Energy Retrofit Research Articles

A Modeling-Based Decision Support System for Enabling Mass Net-Zero Energy Retrofit of Building Communities in Developing Countries

A Modeling-Based Decision Support System for Enabling Mass Net-Zero Energy Retrofit of Building Communities in Developing Countries

The role of practical knowledge in keeping existing systems: a qualitative study of Finnish homeowners with oil heating

The uptake of homeowner energy retrofits and related policy instruments are lagging behind targets. The Finnish government has decided on the phasing out of oil heating by 2035, but despite financial and other support for homeowners, only 14 per cent of homeowners with oil heating reported planning to switch their heating systems. Homeowner decision-making on energy investments is typically seen as an outcome of rational evaluation based on calculations about costs, payback times, and savings in energy and money. However, informal, experience-based knowledge contributes centrally to situations where people end up keeping their current heating system, yet there is little research on practical knowledge when households consider energy investments. This article presents findings from interviews with Finnish homeowners (N=29) living in detached houses with oil heating systems and argues that homeowners’ embodied heating habits and practical knowledge are important in understanding homeowner willingness to keep existing heating systems. In the in-depth interviews conducted in spring 2022, homeowners discussed their energy use practices, past renovations and future renovation needs, as well as concerns related to switching oil heating to a low carbon heating system. The findings suggest that homeowners’ practical knowledge on heating with their existing system and the lack of such knowledge in relation to alternative heating systems may be one reason why homeowners are reluctant to switch their heating systems. The study contributes to a growing body of research which highlights the relevance of everyday practices in homeowner energy renovations.

Energy transition in the retail sector: Revealing decision-making behaviours for energy efficiency retrofits of Dutch shopping centres

Shopping centres hold significant energy retrofit potential in the retail sector. However, their complex multi-stakeholder governance structure complicates decision-making for Energy Efficiency Retrofits (EER). Although literature identifies some barriers linked to EER, they are often scattered and not identified within a process perspective that considers their contextual complexities. This study addressed this gap by examining stakeholders’ behaviours, barriers, and relations during EER decision-making processes, to detect stakeholders’ needs to catalyse the energy transition. Qualitative research was conducted on three representative Dutch shopping centres case studies. The cross-case analysis uncovered the decision-making process for EER and new barriers attributed to this building typology. Amongst other, detected barriers can be attributed to limitations with governmental and internal regulations, lifecycle conflicts, proposed interventions being out of scope, and existing technical challenges. The study also revealed causal relationships among stakeholders, showcasing varying interpretations of barriers and highlighting the roles of owners, property managers, and public authorities in overcoming them. Furthermore, the findings indicate the key role that different contextual variables play in the EER decision-making process, such as ownership type, governance structure, and leasing structure. This study offers insights and recommendations for shopping centre owners, property managers, and policymakers, to support them in navigating the energy transition of the retail building stock. Key recommendations include decentralizing decision-making, optimizing governance structure, streamlining sustainability advisors, and acknowledging the collaborative roles of property managers and policymakers in providing effective and holistic solutions.

Advanced Decision- Making Framework for Sustainable Energy Retrofit of Existing Commercial Office Buildings

