Periodic Reporting for period 1 - 0E-BUILDINGS (Open Access Platform for Zero-Energy Buildings)
Période du rapport: 2021-09-02 au 2023-09-01
Achieving energy-efficient buildings has become a major global challenge for science and industry due to the urgent need to reduce greenhouse gas emissions. Buildings currently contribute to over a third of global energy consumption and nearly 40% of CO2 emissions. The EU recognizes improving building efficiency is crucial in achieving climate goals outlined in the Paris Agreement.
Among the various available technologies for improving building energy efficiency, innovative thermal energy storage solutions show enormous potential for energy savings. Particularly in the last decade, phase change materials (PCMs) have attracted great attention from the construction sector because of their high energy storage density, i.e. large amounts of energy can be stored in small volumes.
PCMs undergo a phase transition (solid-liquid or liquid-solid) around a narrow region of utilization temperatures, through which they can store (during melting) and release (during solidification) large amounts of heat energy. However, to achieve an effective use of passive PCM systems in buildings, a proper design of their thermophysical properties, their quantities, and their location is required. Moreover, such features are highly influenced by the climate conditions where a building is located and its typology. Therefore, given the complexity of building thermal behavior, the thermophysical phenomena of PCMs integrated into a building need to be analyzed through novel whole-building performance simulation (BPS) tools.
Within this context, the main aim of the 0E-BUILDINGS project was to propose and develop a novel simulation-based multi-objective platform to evaluate and optimize the energy performance of buildings through the optimal use of passive PCM systems. Beyond this, the present project also allowed to employ the developed numerical tools for determining innovative building applications with PCMs, understanding their thermal behavior in buildings, deriving design guidelines, enhancing their cooling and heating performances, and optimizing their designs through an integral combination with architectural variables and other passive cooling and heating strategies.
Among the various available technologies for improving building energy efficiency, innovative thermal energy storage solutions show enormous potential for energy savings. Particularly in the last decade, phase change materials (PCMs) have attracted great attention from the construction sector because of their high energy storage density, i.e. large amounts of energy can be stored in small volumes.
PCMs undergo a phase transition (solid-liquid or liquid-solid) around a narrow region of utilization temperatures, through which they can store (during melting) and release (during solidification) large amounts of heat energy. However, to achieve an effective use of passive PCM systems in buildings, a proper design of their thermophysical properties, their quantities, and their location is required. Moreover, such features are highly influenced by the climate conditions where a building is located and its typology. Therefore, given the complexity of building thermal behavior, the thermophysical phenomena of PCMs integrated into a building need to be analyzed through novel whole-building performance simulation (BPS) tools.
Within this context, the main aim of the 0E-BUILDINGS project was to propose and develop a novel simulation-based multi-objective platform to evaluate and optimize the energy performance of buildings through the optimal use of passive PCM systems. Beyond this, the present project also allowed to employ the developed numerical tools for determining innovative building applications with PCMs, understanding their thermal behavior in buildings, deriving design guidelines, enhancing their cooling and heating performances, and optimizing their designs through an integral combination with architectural variables and other passive cooling and heating strategies.
First, the development of the simulation-based multi-objective computational platform to evaluate and optimize passive phase change materials (PCMs) in buildings was performed. For this, the accuracy of different PCM models to represent their thermal performance in buildings was evaluated, including specific phenomena such as phase change hysteresis. Furthermore, a proper numerical setup of algorithms was tested to achieve accurate results using whole-building performance simulations in the EnergyPlus software. A parametric module was developed to dynamically modify the thermophysical properties of various PCMs simultaneously. Then, the core of the platform was achieved by coupling this module with EnergyPlus and a multi-objective genetic algorithm.
Using the newly developed numerical tools, several applications were performed to validate and improve the platform workflow, to determine innovative building applications of PCMs, to understand their behavior in buildings, and to derive general design rules throughout different climate regions.
Regarding the applications, the performance of PCMs in buildings was evaluated and optimized for different incorporation technologies (e.g. microencapsulated PCMs) and in combination with other passive strategies (e.g. embedded in insulating cementitious foams). Moreover, innovative utilization of PCMs with different melting temperatures was proposed, while their optimization was performed for various climate-representative locations within WMO Region VI (Europe). Beyond the specific results reported from these applications, the performance of PCMs in buildings showed itself to be complex, and their proper design essentially requires the use of whole-building performance simulation. The melting temperature, amount, and location of PCMs should be carefully designed to maximize their thermal performance. The proposed approach of using PCMs with different melting temperatures was preferred. This approach achieved the best performances in various climate zones and case studies with both heating and cooling thermal loads.
Because a moderated performance of passive PCMs was mostly observed (compared to their theoretical potential), novel effectiveness indicators were developed to deeply understand the behavior of PCMs in buildings. By employing these novel indicators, unprecedented findings were obtained, which revealed that building design variables, such as the window-to-wall ratio, have a significantly higher impact on the effectiveness of PCMs than typically employed PCM design variables, such as melting temperatures. These unprecedented findings indicate that designers could significantly improve the performance of passive PCM systems in buildings by simultaneously designing the PCMs along with other building design variables, preferably at the initial stage. Moreover, the results show that a contradiction can exist between the building’s energy performance and the effectiveness of PCMs. This means that the best effectiveness for PCMs is achieved in buildings with a low energy performance.
