Low Energy Buildings Research Articles

Extending the concept of high-performance buildings to existing dwellings

Extending the concept of high-performance buildings to existing dwellings

Feasibility Analysis of Nearly Zero-Energy Building Design Oriented to the Optimization of Thermal Performance Parameters

The effective control and reduction of building energy consumption are major global focuses. The building sector is responsible for over 40% of all direct and indirect CO2 emissions. Nearly zero-energy buildings have been the subject of aims and regulations from several developed nations. An office building located in the severe cold region of China was chosen for this case study. The building was equipped with multiple NZEB technologies. Building indoor environment parameters and energy efficiency indexes were used as performance targets, and a performance-based design approach was used to optimize building design parameters. Thermal performance of the building envelope, airtightness, energy demand, and indoor thermal environment were tested according to different evaluation criteria. The total energy demand was as low as 53.93 KWh/(m2·a), and this can be attributed to the exceptional insulation of the building. In this test, the indoor thermal environment comfort was satisfactory. This study can be used as a reference for the design and evaluation of low-carbon buildings and low-energy buildings.

Crab-claw inspired high performance and flame-retardant magnesium oxychloride cement based adhesive reinforced by 4-arms EDTA and tartaric acid for wood industry

The high CO2 emissions and instability of silicate cement binders during production and use have encouraged the development of low-carbon materials. In this study, an environmentally friendly and flame-retardant building material was produced from magnesium oxychloride cement (MOC) and wood. In practice, the considerable microcracking that forms during the hardening process makes MOC materials very sensitive to water, which limits their further use. Inspired by the predation of crabs, a simple and effective method was proposed to obtain better water resistance and mechanical strength of MOC composite by co-modifying with ethylenediaminetetraacetic acid (EDTA) or disodium ethylenediaminetetraacetic acid (EDTA-Na) in conjunction with tartaric acid. The four –COOH of EDTA and EDTA-Na coordinated well with the 5-phase structure and tightly aggregated the 5-phase crystals, effectively reducing the formation of microcracks. The synergistic effect between EDTA/EDTA-Na and tartaric acid prevented the disruption of 5-phase crystal structures by water molecules, thus improving the water resistance of the MOC composite. The softening coefficients of the MOC composite modified by EDTA and EDTA-Na in cooperation with tartaric acid after soaking for seven days were 0.97 and 0.98, respectively, which is significantly higher than that of the MOC composite modified by tartaric acid alone (0.54). At the same time, the co-modified MOC composite can be utilised as an inorganic adhesive for plywood, and the wet strength of plywood modified with EDTA in cooperation with tartaric acid being 25% higher than that of the unmodified MOC composite. In addition, the resulting composites showed great potential for application in low-carbon building materials, which can help alleviate the environmental impact of construction industries.

Low carbon and environmental preservation of residential buildings: MOESOM

Introduction: The crucial transition toward carbon neutrality is developing and adopting low-carbon buildings and communities to achieve the recycling and reuse of resources and to minimize the damage to the natural environment by humans. Energy saving for residential buildings is essential for enhancing cost-effectiveness and redundant energy drain. Considering the increasing attention to energy conservation and the accessibility of sustainable energy sources, common energy-saving solutions expose inherent inadequacies limiting their effectiveness. The ineffectual use of traditional energy sources can result in waste, greater operating costs, and excessive energy consumption in residential structures.Methods: Hence, a Multi-Objective Energy-Saving Optimization Method (MOESOM) has been proposed to optimize energy use and conservation in residential buildings in southern Anhui, China. The proposed approach examines lower operational costs and carbon emissions by using green energy sources and encouraging effective energy consumption habits. The suggested Multi-Objective Energy-Saving Optimization Method technique offers insight into energy saving by utilizing green energy sources and confining energy uses. The multi-objective turns around energy saving and resource usage for decreasing operational costs and averting carbon emissions. Thus, the suggested technique is verified utilizing the Osprey Optimization Algorithm (OOA); the detailed goal is recognized utilizing the multiple objectives described. Based on the progress of low-carbon emissions and energy saving, the number of iterations for augmenting Osprey agents is identified. This agent-based optimization is executed if the novel augmented agent fulfills any of the trailing progression. The emission control level and energy-saving factor are assessed considering the variance between new and old agent progression. This encourages the various objectives to be fulfilled under similar criteria balancing their outcomes.Results and discussion: The output from different Osprey agents is induced for consecutive objectives and optimization factors. Then, the system ensures 8.97% energy savings and 8.04% high objectives compared to the other methods.

