Refurbishment Options Research Articles

Enhancing efficiency and user-centricity in architectural remodeling: A comprehensive system design for structural renovation

The home renovation industry has witnessed remarkable growth, driven by shifts in lifestyle necessitating adjustments in living spaces. This paper addresses critical gaps in the domain of architectural remodeling, with a particular focus on improving efficiency, referenceability, and user-centricity in structural remodeling. This research introduces a system design tailored for structural remodeling within house renovation, catering to both comprehensive and partial projects to facilitate the creation of structurally viable renovation options and optimizing them to align precisely with user requirements. The proposed system's accessibility and consideration of architectural factors set it apart. While offering substantial benefits, the system has limitations, such as the exclusion of interior furnishing styles in output solutions. In conclusion, contributes to the improvement of remodeling projects and offers a promising approach, particularly in the early stages of these endeavors.

A New Approach to the Economic Evaluation of Thermomodernization: Annual Assessment Based on the Example of Production Space

Energy and economic assessments are of great relevance in the context of decision processes for the most optimal solutions for building renovations. Following the method recommended by UNIDO, economic analyses of thermal modernization options are carried out based on the Simple Payback Time (SPBT), Net Present Value Ratio (NPVR) and Internal Rate of Return (IRR) indices. Incorporating these indicators and a new approach that involves aggregating thermomodernization activities not only in the cold and warm seasons separately, but throughout the whole year, an economic evaluation of the thermomodernization of a production space was carried out. In this case study, the renovation options included wall insulation, window replacement, the installation of infrared heater, a two-flow air diffuser (TFAD) and variable air volume. The economic effect indicated by the highest NPVR over a normative period of 15 years was obtained for the installation of an infrared heater and a TFAD with a variable mode ventilation system. The SPBT for this case was also the lowest.

Strategies for robust renovation of residential buildings in Switzerland

Building renovation is urgently required to reduce the environmental impact associated with the building stock. Typically, building renovation is performed by envelope insulation and/or changing the fossil-based heating system. The goal of this paper is to provide strategies for robust renovation considering uncertainties on the future evolution of climate, energy grid, and user behaviors, amongst others by applying life cycle assessment and life cycle cost analysis. The study includes identifying optimal renovation options for the envelope and heating systems for building representatives from all construction periods that are currently in need of renovation in Switzerland. The findings emphasize the paramount importance of heating system replacements across all construction periods. Notably, when incorporating bio-based insulation materials, a balance emerges between environmental impact reduction and low energy operation costs. This facilitates robust, equitable, and low-carbon transformations in Switzerland and similar Northern European contexts while avoiding a carbon spike due to the embodied carbon of the renovation.

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.

The challenge of rehabilitating relocated listed heritage Buildings: Requirements and opportunities

This study evaluates three listed farmhouses in Ørland Municipality which are going to be relocated and rehabilitated according to current Norwegian standards and requirements. Accordingly, the study assesses possible challenges and solutions regarding energy upgrading and restoration while preserving their historic features and cultural heritage. The study suggests solutions for the energy rehabilitation of the three farmhouses based on a literature review, hygrothermal simulations and energy simulations. These solutions include thermal post-insulation of external walls and above the framework of joists against the cold attics with mineral wool, vacuum insulation panels (VIP), and aerogel blankets. Additionally, fenestration renovation options and the potential for implementation of building integrated photovoltaics (BIPV) are reviewed. Lastly, simulations of multiple energy-saving measures for each of the farmhouses have been conducted.A new foundation due to the relocation, together with post-insulation of the cold attic are found to be feasible measures considering the preservation of architectural appearance and authenticity. Regarding the external walls, post-insulating externally is preferable for the farmhouses considering moisture issues and interior space savings. However, it is important to consider any possible loss of cultural heritage value. Alternatively, internal thermal insulation with aerogel blankets may be a feasible solution due to its high thermal resistance applying small thicknesses. The results show that in some cases, enhancing old original windows with a secondary glazing is an equally good solution compared to a total replacement of the windows, and is recommended for cultural preservation. Implementation of BIPV contributed to meet the net energy demand requirement. Nevertheless, it is recommended that the chosen BIPV systems resemble an accepted roofing material from the regulatory requirements, e.g., slates, to accommodate the building’s architectural aesthetics and authenticity.This study provides insight and recommendations for the rehabilitation of three listed traditional farmhouses in Trøndelag County, addressing energy efficiency while preserving their cultural significance. The findings show that it is possible to achieve today’s energy requirements when rehabilitating listed heritage buildings. Results from energy simulations show that a reduction in net energy demand between 55 % and 75% is possible, while it is essential to note that each building is unique, and a case-by-case approach is needed. Nevertheless, the findings can be applicable for a general energy upgrading of heritage buildings.