In the background of rising global initiatives to combat climate change and promote better energy management, retrofitting of current structures has become a major strategy. This abstract and literature review aims at presenting a full review of a decision-making approach that can be used in choosing sustainable options for energy retrofitting. This particular framework is designed to help guide retrofit decision-making due to the many issues that surround the process by providing an economic as well as an environmental and social context. Energy retrofitting means improving the existing structure or complex to decrease its energy intensity and have a negative impact on the environment. As stated earlier, it is a critical process for attaining sustainability goals and advancing the performance of buildings. But the decision on which retrofit measures should be implemented can be rather difficult because of the availability of a vast number of technologies and because more factors must be considered, such as cost and energy savings. The decision-making framework provided in this article aims at categorizing retrofit selection into this list of features and views the current article as a way of making the process more efficient. It encompasses the life-cycle cost analysis (LCCA), the economic valuation, and the multi-criteria decision analysis tools and criteria. These tools facilitate the evaluation of financial viability, the advantages of climatically retrofitting, and the environmental effects of distinct retrofitting choices. The above-mentioned framework is exemplified with a case study of an office building retrofit project. The following case includes an example of the application of the mentioned framework and illustrates the explanation of how it helps to make decisions. Due to the consideration of costs, energy, and environmental performance, the framework enables the stakeholders to choose appropriate retrofit measures. Other than the case study, the framework also focuses on the need to establish a sustainable energy retrofit DSS. Thus, the DSS supplements collected data on building performance, retrofit technologies, and economic aspects, which can be accessed by the stakeholders in real-time and with built-in facilities for scenario analysis. This system improves decision-making since retrofit results can be monitored and evaluated frequently. Both tools and strategies for the decision-making of sustainable energy retrofits bring a logical and systematic approach aimed at neutralizing the decision-making challenges related to retrofit selection. By applying economic, environmental, and social factors in the decision-making process, the framework assists the stakeholders in reaching energy efficiency and sustainability goals. The development of another strong decision-support system also improves the working of the framework and checks that retrofit projects are done efficiently and are strategic to the general goal of sustainable development.

Natural Lime–Cork Mortar for the Seismic and Energetic Retrofit of Infill Walls: Design, Materials, and Method

Recent seismic events have prompted research into innovative and sustainable materials for strengthening and repairing obsolete and vulnerable buildings. These earthquakes have exposed the high seismic vulnerability of existing reinforced concrete (RC) buildings, particularly in secondary structural elements like infill walls. In addition to structural issues, these buildings often face significant energy deficiencies, such as thermal bridges, due to inadequate insulation. Traditionally, structural and energy improvements for residential buildings are addressed separately with different methods and protocols. This preliminary study is part of a broader research initiative at the University of Reggio Calabria (Italy), aiming to design an innovative fiber-reinforced plaster using natural, sustainable, and locally produced materials to enhance the energy and structural performance of existing wall infills. The study investigates two plaster matrices made of natural hydraulic lime and silica sand, with 15% and 30% cork granules added. Mechanical and thermophysical tests on multiple specimens were conducted to evaluate their suitability for seismic and energy retrofitting of infill walls. Results indicate that adding cork reduces mechanical strength by approximately 42% at a 30% cork content without compromising its use in seismic retrofitting. Thermophysical tests show improved thermal performance with a higher cork content. These findings suggest that the lime–cork mixture at 30% is effective, offering excellent ductility and serving as a promising alternative to traditional cementitious plaster systems. The next experimental phase will test matrices with varying percentages of gorse fiber.

New robust multi-criteria decision-making framework for thermal insulation of buildings under conflicting stakeholder interests

The choice of thermal insulation technology for existing building retrofit can be a complex multi-criteria decision-making (MCDM) problem characterized by multiple stakeholders with conflicting interests. The conflicting interests of the building owners and the policymakers could negatively influence the adoption of low-carbon energy retrofit measures by building possessors, slowing down the progress toward sustainable development. The investigation of this issue is, therefore, crucial to support more informed decisions and offer policymakers useful insights to develop future economic incentives for energy refurbishment of buildings. Most of the existing MCDM studies on the subject do not emphasize the differences among different stakeholders nor consider the outcomes' robustness. To overcome this gap, this paper integrates multi-stakeholder analyses and robustness assessments to provide broad-spectrum and reliable results. An innovative robust MCDM framework for building thermal insulation under conflicting stakeholder interests is proposed and tested on a real case study building (located in Southern Italy) using building dynamic energy simulation. Several alternatives of thermal insulation are evaluated under environmental, energy, and economic key performance indicators (KPIs). The Analytic Hierarchy Process is used to define criteria weights for conflicting decision-makers representing collectivity (policymakers) and private interests. TOPSIS, VIKOR, WASPAS, and MULTIMOORA methods are integrated to perform initial rankings of the alternatives. A rank similarity analysis is performed to evaluate the consensus between MCDM methods, and an ensemble ranking is obtained for each decision-maker using an approach based on the half-quadratic theory. A Confidence Index and a Trust Level are used to evaluate the agreement among the MCDM approaches, verifying the reliability of the final ensemble ranking. The robustness of the framework is attained by complying with well-established literature guidance. The hybrid MCDM analysis showed that porous materials like expanded clay and expanded perlite lead to better results under the KPIs investigated. The worst performances are attained by vacuum insulation panels and aerogel, mainly due to high values of embodied CO2 emissions and long payback periods. Insights upon the performance of different thermal insulating alternatives are also highlighted by the study and a stakeholder comparative analysis demonstrates that global rankings obtained for the different decision-makers show some similarities, but also important deviations, and a full compromise solution is not achieved.

