Retrofit Strategies Research Articles

Energy consumption and environmental parameters in Madrid social housing. Performance in the face of extreme weather events

Housing energy rehabilitation is currently a priority in Europe. In vulnerable neighbourhoods, improving energy efficiency and comfort conditions has an important impact on people living conditions. Rehabilitation strategies are usually designed according to standard scenarios, without taking into account variations related to the users or the type of building. Monitoring this type of housing offers valuable information to be able to select the best strategies based on a diagnosis of their real performance.In this paper we present one year data on energy consumption, hygrothermal comfort and CO2 monitored for 22 dwellings in Madrid, located in six different vulnerable locations. In addition to normal periods, the monitoring campaign includes periods of extreme heat and cold, and two exceptional situations, the “Filomena" snowfall and the COVID pandemic period.The results report poor indoor environmental quality in these dwellings, both in the main rooms and in the bedrooms. Also poor building quality is observed. The recorded energy consumption is lower than that given as a reference in the standards or models, at the cost of a worse indoor environment. The analisys supports the importance of retrofit strategies that take into account the composition of the household, such as single-person households or those with children, the higher vulnerability of dwellings with higher demand, the subjective perception and the role of users, and the need to incorporate improvements in indoor air renewal.

Exploring the Land Cover Material Interaction of Urban Open Space on the Thermal Comfort of Crowds in High-Temperature Environments and Retrofit Strategies: Two Case Studies in the Nanjing Xinjiekou District

The increased frequency of extreme hot weather events in recent years poses a significant threat to the lives and health of urban residents. Consequently, the thermal comfort of urban open areas has garnered growing attention. The ground material in these urban open areas directly impacts the thermal environment, which significantly influences the comfort of crowds. This study aimed to assess the effect of land cover materials in urban center squares on the thermal comfort of people in high-temperature conditions. Eight types of land cover materials were selected from the two urban squares in the central district of Nanjing Xinjiekou. Physiological equivalent temperature (PET) calculations were performed by measuring the surface temperature, the air temperature, the humidity, and other relevant data to evaluate population thermal comfort. The findings indicated that grass provided the highest thermal comfort, with PET scores ranked as follows, from low to high: grass, permeable bricks, granite, concrete, basalt, bluestone, andesite, and asphalt. Additionally, factors such as color, roughness, and shade within the same material also impacted thermal comfort. Subsequently, using the ENVI-met 5.1 software, surface materials exhibiting superior thermal comfort were simulated for replacement, aiming to confirm the experimental results and propose retrofit strategies for improving urban square thermal comfort by optimizing material selection. The outcomes of this study hold significant implications for urban open space design and the overall well-being of city dwellers. The thermal environment in urban centers during high-temperature conditions can be improved by optimizing the choice of land cover materials in urban open areas, thereby enhancing the comfort of the population.

SUSTAINABLE RETROFITTING STRATEGIES FOR CULTURALLY SIGNIFICANT BRUTALIST BUILDINGS: ENERGY-EFFICIENT STRATEGIES FOR A HIGH-RISE RESIDENTIAL COMPLEX IN SARAJEVO, BOSNIA AND HERZEGOVINA

ABSTRACT This research investigated energy-efficient (EE) retrofit strategies for a historically and culturally significant residential building complex, located in Sarajevo, Bosnia and Herzegovina. The objective was to evaluate existing building performance and propose delicate, EE retrofit strategies while preserving the original design character. The overarching objective was to demonstrate a framework through which historically and culturally significant buildings can be investigated for EE retrofitting. Using original construction drawings and current photographs, a 3D BIM model of a typical residential building was developed for analysis and energy simulations. Next, using Revit and Insight 360 simulations, the building's response to environmental conditions was evaluated. Thermal behavior and moisture resistance performance of typical facade systems were evaluated using WINDOW, THERM, and WUFI simulations. Lastly, a full-building energy model was developed in IES-VE software to simulate full-building performance. Results showed that while the conceptualization of this neighborhood paid careful attention to social and environmental factors and had implemented some of the most advanced passive and active technologies of that time, a typical residential building generally underperformed in all evaluated criteria. The proposed retrofit strategies, focusing on improving the building enclosure and implementation of EE mechanical systems, achieved 53% energy-use reduction and elimination of fossil-fuel energy sources.

