Renovation Rate Research Articles

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.

100% renewable heat supply in Berlin by 2050 – A model-based approach

The energy crisis posed major challenges, especially for the heating sector. The European gas price increased from 16€/MWh in March 2021 to 227€/MWh in March 2022, which led to a debate in Germany around reshaping the heat supply to decrease energy import dependence. However, many actors on the heating market are reluctant to make the necessary investments to reduce dependence on natural gas. Although, independence of fossil energy imports by 2050 would be possible with a switch to a 100% renewable heat supply for Berlin.Based on the linear open-source energy system model GENeSYS-MOD, a 100% renewable-based energy system is modeled. GENeSYS-MOD is extended to model district heating, which is crucial for Berlin's heat supply. Furthermore, the modeling of heat pumps and a data set for Berlin is revised.The modeling considers the tightened climate protection targets, which means a 95% CO2 reduction by 2045 compared to 1990. By 2050, 100% of the transport, industry, electricity, and building sectors` emissions are mitigated.The results suggest the immediate exploitation of the existing renewable energy potential and seasonal heat storages, as well as a necessity for a major increase in renovation rates. The upcoming coal phase-out in Berlin in 2030 should be met by a mix of heat pumps and biomass. If heat pump resources are exhausted, direct electric heating is deployed as last resort option.

Mycelium-wood composites as a circular material for building insulation

In Europe, buildings account for 40% of the energy consumption and produce 36% of CO2 emissions. Renovation could be a great tool to decarbonize the building stock since it allows for a decrease in the operational energy required for buildings and is less material-consuming than new construction. Further benefits are brought by the usage of bio-based insulation materials that can drastically reduce embodied emissions and transform structures into factual carbon sinks. This study focuses on a particular kind of biogenic material, mycelium-wood composites, consisting of organic matter bound by the root structure of fungal organisms. This innovative insulation material was compared with traditional ones for the renovation of the building stock, with a focus on vertical components like walls in the Helsinki metropolitan area. To characterize mycelium-wood composites, density and carbon content information were gathered from the samples realized in the Politecnico di Milano MaBa.SAPERLab, while the production processes were included in a SimaPro model to obtain the GWP value. Different scenarios were then defined by two variables: the renovation rate of the building stock and the market penetration of mycelium-wood composites. For each scenario, the overall GWP and CO2 stored values were calculated. Results show the great potential of the innovative material that grants carbon storage in the building stock that could even surpass the amount stored in the 32,500 ha of forest in the area. However, this possibility is heavily influenced by factors independent of the type of insulation used that should be further investigated.

Main Principles and Solutions for Acceleration of Energy Efficient Renovation in Latvia

The European Renovation Wave aims to at least double the annual energy renovation rate by 2030, especially promoting deep renovation. In order to achieve this goal, EU member states need to overcome the existing obstacles in the whole chain of the building renovation process by using certain policy measures and finance instruments. According to the Ministry of Economics of Latvia, the current necessity is to renovate around 26 thousand multi-apartment buildings. Therefore, not only the problem of the lack of additional financing should be solved but also the pace of implementation should be significantly increased. This study starts with an overview of the main obstacles of the building renovation in Latvia and gives an insight into the main challenges in the achievement of the goal. The study includes the review of existing support programmes and financing schemes, designed to improve the energy efficiency of multi-apartment buildings in Latvia. Moreover, the study analyses the existing support mechanisms in Latvia, and reviews different policy measures for regulatory requirements, fiscal and economic incentives and information campaigns in Europe. In addition, the study proposes an assessment of the availability of financial support for the low-income households, and analyses energy poverty solving tools. As a result, the study defines basic principles and examines the solutions for energy efficient renovation in Latvia – including tax incentives, regulatory framework, development of financial schemes and models for acceleration of building renovation. The solutions have been evaluated considering country specific economic, technical, and social aspects, and defined as a set of recommendations for decision makers.

Renovation Wave in Europe: Low-Carbon Design for the Refurbishment of Social Housing in Southern Italy

The public housing stock, called social housing, in Italy was developed between the 1950s and the 1980s. As of today, the first residential developments are almost nearing their end-of-life age and are in need of urgent and intensive renovation. The European Commission, with the Renovation Wave, has set a goal of doubling the rate of building renovation over the next 10 years, reducing emissions, improving energy performance, and promoting decarburization. Renovation interventions, including structural, functional, energy, and plant upgrading interventions, etc., are to be preferred over integral demolition and reconstruction interventions, which have significant repercussions in terms of managerial and social discomfort. The case studies examined concern renovation interventions aimed at energy efficiency, functional adaptation of housing, as well as façade restyling. The design variants analyzed were evaluated in terms of CO2e emissions, according to life cycle inventory (LCI) and Environmental Product Declaration (EPD) approaches. This approach has a twofold purpose: to propose design guidelines, with low CO2e emissions, through hypotheses of variants in the case studies, and to propose, to the economic operators, economically advantageous bidding scenarios in the procurement process.