Effects of an extreme heat event on indoor conditions of social heritage housing in Mediterranean climate

Social heritage housing in Mediterranean historic cities is particularly vulnerable to climate change hazards as protection policies lead to its exclusion from energy retrofitting programmes, leaving their residents - at higher risk of fuel poverty and the heat-island effect – defenceless. Increasingly frequent heatwaves can potentially produce “overheating” in these buildings, a thermal state that impedes people's comfort with harmful consequences to their health. Other indoor air quality factors, like humidity and CO₂ levels, also affect residents' health. The objective of this research is to evaluate the actual indoor environmental quality of three occupied dwellings in social buildings of high heritage value located in two historic cities in Andalusia (Spain) during the extreme heat events that occurred in 2022. A monitoring campaign was conducted and the data collected over the summer was analysed and evaluated using existing metrics. Our results show that the CO2 concentration rates generally remained below the upper limit of 1000 ppm in all cases, probably due to the high air infiltration rates measured (5.83 h−1, 4.39 h−1 and 14.65 h−1). On the contrary, the relative humidity rates were outside the acceptable range (45–60 %) for 90 % of the occupied hours in all cases. In the warmest city, overheating was continuous and severe in all rooms, according to the metric adopted (CIBSE standards TM52 and TM59 under the adaptive thermal comfort model). The situation was particularly critical in the free-running bedroom, but the overheating index values in the living rooms, where air conditioning was installed and used about 50 % of the occupied time, also deviated significantly from the acceptable limits.

Performance Analysis and Techno-Economic Evaluation of Solar Energy Retrofitting for Coal-Fired Power Plant in Central Kalimantan Province

The power generation sector significantly contributes to climate change. Mitigation efforts are crucial to adhering to the global commitment to limit temperature increases below 2°C. One potential solution is retrofitting existing power plants with technologies that integrate renewable energy. This study explores the integration of solar energy into the operational processes of a coal-fired power plant in Central Kalimantan, replacing the extraction steam turbine in the high-pressure feed water heater No. 7. Using STEAG EBSILON for simulation, this research evaluates the power plant's performance before and after retrofitting in both power-boost (PB) and fuel-save (FS) modes under varying load conditions. The results demonstrate that thermal efficiency in both PB and FS modes increased by up to 2% compared to the base scenario. Specific fuel consumption decreased by 15.05 g/kWh in PB mode and 15.75 g/kWh in FS mode, leading to a reduction in coal consumption and CO2 emissions by 4.69% and 4.94% respectively. Additionally, the study observed that the solar percentage and solar-to-electricity efficiency increased as the load decreased. In FS mode, the solar electricity proportions at VWO, 100%, 75%, and 50% load rates were 5.23%, 5.53%, 7.76%, and 11.92%, respectively. The levelized cost of energy (LCOE) for solar electricity was calculated to be 431.82 IDR/kWh, with an expected investment return period of 5.87 years.

