Renovation Scenarios Research Articles

Assessing the Environmental Impact of Demountable Space-Dividing Walls: A Scenario Analysis Approach in a Semi-Detached Case Study Dwelling

The transition towards sustainable construction is crucial, and demountable building elements are frequently advocated for achieving this goal. While these elements offer relocatability during refurbishments, their adoption may increase initial environmental impact due to higher material use and steel connections. To address this, a quantitative assessment of demountable building elements in refurbishment scenarios at the building level is needed, filling a gap in the existing literature. This study bridges the gap by comparing the total environmental impact of demountable and traditional space-dividing walls in refurbishment scenarios for a semi-detached dwelling. Using a life cycle assessment, seven space-dividing wall types, including metal studs, wood structures, and masonry walls, are evaluated under four refurbishment scenarios spanning a 60-year building lifespan. The results reveal that traditional metal stud walls have a lower environmental impact in scenarios with limited refurbishments. In contrast, demountable walls become more environmentally beneficial only when refurbishing at least 60% of the wall area with three or more refurbishments. This conclusion was further validated through sensitivity analysis on the refurbishment rate, refurbished area, and impact assessment method. In this study, the assumed environmental benefits of demountable walls are challenged, providing a robust evaluation in a specific building typology and offering insights for policymakers and industry professionals on the environmental implications of incorporating demountable building elements.

Multi-objective assessment of the retrofit of traditional walls located in a historical city centre using an urban climate model

Historical city centres face two major challenges in the 21st century: heritage conservation and energy retrofitting. Wall insulation in traditional buildings is at the crossroads of these two issues. When studying the retrofit of the walls, other factors also need to be considered, such as the durability of the walls, the life cycle of the materials used for insulation, the indoor and outdoor comfort in summer. The aim is to propose a method for taking all these objectives into account when choosing the insulation technique for historical walls. To do this, the TEB (Town Energy Balance) urban climate model is used, because it considers the urban microclimate, the energy behaviour of buildings and moisture transfer through walls. A VTT model is integrated into TEB, to include the risk of mold growth. The medieval city centre of Cahors (France) was used as a case study. The retrofit of two types of wall was assessed: “massive” brick walls, and “light” walls with a timber-framed structure, filled with bricks. Six renovation scenarios were studied, including four insulation materials and both internal and external insulation positions. The results obtained underline the need to study the retrofit of the two types of building separately, because the recommendations made for insulation vary depending on the type of wall studied.

Mitigating Household Air Pollution Exposure Through Kitchen Renovation

Globally, over three billion people rely on traditional solid fuels for cooking and heating, leading to significant household air pollution and critical public health concerns. While transitioning to clean energy carriers faces challenges of accessibility and affordability—especially among low-income, rural populations—alternative strategies like kitchen layout modifications and the use of ventilation fans may effectively reduce exposure to pollutants. Here, we analyze factors influencing the adoption of separated kitchens and mechanical ventilation and evaluate changes in human exposure to PM2.5 under different kitchen renovation scenarios by conducting a nationwide survey of household kitchen characteristics in rural China. We found that although 82% of rural households have kitchens separated from other rooms, only 34% use mechanical ventilation. The adoption of ventilation fans is significantly influenced by income and education levels. We estimate that widespread implementation of ventilation fans and separated kitchen designs could prevent approximately 67400 premature deaths annually, resulting in a health benefit of about USD 19 billion per year—substantially exceeding the costs involved. These findings suggest that cost-effective kitchen renovations offer enormous potential for substantial health benefits and present a practical solution compared to the challenges of clean energy transitions in rural areas.

Designing with building-integrated photovoltaics (BIPV): A pathway to decarbonize residential buildings

The ambitious targets set for greenhouse gas emissions and energy efficiency by 2050 demand a critical increase of building renovation rates. This challenge is shared by most Western nations, including Europe and Switzerland, where the current annual renovation rate stands at a mere 0.6 %. In this context, designing renovation strategies using building integrated photovoltaic (BIPV) components as a new building material is one of the most promising ways to achieve decarbonization of the building stock in an economical and environmentally efficient manner. To this end, building design teams are key, especially in promoting BIPV-based projects to their clients and taking this approach into account from the initial design phase where pivotal decisions with significant impact are made. This article illustrates the potential impact of specific choices in renovation processes on the overall building performance, considering a Life-Cycle Analysis/Cost (LCA/LCC) and multi-criteria analysis. It uses a 1970's residential building as case study, examining different refurbishment scenarios. Findings reveal that scenarios integrating BIPV can significantly enhance energy savings, achieving up to 122 % in energy efficiency gains, and can meet the 2050 targets for cumulative energy demand (CED) and global warming potential (GWP). Additionally, the most effective BIPV scenarios demonstrate economic viability with a payback period of 14–18 years and internal rates of return (IRR) between 5.3 % and 5.9 %. These results underscore the economic and environmental benefits of BIPV in building renovations and advocate for its broader adoption to achieve national and international climate goals.

