Retrofit Solutions Research Articles

Sustainable energy synergy for historic building: Conservation retrofit solution of hygrothermal control

Historic buildings require groundbreaking retrofit technology to prevent damage to the exterior appearance of the exterior. This paper presents a retrofit technology to increase the energy efficiency of old historic buildings that were heavily exposed to hygrothermal conditions. The study employed an innovative interior finishing material composed of diatomaceous earth and microencapsulated phase change materials to achieve a trade-off between performance improvement and heritage conservation. Based on previous studies, an optimal formulation was identified through evaluation. The developed retrofit technology displays crack resistance, high latent heat capacity, and remarkable moisture stability. Our analysis revealed that the application of this retrofit solution would effectively reduce moisture levels and mitigate condensation risks without compromising the building’s historical integrity. The retrofit technology yielded a reduction in cooling and heating energy consumption by over 10% while concurrently addressing moisture stability through a decrease in the thermal transmittance of the exterior walls. By utilizing passive technologies and the unique properties of diatomaceous earth, our pioneering research on the sustainable preservation of historic buildings has laid the foundation for widespread retrofit adoption in heritage conservation.

Systematic review turning existing Egyptian residential buildings in green ones

Due to the continuous technological advancements, expensive utility bills became a major concern for the world residents as well as governments. As a result, energy consumption mitigation became a prominent target for modern researchers. Consequently, solutions were introduced, suggesting that green principles be applied to the construction field. However, even if newly built structures became completely green and emitted no harmful emissions, the net emissions of a given city's overall construction would still be in operation, harming and polluting the environment with all their might. Therefore, it is needed to work on the net green score and rather focus on the conversion of existing buildings into green. Using a questionnaire to create a hypothetical typical Egyptian home, this study aims to apply green solutions to existing buildings in Egypt. The questionnaire also tackles other areas of Egyptian society in order to better understand their awareness and understanding of green concepts. The study’s methodology is based on the collective data gathered from other researchers in the field with applied case studies in climates similar to Egypt’s due to its lack of these solutions applications and concepts. The solutions suggested included solar panels as a retrofitting solution, and windows orientation and window-to-wall ratio (WRR) as a renovating one. As a result, the "windows" solutions suggested in this paper happened to be the most effective.

Multi-Parametric Methodology for the Feasibility Assessment of Alternative-Fuelled Ships

The shipping industry significantly influences global greenhouse gas emissions through a predominant fossil fuel-based fleet. Regulating bodies are continuously developing rules to reduce the shipping carbon footprint. Adopting low-carbon fuels is considered a step toward achieving the Paris Agreement’s goals; however, it represents a significant paradigm shift in ship design. This work aims to illustrate a methodology for the feasibility assessment of alternative-fuelled vessels considering technical, environmental, and economic perspectives. The technical feasibility focuses on ship propulsion, fuel system safety, and design parameters. The environmental impact evaluation is based on the Tank-to-Wake and the Well-to-Wake approaches. The cost assessment is performed by estimating capital and operational expenditures, considering only the modifications required by the new fuel. The methodology addresses new-building and retrofit solutions, and can be used as a decision support tool for selecting the best strategy. A key output of the methodology is the cargo emission footprint, expressed in equivalent carbon dioxide per cargo unit. Using a handysize bulk carrier as a case study, this work points out the effects of using methanol as an alternative fuel, highlighting its impact on market and transport strategies in a sector evolving towards Eco-Delivery services.

Process Integration and Electrification for retrofit: Case studies of milk evaporator systems

Industrial Process Integration and Electrification represents a critical path to harnessing renewable electricity for a net-zero future, particularly through advancements in heat pump and vapour recompression technologies for industrial applications. This paper addresses the challenge of decarbonising an energy-intensive aspect of dairy processing plants, milk evaporation, which is a critical processing step in milk powder production. Employing three different milk evaporator case studies, it introduces a retrofit methodology that merges Process Integration with Electrification technologies to achieve energy, emissions and cost savings. The study leverages Heat Pump Bridge Analysis, extended to evaluate process unit operations, and work consumption and generation, facilitating a comprehensive retrofit analysis for optimal energy use. The study concludes with several retrofit solutions, notably replacing steam ejectors with mechanical vapour recompression fans, resulting in energy savings of 13.7 %–41.6 % and emissions reductions of 14.5 %–47.3 %. This approach offers a holistic framework for industrial electrification, demonstrating significant efficiency and sustainability gains in dairy processing.