A probabilistic framework for stranding risk assessment and EPBD IV scenario analysis for the Italian building stock

The building sector is a major contributor to global GHG emissions, constituting an essential player in national and global decarbonization strategies. In this framework, governments have started requiring higher building energy performances to reduce emissions, with the new European Energy Performance of Buildings Directive (EPBD) representing a further step in this direction. Such requirements could be enforced at a large scale with specific penalties for the property owners, such as the stranding of non-compliant assets, making them not rentable or marketable until requirements are met. A few countries have already applied these measures but with a limited extent and effective implications compared to the decarbonization goals. Thus, while the consequent impact is potentially considerable given that a significant share of existing buildings would be stranded, a high uncertainty characterizes its assessment, calling for a probabilistic approach. However, no probabilistic methods have been formulated for stranding risk. This paper critically reviews the state-of-the-art approaches for stranding assessment of buildings. A probabilistic framework based on methodologies derived from natcat risk assessment is also presented. A scenario-based analysis is carried out on the Italian building stock and compared to the impact of natural hazards. Results reveal that stranding risk can be relatively significant in terms of expected monetary losses. The categorization of this risk as sustainability-induced “creative destruction” is also discussed. The findings provide insights into which policies would be required to implement decarbonization pathways for the building stock while underlining how energy retrofit design can adapt to mitigate stranding risk.

Dwelling conversion and energy retrofit modify building anthropogenic heat emission under past and future climates: A case study of London terraced houses

Energy demand per capita is expected to increase with smaller dwelling units in Europe, as less energy is shared linked to the trend of fewer people per household. To meet the demand for more smaller units, a popular retrofitting approach is to split existing large dwellings. As this type of dwelling conversion (DC) affects both household size (HHS) and therefore the likely energy use behaviour of residents, building thermal performance and anthropogenic heat emission (QF,B) to outdoor environment are impacted. Here, the UK time use survey (TUS) provides activity information to allow comparison of the implications of DC to energy conservation measures (ECM) for terraced houses in both past and future London climates. Our results show that ECM can substantially reduce both heating energy demand and QF,B during cold seasons, whilst due to the absence of space cooling in UK residential buildings the ECM ineffectively diminishes summer demands. Further to this, the increased occupancy density resulting from DC increases summer peak QF,B by 53.8% at 17:00, which could intensify canopy-layer urban heat island effects. Although climate projected for the 2050′s should result in a decreased wintertime QF,B, the potential increase in summertime space cooling energy demand will see an associated increase in summertime QF,B. Occupancy patterns need to be considered as part of retrofitting assessments and climate change impacts due to their influence on HVAC usage schedule. The role of occupancy behaviour extends beyond retrofit strategies themselves, to larger urban extents (e.g. planning, policy making, urban weather/climate feedbacks) to ensure both energy saving and urban heat mitigation.

Evaluation of Exterior Insulated Panels for Residential Deep Energy Retrofits

This paper provides an analysis of challenges and available solutions for exterior insulated panels suitable for deep energy retrofits of existing building envelopes. The analysis covers a review of available technologies that provide flexible retrofit insulated panels suitable for multiple climates and building typologies. Moreover, the paper proposes a new design for insulated retrofit panels that account for the majority of identified technical risks including cost, architectural diversity, climate variations, structural concerns, moisture resilience, air sealing, and water sealing. Additionally, the proposed design can be easily installed with minimal disruption to the occupants. A series of parametric and optimization analyses is carried out to identify the optimal design specifications for insulated panels suitable for deep retrofits of existing US housing stocks. The analysis results show that the optimal design criteria for the insulated panels can reduce heating and cooling energy consumption by up to 80% and HVAC capacities by 70%. Moreover, the results indicate that these insulated panels are highly cost effective for retrofitting US housing units located in cold climates.

Assessing microclimate thresholds for heritage preventive conservation to achieve sustainable and energy efficiency goals in a changing climate

This research addresses the issue of the heritage preventive conservation in the perspective of energy sustainability, for contributing to the achievement of the Sustainable Development Goals (SDGs) and towards the EU Green Deal. The study analyses and compares four cases associated with different microclimate thresholds as suggested by the standard EN 16893:2018 (Cases 1–3) and as derived from the outputs of three degradation models for preserving paper, wood, and canvas paintings (Case 4). Weather-based indices (degree and gram days) were calculated to estimate trends in the potential energy demand of collection facilities in three European cities belonging to different Köppen-Geiger climate zones (Cfb, Csa, and Dfb), under recent past (1981–2010) and near/far future climate scenarios (2021–2050 and 2071–2100) from two Shared Socioeconomic Pathways (SSP2-4.5 and SSP5-8.5). The findings suggest that adapting facilities’ management strategies to focus on collections preservation can facilitate the achievement of 5 out of 17 SDGs, offering a viable alternative to costly energy retrofits and encouraging the development of shared solutions for similar facilities in the same climate zone. The results can contribute to inform the revision of EN 16893 and to face major challenges such as the preservation of paper collections in southern latitudes.

