Acoustic and Thermal Retrofit of Office Building Stock in EU

Project Information

ActaReBuild

Grant agreement ID: 101072598

DOI

10.3030/101072598

EC signature date 15 July 2022

Start date 1 September 2022

End date 31 August 2026

Funded under

• Marie Skłodowska-Curie Actions (MSCA)

Total cost

No data

EU contribution

€ 2 525 875,86

Coordinated by

KATHOLIEKE UNIVERSITEIT LEUVEN
Belgium

Periodic Reporting for period 1 - ActaReBuild (Acoustic and Thermal Retrofit of Office Building Stock in EU)

Reporting period: 2022-09-01 to 2024-08-31

Summary of the context and overall objectives of the project

The main objective of ActaReBuild is to train Doctoral Candidates in retrofitting Europe’s office building stock using a new generation of sustainable materials and components to improve and guarantee acoustic and thermal performance during renovation processes while minimising embodied carbon emissions. Through interdisciplinary training, ActaReBuild combines engineering, environmental science, and social considerations to address urgent needs for sustainable, comfortable, and energy-efficient building retrofits.
Research focuses on developing novel mycelium bio-composites, composite materials using recycled plastics, and bio-based materials with customisable acoustic & thermal properties towards improved acoustic solutions and thermal energy storage. The project explores unique applications of metamaterials in buildings for improved airborne sound insulation of lightweight constructions at low frequencies and includes advanced measurement techniques for remote in situ sound absorption determination of ETFE-based building façades.
ActaReBuild takes steps towards the proposal of better descriptors for airborne sound insulations of building façades, addressing not only spectral but also temporal features of noise in its perceived loudness and annoyance. Investigating the relationship between airtightness and acoustic performance in retrofitting processes addresses the challenge of energy efficiency vs indoor air quality and acoustic comfort. Finally, biotic materials for reducing embodied carbon in curtain façades are investigated, all adhering to circular economy principles, and transparent ultralightweight materials are examined for energy-efficient façade retrofitting to minimise environmental impact while maintaining structural integrity.
ActaReBuild fosters solutions that balance historic and modern building retrofit challenges with sustainability goals, preparing DCs to lead advancements in building technologies that enhance comfort, reduce carbon emissions, and promote sustainable practices across EU.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The preliminary findings of ActaReBuild at its midterm can be seen in:
Development and characterisation of innovative materials like mycelium-based composites and bio-materials, showing their potential as sustainable acoustic absorbers despite challenges like sample standardisation.
Improvements in experimental methodologies, such as advanced tortuosity characterisation and airflow resistivity calibration, optimised microphone setups, and enhanced measurement precision and efficiency, have been made.
Exploring recycled and bio-based materials, including agro-industrial residues and bioplastics, for acoustic and thermal insulation and fine-tuning simulation models for multilayer systems.
Research on lightweight systems, including ETFE foil, provided insights into environmental impacts, material durability, and second-skin prototypes, focusing on end-of-life scenarios, recycling challenges and opportunities.
At this stage of the project, optimising finite element modelling and experimental testing methods used in research on acoustic metamaterials has already demonstrated promising enhancements in the mitigation of tonal noise in HVAC equipment, such as heat pump applications.
Investigations into airtightness and sound insulation have revealed novel findings regarding flow regimes and aperture size, challenging conventional assumptions and leading to the development of new diagnostic methods using acoustic imaging.
Research on bio-based phase change materials (PCMs) has demonstrated their potential for energy efficiency, highlighting gaps and future directions for composite applications.
A literature review on sound insulation rating systems and preliminary perceptual tests revealed discrepancies in subjective noise disturbance assessments, resulting in alternative approaches that incorporate cognitive performance tests and temporal sound analysis.
Preliminary ActaReBuild results establish a solid foundation for sustainable building applications, enhancing acoustic and thermal performance while tackling environmental challenges.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

At this stage of the ActaReBuild project (midterm), we can already report the promising potential for future scientific, ecological, societal and economic impacts.
The preliminary studies performed by DCs (both experimental and modeling), help to navigate in finetuning the pathways in:
- Optimisation of guided growth of mycelium-based materials offering broadband acoustic absorption
- Understanding the impact of geometries and recycled plastics in cavities of resonators paves the way for eco-friendly noise-reducing solutions with minimal environmental impact that will be applicable for both building interiors and urban scales.
- Recycled materials were successfully integrated into insulating panels, emphasizing collaboration with waste management industries to enhance resource efficiency.
- Innovative metamaterial designs addressed noise control of heat pumps, indicating the achievement of scalable and cost-effective solutions for residential comfort.
- Supporting the retrofitting of older buildings, a hybrid protocol that combines acoustic imaging with blower door testing for efficient diagnostics is proposed and will be further validated.
- advancements in ETFE cushion systems, including life cycle assessment and prototype development, showcased the potential for recyclable, energy-efficient façades.
To ensure uptake, production techniques must be further refined, regulatory frameworks aligned, and market pathways aligned. Collaboration with industry and policymakers is foreseen to accelerate commercialization and integration, contributing to a sustainable, efficient, and resilient built environment.