Exploring occupant behaviors and interactions in buildings with energy-efficient renovations: A hybrid virtual-physical experimental approach

Energy-efficient renovations significantly affect how people use buildings, and these occupant behaviors, in turn, influence the effectiveness of building renovations. Exploring interactions between occupants and renovations is essential for implementing building energy-efficient renovation. However, physical experiments for this purpose require extensive setups in the laboratory to observe occupant behaviors under various renovations. Immersive virtual environment (IVE) experiments as an emerging method still need to adequately incorporate thermal stimuli, essential for studying occupant behaviors, building renovations, and related interactions.Therefore, this study proposes a novel approach that integrates virtual and physical environments in experiments to explore occupant behaviors and their interactions with building renovations. The interactive and immersive capabilities of IVE experiments allow for effective simulation of various renovations and occupant behaviors. By incorporating thermal stimuli from physical experiments, this approach overcomes previous limitations in studying thermal-related occupant behaviors. In a field study, an office building looking for renovation is used to explore occupant behaviors and their interactions with building renovations. It is found that energy-efficient renovation impacts personal heater use and door opening behaviors, but not clothing behaviors; such changes in heater use subsequently impact the energy performance of building renovation. In further analysis, obvious correlations are revealed between personal heater use and renovation scenarios, thermal perception, and times of day. The proposed approach is validated as a novel method to engage the occupants in achieving occupant-centric building energy-efficient transitions.

The effect of considering the real consumption on the assessment of the renovation of social housing buildings

Social housing is a priority within the European Union (EU) for boosting the necessary building renovation. The predicted and real consumption of buildings usually differ, and this is the Energy Performance Gap (EPG). Here, the effect the EPG has on the renovation decision-making process is analysed. The results show that a significant error in energy consumption reduction can occur if real consumption is not considered. Generally, it has been found that the average difference between considering real consumption or not is 22 percentage points. The economic perspective of the renovation is therefore influenced by the tenants’ real consumption and some renovation scenarios can become non-profitable or vice-versa. However, considering real consumption is complex and time consuming, so a simplified methodology intended for use by investors or administrators without considerable effort is proposed. This methodology has been proved to be reliable, accounts for real consumption, and allows a more accurate assessment of building renovation. Particularly, when real consumption is considered, the actual contribution of the building’s renovation regarding CO2 emissions reduction targets can be properly assessed. Finally, the improvement in the dwellings’ indoor conditions is analysed, as a key additional aspect to support the EU priority to renovate social housing.

Integration of moisture transfer through walls into an urban climate model and application to the medieval city centre of Cahors (France)

Moisture transfer is a key phenomenon for simulating the energy balance of the walls of historical buildings as it has an impact on indoor and outdoor comfort, energy consumption and the durability of the walls. It is therefore essential to consider moisture transfer through walls when simulating old city centres, in order to properly assess the impact of different retrofit solutions on building and city energy balances. However, urban climate models neglect this phenomenon. The objective of this paper is to integrate the coupled mass and heat transfers into the urban climate model Town Energy Balance (TEB). A specially designed numerical method for solving hygrothermal transfers at the urban scale is updated and the hygrothermal transfer through walls is integrated using an IMplicit/EXplicit (IMEX) discretization scheme with large spatiotemporal scales. The reliability of this modified version of TEB for representing a historical district is verified by comparing the simulated results with in-situ measurements in a building of the medieval city centre of Cahors (France). The comparison is carried out for several points in the wall and for indoor conditions, running from June to December 2021. The integration of the moisture transfers through the walls greatly improves the moisture estimation inside the building. This new version of the model gives a good representation of the hygrothermal behaviour of a historical building and could therefore be used to compare several renovation scenarios for the medieval centre of Cahors, with regard to durability, energy and microclimatic issues.