Mechanical properties of geopolymer concrete specimens exposed to fire retrofitted with glass and basalt fiber reinforced polymer laminates

AbstractExposure of concrete to elevated temperature affects its mechanical and physical properties. One of the important reasons for the use of fiber‐reinforced polymer (FRP) composite materials is because of its superior mechanical properties. These mechanical properties include impact resistance, strength, stiffness, flexibility, and also it is enhanced ability to carry loads. The high strength–weight ratio, and corrosion resistance of FRPs made them suitable for repair. For strengthening and retrofitting of concrete structures confinement with FRP has received considerable attention in recent years. Geopolymer concrete (GPC) can be expressed as “concrete without cement.” GPC is environmentally friendly and an inventive way to replace the conservative concrete which contributes 7%–8% of total CO2 production in the world. “The concrete which entails of the source materials and the alkaline solution.” The composite material made of fiber‐reinforced polymer (FRP) has recently gained attention as a potential repair method for concrete structures that have been damaged. This study investigates the performance of glass and basalt fiber‐reinforced polymer (GFRP and BFRP) laminates as a retrofit solution for fire‐damaged GPC specimens. The specimens were subjected to temperatures of 200°C, 400°C, 600°C, and 800°C for a period of 1, 2, and 3 h, followed by retrofitting with FRP laminates. The results indicated an increase in the ultimate load‐carrying capacity of GPC specimens when subjected to 200°C for 1 h, beyond which it decreased. However, a fall in ultimate load capacity was observed for higher ranges of temperature and duration of the fire. In this project, geopolymer specimens that had been damaged by fire are wrapped with GFRP and BFRP laminates to study the effect of confinement on the strength of GPC specimens. The fiber laminate used was bi‐directional glass and bi‐directional basalt. Based on the analysis of test data, there was the conclusion that the fire‐damaged GPC was strengthened when retrofitted with GFRP and BFRP laminates was attainable.

Cost-effective topology optimization of masonry structure reinforcements by a linear static analysis-based GA framework

The paper presents a novel optimization framework aimed at the minimization of seismic retrofitting-related costs for existing unreinforced masonry building structures. The framework provides topology optimization of reinforcements (reinforced plasters) to implement in masonry walls for the accomplishment of seismic safety checks under the reference seismic load combinations. Optimization is carried out by a genetic algorithm (GA) developed in MATLAB®, which controls a 3D finite element equivalent frame model of the masonry structure developed in OpenSees. The GA routine iterates the reinforcement configurations employing specific genetic operators. The feasibility of each candidate retrofitting solution is assessed by performing in-plane shear and flexural safety checks of masonry walls. The framework is finally tested with a case study masonry structure supposed to be made of average-quality or poor-quality masonry. Results will show that the proposed framework can effectively provide the minimization of seismic retrofitting costs for existing masonry structures, giving as output the optimal configuration of the reinforcements within the structural layout.

Optimal design of steel exoskeleton for the retrofitting of RC buildings via genetic algorithm

In recent decades, steel exoskeletons have gathered significant attention as a seismic retrofitting technique for existing structures. The design methods proposed so far are focused on the identification of the system's overall parameters through simplified models. Although these methodologies provide helpful guidance at the preliminary design stage, they do not consider aspects such as the distribution of the exoskeletons and sizing of their components. To overcome these limitations, an optimization process based on the Genetic Algorithm is proposed in this paper to identify the optimal exoskeleton number and spatial arrangement, and to determine the optimal size of their constituent elements. The algorithm aims to minimize the weight of the retrofit solution while keeping the whole existing structure in the elastic field and ensuring the structural verification of the exoskeleton's elements. The analyses have been conducted using a finite-element code with an Open Application Programming Interface, which allows the models to be handled through automatic routines. The proposed optimization tool has been applied to several case studies, considering two different layouts for the exoskeletons. Finally, the effectiveness of the retrofit method has been demonstrated, and the proposed optimization tool has been able to significantly reduce the weight and cost of the intervention.

