Search Results (243)

With government, industry, and public pressure to decarbonize the building sector through reducing embodied and operational emissions, there have been a wide range of innovative materials used in building envelope retrofits. Although these innovative materials, such as super insulating materials, bio-based insulation, and many others, are assessed on thermal performance and code requirements before use in retrofits, there is no unified standard assessment metric for hygrothermal performance of innovative materials in building envelope retrofits. This paper performs a rapid review of the available literature from January 2013 to March 2025 on hygrothermal performance assessment metrics used in retrofits. Using rapid review methods to search for records in Scopus, Web of Science, and Google Scholar, fifty-nine publications were selected for bibliometric and qualitative analysis. Most selected publications include discussions and analysis of relative humidity in the wall assembly post retrofit, moisture content, and mould index within the envelope. There is a research gap in publications considering hygrothermal damage functions such as freeze–thaw index, relative humidity and temperature (RHT) index, or condensation prediction. There is also a research gap in country and climate studies and analyses of in situ retrofits with innovative materials, and occupant comfort post retrofit. Full article

Rural residential structures account for a substantial share of carbon emissions within the construction industry. Enhancing building envelopes can diminish structural carbon emissions, thereby facilitating the attainment of “dual carbon” objectives. Current algorithm-driven research on the low-carbon retrofitting of residential building envelopes generally neglects temperate regions in low-latitude plateaus, often misses embodied carbon, and utilizes rather limited methodologies for issue identification. This study focuses on rural dwellings in Lijiang, utilizing a cross-validation method that incorporates sensitivity analysis, infrared thermal imaging, and energy efficiency criteria to systematically identify vulnerable regions in the building envelope. Consequently, critical issues are converted into optimization variables for the NSGA-II method, aiming to minimize both embodied carbon and operational energy usage. BAPV is concurrently implemented to partially mitigate renovation expenses. A weighted summation approach delineates stakeholder preferences, resulting in three optimum options. The findings reveal that all three methods correspond to their unique preferences, illustrating distinct trade-offs among energy efficiency, carbon reduction, and economic feasibility. The government-oriented approach attained an energy saving rate (ESR) of 45.11%, a life cycle carbon reduction (LCCR) of 1215.76 kgCO₂/m², and a dynamic payback period (DPP) of 3.65 years. The architect-oriented approach realized the highest energy savings and carbon reduction (45.41%, 1218.96 kgCO₂/m²), with a payback period of 3.99 years. The villager-oriented approach emphasized economic viability, achieving an energy savings rate of 41.55%, a carbon reduction of 1149.46 kgCO₂/m², and the shortest payback period of 2.87 years. This study provides an optimization process and reference parameters for building envelopes in a low-carbon design for residential buildings in temperate regions of low-latitude plateaus. Full article

This study examines the impact of envelope renovation using Expanded Polystyrene (EPS) insulation and double glazing on reducing CO₂ emissions and energy consumption in low-income residential buildings in Mozambique’s tropical climate. Conducted in Maputo over 12 months (2023–2024), it targets urban households, addressing high energy use and emissions caused by inefficient building envelopes and limited access to sustainable technologies. The study uses DesignBuilder’s validated EnergyPlus engine to evaluate energy savings and financial viability within cultural and economic contexts. Results show a 42.16% reduction in energy consumption (from 5392.04 to 3118.69 kWh) and a 42.20% decrease in CO₂ emissions (from 3.27 × 10³ to 1.89 × 10³ kg) compared to conventional designs. With an 11.75% discount rate accounting for inflation and opportunity costs, the retrofit achieves a payback period of 6.9 years, confirming its financial viability. These findings offer policymakers, architects, and low-income communities a cost-effective retrofit model, advocating for policy integration of low-U-value materials to improve environmental and economic sustainability. Full article