An Energy and Ecological Assessment of The Prior and Post-Hybrid Renovation State of Multi-Dwelling Building in the Algerian City of Skikda

In the context of Algerian energy and environmental concerns and its aspirations for energy transition, this article examines the pre- and post-state of a multi-family residential building in the city of Skikda, in northern Algeria, utilizing the UBEM reduced-order approach, alongside QGIS, CEA and METEONORM tools. Primarily focusing on the building's solar exposure, energy aspects, and environmental considerations. Six hybrid renovation scenarios were considered then, and assessed for their contribution for energy savings and ecological improvement. The main results revealed that 87% of annual energy requirements were related to heating and hot water, which are supplied by a natural gas system, a source of various types of greenhouse gases, which suggested the use of triple glazing, with or without two selective low-emissivity coatings only, or be combined by changing hot-water supply system to an electric one, alongside the installation of the hybrid PVT panels on the south façade. This triple glazing was joint in another scenario by integrating the same type of panels on the roof alongside a seasonal thermal energy storage system. This latter scenario being the best in terms of energy and ecology, and making the building highly performant in both aspects.

Energy Performance Analysis of the Renovation Process in an Italian Cultural Heritage Building

Renovating buildings with cultural heritage significance is an important step toward achieving sustainability in our cities. The benefits are not only energy-related but also encompass social aspects that make these renovations a high apriority. The present work investigates the renovation process of a cultural heritage building in the Municipality of Trento in Italy, specifically focusing on achieving energy savings and renewable energy integration by implementing various renovation actions. These renovation actions include improvements to the building envelope, such as roof insulation and window replacements. Additionally, the renovation actions for active systems involve the installation of a ground-source heat pump for heating/cooling coupled with a borehole thermal energy storage system, which is an innovative technology for the renovation of cultural heritage buildings. The electrical systems of the building are upgraded through the addition of standard rooftop photovoltaics, innovative building-integrated photovoltaics (shingles), and the installation of an LED lighting system. The baseline and the renovation scenarios are studied using the dynamic simulation tool INTEMA.building, written in the programming language Modelica. This tool simulates both the building envelope and the energy systems with a high level of detail, using advanced control systems and adjustable time steps. According to the simulation analysis, the primary energy demand is reduced by 30.49%, the final energy demand by 36.74%, and the net electricity demand by 8.72%. Results from this study can be useful to interested stakeholders (e.g., building owners, architects, construction companies, public agents, and urban planners) dealing with the renovation of cultural heritage and protected buildings. Also, the results can be exploited for estimating energy savings by applying advanced renovation strategies for cultural heritage buildings.

Low carbon emission renovation of historical residential buildings

The urgency of renovating residential buildings in heritage conservation areas while addressing carbon emission reduction and energy performance has become a concern in the context of climate change. European directives stress the importance of enhancing existing buildings to achieve climate neutrality by 2050. An approximately 100-year-old wooden apartment building in the heritage conservation area in Võru, Estonia, was designed as a nearly zero-energy building (nZEB). This study examined the impact of different renovation scenarios, considering both embodied and operational carbon emissions. During the study, the technical requirements of the National Heritage Board were developed in several aspects. The results of this study indicate that it is possible to renovate buildings in heritage conservation areas and achieve great energy performance. In addition to improving energy performance, it is possible to make the restoration of a significantly damaged exterior with intermediate repairs more cost-effective for the owner. Deep renovation of a historical wooden building decreases its carbon footprint as it leads to more energy-efficient renovation solutions. This is because operational emissions dominate over embodied emissions in a cold climate. From an environmental perspective, it is more feasible to renovate historically valuable buildings more deeply than it is to upgrade the external appearance of buildings. Renovation work to achieve an nZEB building should include insulating the thermal envelope while restoring the historical appearance and preserving the original building profile. In conclusion, this study offers a comprehensive analysis of various scenarios, including carbon footprint, energy performance, and cost optimality, related to different renovation strategies for buildings located in heritage conservation areas. There is a need to align heritage board technical requirements with the environmental perspective. Given that major renovation is more cost-effective and better at preserving the exterior appearance compared to staged renovation, the former should be preferred to ensure the owner's willingness to pay.