Seismic evaluation of a self-centering retrofit solution for modular steel structure connections

In this study, a novel plug-in modular steel structure (MSS) connection is proposed, in which the connector, cover plates, and bolts form a complete connecting system. To improve the seismic performance and post-earthquake functional recoverability of the MSS connection, a retrofit solution with diagonal self-centering (SC) haunch braces is introduced, and the self-centering modular steel structure (SC-MSS) connection is developed. Theoretical analysis of the mechanical properties of the MSS and SC-MSS connections are conducted, and the calculation formulas for the initial stiffness and bending bearing capacity are derived. A comparative experimental study of one MSS connection and five SC-MSS connections under cyclic loading was carried out to evaluate their seismic performance, and to explore the influences of the main haunch parameters on the behavior of the SC-MSS connection. The results demonstrate that the plug-in connector, cover plate, and bolts can realize reliable continuity and integrity between modules. The SC haunch braces have good collaborative work with the modules and provide sufficient restoring force, and the damage in all the SC-MSS connections was found to be effectively controlled and delayed as compared with the MSS connection. The MSS connection displays a full shuttle-shaped hysteretic response with adequate plastic development, while the SC-MSS connections successfully exhibit expected flag-shaped hysteretic responses with higher bearing capacity and lower residual displacement. The adjustment of the post-activation stiffness and pre-pressed force of the haunch brace is found to improve the connection performance, and a reasonable selection of the installation scheme could achieve optimal self-centering efficiency. The experimental results also verify the feasibility and correctness of the proposed theoretical formulas and mechanical assumptions.

Towards High-Efficiency Buildings for Sustainable Energy Transition: Standardized Prefabricated Solutions for Roof Retrofitting

Enhancing energy efficiency in buildings plays a pivotal role in realizing the ambitious objective of achieving carbon neutrality by 2050, as outlined in the European Green Deal. Roofs represent the technical element most affected by energy phenomena related to heat transfer: in winter, roofing can lose up to 35% of heat, and the summer heat flux can even be higher. This paper provides a catalogue of optimized and sustainable solutions, with a specific focus on standardization and prefabrication principles, for enhancing the energy efficiency of the most prevalent types of roofs that characterize the national residential building heritage. The methodological approach that guided the research presented in this article was based on the identification and study of the most common roofings in the diverse national residential building heritage, followed by their classification according to their construction era. In the context of essential energy retrofitting of deteriorated residential building stock, 21 optimized standardized solutions have been identified. The outcome of performance evaluations of the proposed solutions allowed the implementation of a matrix that can be a valuable support for designers in selecting the most efficient precalculated and prefabricated solutions for the national residential building heritage based on energy performance and sustainability criteria.

Decreasing the environmental impact of the electric steel making process through implementation of furnace retrofitting solutions

Steel production in the electric arc furnace is an energy-intensive process and generates a high amount of climate-relevant CO2 emissions. During the last decades, various improvements of the furnace and its operation have been developed and implemented, so that the efficiency of modern steel plants has reached a high level. Due to the standardized process flows and high production volumes, even small improvements in resource efficiency can lead to significant savings and improve the environmental impact of the steel production. This paper presents several optimization activities and retrofitting solutions for the metallurgical sector and in particular for the electric steel route. On the example of a Spanish electric steel plant, a life cycle analysis is carried out to calculate the potential improvements in environmental impacts and compare them with the current state of the art. For this purpose, real process data were collected and transferred to a life cycle assessment model with the use of a material flow analysis. A comparison of the ecological impact categories provides information on which retrofitting solutions can improve the process in the electric arc furnace and ensure a lower environmental impact.