Deep energy efficiency renovation of Germany’s residential buildings: is this as economically viable as Germany’s policymakers and popular promoters often claim?

Germany needs to steeply increase the rate of deep energy-efficiency renovation of its old buildings, to meet climate goals. The government has long maintained that deep renovation to a specified “minimum” energy efficiency standard is economically viable: that the costs are paid back, through energy savings, over the technical lifetime of the energy-efficiency measures. Many private and public organisations support and promulgate this view. It accords with a stream of academic literature which suggests that the under-adoption of energy efficiency measures is a paradox indicating market failures and economically irrational behaviour by property owners. This paper offers cost–benefit analyses of 44 case study scenarios to test whether deep renovation in Germany pays back in monetary terms. These include both specific buildings and Germany-wide averages of classes of buildings. It uses current construction, finance and energy costs, and takes account of inflation, discount rates and opportunity costs. None of the scenarios are economically viable in monetary terms, and the average payback after 25 years is around 22.5%. Sensitivity analyses suggest payback would only be achieved using improbable parameter values. Energy-efficiency renovation is necessary but promoting it needs to take account of these realities.

Building renovation Roadmapping: an automated methodology framework for energy efficiency improvement and sustainable renovation planning

ABSTRACT A significant portion of energy consumption currently derives from the building stock, which has harms both the environment and the living standard of occupants, while at the European level, the renovation rate of the current building stock remains low. This study presents a methodology for automated retrofitting scenarios in buildings that enhances user awareness through meaningful visualisations and fosters collaboration of renovation professionals with interoperable software solutions. Commercial design software (Autodesk Revit, Graphisoft ArchiCad) generates the Building Information Model (BIM) in the Industry Foundation Class (IFC) format. IFCs are processed by a parsing tool, which translates IFC files into a comprehensible data model. The proposed framework initially examines the asset-based elements and calculates as-designed energy consumption by extracting information from the produced data model. Based on conducted calculations, the proposed schema identifies mandatory renovation actions and generates scenarios for a variety of examined categories. The final output consists of a renovation roadmap that prioritises changes with the greatest impact based on the demand of the building’s stakeholders. The proposed methodology provides a promising approach to help building owners and stakeholders with the identification and prioritisation of energy-saving retrofitting actions, thus contributing to the achievement of energy efficiency goals.

Identifying future district heating potentials in Germany: a study using empirical insights and distribution cost analysis

District heating will play an important role in the transition towards climate-neutral heating. Various studies on modelling the energy system show that district heating and the related expansion of the networks can have different levels of importance. A main reason is that the costs for distribution grid expansion are not well or not at all considered and empirical evidence for a threshold for cost-effective distribution costs is missing in such studies. In this paper, we aim to improve empirical evidence allowing to improve the representation of future district heating expansion in energy systems models. For that, the current status of district heating is analysed in high spatial resolution for Germany. The results show that with the currently accepted average costs, a large range of the possible future market share of district heating for buildings between 17 - 52% is possible by 2050, with the parameters of the connection rate and the renovation rate of the building stock. We conclude that the district heating share could be increased by the factor of 2 to 5 in the future, proving the importance of climate-neutral district heating in the transition.

A distributed collaborative platform for multi-stakeholder multi-level management of renovation projects

To meet European energy-saving and decarbonisation goals, the annual renovation rate of buildings requires to be at least twice its current level; an aspiration to which the use of innovative and automated solutions can contribute. This paper presents such a solution, the RINNO Retrofitting Manager (RRM) which is part of a large, ambitious research and development project (RINNO) that aims to provide an augmented intelligence-enabled framework for deep, energy-focused retrofitting of buildings. The RRM uses web-service technologies to rationalise the retrofitting process and optimise the delivery of renovation works, while making data readily accessible through an integrated set of role-based user interfaces. The RRM is designed and developed as an open distributed system, that is extensible and portable, by implementing a collaborative research and development approach. The RRM platform implements a multi-level, multi-stakeholder planning approach. It addresses the dearth, insufficiency, and isolation of existing renovation tools by enhancing collaboration, interoperability, and data security, and avoiding information loss and misunderstanding. Employing the Unified Theory of Acceptance and Use of Technology (UTAUT) model, tests conducted with users from independent construction organisations confirmed the RRM's satisfactory performance, ease of deployment, and overall suitability for the management of renovation projects. While this research provides a free collaborative platform for managing renovation projects that can be used by all building retrofit stakeholders in Europe, it also introduces a set of web-services that can be easily reused by third-party developers and integrated into their software tools.