An effective decision-making method for building retrofit measures strategy

The energy efficiency and sustainability of existing buildings have become a critical concern in Algeria’s efforts to reduce energy consumption and mitigate environmental and economic impacts. To address this challenge, a systematic and effective decision-making method is required to select optimal building retrofit measures in alignment with Algeria’s 2030 energy strategy. In this study, we propose an innovative approach based on the Fuzzy Analytical Hierarchy Process (FAHP), a widely used multi-criteria decision-making method, to evaluate and prioritize different retrofit measures. The FAHP allows decision-makers to have a comprehensive framework for making informed choices by incorporating independently proposed economic, environmental and technical criteria. The results demonstrate the high significance of retrofit measures that enhance thermal insulation, with double glazing and roof insulation emerging as top priorities. Sensitivity analyses confirm the stability and robustness of the decision-making process. This approach offers valuable insights for policymakers and building professionals seeking to implement sustainable and energy-efficient retrofitting strategies in Algeria’s construction sector. By aligning with the country’s energy goals, this decision-making method contributes to achieving a more sustainable and environmentally responsible built environment.

Evaluation of passive cooling through natural ventilation strategies in historic residential buildings using CFD simulations

Natural ventilation in hot climates has the potential to save energy by reducing the need to use mechanical systems. Particularly in historic buildings, it should be considered as a passive retrofit strategy before the addition of any mechanical systems to accommodate their unique indoor environmental characteristics and ensure their preservation. This study investigates the efficiency of multiple natural ventilation strategies in cooling a historic residential structure located in San Antonio, Texas, USA, a hot and humid climate area. It also analyzes their potential to provide a thermally comfortable indoor environment during the spring and summer. Onsite data and ASHRAE standards were used to create and validate Computational Fluid Dynamics (CFD) and energy models. Six different natural ventilation approaches were simulated, and the results were analyzed and compared. The analysis revealed that all the considered scenarios can contribute to energy savings in both seasons, especially in spring, with cross ventilation being the most efficient strategy. It also proved that the size of the openings has an impact on thermal comfort. This study demonstrated that historic preservation and thermal comfort goals can be achieved simultaneously, and the results can be replicated in multiple historic structures in similar climate regions around the globe.

Double-Skin Facades for Thermal Comfort and Energy Efficiency in Mediterranean Climate Buildings: Rehabilitating Vulnerable Neighbourhoods

The ongoing global energy crisis in Europe has intensified energy poverty in vulnerable households, prompting a critical examination of passive retrofit strategies for improving the habitability of obsolete social housing in southern Europe from the 1960s. Given the Mediterranean climate’s characteristics (hot summers and mild winters), these buildings possess low thermal resistance envelopes designed for heat dissipation in summer but contribute to elevated heating demands in colder months. In response to the pressing need for solutions that strike a balance between reducing energy demand and ensuring year-round comfort, this research explores diverse approaches. Drawing insights from built prototypes in Colombia and Hungary and utilizing a validated simulation model in Seville, Spain, this study investigates the feasibility of implementing a double-skin envelope on building facades and assesses the impact of thermal insulation in the air chamber. So, the research specifically aims to find an equilibrium between lowering energy demand and maintaining adequate comfort conditions, concentrating on the renovation of obsolete social housing with envelopes featuring low thermal resistance in the Mediterranean climate. Results indicate that, due to the poor thermal envelope, the influence of thermal insulation on comfort conditions and energy savings outweighs that of the double skin. Consequently, the emphasis of renovation projects for this climate should not solely concentrate on passive cooling strategies but should strive to achieve a positive balance in comfort conditions throughout the year, encompassing both warm and cold months.