Incentive mechanism and scenario simulation of residential energy-efficiency retrofits – From the perspective of tripartite evolutionary game

Energy-efficiency retrofits (EER) are increasingly becoming a key tool for sustainable building development. Compared to extensive urban renewal, refined building energy retrofits hold more practical value. Of this, the complexities arising from the differences in the claims of multiple stakeholders deserve our attention. However, limited efforts have been made in the existing literature to explore this issue. This paper constructs a tripartite evolutionary game model for residential EER from the perspective of engineering management. Taking a typical building in an old neighborhood in Nanchang, Jiangxi Province as an example, the theoretical model is validated. The results indicate that participants in the residential EER market display varying decision-making behaviors at different developmental stages. The government’s implementation of appropriate punitive measures in the early stages will encourage enterprises to participate in EER. Simultaneously, attention should also be paid to the demands of residents to ensure the smooth progress. Market-based renovation models should be actively promoted, and specific renovation programs should be created to accommodate varying requirements. This paper offers theoretical guidance for decision-making and developing residential EER.

Integrated rehabilitation of reinforced concrete buildings: Combining seismic retrofit by means of low-damage exoskeleton and energy refurbishment using multi-functional prefabricated facade

The European building stock was mostly built before the mid-20th century and is characterized by buildings with high energy demand and high seismic vulnerability. Integrated upgrading interventions are therefore urgently needed for moving towards a more resilient community. In this study, rehabilitation interventions are proposed for reinforced concrete buildings to improve their energy efficiency as well as their structural/seismic performance. An integrated refurbishment aiming at structural, architectural, and energy upgrading is targeted. Energy retrofitting with multifunctional wood-based prefabricated modular facades has been evaluated, as capable of reducing heat consumption by an average of 84 % in different climate zones. More specifically, an exoskeleton system consisting of Prestressed Laminated timber (Pres-Lam) technology is considered, which will act as a structural support-skeleton system for a high-performance “double-skin” solution composed of prefabricated panels. This solution can reduce the seismic risk class in high seismic zones. The seismic-energetic integrated intervention is developed for a representative case study building and evaluated with reference to different climates and seismic zones. Furthermore, a preliminary cost-benefit analysis of the integrated solution has been performed, showing higher benefits when compared to the sole energy retrofit. Specifically, considering the seismic retrofit interventions, the cost analysis pointed out that moving up to higher-use classes results in higher performance and costs. Nevertheless, approximately comparable breakeven times have been obtained in the same seismic region by achieving higher targets. The proposed integrated solution is a promising alternative to demolition and reconstruction, providing a deep energy renovation and structural retrofit, avoiding inevitable waste production, additional energy consumption, and C02 emissions; and allowing for a sustainable renovation of the existing building stock.

Correction: Examining building energy retrofit effects on indoor environmental quality before the Covid-19 era: a critical assessment

Correction: Examining building energy retrofit effects on indoor environmental quality before the Covid-19 era: a critical assessment

BUILDING PERFORMANCE ANALYSIS OF CHILDCARE CENTERS IN KOREA FOR RETROFIT DESIGN: TYPOLOGY BASED STUDY ON ENERGY PERFORMANCE

ABSTRACT This study investigates different architectural types of Korean national childcare centers. The goal of this study is to provide a preliminary study of the energy retrofit of childcare centers. Given the growing concern over climate change, renovation and remodeling of current buildings for energy use improvement has become a major movement. Thus, today’s improvement in the building environment inevitably accompanies energy use improvement. An examination of 17 childcare centers in the Dongdaemon-gu district in Korea has been carried out. This includes the history of the buildings, construction information and energy use of the buildings. The cases are classified depending on their architecture type and have been analyzed with their energy use. Korea has embraced the influence of other countries with child care policies and types. The typology has been adapted to the Korean environment. This research is the preliminary study for green renovation of national childcare centers under a Korean context.

