Deep Renovation Research Articles

Hybrid timber-based systems for low-carbon, deep renovation of aged buildings: Three exemplary buildings in the Republic of Korea

The ageing of buildings is associated with their degradation. By the end of a building's operative life, two solutions are provided: demolition and new construction, or renovation. New construction can cause higher greenhouse gas equivalent emissions than renovations, related to higher demand for building materials, processes, and waste management. Conversely, building renovation requires greater effort in planning and implementation. Moreover, when improperly planned, renovation might ensure only limited improvements in building performance. This study presents three renovation systems based on hybrid timber technologies for three common case-study building types in the Republic of Korea: apartment, low-rise residential, and mixed-use (industrial–commercial). Following analysis of the current regulations for building component performance in Korea, three modular building envelope renovation systems have been developed: (i) cross-laminated timber, (ii) glue-laminated frame with integrated timber stud panels, and (iii) steel frame with integrated timber stud walls. The development of the three systems focuses on designing modular self-supporting components that allow both horizontal and vertical extension, and the structural support of occupied buildings. The hybrid timber-based construction provides a low-carbon alternative to demolition and new construction, helping to solve spatial constraints to renovation determined by the high urban density of Korean cities.

Efficient District Heating in a Decarbonisation Perspective: A Case Study in Italy

The European and national regulations in the decarbonisation path towards 2050 promote district heating in achieving the goals of efficiency, energy sustainability, use of renewables, and reduction of fossil fuel use. Improved management and optimisation, use of RES, and waste heat/cold sources decrease the overall demand for primary energy, a condition that is further supported by building renovations and new construction of under (almost) zero energy buildings, with a foreseeable decrease in the temperature of domestic heating systems. Models for the simulation of efficient thermal networks were implemented and described in this paper, together with results from a real case study in Italy, i.e., University Campus of Parma. Activities include the creation and validation of calculation codes and specific models in the Modelica language (Dymola software), aimed at investigating stationary regimes and dynamic behaviour as well. An indirect heat exchange substation was coupled with a resistive-capacitive model, which describes the building behaviour and the thermal exchanges by the use of thermos-physical parameters. To optimise indoor comfort conditions and minimise consumption, dynamic simulations were carried out for different operating sets: modulating the supply temperature in the plant depending on external conditions (Scenario 4) decreases the supplied thermal energy (−2.34%) and heat losses (−8.91%), even if a lower temperature level results in higher electricity consumption for pumping (+12.96%), the total energy consumption is reduced by 1.41%. A simulation of the entire heating season was performed for the optimised scenario, combining benefits from turning off the supply in the case of no thermal demand (Scenario 3) and from the modulation of the supply temperature (Scenario 4), resulting in lower energy consumption (the thermal energy supplied by the power plant −3.54%, pumping +7.76%), operating costs (−2.40), and emissions (−3.02%). The energy balance ex-ante and ex-post deep renovation in a single user was then assessed, showing how lowering the network operating temperature at 55 °C decreases the supplied thermal energy (−22.38%) and heat losses (−22.11%) with a slightly higher pumping consumption (+3.28%), while maintaining good comfort conditions. These promising results are useful for evaluating the application of low-temperature operations to the existing district heating networks, especially for large interventions of building renovation, and confirm their potential contribution to the energy efficiency targets.