Greenhouse Gas Payback Time of Different HVAC Systems in the Renovation of Nordic District-Heated Multifamily Buildings Considering Future Energy Production Scenarios

The European Union (EU) has implemented several policies to enhance energy efficiency. Among these policies is the objective of achieving energy-efficient renovations in at least 3% of EU buildings annually. The primary aim of this study was to offer a precise environmental comparison among four similar district-heated multifamily buildings that have undergone identical energy efficiency measures. The key distinguishing factor among them lies in the HVAC systems installed. The chosen systems were as follows: (1) exhaust ventilation with air pressure control; (2) mechanical ventilation with heat recovery; (3) exhaust ventilation with an exhaust air heat pump; and (4) exhaust ventilation with an exhaust air heat pump with a Photovoltaic (PV) panel. This study involved a life cycle assessment that relied on actual material data from the housing company and energy consumption measurements. This study covered a period of 50 years for thorough analysis. A sensitivity analysis was also conducted to account for various future scenarios of energy production. The findings revealed that the building with an exhaust air heat pump exhibited the lowest greenhouse gas emissions and the shortest carbon payback period (GBPT), needing only around 7 years. In contrast, the building with exhaust ventilation without heat recovery showed the highest emissions and the longest carbon payback period (GBPT), requiring approximately 11 years. Notably, the results were significantly influenced by future scenarios of energy production, emphasizing the crucial role of emission factors in determining the environmental performance of distinct renovation scenarios.

An ontology-based tool for safety management in building renovation projects

Managing deep renovation projects is challenging due to the interactions with their surroundings, the issues of limited access and space, and the uncertainty around the composition and conditions of existing buildings. The interplay between the building areas, the building elements involved in the deep renovation, and the renovation scenarios and activities present challenging situations for managing safety risks. Research on enhancing safety in building projects using digital approaches such as BIM has mainly focussed on new construction works, yet limited research is available for deep building renovation projects. Using a Design Science Research (DSR) methodology, this paper develops an ontology for representation and identification of hazards in deep building renovations, instantiates the ontology through the development of a digital tool, and demonstrates its usefulness in hazard representation and identification by performing tests with real industry data from deep renovation projects, as part of a Horizon Europe 2020 research project, called RINNO. The testing involved a multi-residence apartment case study and three different renovation scenarios and successfully demonstrated the ability to automatically identify potential hazards relating to a particular renovation strategy. While the proposed ontology can be used to reduce the risk of accidents and injuries in building retrofit projects, its main implication is in laying the foundation for future digitally enabled approaches for managing safety in building renovation projects.

Definition and design of a prefabricated and modular façade system to incorporate solar harvesting technologies

The current research presents the design and development of a prefabricated modular façade solution for renovating residential buildings. The system is conceived as an industrialised solution that incorporates solar harvesting technologies, contributing to reducing energy consumption by employing an “active façade” concept. One of the main challenges was to achieve a highly flexible solution both in terms of geometry and enabling the incorporation of different solar-capturing devices (photovoltaic, thermal, and hybrid). Therefore, to be able to provide alternative customised configurations that can be fitted to various building renovation scenarios. Guided by the requirements and specifications, the design was defined after an iterative process, concluding with a final system design validated and adopted as viable for the intended purpose. A dimensional study for interconnecting all the technologies composing the system was carried out. Potential alternative configurations were assessed under the modularity and versatility perspective, resulting in a set of alternative combinations that better fit the established requirements. Complementarily, the system also integrates an active window solution a component that incorporates an autonomous energy recovery system through ventilation. The main outcome is explicated in a highly versatile modular façade system, which gives existing buildings the possibility to achieve Nearly Zero Energy Building requirements.

To renovate or to reconstruct – A comparative life-cycle assessment study over an existing building in Fribourg, Switzerland

This study presents a simple and agile yet holistic comparative assessment of the impact, in terms of non-renewable cumulative energy demand (nrCED) and global warming potential (GWP), of two envisioned scenarios for the future of an existing administrative building located in Fribourg, Switzerland: its demolition and reconstruction versus its in-depth renovation. Based on our set of hypotheses, results show that over all life-cycle phases (construction and operation) and the building’s lifetime, the renovation scenario’s GWP is 540 kgCO2-eq/m2 lower than that of the reconstruction scenario, corresponding to a 50% savings. In terms of nrCED, the difference is of about 2 MWh/m2, a 45% savings in the renovation scenario. Both scenarios are found to comply with the SIA 2040 target values. These results, including findings on the most impactful elements, provide useful quantitative information for the decision-making and design team in their next steps toward defining the project.