There is an urgent need to implement sustainable solutions in the construction sector, particularly within the Peruvian context, where regulations on energy efficiency and building rehabilitation are still under development. This study addresses the energy and social rehabilitation of the Mercado Central in Lima, with the aim of identifying the most effective interventions from both energy and economic perspectives while promoting urban sustainability. A detailed assessment of the building’s original state—covering the thermal envelope and technical systems—was conducted, followed by fifty energy simulations using Ce3X© v.2.3. software. Based on the obtained energy rating, several envelopes and system improvements were proposed and evaluated in terms of energy savings, cost-effectiveness, and social benefits. The most advantageous option, Measure M9, combines interventions in roofs, openings, and installations. It achieved a global energy rating of 17.6 A, with a projected lifespan of 75 years and an investment of EUR 1,642,457.01, recoverable in just 1.4 years. The results highlight the potential of integrated retrofitting strategies to simultaneously improve energy performance and social impact. Measure M9 emerges as the most viable solution, providing a replicable model for sustainable urban rehabilitation in Peru and other regions facing similar challenges. Full article

This study evaluates the passive thermal resilience of two full-scale residential buildings during natural summer heatwaves and blackout-like conditions in a temperate European climate. The buildings share identical geometry and ventilation but differ in envelope mass and ground coupling. Building B1 is a masonry structure with a slab-on-ground floor, while B2 is a lightweight timber-frame house. In 2019, B1 underwent a retrofit in which floor insulation was removed to enable direct subsoil heat exchange. Three complementary frameworks were applied: model IOD, AWD, OEF, the indicators AF and αIOD, and the health-based scenario rating HE, HIHH, and WBGT. Across all metrics, B1 demonstrated superior resilience, with overheating fully eliminated after ground coupling was introduced. B2, in contrast, remained vulnerable under both moderate and extreme events. The findings highlight the critical role of thermal mass and soil buffering in maintaining safe indoor conditions without active systems. Under certain circumstances, omitting under-slab insulation can improve summer resilience without significantly compromising winter performance. A companion life-cycle analysis confirms lower cumulative carbon emissions for B1 under all SSP scenarios to 2100. Passive ground coupling thus emerges as a low-cost, maintenance-free adaptation strategy with co-benefits for mitigation and occupant safety. Full article

This study presents a detailed analysis of the energy performance and thermal comfort conditions in four existing school buildings located in Madrid, Spain. Dynamic simulations were conducted using TeKton3D—(iMventa Ingenieros, Málaga, Spain)- an open-source tool based on the EnergyPlus engine—to model four improvement scenarios: (I) current state, (II) envelope retrofitting with ETICS and high-performance glazing, (III) solar control strategies, and (IV) incorporation of mechanical ventilation with heat recovery. Each building was simulated under both current and projected 2050 climate conditions. The case studies were selected to represent different construction periods and urban contexts, including varying levels of exposure to the urban heat island effect. This approach allows the results to reflect the diversity of the existing school building stock and its different vulnerabilities to climate change. The results show that envelope retrofitting substantially reduces heating demand but may increase cooling needs, particularly under warmer future conditions. Solar control strategies effectively mitigate overheating, while mechanical ventilation with heat recovery contributes to improved comfort and overall efficiency. This study highlights the trade-offs between energy savings and indoor environmental quality, underlining the importance of integrated renovation measures. The study provides relevant data for decision-making in climate-resilient building renovation, aligned with EU goals for nearly zero and zero-emission buildings. Full article