Lower-Temperature-Ready Renovation: An Approach to Identify the Extent of Renovation Interventions for Lower-Temperature District Heating in Existing Dutch Homes

This study presents an approach to determine the extent of renovation interventions required for existing Dutch dwellings aiming to transition to lower-temperature district heating (DH) systems. The proposed method is applied to a typical intermediate terraced house built before 1945 in the Netherlands, and it consists of two steps: first, assessing the potential of a dwelling to be heated with a lower temperature supply from DH systems and subsequently developing and evaluating alternative renovation solutions if necessary. This study defines a set of criteria for evaluating the readiness of a dwelling for lower-temperature heating (LTH), considering energy efficiency and thermal comfort as non-compensatory criteria. The application of the approach reveals that the case study dwelling is presently unsuitable for a medium-temperature (70/50 °C) and low-temperature (55/35 °C) supply compared to a high-temperature supply (90/70 °C), thus requiring energy renovations. Furthermore, this study indicates that moderate intervention levels are required for the dwelling to be lower-temperature-ready in both supply temperature goals. These interventions include strategies and measures that upgrade the building envelope to the minimum insulation levels stipulated by the Dutch Building Decree, improve airtightness, and replace existing radiators with low-temperature radiators. By systematically narrowing down renovation options, this approach aids in simplifying the decision-making process for selecting renovations for heating dwellings with LTH through DH systems, which could reduce stakeholders’ decision paralysis.

Designing a model for the cost-optimal decommissioning and refurbishment investment decision for gas networks: Application on a real test bed in Austria until 2050

The primary goal of this paper is to investigate the most cost-effective decommissioning and refurbishment investment decision for existing gas networks. An optimization model is developed and tested on a real test bed in an Austrian federal state. The analysis is performed from the network operator’s perspective and depicts different network decommissioning or refurbishment options under the decision of supplying or not supplying available gas demands. Whether or not there is ensured supply, we find that smaller gas networks (in terms of pipeline capacity and network length) are needed in the future. Analyzed shadow prices indicate that a balance/trade-off between the cost-optimal gas network design with and without ensured supply could lead to a robust and economically competitive future for downsized gas networks. The results demonstrate that it is necessary to socialize network operators’ costs among the remaining consumers connected to the network in the future. This adds a cost component to consumers, which needs to be considered when determining the profitability of sustainable alternatives to natural gas.

Evaluation of renovation strategies: cost-optimal, CO₂e optimal, or total energy optimal?

Currently, building renovation decisions are often driven by immediate investment expenses and short-term energy cost savings, rather than long-term optimisation. The difference between the national carbon footprint (CF) methodologies and the LEVEL(s) framework methodology is significant in relation to the application of energy scenarios. Energy scenarios are created at the national level and are not harmonised. CO2e emission factor of Estonian grid electricity is among the highest in Europe and carbon footprints of Estonian buildings are typically dominated by operational energy use (B6) in Life-Cycle Assessment methodology. Therefore, carbon optimisation leads to better energy performance, than the previous cost-optimal benchmark. The application of the LEVEL(S) methodology would further emphasize the dominance of operational energy stage (B6) in Estonian results and guide towards even higher energy efficiency targets.This study shows, that CF optimal renovation solutions differ from cost-optimal solutions and that CF optimal can be considered a more relevant energy efficiency benchmark for deep renovations, instead of cost optimal. It provides an analysis of different renovation solutions for a typical apartment building renovated in 2021. These solutions were examined using three parameters: life-cycle costs, total energy demand, and CF by applying the Estonian assessment method for the CF of construction works.The results of this case study indicate that the renovation options for both CO₂e optimal end operational energy use (B6) throughout the life cycle provide similar results. The CO₂e optimal solution leads to lower building energy performance indicator level, than conditioned by cost optimal solution.The current increasing energy prices are more substantially supporting solutions with lower CF, as total energy demand is an important economic factor not only in operational energy stage (B6), but also in material production, which was also investigated in this study. The results show that, if operational energy (B6) is excluded, there are significant differences in embodied carbon between the materials used for renovation. Lower carbon footprint renovation strategy involves the usage of pre-fabricated timber frame elements, mineral wool for insulation, wooden cladding or cement fibreboard in the facade. The prevalent External Thermal Insulation Composite System (ETICS) had the highest CF value and maintenance requirements during the building’s lifetime. As the main objective of the Energy Performance of Buildings Directive is to drive greenhouse gas reductions, then the steering mechanism should be based on CO2e optimal instead of cost optimal.