Protection of Reinforced Concrete Columns from Pounding-Induced Effects in Adjacent Buildings

The pounding damage is one of the most common seismic damages observed after past earthquakes in adjacent reinforced concrete (RC) buildings having insufficient gap in-between. Particularly in highly populated regions, there are numerous adjacent RC buildings, in which pounding can cause severe damage or total collapse. Many previous reconnaissance reports following earthquakes have emphasized severe column damage due to pounding with the slab of adjacent building. In this paper, a retrofitting method is presented to reduce the seismic damage caused by pounding on existing RC structural elements in cases where collision is unavoidable. Pounding effects are investigated by using 4- and 7-story RC buildings with unequal floor elevations. As a retrofitting solution for pounding, steel columns and neoprene rubber pads are placed at the mid-height of the story so that the pounding takes place between the neighboring slab and added steel columns instead of existing RC columns. The mid-column pounding of existing RC buildings with and without retrofitting are numerically investigated. In the numerical model, buildings are connected by link elements to reproduce the pounding in-between. Nonlinear response history analyses are performed using 11 different real ground-motion records. Pounding forces, peak floor accelerations, inter-story drift ratios, story shear force distributions, and plastic hinge distributions are obtained and compared for each of the pounding conditions. The analysis results revealed that the proposed retrofitting method protects the existing RC columns from brittle type of shear failure and reduces the destructive effects of pounding.

Advancing Urban Building Energy Modeling: Building Energy Simulations for Three Commercial Building Stocks through Archetype Development

Urban building energy models (UBEMs), developed to understand the energy performance of building stocks of a region, can aid in key decisions related to energy policy and climate change solutions. However, creating a city-scale UBEM is challenging due to the requirements of diverse geometric and non-geometric datasets. Thus, we aimed to further elucidate the process of creating a UBEM with disparate and scarce data based on a bottom-up, physics-based approach. We focused on three typically overlooked but functionally important commercial building stocks, which are sales and shopping, healthcare facilities, and food sales and services, in the region of Pittsburgh, Pennsylvania. We harvested relevant local building information and employed photogrammetry and image processing. We created archetypes for key building types, designed 3D buildings with SketchUp, and performed an energy analysis using EnergyPlus. The average annual simulated energy use intensities (EUIs) were 528 kWh/m2, 822 kWh/m2, and 2894 kWh/m2 for sales and shopping, healthcare facilities, and food sales and services, respectively. In addition to variations found in the simulated energy use pattern among the stocks, considerable variations were observed within buildings of the same stock. About 9% and 11% errors were observed for sales and shopping and healthcare facilities when validating the simulated results with the actual data. The suggested energy conservation measures could reduce the annual EUI by 10–26% depending on the building use type. The UBEM results can assist in finding energy-efficient retrofit solutions with respect to the energy and carbon reduction goal for commercial building stocks at the city scale. The limitations highlighted may be considered for higher accuracy, and the UBEM has a high potential to integrate with urban climate and energy models, circular economy, and life cycle assessment for sustainable urban planning.

Renewable Hydrogen Supply Scenarios for Inland Waterway Transport in Europe

The European inland waterway transport needs to substitute 6.2 TWh of fossil diesel by renewable energy carriers. For hydrogen retrofit solutions investigated in the European project “Synergetics”, different Well-to-Tank pathways have been analysed to supply renewable hydrogen to Rotterdam, including buffer storage and fuelling to vessels. This paper compares two dominant scenarios with regards to GHG emissions and costs. One scenario is based on PV electricity from Morocco, transported to Rotterdam for electrolysis. The other scenario is calculated with electricity from offshore wind farms in the Northern Sea. The calculation of the PV scenario leads to specific emissions for the hydrogen supplied to vessels of 51 gCO2eq/kWhH2 with levelized costs of hydrogen of 0.12 €/kWhH2. The wind scenario led to 16 gCO2eq/kWhH2 with 0.19 €/kWhH2. The electrolysis has the highest impact on emissions and costs, especially the electricity demand. Accordingly, lower emissions of PV electricity supply would have a high influence on the overall results. On the other hand, for the low emission renewable hydrogen supply with wind power a further reduction of the costs of the installation will be relevant.