Informing building retrofits at low computational costs: a multi-objective optimisation using machine learning surrogates of building performance simulation models

Machine learning (ML) algorithms are increasingly used as surrogates for building performance simulation (BPS) models to leverage their energy predictive capabilities while reducing computational costs. In parallel, researchers are developing optimisation methods to inform building design and retrofit strategies but rarely employ ML-based BPS surrogates for this purpose. This study proposes a coupled modelling approach that leverages the capabilities of ML-based BPS surrogate models and multi-objective optimisation to inform holistic design and operation retrofits at low computational costs. The proposed methodology is demonstrated using an archetypal office building in Ottawa, Canada. The developed models achieved competitive predictive accuracies (adjusted R2: 0.90–0.99), identifying total and peak energy saving measures with up to 34% improvement in occupant thermal comfort at computational speeds 1266 times faster than a traditional BPS-based optimisation approach. Results offer a promising modelling workflow for design applications requiring extensive computations and scenario analyses, such as net-zero energy retrofits.

Energy retrofitting of hospital buildings considering climate change: An approach integrating automated machine learning with NSGA-III for multi-objective optimization

In the context of sustainable development, energy-saving renovation of existing buildings can not only effectively reduce energy consumption but also improvement the residential comfort and office environments. This study proposes an optimization method for building energy-saving renovation based on automated machine learning and the NSGA-III algorithm, aiming at efficiently and accurately identifying the best energy-saving renovation schemes. The results showed that automated machine learning could provide a predictive model for multi-objective optimization analysis in a relatively short training time, with an average prediction accuracy of over 95%. And the Stacked Ensemble algorithm and Gradient Boosting Machine algorithm perform the best among all the algorithms considered in this study. Additionally, climate change significantly affects the energy-saving benefits and thermal comfort performance of renovation measures, thereby altering the choice of optimal schemes. The final renovation schemes obtained through the NSGA-III and entropy weight TOPSIS method can achieve an energy saving rate of 22.06% to 26.48% under typical climate scenarios, while also improving thermal comfort time by 31.87% to 43.73%. In future climate scenarios, an energy saving rate of 32.73% to 33.02% and a thermal comfort time of 40.20% to 42.29% can be achieved. Combining these two technologies can quickly and effectively find the best balance among energy consumption, whole life cycle cost, and thermal comfort time. The method proposed in this paper offers new perspectives and tools for researchers in the field of building energy conservation, demonstrating the application potential of automated machine learning and the NSGA-III algorithm in the energy-saving renovation of hospital buildings.

Heritage conservation and energy efficiency in adaptive reuse projects the case of Gaziantep, Türkiye

PurposeThis article explores the challenges and opportunities in adaptive reuse projects for historic buildings, focusing on the interrelationship between energy efficiency and heritage conservation.Design/methodology/approachThe study utilises a mixed-method approach, including semi-structured interviews and energy retrofit surveys, conducted in seven adaptively reused historical buildings in the Bey neighbourhood, Gaziantep, Türkiye. Thematic analysis is used for interviews, and survey results were discussed together within the framework of CSN EN16883.FindingsThe adaptive reuse of historic buildings can result in economic, social, cultural and environmental benefits for local communities. However, for this to occur, careful consideration must be given when selecting the new function, ensuring that it aligns with the buildings' environmental performance potential and the community’s needs. Considering the CSN EN16883 Guidelines for improving the energy performance of historic buildings, when the retrofits made by the users are assessed, the general approach is to preserve the heritage value of the building rather than making it energy efficient.Originality/valueThis study will add to a cross-cultural understanding of the complex relationship between adaptive reuse, energy efficiency and heritage conservation by looking at the local context of Gaziantep. No similar qualitative study addresses this issue in this region.

Passive Envelope Measures for Improving Energy Efficiency in the Energy Retrofit of Buildings in Italy

Passive Envelope Measures for Improving Energy Efficiency in the Energy Retrofit of Buildings in Italy