Implementation strategies for renovation concepts based on participative planning

The potential for reducing Greenhouse gas (GHG) emissions by district renovation is largely untapped. It not only requires a thorough Energy Master Planning (EMP) of the district but also support of the decision-making processes. This can not only contribute significantly to reducing energy consumption and securing the location of energy infrastructure (generation, distribution, storage), but also to long-term sustainable development and climate neutrality. Understanding the different solutions for district renovation which include combinations with energy supply and consumption is important in districts. A technical as well as economical analysis is proposed that combines reduction of GHG emissions potential with an economic appraisal. A district near Winterthur, Switzerland was analyzed in respect to the aforementioned aspects. Site visits and structured interviews with key stakeholders were used to collect data which was then analyzed. Different renovation options were simulated, and investment and energy costs were calculated. The results show that the technical potential for a decarbonization is large. However, financial and social aspects are significant and lead to a delay in implementation.

Improved methodology for affordable, reliable deep building renovations

European Union energy efficiency goals put refurbishments in focus as the existing building stock takes a high share in the final energy consumption meanwhile current refurbishment rates are lower than expected. This research attempts to answer the question: How can renovation processes be improved to raise renovation rates? The methodology development process consisted of identifying the methodological background, the phases and steps of the renovation process and the validation strategies. As a result, five methodological phases were identified. Renovations start with the Feasibility phase where a simple financial and technical assessment is carried out. During the Preparation phase necessary information is collected which results in a calibrated simulation model that can support the design. In the Design phase the renovation options are developed and assessed together with a business plan for financing the implementation through renovation cycles. The renovation measures are carried out during the Implementation phase. In the Operation phase the performance of the refurbished building is monitored and improved. The developed methodology is expected to provide more affordable, reliable building renovations, which reduces the performance gap, the upfront investment and the disruption of user life by reducing overall time on site. This results in an increased investment efficiency leading to higher uptake of refurbishments.

Dynamic Versus Static Life Cycle Assessment of Energy Renovation for Residential Buildings

Currently, a life cycle assessment is mostly used in a static way to assess the environmental impacts of the energy renovation of buildings. However, various aspects of energy renovation vary in time. This paper reports the development of a framework for a dynamic life cycle assessment and its application to assess the energy renovation of buildings. To investigate whether a dynamic approach leads to different decisions than a static approach, several renovation options of a residential house were compared. To identify the main drivers of the impact and to support decision-making for renovation, a shift of the reference study period—as defined in EN 15643-1 and EN 15978—is proposed (from construction to renovation). Interventions related to the energy renovation are modelled as current events, while interventions and processes that happen afterwards are modelled as future events, including dynamic parameters, considering changes in the operational energy use, changes in the energy mix, and future (cleaner) production processes. For a specific case study building, the dynamic approach resulted in a lower environmental impact than the static approach. However, the dynamic approach did not result in other renovation recommendations, except when a dynamic parameter for electricity production was included.

Renovation of Modernist Housing Developments in the Pursuit of Modernity for Well-Being and Clean Energy

The research concerns renovation variants for modernist housing estates built in Szczecin, Poland during 1918–1925 and in Bialystok, Poland during 1950–1990. These buildings are now substandard in many ways; functionally, aesthetically, technically, and ecologically they do not fulfil the current energy efficiency standards. Some of them have architectural heritage, so not all energy-saving technologies can be applied. Renovations must include energy-saving improvements and the use of renewable energy sources. Equally important is the well-being of residents, meaning the quality of the apartments should be increased. The aim of this research was to analyze the renovation options in terms of energy efficiency and well-being criteria, as well as in relation to the cultural value of the buildings. The simplified energy calculation method was used to check the present buildings’ energy demands to compare them with retrofitting results. Three retrofitting possibilities were considered: low-cost, current standards, and near-zero energy. The results show that without EU financial aid, which will soon be introduced under the “Renovation Wave” program, such modernization projects will be difficult, making the target of 55% CO2 emission reductions compared to 1990 levels by 2030 impossible.