The energy saving performance of the thermal diode composite wall in different climate regions

The effective management of energy consumption during building operations continues to be of utmost importance. The role of a building's envelope in regulating energy consumption is critical. However, traditional building insulation systems often struggle to maintain optimal indoor temperatures in the face of fluctuating external temperatures. Solar energy, for instance, can easily penetrate a room through windows during the cooling season, leading to increased energy consumption. Similarly, heat dissipates easily during the heating season. To address these challenges, thermal diode composite walls with unidirectional heat transfer offer a groundbreaking approach to simplifying the design of thermal management systems. The thermal diode composite wall effectively controls heat conduction, convection, and radiation through the implementation of different functional layers. By regulating the heat flux through the building envelope, this technology significantly reduces energy consumption during building operations while maintaining a stable indoor temperature. To evaluate the performance of an adaptable thermal diode composite wall, we designed, implemented, and conducted tests on a thermal diode composite wall building. The results of the study demonstrate substantial energy savings, ranging from 3.5% to 69.3% for annual operation in various regions, with better performance observed in colder regions. In the forward heat conduction mode, the temperature difference between the inside and outside wall surfaces reached a maximum of 20.99 K, while in the reverse mode, it reached −35.67 K. These findings highlight the remarkable potential of thermal diode composite walls in significantly improving the energy efficiency and comfort of buildings. Consequently, the adoption of thermal diode composite walls presents numerous opportunities for the development of low-carbon buildings.

Automation of embodied carbon calculation in digital built environment- tool utilizing UK LCI database

Global and governmental pressures have been acting as motivators towards delivering sustainable and low carbon buildings. One of the main sources responsible for carbon in buildings is embodied carbon that depends on material choices. Life cycle assessment (LCA) is a methodology developed to assess the materials, using embodied factors throughout the whole life cycle of the material. Although there are promising possibilities for incorporating LCA with building information modelling platforms, dynamic,early design assessment and automated integration still lacking. This paper proposes a novel framework and tool for automating embodied carbon calculations within the BIM environment. The approach leverages literature reviews and hands-on exploration to establish the foundation of a BIM-integrated LCA tool. The proposed tool aims to provide vital information for informed decision-making, minimizing errors, and facilitating low carbon building design. Ultimately, this framework could enhance early decision making, reduce error, time, effort and accelerate iterative design assessment.

Research on the Path of Urban Buildings’ Emission Reduction under the "Dual Carbon" Goal

Construction industry in China has always been a "high-carbon" industry, based on China's goals of reaching "carbon peak" in 2030 and "carbon neutrality" in 2060, it is particularly important to carry out low-carbon transformation of traditional buildings. Under the background of the "dual carbon" goal, this paper analyzes the whole life cycle of urban buildings and explores the four stages of preparation, construction, operation and recycling to find possible problems and solutions in the development of low-carbon green buildings. Low-carbon, environmentally friendly green buildings are the development trend of urban buildings, which can meet people's growing needs on the one hand, and accelerate the transition of original urban buildings to green buildings on the other hand, ensuring the smooth realization of China's "dual carbon" goal.