Subsidies or green taxes? Evaluating the distributional effects of housing renovation policies among Dutch households

Despite persistent housing affordability issues, energy policy and housing renovation are usually investigated separately from housing costs other than energy. Researchers have examined the financial viability of renovation attending to building conditions and the socio-economic characteristics of their occupants. However, the distributional impacts of renovation incentives and the potential of fiscal policy to redistribute housing costs remain understudied. Dutch fiscal policy, favouring homeownership, offers a relevant context to evaluate how property taxation can boost renovation rates. The novelty of this paper resides in investigating the impact of two policies, the current direct subsidy and a proposal for a green tax, on both the financial viability of renovation and the subsequent distribution of housing costs. The proposed green tax combines energy efficiency and taxation of property revenue. We employ a model considering marginal costs of housing renovation, obtained from a government dataset, and marginal benefits, drawn from a hedonic regression. We assess the distributional impacts of different policy scenarios by examining changes in user costs across income deciles. Our findings indicate that existing renovation subsidies exacerbate the regressive distributional impacts resulting from the current housing taxation system in the Netherlands. Introducing energy-efficiency-linked property taxation can make homeownership fiscality less regressive while incentivising housing renovation. Ultimately, this study highlights the importance of incorporating housing affordability as a fundamental element in renovation policies to balance environmental and distributional objectives.

Building renovation plan - introducing energy and cost into the managerial perspectives: A case study

Implementing more stringent energy requirements for public buildings has the potential to expedite the renovation rate of building stocks. While many studies have explored optimal renovation solutions to reduce energy consumption and cost, few have established a comprehensive building portfolio strategy from the perspective of portfolio managers. This study addresses this gap by developing a framework that empowers building portfolio managers to make informed decisions regarding building renovations. Through an in-depth case study, the current workflow for determining renovation needs, which involves analyzing maintenance requirements, building usability, and adaptability, is enhanced by incorporating a cost-optimal renovation framework. The study utilizes building simulations and life cycle cost analysis to assess the energy reduction potential of six school buildings requiring renovation. The results demonstrate a potential for energy use reduction, ranging from 11% to 44% when incorporating energy-saving measures into the renovations. Cost-optimal solutions are achieved for two buildings, resulting in energy reduction ranging from 31% to 36% and cost reduction ranging from 7% to 8%. The primary contribution of this research is developing a framework that reduces ambiguities of which buildings a portfolio manager should prioritize for renovation. By identifying current performance and improvement potential, the framework enables benchmarking against energy performance classes, aiding in strategic decision-making. However, the study also underscores the complexities of assessing a diverse building stock from a bottom-up perspective. Barriers such as obtaining high-quality data, scaling assessments, time constraints, and knowledge transfer are problems to overcome. Additionally, evaluating various building typologies with diverse characteristics, including those with legal restrictions due to heritage status, presents unique challenges. Future research directions should focus on expanding the framework to incorporate a life cycle assessment perspective. This approach will ensure a comprehensive building portfolio strategy that mitigates the risk of sub-optimal solutions.

Application of the Typology Approach for Energy Renovation Planning of Public Buildings’ Stocks at the Local Level: A Case Study in Greece

According to the latest energy efficiency European directive (EED 2023/1791/EU), the expected energy renovation rate of at least 3% of the buildings’ floor area each year towards nearly zero-energy buildings (nZEBs) is extended to include public buildings not only of the central government (as per the first EED 2012/27/EU) but also of regional and local authorities. This poses a great challenge, especially for Municipalities that often manage large building stocks with high energy demands. In response to this challenge, this paper presents the application of the so-called “typology approach” for conducting public buildings’ energy renovation plans at the local level. A computational survey is initially introduced to decide the optimal set of building-stock clustering criteria among all possible combinations, involving the minimization of the RMSE index regarding the primary energy consumption of each building. For a representative building from each identified typology, the key performance indicators (KPIs) are computed for alternative energy-upgrading scenarios. Exploiting the IMPULSE Interreg-MED project tools, the KPIs from each representative building are at first extrapolated to all buildings of the examined stock and, finally, a gradual energy renovation plan is automatically produced based on user-defined decision parameters including the required annual renovation rate. The methodology is applied for the case of the Municipality of Hersonissos in Greece. For the specific 44-buildings’ stock it was found that the optimal clustering set included four criteria, building use, construction year, heating, and a cooling system, leading to 15 building typologies. Finally, assuming a 7% renovation rate per year, a 12-year gradual renovation (nZEB transformation) plan is obtained foreseeing an 85% CO2 emissions’ reduction.