Carbon emission measurement of the envelope of a university teaching building in Hefei City

Abstract In response to the challenges posed by global warming, China has formulated dual carbon goals. In this context, the construction industry, a key carbon emitter, is vital for implementing energy-saving and emission-reducing strategies. This study zeroes in on the pivotal role of building envelope structures in carbon emissions, with a focus on a university building in Hefei. Commencing with onsite measurements to gather initial data, the study leverages simulation software to conduct an in-depth analysis. Employing orthogonal experimental design and variance analysis, it meticulously assesses the carbon emissions associated with different materials used in exterior walls, roofs and windows, considering both the material production and building operation phases. The research scrutinizes the impact of these materials on carbon emissions, with a special focus on the performance of seven distinct building retrofit schemes. Key findings of the study underscore that the type and thickness of exterior wall materials substantially influence carbon emissions during the production phase. Conversely, the choice of window materials emerges as more critical in reducing emissions during the building operation phase. The implementation of the various retrofit schemes demonstrates a tangible reduction in overall building carbon emissions. Specifically, these schemes yield a yearly reduction in carbon emissions of 2.96–3.62 tons during operation and a substantial decrease of 30.36–165.97 tons in the production phase, compared to the original structure of the case study building. These insights not only offer practical and viable strategies for the construction industry’s low-carbon development but also provide theoretical underpinnings and references for future building designs and retrofits.

Methodical Investigations on Seismic Retrofitting of Steel Plate Shear Wall Systems

An efficient retrofitting technique is expected to improve the seismic performance of a lateral force-resisting system without increasing the seismic demand on the structure, which can unfavorably lead to irreparable damages during a seismic event. On this basis, the present study aims to introduce an optimal strategy for seismic retrofitting of steel plate shear wall (SPSW) systems using low yield point (LYP) steel material and to demonstrate its effectiveness through systematic investigations. To this end, detailed nonlinear static, cyclic, and dynamic analyses, as well as fragility analyses, have been performed on single- and multi-story, code-designed as well as retrofitted SPSWs. The aim is to identify the most efficient retrofitting approach and to demonstrate its effectiveness in enhancing the seismic performance and lowering the seismic vulnerability of the system. It is shown that replacing the original, conventional steel infill plate in an SPSW system with an LYP steel plate having twice the original thickness can improve not only the buckling capacity and serviceability, but also the structural performance and seismic response of the system, without increasing the demand on the structure and creating overstrength concerns. Fragility analysis also shows that the vulnerability, as well as probability, of damage to system can be considerably lowered as a result of the implementation of such a retrofitting strategy.

Morphodynamic numerical modelling of bridge pier erosion induced by downstream check-dam partial collapse

The paper presents a case study in which a severe bridge pier erosion effect was triggered by a partial collapse of a downstream check-dam, due to a flood event in June 2020. The area under study is about 30 km east from the city of Udine (Italy), along the river Torre, which is the main tributary of the river Isonzo. In particular, it is 1 km downstream of the confluence between river Torre and its main tributary, river Natisone. The hydrodynamic complexity of the reach is further exacerbated by the presence of two bridges, close to each other and almost parallel (the new one is just upstream and it is under construction, although almost finished, while the old one is still in service). The result is that there are many bridge piers in the riverbed, determining some interference effects also increasing local erosion. The presence of a check-dam 600 m downstream of the old bridge had a stabilizing effect in this sense, although it was originally designed as a grade control structure of the river. The flood event determined a partial collapse of such structure, whose central portion was progressively excised by tipping. The backward propagation of the erosion reached the area of the bridges, determining a progressive general lowering of the river bed. As a consequence, many bridge piers of the old bridge were excavated, determining severe conditions for the stability of the structure (the traffic was interrupted). The paper presents the methodology adopted and the main results obtained by hydrodynamic and morphodynamic numerical analyses, which were conducted through a two-dimensional, finite volume, shallow water model able to determine the hydrodynamic fields (water depth and flow velocity) and the evolutionary trends of the river bed, allowing to identify the best retrofitting strategy for the design phase.