In-plane capacity of existing post-WWII beam-and-clay block floor systems

A growing attention has been paid to the deep renovation of RC buildings, particularly focusing on their structural vulnerability and on the development of retrofit strategies; however, the issue of the in-plane diaphragm action and the capacity of existing floors has rarely been addressed. Although floor capacity does not seem critical for the seismic capacity of existing structures, commonly affected by greater vulnerabilities, it may become critical when an additional lateral force resisting system is introduced. This paper investigates the in-plane capacity of beam and hollow-clay-block floor system, typical of the European post-WWII RC buildings. Considering the diaphragm action as associated with an in-plane tied-arch mechanism developing within the floor thickness, the main failure mechanisms are discussed, and some simplified equations are provided to preliminary estimate the maximum capacity of floors. Experimental and numerical analyses are than carried out to validate the simplified analytical model. The relevant influence of possible staircase openings on the in-plane load paths and on diaphragm flexibility and capacity are also considered. Finally, the influence of the floor capacity on the seismic vulnerability assessment and in the conceptual design of a seismic retrofit intervention is discussed. This preliminary study shows that only some of the beam-and-block floor systems have a reliable in-plane capacity, while other typologies cannot serve as floor diaphragms. When the diaphragm action can be relied upon, the diaphragms often exhibit a fairly stiff behaviour up to a brittle failure, which is commonly associated with the ultimate capacity at the tied-arch supports.

De-Risking the Energy Efficient Renovation of Commercial Office Buildings through Technical-Financial Risk Assessment

Energy efficiency in the building sector plays a key role in supporting European and global commitments against the current climate crisis. A massive adoption of deep renovation measures would allow a global reduction of energy need up to 36%, based on estimations. However, the market for building renovation is still limited, due to uncertainties associated with risk evaluation. This paper aims to suggest a method to evaluate the financial impacts of technical risks related to energy efficiency investments. Key performance indicators (KPIs) necessary to evaluate the investment risk associated with energy renovation have been defined based on an analysis of the correlation between technical and financial risks, and their originating factors or root causes. The evaluation has been carried out thanks to the EEnvest tool: a web-based search and match platform, developed within the EEnvest collaborative research project funded by the European Commission (EC). This evaluation methodology has then been applied to a case study, an office building located in Rome, for whom an energy efficient renovation project was already in place to reduce energy needs. The investment risk of the renovation project is calculated for two different scenarios: with and without risk mitigation measures being applied during the design, installation and operation phases. The results show the different technical and financial risk trends of these two scenarios, highlighting the benefits obtained by the implementation of mitigation measures.

Application of the Renewable Energy Sources at District Scale—A Case Study of the Suburban Area

The protection of the natural environment and countering global warming are crucial worldwide issues. The residential sector has a significant impact on overall energy consumption and associated greenhouse gas emissions. Therefore, it is extremely important to focus on all of the activities that can result in more energy efficient and sustainable city scale areas, preventing global warming. The highest improvement in the energy efficiency of existing buildings is possible by combining their deep refurbishment and the use of renewable energy sources (RES), where solar energy appears to be the best for application in buildings. Modernizations that provide full electrification seem to be a trend towards providing modern, energy efficient and environmentally friendly, smart buildings. Moreover, switching from an analysis at the single building level to the district scale allows us to develop more sustainable neighborhoods, following the urban energy modelling (UEM) paradigm. Then, it is possible to use the energy cluster (EC) concept, focusing on energy-, environmental- and economic-related aspects of an examined region. In this paper, an actual Polish suburban district is examined using the home-developed TEAC software. The software is briefly described and compared with other computer codes applied for UEM. In this study, the examined suburban area is modernized, assuming buildings’ deep retrofitting, the application of RES and energy storage systems, as well as usage of smart metering techniques. The proposed modernizations assumed full electrification of the cluster. Moreover, the examined scenarios show potential electricity savings up to approximately 60%, as well as GHG emission reduction by 90% on average. It is demonstrated that the proposed approach is a valid method to estimate various energy- and environment-related issues of modernization for actual residential clusters.

