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The crest of the Renovation Wave: A toolkit to decarbonise the European building stock

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by Sudhanshu Verma (REVOLVE)

For Europe to reach its carbon-neutral goal by 2050, we will need to decarbonise the building sector and with millions of buildings to be renovated, retrofit technologies are going to play a crucial role in achieving this target. 


The European Commission launched the new Renovation Wave initiative under the EU Green Deal on 14 October 2020, aiming to rally popular support behind plans to cut polluting emissions from buildings and to reduce energy bills.


Three-quarters of Europe’s buildings are energy inefficient by modern standards, and many are heated using fossil fuels.


Europe’s building stock is responsible for more than a third of EU’s carbon dioxide emissions and bringing these buildings to near Zero-Emission Building (nZEB) levels is integral to the EU’s plans to be carbon neutral by 2050.


With the Renovation Wave initiative the EU took a bold approach to turn the current economic crisis into an opportunity by committing to double the EU’s annual rate of energy-related building renovations, which is currently just 1%, and in the process upgrade 35 million building units by 2030.


The Renovation Wave initiative will help Europe meets its target towards carbon neutrality and is estimated to create around 160,000 jobs in the construction sector.


Frans Timmermans, the Executive Vice-President of the European Green Deal, described the Renovation Wave as a strategy to achieve long-term climate objective with short- term economic results. He tweeted:


"I’m really excited about the #RenovationWave. Reducing energy consumption is necessary to tackle climate change. Renovation is a huge opportunity to embellish our cities and countrysides. And it can get people to work immediately. So it’s a long-term goal with short-term results."


While the opportunities related to the Renovation Wave are great, renovating 35 million building units in 10 years is a going to be a challenge, and the success of it would depend on numerous factors.


Yet, could prefabricated retrofit toolkit be part of the solution? If they can simplify and make the renovation process more holistic and quicker?


The HEART Toolkit


Renovation toolkits are integrated packages of prefabricated components, such as insulation/façades, heating, ventilation, and air-conditioning; (renewable) energy systems, user interfaces and digital solutions offered by a group of suppliers to ensure quicker, higher quality and more cost-effective home renovations.


One such solution is the HEART Toolkit. The HEART project is developing and testing several components that will facilitate renovation by using: a multifunctional prefabricated facade system, universal photovoltaic tiles, a high-efficiency water storage tank, direct-current smart fan coils and heat pumps, a multi-input/multi-output controller and a cloud-based platform to support decision-making and energy management phases.


HEART is a multifunctional toolkit dedicated to converting an existing building into a “Smart-Building” within which, tools and components such as, MIMO (Multi-Input Multi-Output) power converter, Cloud-Based Platform, Modular Thermal Façade, DC-Heat pump, Advanced Thermal Storage, Smart Fan Coil, photovoltaic (PV) Tiles and IoT Devices cooperate systematically to achieve high levels of energy efficiency and allow for an effective interface with the Smart Grid.


Toolkit installation and envelope technologies are structured as a function of their synergic action, practicality, installation time and non-invasiveness.


Applying the HEART’s envelope solutions (thermal insulation and windows) ensures the reduction of thermal loads while applying installation technologies (PV, heat pump, fan-coils, storage system) provides energy efficiency and RES exploitation. HEART’s control system optimises the building energy performance, enhancing synergies between different installation and technology sub-systems and operating according to an integrated logic.


Moreover, the system manages efficiently the different energy fluxes, produced locally by the PV plant or collected from the grid, deciding between direct use, thermal or electric storage or feeding in the grid (for PV) based on timing, convenience and opportunity.


In this perspective, the user is transformed from being a consumer to prosumer. Optimisation of energy management and grid, or preferably Smart Grid, interaction is carried out by the web platform, harnessing external (weather forecast, variation in energy tariffs) or internal (users’ inputs) information.


In this sense, the platform exploits the previously elaborated virtual model applying a predictive-adaptive logic which guides the building-system efficiency.


A functional flow-chart, which illustrates, in a synoptic way, all the Toolkit’s components highlighting the interaction/intercommunication schemes:



This allows the HEART multi-technology toolkit to transform an existing building in a highly efficient Smart Building exploiting installation and building sub-components synergistically.


Finally, the use of HEART allows not only to optimise a building’s energy performance but also to make it extremely reliable, documented, and transparent.


This latter aspect proves to be one of HEART’s greatest strengths as it constitutes an instrument of control and guarantees for the stimulation and promotion of incentives and (private or public) financial investments in building energy retrofit.      


The development of HEART Toolkit is, at present, in an advanced stage. The Toolkit is being deployed in two demo cases, one in Italy (Reggio Emilia), and another is in France (Lyon).



Energy Renovation


In the building sector, CO2 operational emissions account for 30% of total energy-related carbon emissions. In fact, the decarbonisation of the building sector plays a major role in the actions against climate change.


All the actions related to the reduction in building carbon emissions pass through the improvement of energy efficiency, the electrification of building final energy consumption and the spread of renewable energy sources.