Apart from the research activities, the fellow performed other activities to carry out his research career plan, including the preparation and application for new research funding.
To encourage the dissemination of the obtained results and their exploitation, several actions were performed within the project, among them:
- Publication of two research papers in peer-reviewed journals. One more is under review.
- Publication and presentation at three international conferences.
- Open-access publication of research data (five datasets) of the project at the Zenodo repository (https://zenodo.org/communities/0e-buildings/(s’ouvre dans une nouvelle fenêtre)).
- Plenary presentation at the IBPSA LATAM 2023 conference.
- Website of the project.
- Invited speaker at the Postdoc Career Weeks 2022 of the Rhine-Main University Alliance.
Using the newly developed numerical tools, several applications were performed to validate and improve the platform workflow, to determine innovative building applications of PCMs, to understand their behavior in buildings, and to derive general design rules throughout different climate regions.
Regarding the applications, the performance of PCMs in buildings was evaluated and optimized for different incorporation technologies (e.g. microencapsulated PCMs) and in combination with other passive strategies (e.g. embedded in insulating cementitious foams). Moreover, innovative utilization of PCMs with different melting temperatures was proposed, while their optimization was performed for various climate-representative locations within WMO Region VI (Europe). Beyond the specific results reported from these applications, the performance of PCMs in buildings showed itself to be complex, and their proper design essentially requires the use of whole-building performance simulation. The melting temperature, amount, and location of PCMs should be carefully designed to maximize their thermal performance. The proposed approach of using PCMs with different melting temperatures was preferred. This approach achieved the best performances in various climate zones and case studies with both heating and cooling thermal loads.
Because a moderated performance of passive PCMs was mostly observed (compared to their theoretical potential), novel effectiveness indicators were developed to deeply understand the behavior of PCMs in buildings. By employing these novel indicators, unprecedented findings were obtained, which revealed that building design variables, such as the window-to-wall ratio, have a significantly higher impact on the effectiveness of PCMs than typically employed PCM design variables, such as melting temperatures. These unprecedented findings indicate that designers could significantly improve the performance of passive PCM systems in buildings by simultaneously designing the PCMs along with other building design variables, preferably at the initial stage. Moreover, the results show that a contradiction can exist between the building’s energy performance and the effectiveness of PCMs. This means that the best effectiveness for PCMs is achieved in buildings with a low energy performance.
Apart from the research activities, the fellow performed other activities to carry out his research career plan, including the preparation and application for new research funding.
To encourage the dissemination of the obtained results and their exploitation, several actions were performed within the project, among them:
- Publication of two research papers in peer-reviewed journals. One more is under review.
- Publication and presentation at three international conferences.
- Open-access publication of research data (five datasets) of the project at the Zenodo repository (https://zenodo.org/communities/0e-buildings/(s’ouvre dans une nouvelle fenêtre)).
- Plenary presentation at the IBPSA LATAM 2023 conference.
- Website of the project.
- Invited speaker at the Postdoc Career Weeks 2022 of the Rhine-Main University Alliance.
The most important achievements beyond the state-of-the-art of the 0E-BUILDINGS project are:
- A numerical toolkit to assess and optimize the design of passive phase change materials (PCMs) in buildings. These can be employed for any case study, regardless of the building typology and climate region.
- The reported findings and conclusions regarding the potential and limitations of optimally designed PCMs in buildings, which include several climate zones.
- A deep understanding of the thermal behavior of passive PCMs, which allowed for the development of unprecedented indicators regarding the effectiveness of PCMs in buildings.
Thanks to these important advances achieved in the 0E-BUILDINGS project, building designers can better design passive PCMs in buildings to maximize energy savings and improve the thermal comfort of residents. This can be reached either by the application of findings, the use of research data for other applications, or the use of the developed computational tools. Furthermore, a huge impact is expected from the PCM effectiveness indicators introduced in this project. These indicators will allow new research to reach important findings in comprehending the physical behavior of PCMs in buildings and resolve new areas of research to improve their actual effectiveness.
- A numerical toolkit to assess and optimize the design of passive phase change materials (PCMs) in buildings. These can be employed for any case study, regardless of the building typology and climate region.
- The reported findings and conclusions regarding the potential and limitations of optimally designed PCMs in buildings, which include several climate zones.
- A deep understanding of the thermal behavior of passive PCMs, which allowed for the development of unprecedented indicators regarding the effectiveness of PCMs in buildings.
Thanks to these important advances achieved in the 0E-BUILDINGS project, building designers can better design passive PCMs in buildings to maximize energy savings and improve the thermal comfort of residents. This can be reached either by the application of findings, the use of research data for other applications, or the use of the developed computational tools. Furthermore, a huge impact is expected from the PCM effectiveness indicators introduced in this project. These indicators will allow new research to reach important findings in comprehending the physical behavior of PCMs in buildings and resolve new areas of research to improve their actual effectiveness.