A Community-based Whole Life Carbon Assessment: Case study of a London estate community plan

In the attempt to adhere to the UK’s 2050 Net-Zero Strategy, more attention has been given to energy-centric decision-making over the regeneration of housing estates. Whole Life Carbon Assessment (WLCA) is the methodology used for the evaluation of the overall carbon dioxide equivalent (CO2e) emissions of building projects over their lifecycle. The WLCA studies are mostly not understood by different stakeholders and are less effective in reducing the Global Warming Potential (GWP) impacts in the development of regeneration scenarios. This paper is part of a larger study on a multistakeholder lifecycle-based sustainability assessment framework and aims to further explore whether retrofitting can outperform the existing and new build scenarios for lower GWP impacts, and intends to examine the use of WLCA for the development of a regeneration scenario. The research consists of a single-case case study employing co-design workshops, surveys, and WLCA experiments. The community’s preferred regeneration scenario has been developed through knowledge mobility and co-design workshops with the members of the community and a UCL team of designers and researchers. The WLCA of different regeneration scenarios (existing building, different refurbishment scenarios, and a previously approved redevelopment scheme) has been conducted using the data from desk-based research, site surveys, building regulations, retrofit case studies and guidelines, and the planning documents of the council’s previously approved new build scheme. The results of the WLCA support the current studies in favour of the refurbishment scenarios over the demolition and rebuilding of the estate, and make a case for the necessity of understanding the GWP in design development to reduce the GWP of regeneration scenarios.

The role of LCA in the renovation’s early decision-making for the design of a multifunctional, modular building envelope system

The renovation of buildings has a high capacity to influence the environmental impacts and global objectives of climate change mitigation. In the context of designing low-energy buildings with minimized environmental impacts, the life cycle assessment (LCA) has been proven a straightforward method, to evaluate the direct and indirect environmental impacts of a building concept. Even though it is the most energy-intensive element, the use phase is not only a source of environmental concern but also the whole life cycle of the building and its components. However, energy-efficient renovation decisions tend to be financially motivated events, subject to exogenous constraints or barriers, that do not integrate whole life cycle thinking. This study aims to identify how the LCA information can be considered in comparing renovation options. compare renovation options, taking into account the modular envelope system developed as part of the European research project ENSNARE (ENvelope meSh aNd digitAl framework for building Renovation) case study. The study analysed different renovation scenarios, generated according to combinations of renewable energy sources and compare them to the base case and typical renovation scenario. Such information can support the design team in making decisions that consider the whole building and its components’ life cycles.

A BIM based tool for evaluating building renovation strategies: the case of three demonstration sites in different European countries

Purpose Buildings are among the biggest contributors to environmental impacts. To achieve energy-saving and decarbonisation objectives while also improving living conditions, it is imperative to undertake large-scale renovations of existing buildings, which constitute the greater part of building stock and have relatively low energy efficiency. However, building renovation projects poses significant challenges owing to the absence of optimised tools and methods for planning and executing renovation works, coupled with the need for a high degree of interaction with occupants. Design/methodology/approach This paper describes the development of an automated process, based on building information modelling (BIM) and the principal component analysis method, for overcoming building renovation challenges. The process involves the assessment and simulation of renovation scenarios in terms of duration, cost, effort needed and disruptive potential. The proposed process was tested in three case studies; multi-residence apartment buildings comprising different construction components and systems, located in Greece, France and Denmark, on which six different renovation strategies were evaluated using sensitivity analysis. Findings The developed tool was successfully able to model and simulate the six renovation scenarios across the three demonstration sites. The ability to simulate various renovation scenarios for a given project can help to strategise renovation interventions based on selected key performance indicators as well as their correlation at two different levels: the building level and the renovated surface area level. Originality/value The objectives of this paper are twofold: firstly, to present an automated process, using BIM, for evaluating and comparing renovation scenarios in terms of duration, cost, workers needed and disruptive potential; next, to show the subsequent testing of the process and the analysis of its applicability and behaviour when applied on three live demonstration sites located in three different European countries (France, Greece and Denmark), involving six renovation scenarios.