Balancing Social and Economic Sustainability in Renovation with an Affordable Option for Tenants? A Pilot Study from Sweden

A public housing company has applied a new renovation strategy, comprising no standards raising and thus rent-raising measures, in 20% of its apartments. Prior to renovation, the tenants were given the opportunity to choose renovation options involving different standards and costs after renovation. The purpose of the study is to follow up and give feedback on the renovation strategy. The aim was to evaluate implementation of the strategy in practice using a case study, in terms of the tenants’ opportunity to influence and the housing company’s profitability. To follow up, two methods were used: a survey of the tenants’ perception of choosing renovation options, and a financial assessment of the profitability based on the renovation cost and rent increase for different choice scenarios. The results from the survey show that the tenants appreciate being able to choose between different renovation options as it gives them the opportunity to decide on their housing costs and standard. With more than half of the tenants choosing the maintenance option involving a very low rent increase, the dividend yield will not be high enough to make the renovation profitable, but if only 20% had chosen the maintenance option, the dividend yield would be more feasible in the long run.

Processes for Sustaining Energy in Noncertified Historic Buildings: A Case Study of Smith Plantation

This paper addresses energy efficiency, indoor air quality, and water consumption in historic buildings. Building sustainability has become a worldwide issue from new construction to existing buildings. Historic buildings make up a large part of existing buildings throughout the world, making it essential that research is done to provide these buildings with sustainable options. The areas of special concerns in renovating historic buildings are improving indoor environmental quality, indoor air quality, water efficiency, and energy efficiency while maintaining the historical value of these buildings. This paper presents a case study of the Smith Plantation in Metro Atlanta, Georgia. The study includes 1) field verification and existing condition assessment of the thermal comfort, energy consumption, and indoor air quality. 2) Building information modeling was used to simulate the energy performance of the buildings as well as determining the CO₂ footprint. These models were calibrated and verified against field readings. 3) the simulation models were used to generate design and renovation alternatives to improve the energy efficiency of these buildings as well as reducing the CO₂ footprint without impacting the originality of these buildings. This study will provide general design guidelines and renovation options for historic buildings to reduce energy consumption and creating a smaller carbon footprint while maintaining the authenticity of the buildings.

Decision support for retrofitting building envelopes using multi-objective optimization under uncertainties

In the last decade, retrofitting strategies have been reviewed to improve energy efficiency and reduce the environmental impact of existing buildings. One retrofitting strategy consists of innovating building envelopes with the adoption of high-performance materials or systems. Despite the potential performance enhancement, opportunities for new envelopes have been constrained because various envelope options are difficult to be evaluated synthetically. Also, the decisions should consider the optimization of multiple objectives as well as uncertainties. In this respect, this paper aims to support the decision of selecting building envelopes to meet multiple objectives under uncertainties while considering possible envelope options. A multi-objective optimization model is developed considering the existing built form, uncertainties in performance predictions, and incorporating newly developed façade systems. The optimal selection includes emerging materials and technologies that are provided with building envelope renovation options to satisfy indoor thermal comfort, energy balance, environmental emissions, and economic aspects. The decision-support framework is also devised to add any envelope options. This adaptable framework enables decision makers to accommodate new system materials and proactively evaluate their feasibility. The optimization model and framework proposed in this research will contribute to providing a roadmap for transforming existing buildings into smart and sustainable built systems.

High energy efficiency renovation options for a typical apartment. The case study of the SPITI project

The need for reduced energy consumption dictates a new way of thinking about the design, construction, and renovation of buildings. Proposing a repurposing retrofit of a top-floor apartment of a typical Greek multi-storey building, the International Hellenic University has qualified to the final stage of the Solar Decathlon Europe 2019 competition. The main aim of this study is to provide a solution towards the nearly (or net) zero energy buildings, paving the way for EU countries to achieve their energy conservation targets in the building sector. The solution includes the upgrade of the building envelope and its energy systems, the rearrangement of the interior space and the implementation of renewable energy sources. The assessment of the different retrofitting measures was carried out using EnergyPlus, while the System Advisory Model was employed to simulate the prototype’s solar systems. The final energy demand was reduced by approximately 88%, with the requirements for heating and cooling at 10.3 kWh/m2 and 14.1 kWh/m2, respectively. The electricity production from the photovoltaic system, namely 4,959 kWhe, can meet the annual electricity requirements leading to a 100% self-sufficient building.

The Role of Trans-Disciplinary Research in Sustainable Renovation

The paper discusses the role of trans-disciplinary research networks tackling the challenges of sustainable renovation such as; environmental impact of substitute building materials and waste, relocation of tenants, lack of skilled labor, rent increase due to high renovation costs, and provides a detailed perspective on the effects in terms of both new forms of collaboration and research results obtained by the researchers and practitioners within the network. The research network Sustainable Integrated Renovation SIRen has become a platform for researchers and actors such as building owners, housing companies, facility managers, contractors, consultants, architects, building conservationists, authorities and tenants’ organisations to meet and work together on technical, environmental, economic, social and cultural historical aspects on renovation of buildings, as well as to identify and discuss new challenges. A multi-aspect process covering all aspects that must be considered by the various actors during different stages of the renovation process has been developed and implemented in four ‘Living Labs’ in real renovation projects. This involved using new modes of work in early stages to place the focus on sustainability aspects and work on new dialogue methods and using methods to evaluate the various renovation options based on technical, environmental, economic, social and cultural historical perspectives.