Reducing thermal losses through building envelopes remains a key strategy in the pursuit of low-carbon, energy-efficient buildings. This study presents an innovative and sustainable retrofitting approach involving thermal insulation plaster modified with finely ground hazelnut shells, an abundant agricultural by-product in Türkiye. The modified plaster is applied symmetrically on both sides of standard masonry briquettes in varying proportions (2%, 4%, and 6%), and its thermal performance is experimentally assessed via the laboratory-scale coheating test method. The results reveal a substantial reduction in U-values compared to the uninsulated briquette (5.5 W/m²K): the 2% shell-modified plaster achieves a U-value of 2.40 W/m²K (56.4% improvement), the 4% variant achieves 2.14 W/m²K (61.1%), and the 6% formulation performs best at 2.04 W/m²K (62.9%). In terms of effective thermal conductivity, the modified plasters exhibit values in the range of 0.0408–0.04856 W/mK. Additionally, the 6% composition exhibits enhanced thermal inertia, delaying internal heat loss and offering extended indoor comfort. All samples demonstrate exceptional measurement repeatability, with day-to-day U-value variation below 2%. These findings surpass thermal performance benchmarks reported in previous studies using bamboo or plaster thickness alterations, and position hazelnut shell-modified plaster as a high-potential solution for sustainable building retrofits. The outcomes offer practical implications for low-cost housing, rural construction, and building refurbishment programmes, while also informing policymakers and material standardisation bodies about scalable bio-based alternatives that align with circular economy and decarbonisation goals. Full article

Building renovation is widely recognised as a critical strategy for improving energy performance, reducing greenhouse gas emissions, and meeting decarbonisation targets. Although numerous studies have explored retrofit interventions, the existing literature tends to focus on either specific climates or particular building types, lacking a consolidated perspective that links interventions to both climatic context and typological characteristics. This study addresses this gap through a structured literature review of recent scientific publications, aiming to map and categorise climate-sensitive retrofit strategies across different building typologies. The methodological approach involves a qualitative synthesis of peer-reviewed studies, with interventions classified based on climate zone and building use. The results highlight the prevalence of envelope-related measures—such as thermal insulation and high-performance glazing—in residential and educational buildings, particularly in colder climates. Conversely, HVAC upgrades and passive solutions dominate in hot and mixed zones. The findings provide an evidence-based reference for stakeholders involved in designing renovation strategies, while also identifying the need for more context-aware, integrative frameworks that account for climate, building use, and socio-economic factors in retrofit decision-making. Full article

The residential building sector is a major contributor to global energy consumption and carbon emissions, making retrofit strategies essential for meeting climate targets. While many studies focus on reducing operational energy, few comprehensively evaluate the trade-offs between operational savings and the embodied carbon introduced by retrofit measures. This study addresses this gap by developing an integrated, novel scenario-based assessment framework that combines dynamic energy simulation and life cycle assessment (LCA) to quantify whole life carbon impacts. Applied to representative Irish housing typologies, the framework evaluates thirty retrofit scenarios across three intervention levels: original fabric, shallow retrofit, and deep retrofit incorporating multiple HVAC technologies and envelope upgrades. Results reveal that while deep retrofits deliver up to 80.2% operational carbon reductions, they also carry the highest embodied emissions. In contrast, shallow retrofits with high-efficiency air-source heat pumps offer near-comparable energy savings with significantly lower embodied impacts. Comparative analysis confirms that reducing heating setpoints has a greater effect on energy demand than increasing system efficiency, especially in low-performance buildings. Over a 25-year lifespan, shallow retrofits outperform deep retrofits in overall carbon efficiency, achieving up to 76% total emissions reduction versus 74% for deep scenarios. Also, as buildings approach near-zero energy standards, the embodied carbon share increases, highlighting the importance of LCA in design decision-making. This study provides a scalable, evidence-based methodology for evaluating retrofit options and offers practical guidance to engineers, researchers, and policymakers aiming to maximize carbon savings across residential building stocks. Full article