A higher RES penetration and the increase of building-related electricity consumptions require smarter energy management at building levels, as outlined by the revised Energy Performance of Buildings Directive (EPBD 2018/844/EU).


In fact, the integration of RES introduces several problems in electric systems’ management because of their unpredictable energy production profiles and high variable rates, e.g. solar energy.


As RES integration increases in the building sector, the need to properly manage and dispatch energy at building/district level becomes very crucial: buildings must be able to balance their on-site energy generation and consumption. In such framework, the use of electricity-driven heat pump systems for heating, ventilation and air-conditioning (HVAC) needs, combined with photovoltaic (PV), is one of the major options to increase RES coverage of building primary energy consumptions.


However, the increase of electricity consumptions and the extensive diffusion of non-programmable RES technologies may overload the power grid, thus requiring strategies for peak demand reduction and demand-response.


The reason is attributable to the different distribution of thermal loads and solar radiation on both daily and seasonal base, making it necessary to exchange electricity with the grid, with consequent reduction of local RES self-consumption.


An Energy Storage System (ESS) is a solution to store the excess energy and to be exploited in a second moment of the day or longer, reducing the mismatch between solar radiation and energy demand.


HEART’s Demonstration Buildings


The Italian case study is a social housing residential building from 1985 with 12 residential units of a total of 640 m2 and is located in a residential area of the Municipality of Bagnolo in Piano (RE, Italy).


HEART started the retrofit intervention of the Italian demo building in September 2019 with the retrofit of windows. Such intervention alone shows a reduction in the annual heating demand of about 16% (from 65.2 to 54.3 (kWh/m2).


The other construction activities delayed due to COVID-19 pandemic and were started late in May 2020.  In September 2020, the site activities were carried out related to the building and plumbing works of the thermal power plant, laying of the lifeline on the roof, installation of the external thermal façade system, and a part of the works necessary for installation of corrugated pipes for the distribution of electrical cables.


The works will continue with the installation of the photovoltaic system of the smart fan coils inside the units and with the activation activities of the technological systems installed that will have to communicate with each other and with the future cloud platform.


The second case study is located in Saint-Priest, Lyon, France. It is a multi-family building of subsidised public housing built in 1960 with 26 residential units of a total of 1120 m2 and is located in a residential area.


The design of the French demo case is in an advance stage of development, continuously incorporating the details and optimisation of the whole HEART system, also based on the experiences gained during the activities of the Italian demo case.


To date, the relevant activities have been carried out on the existing architectural and technological parts of the building, and the intervention on future new window systems has been assessed in detail.


Based on the experiences that are being gathered following the continuous collaboration between the HEART partners and on the construction site of the Italian case study, the French project is constantly evolving for the optimisation of the HEART Toolkit.


The goal of the HEART project is to reduce the current consumption of buildings by up to 80%. In the two case studies, a monitoring system is active on the pre-intervention building consumption data in order to compare them with those collected in the post-intervention phase.


The data collection campaign has been active since July 2018 in the Italian case study and from September 2019 for the French one.


The final goal of such installations is to demonstrate the impact of HEART Toolkit on real buildings, thereby, collecting reliable data on final cost balance, installation time, effective energy/cost/emission savings (reduction in CO2 emissions energy bills, etc.) is the key.


The HEART Project introduces a technological advancement beyond the current state-of-the-art by proposing system innovations used in a holistic approach to the energy retrofit of residential buildings.


Notably, it aims to maximise the self-consumption of RES in existing residential buildings, by coupling a PV system with DC-Heat Pumps (HP) that are connected with a Thermal Storage (TS) system. The latter can store the excess of PV energy as a thermal form of energy at a low temperature, which can be exploited later, as needed.


This allows a reduction in the mismatch between solar radiation and thermal loads. It is critical to emphasise that the heat or cold produced in a centralised DC-HP is stored at low temperature in the Thermal Storage unit since each apartment contains a small-size fan coil with a DC compressor (local HP), used to increase the thermal power (coming from the centralised HP or TS), according to the thermal demand of each room.


This allows minimising heat losses in the existing distributions system, to avoid condensation in the cooling mode and to increase the COP/EER of the centralised HP.


The Crest of the Wave


Research and international scientific literature have widely demonstrated how the fight against climate change and the reduction of emissions and energy consumption cannot disregard a substantial rethinking of the building sector. Improving solutions to upgrade building efficiency have been considerably developed and applied over the last few years. However, this is often done in an uncoordinated and fragmented manner, while in practice underestimating synergies and benefits gained through the systemic integration of the different technologies. a problem HEART project addresses.


HEART project fits perfectly in the current debate, proposing a systemic solution that can deliver excellent results in terms of reducing fuel consumption, cutting costs, and raising the quality of life for inhabitants.


By providing a holistic renovation toolkit that ensures quicker, higher quality and more cost-effective building renovations, HEART Project could make a crucial contribution to the success of the Renovation Wave and help decarbonise of the European building stock.