ENERGY RENOVATION OF RESIDENTIAL BUILDING ENVELOPE USING ORGANIC MATERIALS FOR THE LEVEL OF COST-OPTIMAL IMPROVEMENT/ UPGRADE IN BOSNIA-HERZEGOVINA AND SERBIA

<jats:p>Towards building renovation strategies, the research is led by a very deep renovation of residential buildings, which would reduce the energy need for heating below 40 kWh/m2 or create energy savings 60%. The renovation of the building envelope, guided by organic materials (such as wood), which is in the one of key principles in the New Renovation Wave Strategy of the European Union from October 2020, is presented in the paper. Energy saving made by renovating building envelopes using wooden modular systems, are shown through characteristic building on which their application is adequate. Case study from Bosnia and Herzegovina indicate possible energy savings of 81% for residential type Multi-family houses – MFH from period 1961-1970.</jats:p>

Next-generation energy performance certificates: End-user needs and expectations

Implementation of Energy Performance Certificates (EPCs) varies significantly across EU Member States in terms of scope and available information, resulting in limited reliability, compliance, market penetration or user acceptance. This paper, therefore, investigates the end-user perspectives towards future development of EPCs to support EPC schemes in the EU. Without a full insight into what end-user's demand and need, it is impossible to make accurate assessments of how EPCs will become key drivers for deep renovation, environmental impact reduction and healthy buildings. A survey with 2563 end-users of EPCs was conducted on ten innovative EPC features in five EU countries (Denmark, Greece, Portugal, Poland, and Romania), including building owners and occupants to learn about their needs and expectations. The results highlight that the features are viewed most positively if homeowners or tenants are energy conscious and energy performance is an important aspect when buying or renting property. Furthermore, the insights gathered through the analysis of the survey provide suggestions for public authorities on how EPC methodologies could be customised to support the advancement of EPC schemes. Further work includes testing and validation of methodologies that are being developed in different EU Member States as a part of the H2020 X-tendo project.

The MedZEB Protocol: a Powerful Tool for Fostering Deep Renovation in the Mediterranean Area

The market uptake of deep energy retrofitting represents a significant challenge in the EU Mediterranean countries, due to specific bottlenecks which lead to a low level of trust. In order to meet these challenges, the H2020 HAPPEN Project has developed the MedZEB Protocol, a tool conceived for enhancing the quality management of the overall renovation process, and tailored for the residential sector of the Mediterranean Area. The Protocol is based on a holistic approach aimed at maximizing the added value generated by retrofitting interventions, as well as on standardized procedures which allow fostering a deeper integration among the actors involved, relying on higher technical expertise and enhancing the market transparency. The paper describes the main features of the MedZEB Protocol, its architecture, the indicators and the actors/procedures involved in each phase. The results of a feasibility analysis are also presented, which show the sustainability of the Protocol adoption, thus highlighting its potential role as a reference framework for fostering deep energy retrofitting in the Mediterranean area.

Circularity concepts for offsite prefabricated energy renovation of apartment buildings

Deep energy renovation includes the realisation of the full potential of energy performance. A circular deep renovation, which contributes to a circular built environment, is based on 100% life cycle renewable energy, and all materials used within the system boundaries are part of infinite technical or biological cycles with the lowest quality loss as possible. In the current study, the circularity potential was assessed for deep energy renovation from different aspects: circularity of materials, building component and building structure. Careful selection of materials as well as connection, position and disassembly possibilities are needed to increase the degree of circularity. This shows a good possibility to increase energy performance by using circularity principles. The window glass circularity analyse showed that, at best, the thermal transmittance of a new circular product can be more than three times lower than the original. The circular use of materials, components, and structures pose new challenges for the building physic design of building envelope structures.

The e-SAFE energy and seismic renovation solutions for the European building stock: main features and requirements

In the framework of the ongoing four-year EU-funded innovation project called e-SAFE (“Energy and seismic affordable renovation solutions”), several solutions for the energy and seismic deep renovation of reinforced concrete (RC) framed buildings in the European countries are going to be developed and demonstrated. These solutions address both the energy performance of the building envelope and the heating and cooling of the indoor spaces, and aim to be prefabricated, customizable, low-disruptive and sustainable in order to boost the decarbonisation of the largely inefficient European building stock. This paper presents the main features of the e-SAFE solutions and the results of a preliminary analysis to verify their effectiveness and compliance with European legislation and standards. The outcomes will be useful for the design and demonstration stage, by identifying issues that need to be tackled.