The construction of buildings using shipping containers (SCs) is a way to extend their useful life. They are constructed by modifying the structure, thermal, and acoustic conditioning by improving the envelope and creating openings for lighting and ventilation purposes. This study explores the architectural adaptation of SCs to sustainable residential housing, focusing on structural, thermal, and acoustic performance. The project centers on a case study in Madrid, Spain, transforming four containers into a semi-detached, multilevel dwelling. The design emphasizes modular coordination, spatial flexibility, and structural reinforcement. The retrofit process includes the integration of thermal insulation systems in the ventilated façades and sandwich roof panels to counteract steel’s high thermal conductivity, enhancing energy efficiency. The acoustic performance of the container-based dwelling was assessed through in situ measurements of façade airborne sound insulation and floor impact noisedemonstrating compliance with building code requirements by means of laminated glazing, sealed joints, and floating floors. This represents a novel contribution, given the scarcity of experimental acoustic data for residential buildings made from shipping containers. Results confirm that despite the structure’s low surface mass, appropriate design strategies can achieve the required sound insulation levels, supporting the viability of this lightweight modular construction system. Structural calculations verify the building’s load-bearing capacity post-modification. Overall, the findings support container architecture as a viable and eco-efficient alternative to conventional construction, while highlighting critical design considerations such as thermal performance, sound attenuation, and load redistribution. The results offer valuable data for designers working with container-based systems and contribute to a strategic methodology for the sustainable refurbishment of modular housing. Full article

In Pakistan and most other developing nations, the residential building sector is one of the highest energy-consuming domains. The residential sector has the highest share of 50% of final electricity use of the country. Though Energy Conservation Building Codes (ECBC-2023) provide structured energy guidelines, no work has been performed to quantify the actual energy-saving potential of code-compliant retrofits in residential buildings. This study investigates the performance of ECBC-compliant retrofitting strategies for residential buildings under Pakistan’s diverse climatic conditions. The Passive House Planning Package (PHPP), a validated simulation tool, was used to assess energy performance improvements through building envelope interventions such as thermal insulation, solar shading, window glazing, and optimal orientation. Field data were collected from three representative cities, Multan (hot desert), Taxila (humid subtropical), and Quetta (cold semi-arid), to simulate both conventional and energy-efficient building scenarios. The results showed substantial seasonal energy savings in all three climates. During the heating period, energy savings were 48%, 50%, and 60% for Taxila, Multan, and Quetta, respectively. Similarly, energy savings during the cooling season were 44%, 33%, and 16%. Life cycle economic analysis revealed that these retrofits yielded Net Present Values (NPVs) of USD 752 (Taxila), USD 1226 (Multan), and USD 1670 (Quetta) over a 30-year period, with discounted payback periods ranging from 6 to 10 years. Furthermore, a life cycle assessment demonstrated that retrofitted buildings yielded up to 26% reduction in overall carbon emissions, combining both embodied and operational sources. The findings highlight that ECBC-2023 is not only a technically viable solution for energy savings but also financially attractive in residential retrofitting. By incorporating localized climate responsiveness into ECBC-compliant building design, the study provides a practical roadmap for achieving Pakistan’s energy efficiency goals. Additionally, the outcomes serve as a basis for informing policy initiatives, supporting building code adaptation, and raising public awareness of sustainable housing practices. Full article

Urban building energy retrofit (UBER) is a critical strategy for advancing the low-carbon and climate-resilience transformation of cities. The integration of machine learning (ML), data-driven clustering, and multi-objective optimization (MOO) is a key aspect of artificial intelligence (AI) that is transforming the process of retrofit decision-making. This integration enables the development of scalable, cost-effective, and robust solutions on an urban scale. This systematic review synthesizes recent advances in AI-driven MOO frameworks for UBER, focusing on how state-of-the-art methods can help to identify and prioritize retrofit targets, balance energy, cost, and environmental objectives, and develop transparent, stakeholder-oriented decision-making processes. Key advances highlighted in this review include the following: (1) the application of ML-based surrogate models for efficient evaluation of retrofit design alternatives; (2) data-driven clustering and classification to identify high-impact interventions across complex urban fabrics; (3) MOO algorithms that support trade-off analysis under real-world constraints; and (4) the emerging integration of explainable AI (XAI) for enhanced transparency and stakeholder engagement in retrofit planning. Representative case studies demonstrate the practical impact of these approaches in optimizing envelope upgrades, active system retrofits, and prioritization schemes. Notwithstanding these advancements, considerable challenges persist, encompassing data heterogeneity, the transferability of models across disparate urban contexts, fragmented digital toolchains, and the paucity of real-world validation of AI-based solutions. The subsequent discussion encompasses prospective research directions, with particular emphasis on the potential of deep learning (DL), spatiotemporal forecasting, generative models, and digital twins to further advance scalable and adaptive urban retrofit. Full article