The Challenge of Integrating Seismic and Energy Retrofitting of Buildings: An Opportunity for Sustainable Materials?

Recent earthquakes and escalating energy demands are exposing building stock deficiencies, particularly in terms of seismic resilience and energy efficiency. Many aged constructions do not fulfil current regulations both in terms of seismic and thermal design principles, thus requiring suitable retrofitting solutions. Integrated approaches for concurrent seismic and energy renovation have emerged as promising strategies in recent years, offering holistic solutions that optimize interventions and maximize benefits. While these combined methods hold significant potential for practical applications, there remain opportunities for further research to enhance their advantages. Furthermore, addressing climate concerns requires concentrated effort within the construction sector, where synergetic refurbishments can serve a dual purpose by reducing emissions and promoting the use of more sustainable materials. This study discusses strategies proposed in the literature for integrated retrofitting, considering their environmental impact, both in terms of energy performance and embodied carbon. The overview shows the innovation potential for the development of materials and systems combining acceptable performance with eco-friendly attributes. Yet, their application in integrated retrofitting systems, either as structural components or insulators, is still limited, underscoring the need for continued investigation and advancement. This paper concludes with recommendations to inspire further research and advancements in this critical field.

Seismic retrofit cost model for Italian masonry residential buildings to support territorial-scale risk analysis

Over the last 50 years, earthquakes forced the Italian Government to pay emergency, recovery and reconstruction costs amounting to 180 billion euros, i.e., about 3.6 billion euros per year. These figures underline the poor seismic resilience of Italy and therefore the need for sustainable risk mitigation plans at national level.Within this context, this study aims to provide a seismic retrofit cost model for Italian unreinforced masonry (URM) residential buildings, to support territorial-scale risk analysis. To this end, well-established intervention techniques, suitable for being analyzed on a large scale, were selected. These interventions include strengthening of masonry walls, stiffening and anchoring of floors, improving the wall system connection, and their possible combinations. First, for each of the selected interventions, the related cost items (obtained via a work-breakdown-structure procedure) were identified. Second, their unit cost was either retrieved from Italian price lists or estimated according to market analysis ad hoc conducted. Third, a quantity-survey-method approach was implemented to a set of 445 URM buildings to estimate the retrofit costs per square meter (€/m2) of investigated retrofit interventions. Lastly, based on the estimated cost of retrofitting of these buildings, parametric cost models were developed to inform seismic risk analyses at various territorial scales, depending on the available building information (i.e., exposure data).The cost models here developed and proposed can be used to support the design of cost-effective seismic mitigation measures, i.e., to identify retrofit solutions that are technically effective but also economically sustainable at large territorial scale.

A Holistic Modular Solution for Energy and Seismic Renovation of Buildings Based on 3D-Printed Thermoplastic Materials

This paper introduces a novel modular retrofitting solution to enhance the energy efficiency and seismic resilience of building façades, particularly within the Portuguese context. In the context of Europe’s “Renovation Wave” strategy, and as a product of the nationally funded ZeroSkin+ project, the proposed renovation solution addresses the urgent need for sustainable building renovations to help mitigate climate change and meet European climate neutrality goals by 2050. Unlike traditional methods that often rely on non-eco-friendly materials without integrating seismic and thermal performances, the renovation solution leverages fused deposition modelling (FDM) 3D printing technology to introduce a dual-layered panel system. This system features a durable, UV-resistant PET-G thermoplastic outer layer and a cork interior to ensure additional thermal insulation. The integrated renovation solution shows a 42% improvement in seismic reinforcement’s out-of-plane capacity and achieves U-values as low as 0.30 W/m2·K, exceeding Portugal’s thermal efficiency standards (0.35 to 0.50 W/m2·K). The proposed renovation solution also embraces circular economy principles, emphasising waste reduction and recyclability.