Beyond Operational Energy Efficiency: A Balanced Sustainability Index from a Life Cycle Consideration

Most deep energy renovation projects focus only on an operating energy reduction and disregard the added embodied energy derived from adding insulation, window/door replacement, and mechanical system replacement or upgrades. It is important to study and address the balance and trade-offs between reduced operating energy and added embodied energy from a whole life cycle perspective to reduce the overall building carbon footprint. However, the added embodied energy and related environmental impact have not been studied extensively. In response to this need, this paper proposes a holistic sustainability index that balances the trade-off between reduced operating energy and added embodied energy. Eight case projects are used to validate the proposed method and calculation. The findings demonstrate that using a balanced sustainability index can reveal results different from a conventional operating energy-centric approach: (a) operating energy savings can be offset by the embodied energy gain, (b) the operating energy savings do not always result in a life cycle emissions reduction, and (c) the sustainability index can vary depending on the priorities the decision makers give to operating carbon, embodied carbon, and operating cost. Overall, the proposed sustainability score can provide us with a more comprehensive understanding of how sustainable the renovation works are from a life cycle carbon emissions perspective, providing a more robust estimation of global warming potential related to building renovation.

Integrated Deep Renovation of Existing Buildings with Prefabricated Shell Exoskeleton

The European goal to reach carbon neutrality in 2050 has further put the focus on the construction sector, which is responsible for great impacts on the environment, and new sustainable solutions to renovate the existing building stock are currently under development. In this paper, the AdESA (Adeguamento Energetico Sismico ed Architettonico, in Italian) system, a holistic retrofit technique for the integrated renovation of the existing buildings, is presented. The system was developed by a consortium of enterprises and universities and was applied to a pilot building. The system consists of a dry, modular and flexible shell exoskeleton technique that implements different layers depending on the building retrofit needs (cross-laminated timber (CLT) panels for the structural retrofit, thermal insulation panels for the energy efficiency amelioration, and claddings for the architectural restyling). In order to foster actual sustainability, the solution contextually targets eco-efficiency, safety and resilience. To this end, the system not only couples the structural and energy interventions to reduce the operating costs, but it is also conceived in compliance with life cycle thinking (LCT) principles to reduce impacts throughout the remaining building service life (from retrofit time to the end of its life). The system is designed to be easily mountable and demountable to allow for the reuse/recycling of its components at the end of life by adopting macro-prefabricated dry components and standardized connections, to reduce damage caused by earthquakes by reducing the allowed inter-story drift, and by amassing the possible damage into sacrificial replaceable elements. The paper describes the AdESA system from a multidisciplinary perspective and its effective application for the deep renovation of an existing gymnasium hall.

Deep renovation of an old single-family house including application of an water repellent agent – a case story

The 145 year old rural case building presented in this paper has undergone a deep renovation including internal insulation of the external walls to reduce the heat loss and improve the indoor thermal comfort. The internal insulation was a PUR-based insulation with channels of calcium silicate, experiencing to some extent capillary active behaviour. Sensors were installed between the existing wall and the internal insulation to monitor the development of hygrothermal conditions. The external façade was later hydrophobized with a water repellent agent to minimize the wind driven rain load. Measurements show that it takes time to get rid of the built-in moisture due to the application of internal insulation, however the moisture content expressed in relative humidity is slowly decreasing, although still high about two years after hydrophobizing the wall. Simulations show that the order of hydrophobizing the wall and applying internal insulation is important to promote drying of the wall.