Assessing the environmental impact of building life cycle: A carbon reduction strategy through innovative design, intelligent construction, and secondary utilization

The sustainable development of low-carbon buildings has aroused widespread concern in the whole society. This study aims to propose a three-step carbon reduction strategy based on innovative design, intelligent construction and secondary utilization, and provide a new solution for carbon reduction in the construction industry. Based on the life cycle assessment method, the system boundary and calculation model of carbon emission and carbon compensation in each stage of building life cycle are redefined, and the carbon reduction effect of the mixed three-step strategy is quantitatively analyzed through the case carbon emission data, which proves the scientific feasibility of the carbon reduction strategy in this paper. The research shows that it has a good carbon reduction effect whether it is adopting structural optimization aided design in the architectural design stage, upgrading the traditional construction technology with 3D printing intelligent construction technology, or effectively disposing of the construction waste for recycling.

Colonial sandcastle-inspired low-carbon building materials

Colonial sandcastle-inspired low-carbon building materials

A systematic literature review on the decarbonisation of the building sector—a case for Nigeria

The buildings sector is responsible for over 36% of total global end-use energy utilization and nearly 40% of the total indirect and direct carbon emissions. Low-carbon or zero-energy buildings remain the only option to lessen the sector’s energy consumption and CO2 emissions. The current systematic study examines low-carbon buildings under deep decarbonization scenarios in selected global south regions from 2010 to 2021. The study was channelled by the PRISMA (“Preferred Reporting Items for Systematic reviews and Meta-Analyses”) review process, which identified 29 related articles from Scopus, Web of Science., and Google Scholar databases. The identified critical drivers of emissions were population, gross domestic product, dwelling characteristics, and urbanization. The dwelling characteristics contributed about 12% and 27% to the total CO2 emissions in the selected regions. The population varies between 23% and 27% across the areas. Specific findings were made for inclusion in the Nigeria model while the general results were observed and further studies proposed. Total investment from the private and public sectors was identified as key to achieving the transition process of decarbonization in the building sector.

Years of education and research driven in sustainable architecture: Where do we stand and where do we go?

PurposeThe purpose of this study is to give an informative map of sustainable architectural education by focusing on publishing trends, prominent publications, prolific contributors, research challenges and future research prospects. As a consequence, an efficient framework for collecting significant knowledge and identifying prevalent topics in sustainable architectural education towards more sustainable environments at the urban and building scales may be provided.Design/methodology/approachThe methodology adopted in this study is based on examining the subjects of many consecutive rounds of the Passive and Low Energy Architecture (PLEA) conference, with an emphasis on the most recent five rounds. The PLEA's official website served as the main source for gathering all proceedings. Earlier rounds from 2016 to 2020, which cover a time span of five years, were utilized to analyze patterns during that time period. The rationale for selecting this time period was the limited availability of data required to observe the trends, area of interest and emerging themes in these fields that could be analyzed qualitatively.FindingsThe findings show that the following drive themes emerged around education and research-driven sustainable architecture: emerging design as a core idea; concentration on the way of delivering and developing education; constructing and shaping the building; assessing current practices; acquiring and recruiting knowledge and new concepts; reporting on the current condition; portraying the target audience and ensuring the long-term viability of the architectural educational process. This insight provides academics and professionals a greater grasp of the state of the art, allowing them to direct their research toward developing concerns in education and research-driven sustainable design.Originality/valueThe study results provide an effective framework for collecting relevant content and identifying prominent topics in sustainable, passive and passive low-energy architecture for the creation of more sustainable urban and building environments. Furthermore, this qualitative and exploratory study may serve as a framework for those researching, creating and verifying different research approaches in education and research-driven sustainable architecture.