Simplified Multi-Life Cycle Assessment at the Urban Block Scale: GIS-Based Comparative Methodology for Evaluating Energy Efficiency Solutions

The Italian residential building stock consists of 12.2 million buildings, with 7.2 constructed post-World War II during the economic boom. These structures were designed without specific regulations for seismic safety, fire resistance, and energy efficiency, and today lies the current state of strong obsolescence. Therefore, energy refurbishment may not always be the best cost/benefit solution due to these intrinsic issues. Consequently, the transition to construction systems based on circular economy principles brings new opportunities and becomes key to proposing replacement interventions for this heritage. This paper presents a comparative GIS-based bottom-up approach to evaluate the lifecycle impact of residential building blocks, encompassing energy, environmental, and economic aspects. Two tools are introduced: one for measuring energy consumption and the other for quantifying the quantities of materials stored in buildings. This methodology permits comparing the new circular buildings and different refurbishment scenarios to identify the most suitable solution from an environmental impact and financial point of view. The application of a case study, a residential urban block in Bologna, built in 1945–1965, highlights how the demolition and reconstruction scenario based on circular economy principles presents the lowest environmental impacts and is economically competitive compared to standard deep renovation techniques.

Building Information Modeling Applications in Energy-Efficient Refurbishment of Existing Building Stock: A Case Study

The built environment contributes to 35% of the global energy consumption and 38% of energy-related carbon emissions. The exponential population growth, coupled with the inability of the existing building stock to meet demands or reach the end of its lifespan, has precipitated the proliferation of new constructions worldwide. However, it has been proven well that retrofitting existing buildings might impact the environment less, save resources, and reduce the carbon footprint while extending their lifecycle. Various techniques are available to assess the performance of existing buildings and quantify the energy-saving potential of renovation measures. Building information modeling (BIM) technology serves as a virtual laboratory for buildings and can be used to model building stocks and measure how building performance changes with alternative envelope and system proposals. This research study explores the potential of BIM-based energy modeling to evaluate the effectiveness of refurbishment scenarios on a residential building. A total of 192 alternative scenarios were developed by considering six variables (wall, roofing, insulation, glazing, lighting power density, and photovoltaic panels). The results were analyzed across annual energy consumption (fuel and electric), annual/lifecycle energy costs, energy use intensity, annual CO2 emissions, and initial investment costs. The optimum alternative scenario decreased the annual fuel and electricity consumption of the sample building by 61% and 64%, respectively. The payback period was calculated as 12 years. This study demonstrates the impact of BIM in enhancing the energy efficiency of the existing building stock, presenting results within the context of a residential building.

Analysis of transparent building envelope renovations for indoor thermal comfort in an educational building

PurposeThe buildings should be designed by respecting the environmental and climatic conditions they are in and their orientation. Then, the characteristics of the building envelope (BE) play an important role in building energy consumption and user comfort. In fact, the type and material of glazing is one of the crucial parameters for BE. The transparency ratio of BE also determines the façade performance. The aim of this study is to analyze the different renovation scenarios for BE with high transparency of an educational building (EB) in hot summer weather to obtain indoor thermal comfort (ITC) for users.Design/methodology/approachThe methodology includes thorough measurement of existing ITC using TESTO-440 and simulation of each retrofit scenario using DesignBuilder building energy modeling (BEM) simulation software with Energyplus to determine optimal thermal comfort. Since the study focuses on the impact of the transparent BE on summer ITC, four main scenarios, naturally ventilated (NV) façade, film-coated glass façade, replacement of glazing with opaque units, sun-controlled façade with overhang and solar shading, were simulated. The results were analyzed comparatively on both performance and cost to find the best renovation solutions.FindingsA total of 7 different renovation scenarios were tested. Simulation results show that passive systems such as NV have limited contribution to indoor air temperature (IAT) improvement, achieving only a 4 °C reduction while offering the lowest cost. A film coating resulted in a reduction of 3–6 °C, but these applications have the highest cost and least impact on ITC. It was found that exterior coating leads to better results in film coating. Preventing and limiting the increase in IAT was achieved by reducing the transparency ratio of BE. The best results were obtained in these scenarios, and it was possible to reduce IAT by more than 10 °C. The best performance/cost value were also obtained by decreasing transparency ratio of roof and sun control.Research limitations/implicationsSince the high transparency ratio has a negative impact on summer comfort, especially in hot climate zones, summer ITC was prioritized in the renovation solutions for the case building.Originality/valueThe study’s findings present a range of solutions for improving the ITC of highly transparent buildings. The solutions can help building managers see the differences in renovation costs and their impacts on ITC to decrease the cooling load of the existing buildings.