Making deep renovation of historic buildings happen learnings from the Historic Buildings Energy Retrofit Atlas

The energy refurbishment of historic buildings is necessary for many reasons, for the preservation and continued use of the buildings themselves, but also to achieve a very much needed reduction of GHG emissions. Good examples of such refurbishments show that the conflicting demands between respecting and protecting the heritage significance and achieving high levels of energy efficiency can be met. The case studies documented in the Historic Building Atlas HiBERatlas are used to examine which influencing factors are responsible for the success. This database is one of the main outcomes of the research projects Interreg AS ATLAS and IEA SHC Task 59 to provide a solid knowledge base on deep renovation of historic buildings and includes so far a broad range of about 50 different case studies published. The case studies presented here as examples were carried out under different framework conditions: as part of a research project, with public financial support or with a committed and experienced planning team operating in an integrated design process. It will be assessed how professional preliminary research, ambitious objectives, and the access to technical solutions can affect the results. Finally, the paper will highlight findings of post occupancy evaluations and lessons learned.

What is the optimal robust environmental and cost-effective solution for building renovation? Not the usual one

Buildings are responsible for a large share of CO2 emissions in the world. Building renovation is crucial to decrease the environmental impact and meet the United Nations climate action goals. However, due to buildings’ long service lives, there are many uncertainties that might cause a deviation in the results of a predicted retrofit outcome. In this paper, we determine climate-friendly and cost-effective renovation scenarios for two typical buildings with low and high energy performance in Switzerland using a methodology of robust optmization. First, we create an integrated model for life cycle assessment (LCA) and life cycle cost analysis (LCCA). Second, we define possible renovation measures and possible levels of renovation. Third, we identify and describe the uncertain parameters related to the production, replacement and dismantling of building elements as well as the operational energy use in LCCA and LCA. Afterwards, we carry out a robust multi-objective optimization to identify optimal renovation solutions. The results show that the replacement of the heating system in the building retrofit process is crucial to decrease the environmental impact. They also show that for a building with already good energy performance, the investments are not paid off by the operational savings. The optimal solution for the building with low energy performance includes the building envelope renovation in combination with the heating system replacement. For both buildings, the optimal robust cost-effective and climate-friendly solution is different from the deep renovation practice promoted to decrease the energy consumption of a building.

Hygrothermal Analysis of CLT-Based Retrofit Strategy of Existing Wall Assemblies According to EN 13788 Standard

In the framework of the ongoing EU-funded innovation project called e-SAFE (energy and Seismic Affordable rEnovation solutions), several solutions for the energy and seismic deep renovation of reinforced-concrete (RC) framed buildings in the EU countries are going to be developed and demonstrated. One of these solutions makes use of cross laminated timber (CLT) panels connected to the existing RC frame through specifically designed dampers to increase the seismic and energy performances of the existing envelope. This paper aims to preliminary assess the hygrothermal performance of such CLT panels when applied to various typical wall structures under different climate conditions in Italy through numerical simulations carried out according to the EN 13788 Standard and considering various indoor vapor production classes. Results show that the most problematic existing wall structures are uninsulated concrete walls, for which a risk of surface condensation and mold growth is predicted in all climate zones because of their low thermal resistance (U-value of 3.55 W·m-2·K-1), followed by uninsulated solid brick walls (U-value of 1.81 W·m-2·K-1). The application of CLT panels is found to not only significantly improve the thermal behaviour of the walls, but also to eliminate any surface and interstitial condensation issues in all climate zones.

The SUNShINE platform: efficiency, transparency and standardization in the dEEP renovation process of multi-family buildings

The given research paper addresses the need for a digital platform to build efficiency and transparency within the energy efficient building renovation sector. The SUNShINE platform is presented as an innovative solution to tackle the obstacles during the complex building renovation process by ensuring efficiency, transparency and standardization. A variety of stakeholders can effectively communicate during the multiple stages of the process with the help of this platform, which makes it a core tool of deep building renovation projects. Costs are cut due to digitalization of the process and we standardize documentation and resources. Currently, it is being tested in six different countries. The SUNShINe platform was developed as part of the EU-funded projects H2020 SUNShINE, H2020 Accelerate SUNShINE, and H2020 FinEERGO-DOM.