Investigation of the bed joint reinforcement effect on the drift capacity of modern unreinforced masonry walls

Bed joint reinforcement significantly affects the shear capacity of masonry walls due to its effective ability to transfer shear forces through a diagonal crack, but how does this phenomenon impact its drift capacity? This paper presents an experimental study containing a series of four quasi-static cyclic tests conducted on masonry walls of same size. Two of them incorporated truss-type bed joint reinforcement, while the other two were completely unreinforced. All specimens were subjected to double bending boundary conditions to observe shear-controlled behaviour and were tested under two levels of compression load. The primary objective of this research is to determine the role of horizontal reinforcement in the seismic properties of unreinforced masonry walls focusing on the displacement capacity. The findings from this experimental study are expected to provide empirical evidence for subsequent numerical simulations and contribute to the development of analytical formulations. The results aim to enhance our understanding of the seismic response of masonry walls, ultimately informing design practices and seismic retrofitting strategies.

The application and potentialities of textile facade retrofit strategies for energy-efficient and resilient buildings

The application and potentialities of textile facade retrofit strategies for energy-efficient and resilient buildings

Perspectives on integrated retrofitting of existing reinforced concrete buildings

Buildings account for 40% of energy consumption and 38% of CO2 emissions in the European Union (EU). This substantial impact is primarily due to the delayed implementation of initial energy codes. Additionally, about 40% of the EU's buildings are situated in seismic-prone areas, many of which were constructed without meeting current safety standards. An estimated 65% of these structures require both energy and seismic upgrades. Given these challenges, there is an urgent socio-economic and environmental need to renovate the existing building stock. It is crucial to adopt an integrated retrofitting strategy, enhancing both efficiency and resilience against extreme events. This study provides a detailed examination of the integrated retrofitting of existing Reinforced Concrete (RC) buildings. Additionally, a review of current international policies (or incentive programs) related to independent (i.e., structural or energy) and integrated retrofitting (i.e., seismic plus structural) is presented and discussed. From the ten incentive programs evaluated, 77% focused on energy retrofitting interventions, while only 33% addressed structural improvement interventions. As anticipated, there is an increasing emphasis on programs that also consider the sustainable impact of these buildings’ interventions but the combination of energy plus structural interventions still has a minor relevance.

Structural Assessment of a Masonry Arch Bridge before and after a traditional inner arch retrofitting technique

To assess the structural behaviour of masonry arch bridge and identify the occurrence of damage reliable numerical models to perform accurate nonlinear structural analyses are needed. The innovative strategy known as Discrete Macro-Element Model (DMEM) is here employed to simulate the performance of a masonry arch bridge before and after a traditional structural retrofitting. The adopted numerical strategy assures a geometrically consistent model characterized by a very low computational burden and reliable results. As case study, a masonry arch bridge located in Maletto (Italy), belonging to the rail network, around Etna volcano, called Ferrovia CircumEtnea (FCE). The bridge has been built in 19th century and was subjected to a structural retrofitting in 1984, because of a light settlement of the central pier due to landslide. The bridge was reinforced with the introduction of a supplemental thin inner reinforced concrete arch, at the intrados of the existing stone arches, externally confined by an external steel corrugated thick plate also used as formworks. In this paper the HiStrA bridge software, where the DMEM is implemented, is used for providing a structural assessment of the bridge in its original configuration and after the structural retrofitting. Both push-down and push-over analyses are performed clearly showing the efficacy of the adopted traditional retrofitting strategy.

A review of the energy retrofitting goal and methods of the building stock across the EU

This study aims to compare and evaluate various energy retrofitting strategies and methods employed in the building sector, with a focus on analysing their effectiveness and feasibility in enhancing energy efficiency. Current renovations in the EU are mostly response to policies in force; however, there is an increasing demand for renovation projects to align with the goals set for 2050. Subsidies or barriers may differ across a whole spectrum, depending on various factors, but leaving the building with the same expected outcomes. It is also important to apply measures in design phases which end in feasible and flexible execution. The paper elaborates an assessment background for the selection of studies. It identifies four main key objectives: improving energy efficiency, phasing-out of fossil fuels, increase the share of renewable energy and applying circularity. These objectives were gathered from various studies and reports, in response to which quantifiable and non-quantifiable values of three energy renovations were compared. The results highlight not only energy, financial and carbon-saving aspects but also address current retrofitting trends and climate change. Performing a comparison along these points helps to understand what drives a renovation and what can be achieved with certain inputs in the beginning. This review explores the extent to which renovation case studies vary in terms of their goal, approach, and the way results are published. It aims to help deciding whether an intervention is adequate or not, through a set of criteria presented.