Feasibility analysis of retrofitting existing residential towards the EnerPHit standard in HSCW zone: A case study in Guilin, China

In response to the increasing demand for thermal comfort and the rising trend of building energy consumption in the hot summer and cold winter (HSCW) zone of China, there is an urgent need to implement higher standards of energy retrofit programs for existing residentials. Practical strategies and technical solutions still need to be improved in China. The Passive House standard (and its EnerPHit standard) aims to achieve ultra-low operational energy consumption through passive strategies. However, studies and examples of passive houses and low-energy buildings are rare in hot climates, especially in the HSCW zone of China. This paper presents the representative of the existing residential in Guilin, China. Simulation modeling through DesignBuilder and a sensitivity analysis were performed to conclude that airtightness, envelope, glazing type, and roof are the most critical factors affecting the energy consumption of the building. Furthermore, the combined solution was validated by optimizing the different retrofit parameters, resulting in a model that meets the energy objectives. The feasibility of the combined solution was also analyzed from the energy, economic, and thermal comfort points of view. Ultimately, the optimal solution that meets the objectives is obtained through a multi-criteria decision making (MCDM) approach for a more sustainable building. The methodology and results of this study provide an effective decision-making process for designing and evaluating energy retrofits for typical residential buildings in the HSCW zone, as well as a rigorous basis for policymakers to update the design codes for retrofitting buildings in HSCW zone.

Experimental Investigation on the Seismic Behavior of Precast Concrete Beam-Column Joints with Five-Spiral Stirrups

Precast concrete structure is a low-carbon building system that has been attracting extensive attention in recent decades. Beam–column joints are the weak links in precast concrete structures. Past studies showed that the five-spiral stirrups had excellent confinement effects and had the potential to enhance the seismic performance of concrete structures. This study proposed the reinforcement of precast concrete beam–column joints by using five-spiral stirrups and investigated their seismic performance. Considering the influences of the joint failure mode, joint type, construction method, and stirrup type, low-cycle loading tests were conducted on six full-scale precast concrete beam–column joint specimens. Various seismic behavior indicators, such as failure modes, hysteresis curves, skeleton curves, ductility, and energy dissipation, were obtained. The results indicated that the deformation capacity of the precast joints with five-spiral stirrups was comparable to that of cast-in-place joints. Under different failure design criteria, the seismic performance of the precast joints was superior to that of cast-in-place joints. Furthermore, the experimental capacities of the precast joints, using five-spiral stirrups, were higher than the calculated values according to the design code, demonstrating an adequate safety margin. This research contributes to the development of low-carbon and sustainable construction practices in the field of precast concrete structures.

From Poor Buildings to High Performance Buildings: The Spontaneous Green Evolution of Vernacular Architecture

The spontaneous evolution of vernacular architecture mainly relies on the inheritance of architectural traditions and the innovative decisions of occupants, rather than the professional guidance of architects and the promotion of government agencies. This study introduces a new and rapidly developing phenomenon of spontaneous green evolution of vernacular architecture into the professional field, and conducts scientific research on its technical characteristics, system effects, and optimization methods. Based on the phenomenon of roofing of courtyards (CBR) in southern Hebei, we intervene from the professional point of view of architects, make the best use of the situation, and moderately intervene in its scientific development. By re-examining the adaptability of the open and closed attributes of courtyard buildings to specific climatic conditions and living patterns, the performance improvement and potential risks brought by CBR to local vernacular buildings are systematically analyzed, and the improvement strategies and promotion paths of CBR are explored. The research aims to form a relay and interaction between the professional intervention of architects and the spontaneous evolution of folk wisdom, and to explore the sustainable development of vernacular architecture. The findings help to improve the health and comfort of existing vernacular buildings, as well as to contribute to the improvement of rural human settlements.

Simulation Study on Natural Ventilation Performance in a Low-Carbon Large-Space Public Building in Hot-Summer and Cold-Winter Region of China