Renovation Strategies for Multi-Residential Buildings from the Record Years in Sweden—Profit-Driven or Socioeconomically Responsible?

An important part of the multi-family housing stock in Sweden was built during the record years 1961–1975 and is in need of extensive renovation to be modernized. The stock is also at the center of political discussion of how to sustain ‘good housing for all’, especially in the rental sector. These renovation needs coincide with present energy targets and provides an opportunity to combine renovation with energy efficiency measures. Common for many of these buildings are that neglected maintenance has led to technical shortcomings, such as high energy use and low thermal comfort due to bad insulation, unsatisfactory air tightness and leaky windows, inefficient heating systems and insufficient ventilation, and moisture damage due to leaking building envelope and leaking pipes. However, the people living in these buildings are not willing to or cannot afford to pay the higher rents that extensive renovations would entail. Earlier research has highlighted the broader societal problem of energy renovations, but also that of housing companies’ priority of measures with short payback times, and those that give the possibility to raise rents. However, recent observations indicated a tendency towards more holistic approaches to housing renovation, and this study was initiated to investigate how public and private housing companies deal with renovation levels, rent increases and related social problems. The main conclusions are that sustainability and social responsibility are moving up on agendas in the public sector, but also, apparently, in the renovations strategies among the private companies. What is also seen is a trend moving from extensive total renovations to more tenant-adapted and step-by-step renovations. Renovation options which do not entail such large rent increases are increasingly being seen. Implications are that housing owners favor gentle renovation with reasonable rent increases of 10%–20%, which at the same time, may be a drawback for reaching energy efficiency targets.

Identify Optimal Renovation Packages for Residential Buildings: A State-of-the-Art Computational Model

Renovating the existing building stock has a significant potential to achieve the goal of reducing greenhouse gas (GHG) emissions in the European Union. However, a common European renovation project focuses primarily on improving the thermal performance of the building shell by adding insulation to the opaque surfaces and improve the thermal performance of the windows. The potentially positive contribution of renewable energies (RE) in balance with energy efficiency measures is often underestimated. Consequently, a more holistic approach can contribute to a reduction in total net energy demand up to 40-45% for the entire buildings sector. Thus, in order to achieve the goal of GHG emission reduction in an economic most responsible way, the share of RE in a renovation project needs to be increased. However, building renovation projects are becoming - apparently - more complicated if more factors are considered in the planning of a renovation project. Thus, a computational tool for evaluating hundreds of different renovation options, including the implementations of renewable energy resources, to obtain an optimal or nearly optimal set of renovation options is essential. Therefore, a novel planning tool has been developed within the framework of DREEAM project, a project funded by the European Union within the Horizon 2020 research framework. The DREEAM-Tool has been designed in the way that it helps designers and other stakeholders to plan a renovation project of a single building or even on a multi-building scale. The tool was built in the way to optimize the renovation project taking into consideration the most critical factors in planning and decision-making processes, such as the economic or environmental performance. In other words, the tool combines an energy calculation model for a building or multiple building with an economic and environmental assessment to identify and optimize the most beneficial refurbishment solutions. The current study presents the concept of the DREEAM-Tool and shows examples of how the optimal renovation packages of a considered building will be determined and how this will support designers or buildings owners in decision-making processes.

Combining embodied and operational energy in buildings refurbishment assessment

Buildings’ refurbishment is becoming a major trend in civil construction in Europe. At the same time European environmental and cultural commitments are being transposed to building and urban regulations. Energy efficiency and heritage safeguarding are two objectives of buildings’ refurbishment policies which do not always lead to the same refurbishment options. Energy efficiency assessment is not always suitable to existing buildings in different local contexts and, while focusing on operational energy, it does not include embodied energy in buildings.This article calculates and combines embodied energy and operational energy, proposing a methodology for the assessment of building components life-cycle energy, suitable for the assessment of repairing and replacing scenarios. The methodology is applied to a case study, comparing walls repair or replacement and considering different scenarios of users’ requirements of thermal comfort. Results show the advantages of preserving building components and materials in terms of whole life cycle energy demand.