Improving the Indoor Air Quality of Office Buildings in the Post-Pandemic Era—Impact on Energy Consumption and Costs

Before the COVID-19 pandemic, ventilation in buildings was not always given its due importance. The World Health Organization has highlighted the important role of air exchange with the outdoors in improving the air quality in buildings; buildings should, therefore, be equipped with mechanical ventilation or adequate air conditioning systems. This paper aims to investigate different retrofit solutions for air conditioning, evaluating them in terms of energy consumption and cost and the impact of increased outdoor air exchange rates on countering the propagation of COVID-19; the latter is the main novelty of the paper. As a case study, we take an existing office building located in Central Italy that was previously not equipped with a mechanical ventilation system (a system with primary air was introduced during the study). The energy analysis was conducted using dynamic simulation software after validation through energy bills; energy and economic analyses were conducted considering different external-air exchange rates. An optimal number of outdoor air changes was found to mitigate the risk of COVID-19 infection, a finding in line with the international literature. The increase in air changes with outdoor air leads to a rise in energy consumption and costs. These values were evaluated for different air conditioning systems and operational schedules. These drawbacks can be made less significant by combining interventions in the system with energy-efficiency measures applied to the building envelope.

Sustainable Retrofitting Solutions: Evaluating the Performance of Jute Fiber Nets and Composite Mortar in Natural Fiber Textile Reinforced Mortars

Sustainable Retrofitting Solutions: Evaluating the Performance of Jute Fiber Nets and Composite Mortar in Natural Fiber Textile Reinforced Mortars

Maintenance of crack with infilling polymer modified mortar for shear deficient of reinforced concrete beam

Being a developing country, Pakistan needs sustainable and cost-effective strengthening/ retrofitting solution to be adopted/ practiced in the construction industry. The research reported in this paper was aimed to study the effectiveness of PMM, an indigenous product, for repairing reinforced concrete beams, resulting more effective and cost benefiting repair and strengthening for restoration of pre-cracked RC structures. This article presents the research results of experimental investigation conducted for repairing of cracks in shear deficient reinforced concrete (RC) beams with locally available novel material polymer modified mortar (PMM). A total of 6 beams; divided in three groups i.e. short beams, medium beams and deep beams with varying depths and same mix design were tested to four point loading under monotonic loading conditions until failure loads. Afterwards, these beams were repaired with PMM and cured with water for 72 h for retesting until failure. Load at first crack and at failure, crack pattern and deflections were recorded for all specimens during testing. Results from the experimental investigation indicate that load carrying capacity of the repaired beams was significantly restored in comparison to the control specimens. However, repaired specimens of medium group showed more improvement in load carrying capacity as compared with those of repaired specimens of short and deep group. The specimens of medium group restored up to 90% of their original load carrying capacity. The ductility is improved significantly for all shear critical repaired RC beams up to opening of cracks. Sudden brittle failure was observed after opening of repaired cracks. The contribution of PMM to load carrying capacity was found more significant for medium beams as compared to short and deep beams. The results of this study indicated that application of polymer modified mortar is effective technique for repairing of cracks in shear deficient RC beams.

Housing in the Capitalocene: Environmental education and sustainable living

Capital and property have been combined since Karl Marx wrote Das Kapital in 1867. Indeed, capitalism and the housing market are interlinked because property is an asset whose indexed value upholds global markets. On the other side of property as real estate is the environmental damage and augmentation of climate change that housing represents - mostly in advanced, technological societies. This paper attends to capital investment in housing as the Capitalocene and subsequently through environmental education according to environmental and social principles (social ecology). This article examines what is offered in the Australian curriculum for pre-tertiary and university students in terms of sustainable housing and uses the latest in sustainable housing research and practice to provide a new, visionary basis for environmental education, that tackles housing through 3D printing. The current Australian curriculum on sustainable housing centers on the ‘Illawarra Flame’ house (University of Wollongong), that presents a retrofitting solution to improve the quality of life of the occupants. Illawarra Flame house is a net-zero, energy-efficient, solar powered house which provides the tenants with thermal comfort. This article expands and updates the data on sustainable housing from the ‘Illawarra Flame’ house to 3D printing and applies the principles of social ecology to make a link with environmental education that deals with the Capitalocene by offering affordable and sustainable housing.