Recently, climate governance has entered a new phase of accelerating decarbonization. In order to achieve low-carbon buildings, natural ventilation has been widely used as it requires no fan power. However, there are great challenges for achieving effective natural ventilation in large-space public buildings especially in areas characterized by hot-summer and cold-winter climatic regions, due to empirically unsuitable ambient temperatures and theoretically complex joint effect of wind pressure and thermal buoyancy. Therefore, this numerical study was conducted on the performance of a natural ventilation strategy in a large-space public building in a hot-summer and cold-winter region by using computational fluid dynamics (CFD) methods. Simulations were performed by applying FLUENT software for obtaining airflow distributions within and around a typical low-carbon public building. The temperature distribution in the atrium of the building was simulated particularly for analyzing the natural ventilation performance in a large-space area. Results demonstrated that thermal pressure was dominant for the large-space building in the case study. The average indoor airflow velocities on different floors ranged from 0.43 m/s to 0.47 m/s on the windward side which met indoor ventilation requirements. Most areas of wind velocities could meet ventilation requirements. The natural ventilation performance could be improved by increasing the relative height difference between the air inlets and air outlets. These findings could help provide references and solutions for realizing natural ventilation in low-carbon large-space public buildings in hot-summer and cold-winter regions.

Integration of booster heat pumps in ultra-low temperature district heating network: Prototype demonstration and refrigerant charge investigation

Decentral booster heat pumps (BHPs) integrated in ultra-low temperature district heating (ULTDH) systems are deemed a sustainable solution for low-carbon building systems. The performance of BHPs is critical for the implementation of ULTDH systems. In this study, we experimentally investigate the effect of refrigerant charge on temperature, pressure, system coefficient of performance (COP), and heating capacity to evaluate the operability and sensitivity of ULTDH. A performance-guaranteed range of refrigerant charge is proposed to ensure the feasibility of the system. We also analyse the component-level exergy destruction and the system-level exergetic efficiency of a BHP prototype. The exergetic efficiencies range from 24.9 % to 33.4 % under operational conditions for ULTDH. The condenser and evaporator's exergy destruction is influenced by the temperature profiles on both sides, suggesting the potential to improve BHP performance by tailoring operating parameters. Additionally, the return water temperature significantly affects the system COP when the domestic hot water supply temperature is fixed. Within the allowable range of return water temperature, BHP operation with high evaporator outlet water temperature can improve the overall efficiency of the ULTDH system.

A multi-objective design tool for decarbonising buildings at the concept stage

To enable the move to carbon-neutral building structures with net-zero operation requires a step change in how buildings are designed. Modern buildings are designed by multidisciplinary design teams each of which has competing performance objectives. Daisy is a flexible performance-based parametric design tool which harnesses computational design workflows to enable designer-led multi-objective optimisation, allowing for the design of buildings which simultaneously achieve high performance across multiple performance objectives. A case study of designs for a 63-storey commercial building is presented that demonstrates how early design space analysis facilitates better-performing buildings across architectural and engineering performance metrics and the potential of multi-objective optimisation for enabling the move towards carbon-neutral building structures. Beyond building structures, the design methodology established for Daisy can be applied to a broad range of civil engineering optimisation problems using a flexible and accessible design space formulation that can be adapted for project-specific design requirements. Designs generated using the Daisy methodology demonstrated that by increasing the spatial daylight autonomy of the benchmark building by 14.7%, the building can be moved from the 10% of designs with the highest energy use intensity to lower than 97% of other simulated designs. However, this design change significantly increases the building embodied carbon, with the new design having a building embodied carbon which is higher than 90% of other buildings simulated. Alternatively, by reducing the spatial daylight autonomy by 32.8%, the design can have an energy use intensity which is lower than 75% of other simulated designs, with a 4.4% reduction in energy use intensity, and a building embodied carbon which is lower than 60% of other simulated designs, enabling a 1.3% reduction in building embodied carbon.

Energy assessment of advanced and switchable windows for less energy-hungry buildings in the UK