Evaluation of Sustainable Energy Development Progress in EU Member States in the Context of Building Renovation

The main goal of setting energy efficiency priorities is to find ways to reduce energy consumption without harming consumers and the environment. The renovation of buildings can be considered one of the main aspects of energy efficiency in the European Union (EU). In the EU, only 5% of the renovation projects have been able to yield energy-saving at the deep renovation level. No other study has thus far ranked the EU member states according to achieved results in terms of increased usage in renewable sources, a decrease in energy usage and import, and reduction in harmful gas emissions due to energy usage. The main purpose of this article is to perform a comparative analysis of EU economies according to selected indicators related to the usage of renewable resources, energy efficiency, and emissions of harmful gasses as a result of energy usage. The methodological contribution of our study is related to developing a complex and robust research method for investment efficiency assessment allowing the study of three groups of indicators related to the usage of renewable energy sources, energy efficiency, and ecological aspects of energy. It was based on the PROMETHEE II method and allows testing it in other time periods, as well as modifying it for research purposes. The EU member states were categorized by such criteria as energy from renewables and biofuels, final energy consumption from renewables and biofuels, gross electricity generation from renewables and biofuels and import dependency, and usage of renewables and biofuels for heating and cooling. The results of energy per unit of Gross Domestic Product (GDP), Greenhouse gasses (GHG) emissions per million inhabitants (ECO2), energy per capita, the share of CO2 emissions from public electricity, and heat production from total CO2 emissions revealed that Latvia, Sweden, Portugal, Croatia, Austria, Lithuania, Romania, Denmark, and Finland are the nine most advanced countries in the area under consideration. In the group of the most advanced countries, energy consumption from renewables and biofuels is higher than the EU average.

Hygrothermal and Acoustic Performance of Two Innovative Envelope Renovation Solutions Developed in the e-SAFE Project

In order to reach the ambitious decarbonizing goals set by the European Union for 2030, deep renovation of the existing European building stock is a key issue. Within this context, the recently funded H2020 project “e-SAFE” is investigating market-ready wooden envelope renovation solutions for non-historic buildings, which encompass both energy and seismic improvement. The research carried out in the project aims at developing, testing and demonstrating these solutions on a real pilot. More specifically, this paper presents preliminary analyses to verify that the solutions satisfy the requisites set by the national regulations in force in most European countries, in terms of hygrothermal and acoustic performance. The analysis, carried out following relevant technical European Standards and based on calculations, considers different climate conditions and existing wall structures, selected amongst those most commonly adopted in Europe. The results show that the addition of a Cross Laminated Timber (CLT) layer with some wooden-based insulation on the outer side allows reaching very good thermal and acoustic performance. However, interstitial condensation may occur in cold climates under high indoor humidity values. This aspect deserves further investigation accounting for the transient behavior of the walls and all vapor transport mechanisms.

Machine Learning for the Improvement of Deep Renovation Building Projects Using As-Built BIM Models

In recent years, new technologies, such as Artificial Intelligence, are emerging to improve decision making based on learning. Their use applied to the Architectural, Engineering and Construction (AEC) sector, together with the increased use of Building Information Modeling (BIM) methodology in all phases of a building’s life cycle, is opening up a wide range of opportunities in the sector. At the same time, the need to reduce CO2 emissions in cities is focusing on the energy renovation of existing buildings, thus tackling one of the main causes of these emissions. This paper shows the potentials, constraints and viable solutions of the use of Machine Learning/Artificial Intelligence approaches at the design stage of deep renovation building projects using As-Built BIM models as input to improve the decision-making process towards the uptake of energy efficiency measures. First, existing databases on buildings pathologies have been studied. Second, a Machine Learning based algorithm has been designed as a prototype diagnosis tool. It determines the critical areas to be solved through deep renovation projects by analysing BIM data according to the Industry Foundation Classes (IFC4) standard and proposing the most convenient renovation alternative (based on a catalogue of Energy Conservation Measures). Finally, the proposed diagnosis tool has been applied to a reference test building for different locations. The comparison shows how significant differences appear in the results depending on the situation of the building and the regulatory requirements to which it must be subjected.