Implementation of the Long-Term Energy Efficiency Program in Households in Latvia

Abstract Considering the trend towards climate neutrality and energy efficiency at the global level as well as the problem of high energy poverty at the national level, the issue of housing renovation was inevitable for Latvia in 2023. The main objective of the study is to analyse the situation in Latvia, its problematic aspects and opportunities for the government, as well as to propose possible methods for solving the problem of low rates of housing renovation in Latvia. The main methods used were PESTLE analysis to identify problems and cluster analysis to compare financial opportunities in each country. The main results of the study are the conclusion that the financial aspect of renovation in Latvia is at a satisfactory level and is not the main reason for the unpopularity of renovation, but the main problem is energy poverty. The main conclusion is that renovation in Latvia requires a new approach that can improve the energy efficiency situation in Latvia, and providing such a method in the form of building renovation based on private-public partnership is the possible approach.

ДОХОДЫ И ЖИЛИЩНЫЕ УСЛОВИЯ НАСЕЛЕНИЯ КАК ФАКТОРЫ ВОЗДЕЙСТВИЯ НА ДЕМОГРАФИЮ В РЕГИОНАХ

The issues of choosing indicators of well-being, level, and quality of life of the population in the scientific community often cause well-founded discussions. The authors of the presented work believe that one of the most significant indicators, considering the availability of information and a fairly broad interpretation, is life expectancy in the territory. This is since this category reflects the general level of development of the region under study, i.e. describes the health, social, environmen-tal, demographic, political and other spheres now, and considers the prospects of functioning. This indicator is also important for the economy, since it is considered in long-term development pro-grams, directly affects the labor market and the activities of social services. In this regard, the basic indicator in this work is life expectancy. The subjects of the Central Federal District (CFD) are the object of monitoring. In the presented article, based on the identified dependencies for the period from 2000 to 2021, the relationship between life expectancy and infrastructural factors is substanti-ated using the example of the regions of the Central Federal District. The latter have found expres-sion in the real incomes of the population and the number of families in need of a change of housing. From the authors' point of view, the situation is aggravated by insufficient rates of housing renova-tion and insignificant income growth. The studied and identified relationships and dependencies can be applied within the framework of national and regional development, as well as draw the attention of representatives of territorial administrations to the level of satisfaction with housing stock, and the population to issues related to financial capital management.

Comparison of solar district heating and renovation of buildings as measures for decarbonization of heat supply in rural areas

In this study two different decarbonization strategies for rural heat supply are compared on the example of 180 buildings located in a small village in Germany with about 860 inhabitants and typically mainly old buildings, partly in half-timbered construction. The comparison shows that erection of a solar district heating system with solar fraction of about 67 % leads to similar heating costs as an energy efficient renovation followed by installation of decentralized air source heat pumps for most of the buildings. Both concepts aim to achieve a heat supply that is free from the local use of fossil fuels. While the solar district heating system can probably be realized within a few years and therefore achieves the full CO2 savings promptly, this would take decades for the implementation of energy efficient renovation and heat pumps due to low renovation rate. Reaching climate-neutrality for the heat supply could thus be accelerated significantly by the construction of a solar district heating system. Moreover, the two decarbonization approaches do not appear to be fundamentally mutually exclusive: subsequent steady renovation of connected buildings will either increase solar share in heat supply or enable connection of new consumers at similar solar coverage rate. However, it should be also noted that with solar district heating alone, not always the same thermal comfort as with reinforced building renovation is achieved.

Strategies and Actions for Achieving Carbon Neutrality in Portuguese Residential Buildings by 2050

As a crucial step in addressing the climate emergency and enhancing energy security, the European Union has set ambitious targets to decarbonise its economy by 2050. While the building sector plays a pivotal role in this transition, being accountable for 36% of the EU’s total carbon emissions, it shows a renovation rate below 1% per year, which is clearly insufficient. To address this challenge, this study uses the cost-optimal methodology from private and social perspectives to assess the cost-effectiveness and environmental impact of five renovation packages with passive and active solutions currently available on the Portuguese market. The results demonstrated that from both perspectives, optimal combinations of market solutions were generally cost-effective and could lead to a 90–99% reduction in energy needs and even to zero carbon levels. Nevertheless, beyond cost-effectiveness, consideration of co-benefits, e.g., social and health improvements, is also crucial, requiring government action. To drive these essential changes, effective policy measures are imperative. Recommendations encompass robust regulatory frameworks, financial support mechanisms, knowledge dissemination, and a shift towards broader-scale renovation. For carbon reduction to be economically attractive, fostering innovative business models and leveraging legal instruments to tackle complex scenarios are needed.

