approach to dealing with this is through the use of optimization models. In this paper, a new multi-objective optimization model is developed for sustainable building design by considering the design objectives of cost and energy consumption minimization and occupant comfort level maximization. In a case study demonstration, it is shown that the model can derive a set of suitable design solutions in terms of life cycle cost, energy consumption and indoor environmental quality so as to help the client and design team gain a better understanding of the design space and trade-off patterns between different design objectives. The model can be very useful in the conceptual design stages to determine appropriate operational settings to achieve the optimal building performance in terms of minimizing energy consumption and maximizing occupant comfort level.

Dynamic Adaptive Building Envelopes – an Innovative and State-of-The-Art Technology

The building envelope has a key role to play in achieving indoor comfort for the occupants and building energy efficiency. A dynamic, active and integrated solution -- able to achieve the optimum thermal performance, harness energy from renewable resources and, integrate active elements and systems -- is the most promising and innovative strategy for the building envelope of tomorrow. To achieve an effective and sustainable building envelope with a dynamic behaviour, considerable efforts in research and development are necessary. This paper endeavours to present a broad review of design, research and development work in the field of Dynamic Adaptive Building Envelope (DABE). Based on detailed studies, the characteristic features, enabling technologies, and the overall motivations that have tendered to the advancement of DABE are discussed. In spite of its positive aspects, the study reveals that the concept of DABE has not yet been well-applied and needs much more exploration. Various challenges need to be resolved and advanced research undertaken to bring it to maturity and acceptance.