Towards Energy-Efficient Residential Buildings In Jeddah, Saudi Arabia

The thesis explores energy retrofitting options for enhancing the energy efficiency of residential buildings in Jeddah, Saudi Arabia. It identifies and validates cost-effective energy retrofit schemes that have the potential for energy savings. The thesis also assesses the feasibility of energy retrofitting scenarios for building envelopes and their impact on reducing energy consumption, improving thermal comfort, and mitigating the environmental impact of buildings. The results of this research can guide architects and decision-makers on energy-saving measures for residential buildings in Saudi Arabia, with Jeddah serving as a representative case study.

Textile Membrane for Façade Retrofitting: Exploring Fabric Potentialities for the Development of Innovative Strategies

The European building stock demands urgent renovation due to the age of the buildings, their expected lifetime, and their excessive energy consumption, which accounts for more than a third of the EU’s total emissions. However, the complexities involved, such as time, costs, and structural modifications, often discourage clients, tenants, and occupants from undergoing a building renovation process. Textile membranes, despite their long history in various architectural applications, have only been employed in façades in the last decades. Their intrinsic properties, such as lightness and flexibility, together with rapid assembly and low maintenance make these materials particularly suitable for façade retrofitting. Therefore, they are worth exploring as a way to promote the development of lightweight and easy-to-assemble façade products that could help overcome the current limitations of building retrofitting efforts. This paper aims to establish relationships between textile membranes and potential building retrofit applications. To this end, this study builds on the categorization of traditional façade retrofit strategies and proposes a new classification for textile façade retrofit products. The methodology includes a comprehensive literature review of textile properties and characteristics, along with a thorough assessment through case studies, of membrane use in façade applications. A sequential investigation leads to the main outcome of identifying three clear pathways for the development of new textile-based façade products for building retrofit.

Continuous DeNOx Technology for Improved Flexibility and Reliability of 1000 MW Coal-Fired Power Plants: Engineering Design, Optimization, and Environmental Benefits

This study endeavors to enhance the operational efficiency of extant coal-fired power plants to mitigate the adverse environmental impact intrinsic to the prevalent utilization of coal-fired power generation, which is particularly dominant in China. It focuses on the assessment and optimization of continuous denitrification systems tailored for a 1000 MW ultra-supercritical pulverized coal boiler. The extant denitrification framework encounters challenges during startup phases owing to diminished selective catalytic reduction (SCR) inlet flue gas temperatures. To ameliorate this, three retrofit schemes were scrutinized: direct mixing of high-temperature flue gas, bypass flue gas mixing, and high-temperature flue gas mixing with cold air. Each option underwent meticulous thermodynamic computations and comprehensive cost analyses. The findings elucidated that bypass flue gas mixing, involving the extraction and blending of high-temperature flue gas, emerged as the most financially prudent and practical recourse. This scheme optimizes fuel combustion heat utilization, significantly curtails fuel consumption, and fosters efficient internal heat transfer mechanisms within the boiler. The evaluation process meticulously considered safety parameters and equipment longevity. The insights derived from this investigation offer valuable guidance for implementing continuous denitrification system retrofits in industrial coal-fired power plants.