Globally, greenhouse gas emissions from the operational phase of buildings are significantly contributing towards climate change. Global and national efforts, through the Sustainable Development Goals and the UK's 2050 targets, aim to reduce these emissions with net zero energy buildings (NZEBs). A building's glazing plays a significant role in overall building energy consumption due to their traditionally ‘leaky’ nature. This study utilises experimental data from test cells and the International Glazing Database to evaluate the performance of advanced and smart/switchable windows on an existing low energy building (LEB) situated in north Wales, UK, as a step towards making the modelled building a NZEB. A number of glazing constructions were considered in this work; advanced window – vacuum, aerogel, vacuum-aerogel and smart window – PDLC, PDLC-aerogel and PDLC-vacuum, in their fixed and switching states. Results revealed that PDLC-vacuum offered the greatest reduction in building energy, yielding a theoretical U-value of 0.810–0.831 W/m2K and a G-value of 0.257–0.455. Despite its successes, it was notably susceptible to window orientation and window-to-wall ratio. Vacuum and aerogel glazing both offered similar energy savings, with the latter prone to overheating, stressing cooling loads. These advanced windows offered differing daylighting potential with vacuum able to meet 78% of useful daylight illuminance compared to aerogel's 60%. Given the prioritisation trilemma between heating, lighting and cooling needs of a building, PDLC-vacuum presents the best step towards a NZEB. As such, further efforts should concentrate on the development of a PDLC-vacuum window, maintaining smart window functionality and achieving low U-value for cold climates.

Summer thermal and energy performances assessment of a modular hydronic thermal barrier wall for ultra-low energy buildings - A field experimental study

Hydronic thermal barriers with ultra-low carbon emission attributes are progressively gaining prominence in the competition of thermal insulation solutions for opaque envelopes of low-energy buildings due to their excellent thermal performance and low-grade energy utilization potential. This paper introduces a novel approach involving a modular hydronic thermal barrier wall (MHTB) that incorporates preset pipe cavities and replaceable filling material. This proposition seeks to address the challenges confronted by conventional hydronic thermal barrier walls (CHTBs), specifically in terms of internal heat transfer enhancement and rapid assembly/dismantling. On-site thermal performance tests and energy-saving evaluations were conducted in summer conditions based on three scaled-down rooms with MHTB, CHTB and a conventional external insulation wall as the south walls. The results showed that the MHTB could significantly reduce heat passing through the south wall in summer, resulting in a decreased cooling load attributed to the wall and subsequently lowering indoor temperatures. At a charging temperature of 17.0 °C, the MHTB exhibited a reduction of 11.3 °C in interior surface temperature compared to the conventional external insulation wall, accompanied by a corresponding increase of 2.76 kWh·m−2 in cumulative heat flux. In addition, the MHTB could effectively mitigate inhomogeneous heat transfer within the wall, enhancing the overall heat transfer effect. Across the four investigated conditions, the MHTB with a steel grit-sand mixture as the filling material demonstrated an approximate 4.7% increase in cumulative heat flux and a 12.2% enhancement in cumulative cooling quantity compared to the CHTB. Overall, the findings substantiated the efficacy of the MHTB system and offered a crucial point of reference for advancing research in optimizing the performance and modular construction of hydronic thermal barrier walls.

Comparison of the embodied and operating energy in agricultural greenhouses and in residential buildings

The increase of the energy efficiency in buildings and greenhouses is important for reducing the use of fossil fuels and the emissions of greenhouse gases. Energy efficiency evaluation requires the consideration of both the embodied and the operational energy. Many estimations regarding the embodied and the operational energy in various types of buildings have been reported so far. However, studies regarding the embodied energy in agricultural greenhouses are rare while there are many estimations regarding their operational energy. The goal of our study is the comparison of the embodied and the operational energy in residential buildings and in agricultural greenhouses. The embodied and operational energies are compared in greenhouses as well as in low-energy and in conventional residential buildings. Our results indicate that the ratio of embodied energy to life-cycle energy in low-energy residential buildings and in nearly-zero energy buildings varies in the range at 36% to 83% that is significantly higher than the ratio in conventional residential buildings which is in the range of 6% to 20%. The ratio of embodied energy to life-cycle energy in agricultural greenhouses, at 0.86% - 70.41%, varies significantly depending on many parameters. The importance of carbon emissions related to embodied energy in low-energy buildings, in net-zero energy buildings and in agricultural greenhouses is highlighted. Our work could be useful to policy makers who are willing to accelerate the green transition to a low carbon economy in the coming decades.