Determine the heat demand of existing buildings with machine learning

The renovation rate of existing buildings plays a major role in the Swiss Energy Strategy 2050+. To increase this rate, there must be a simple and cost-effective method to determine the heat demand of existing buildings. In this paper, the generation of such a method, based on the Swiss cantonal building energy certificate (GEAK) database with the help of machine learning (ML), is studied. The aim of the project was to develop a ML model which allows the heat demand of existing buildings to be determined quickly with a minimal set of parameters. The comparison of the GEAK building envelope class for single family houses calculated with the new ML model and the original GEAK classes shows that approximately 62 % have the same class, 32 % differ by one class and 6 % by two classes. The ML model is a good starting point for further refinements and developments.

Public buildings: Life-cycle GHG emission scenarios and reduction trajectories by 2050

Responsible for 37% of global greenhouse gas (GHG) emissions, the construction and operation of buildings involves substantial potential to mitigate climate change. Although they represent only a small part of the building stock, publicly-owned buildings can lead by example and stimulate emission reductions through public procurement processes that are aligned with existing climate goals. In this paper, possible GHG emission reduction pathways for public office buildings in Austria are explored. A building stock model for Austria’s publicly-owned office buildings is developed, which projects operational and embodied GHG emissions from new construction, renovation and demolition until 2050. Findings show that phasing out fossil fuel use in building operations by 2050 enables GHG emission pathways that are compatible with the Carbon Law but still exceed Austria’s available carbon budget for public office buildings. A higher renovation rate can facilitate the fossil fuel phase-out by reducing energy demand. Embodied GHG emissions are becoming increasingly important and the main source of GHG emissions when phasing out fossil fuels in space heating. More research and policies are therefore needed to accelerate reductions of embodied GHG emissions towards net zero.

Assessment of Subsidization Strategies for Multi-Objective Optimization of Energy Efficiency Measures for Building Renovation at District Scale

In recent years, public authorities around the world have used incentive strategies to encourage the renovation of the existing building stock to meet the set carbon neutrality targets. However, the design of the incentives typically does not consider that the subsidized energy efficiency measures should result in robust long-term improvements with respect to various objectives. Moreover, building energy retrofit analyses are commonly conducted at the individual building level rather than at urban scale, which could instead significantly accelerate the renovation rate. In this context, the current research aims to combine these different factors to support the design of building energy retrofit programs. We developed 21 subsidization strategies and their impact was evaluated on a parametric multi-objective optimization with respect to energy, economic, and environmental performance for a district located in Bolzano, Northern Italy. The optimization was performed considering a set of energy efficiency measures, pertaining to building envelope, climate change, economic scenarios, and two types of energy supplies. The results showed that (1) the impact of climate change is limited for the climate of Bolzano; (2) the type of energy supply strongly influences the economic feasibility of the retrofit investments; (3) when the investment is profitable, the optimal solutions include those measures with the largest impact on energy efficiency; and (4) subsidization strategies modify the number and composition of the Pareto solutions.

Urban Building Energy Modelling for the Renovation Wave: A Bespoke Approach Based on EPC Databases

In 2020, domestic buildings represented 27% of the energy consumption in the European Union. The EC Renovation Wave concluded that the annual renovation rate should be doubled, from 1% to 2%, over the next decade in order to meet the 2030 energy efficiency targets. Funding programs are being implemented at national and European levels to accelerate this process. These aim to prioritize large-scale interventions and the most efficient energy conservation measures by including strict performance targets as eligibility conditions. However, these programs are coordinated by local authorities, and they struggle to generate reliable energy estimates for large areas, not least predict potential savings at both aggregated and individual levels. This paper presents a bespoke energy retrofit analysis methodology based on urban building energy modelling, which is defined and calibrated with the Energy Performance Certificate Database. We apply this method to the case study Barrio das Flores. The model adopts a hybrid approach, defining and simulating representative typologies to extrapolate the results to the whole district according to each dwelling’s specific parameters. This methodology will be used to predict the potential energy savings in the study area and support the grant application for the funding renovation program.