This study addresses the challenge of optimizing envelope retrofit strategies for aged residential buildings across China’s five distinct climate zones. A simulation-based frame work is proposed, applying a standardized Taguchi L27 experimental design to ensure direct comparability across climates. Analysis of variance (ANOVA) and effect size (partial eta squared, η²) are used to identify and quantitatively rank the sensitivity of each retrofit parameter, while interaction analysis reveals the independence or synergy between measures. Technical results are linked with discounted payback period (DPP) analysis to evaluate economic feasibility. The findings show that insulation thickness is most influential in cold climates (η² > 0.95), whereas glazing system upgrades are dominant in warmer regions (η² > 0.97), with parameter interactions generally insignificant. The resulting climate-responsive retrofit priority matrix offers practical guidance for region-specific design and investment decisions. This scalable and replicable method enables policymakers and practitioners to tailor low-carbon, cost-effective retrofit solutions to diverse building and climate contexts, bridging the gap between technical performance and financial viability. Full article

Enhancing the real-world performance of sustainably designed and certified green buildings remains a significant challenge, particularly in hot climates where efforts to improve thermal comfort often conflict with energy efficiency goals. In the United Arab Emirates (UAE), even newly constructed facilities with green building certifications present opportunities for retrofitting and performance optimization. This study investigates the energy and thermal comfort performance of a LEED Gold-certified, mixed-use university campus in Dubai through a calibrated digital twin developed using IES thermal modelling software. The analysis evaluated existing sustainable design strategies alongside three retrofit energy conservation measures (ECMs): (1) improved building envelope U-values, (2) installation of additional daylight sensors, and (3) optimization of fan coil unit efficiency. Simulation results demonstrated that the three ECMs collectively achieved a total reduction of 15% in annual energy consumption. Thermal comfort was assessed using operative temperature distributions, Predicted Mean Vote (PMV), and Predicted Percentage of Dissatisfaction (PPD) metrics. While fan coil optimization yielded the highest energy savings, it led to less favorable comfort outcomes. In contrast, enhancing envelope U-values maintained indoor conditions consistently within ASHRAE-recommended comfort zones. To further support energy reduction and progress toward Net Zero targets, the study also evaluated the integration of a 228.87 kW rooftop solar photovoltaic (PV) system, which offset 8.09% of the campus’s annual energy demand. By applying data-driven thermal modelling to assess retrofit impacts on both energy performance and occupant comfort in a certified green building, this study addresses a critical gap in the literature and offers a replicable framework for advancing building performance in hot climate regions. Full article

This study empirically evaluates the energy and carbon reduction effects of an envelope retrofit applied to an aging public building in South Korea. Unlike previous studies that primarily relied on simulation-based analyses, this work fills the empirical research gap by using actual utility billing data collected over one pre-retrofit year (2019) and two post-retrofit years (2023–2024). The retrofit included improvements to exterior walls, roofs, and windows, aiming to enhance thermal insulation and airtightness. The analysis revealed that monthly electricity consumption was reduced by 14.7% in 2023 and 8.0% in 2024 compared to that in the baseline year, with corresponding decreases in electricity costs and carbon dioxide emissions. Seasonal variations were evident: energy savings were significant in the winter due to reduced heating demand, while cooling energy use slightly increased in the summer, likely due to diminished solar heat gains resulting from improved insulation. By addressing both heating and cooling impacts, this study offers practical insights into the trade-offs of envelope retrofitting. The findings contribute to the body of knowledge by demonstrating the real-world performance of retrofit technologies and providing data-driven evidence that can inform policies and strategies for improving energy efficiency in public buildings. Full article