Numerical Study and Hydrodynamic Calculation of the Feasibility of Retrofitting Tangentially Fired Boilers into Slag-Tap Boilers

Retrofitting a tangentially fired boiler into a slag-tap boiler offers a solution for fully burning high-alkali coal in power plant boilers. Numerical simulation and hydrodynamic calculation of such a retrofit scheme were performed in this study. The maximum temperature in the furnace after retrofitting is 2306.8 K, surpassing the pre-retrofit temperature of 2095.8 K. The average temperature in the combustion chamber of the slag-tap boiler is 2080.3 K, which ensures that the slag can be discharged in a molten state. When the coal consumption is halved relative to the working condition of the boiler maximum continuous rating (BMCR) in the slag-tap boiler, the maximum temperature in the combustion chamber decreases from 2306.8 to 2220.3 K. However, the temperature distribution remains relatively uniform, ensuring that the slag discharge is not disrupted. In both of the working conditions calculated in this study, the fluid flow rates in the water-cold wall are positively correlated with the wall heat fluxes. The maximum wall temperatures under the two working conditions are 653.9 and 590.6 K, respectively, both of which are well within the safe limits for the wall material. The results illustrate the feasibility of the retrofit scheme.

How occupant positioning systems can be applied to help historic residences manage energy consumption: A case study in China

Historic residences often suffer from low energy efficiency due to inadequate management and obsolete infrastructure. To ensure these buildings operate in an environmentally friendly manner, intelligent energy control and management are necessary. Accurate indoor user positioning is fundamental to realizing occupant-centric controls. However, historic dwellings, with architectural heritage preservation requirements and diverse operational modes, present multiple challenges in terms of occupant monitoring and energy management. This research proposes a BLE positioning system based on the SAE-CNN algorithm to realize the analysis and prediction of occupant locations in a cost-effective and minimally-intrusive manner. The process begins by dividing spaces based on the mapped BIM model and cluster analysis. The RSSI maps of wireless signals collected from the Bluetooth beacons in each space are then preprocessed by Gaussian filter and sliding window techniques. Lastly, a machine learning algorithm refines the prediction model, which is integrated into a digital twin platform designed for energy consumption management. The system was implemented in a traditional Chinese dwelling in Wufu town, Fujian Province. The results are promising, showing that the positioning accuracy reached 1.5–2 m (95 % confidence interval), while the platform effectively presented the real-time positioning results as well as realized occupant-centric energy management. Moreover, the collected location information shed light on occupants' spatial usage habits, offering valuable insights for devising decarbonization retrofit strategies.

Electrification of oil refineries through multi-objective multi-period graph-theoretical planning: A crude distillation unit case study

Electrification using renewable energy sources is the key to paving a sustainable and cleaner future for the oil and gas sector, which is known to be a significant carbon dioxide emitter. Nevertheless, the suitability of the electrification designs heavily depends on the seasonal availability of renewable energy sources. This work proposes to use a multi-period graph-theoretical (P-graph) approach to determine the optimal retrofit strategy to achieve electrification with consideration of economic and environmental factors. Both single-period and multi-period models are considered via a graph-theoretical approach to rank and evaluate all the combinatorically feasible electrification pathways based on the overall performance. The effectiveness of the proposed method is developed using a crude distillation unit (CDU) case study adopted from a multinational company. The effectiveness of the proposed method is illustrated using a crude distillation unit (CDU) case study shown in three different scenarios that include prioritizing economic aspect (Scenario 1), prioritizing environmental aspect (Scenario 2), and considering equal importance of both aspects (Scenario 3). For single-period operation, the results showed a mix of natural gas and hydropower energy, exclusive use of onshore wind energy, and a mix of onshore wind energy and biogas cogeneration energy for Scenario 1, Scenario 2, and Scenario 3, respectively. In contrast, the multi-period model also utilized nuclear energy for Scenario 2 and Scenario 3 given the seasonal availability constraint. Following that, a sensitivity analysis is conducted to see the effect of the absence of the most influential energy sources on the optimal solution of each scenario and the top solutions under budget and CO2 emission constraints. Pareto analysis is outlined to offer an understanding of tradeoffs between differently prioritized solutions that decision-makers can select. The combination of the proposed analysis provides a systemic approach towards transforming traditional industries towards a cleaner future via electrification.