cellulose insulation e is often associated with insulating unused attic spaces. However, its applications extend far beyond this traditional use. In both new construction and renovation projects, it can also be incorporated into wall insulation systems, particularly in off-site construction projects.
Through four projects carried out in the Pays de la Loire region with our partner Sybois, Igloo France Cellulose demonstrates another way to use this bio-based insulation: as the core material in prefabricated facades for multi-family housing.
cellulose insulation ation is not limited to unused attic space
Although it is widely used in unused attic spaces, the " cellulose insulation " is not limited to this application.
It can also be used in vertical walls, depending on the construction systems and installation methods chosen. As such, it is suitable for new construction, renovation, and rehabilitation projects involving multi-family housing.
This range of applications opens up new opportunities for construction companies, architects, engineering firms, and project owners who wish to incorporate bio-based materials into their projects.
To illustrate these possibilities, let’s take a look at four projects completed with Sybois, a manufacturer of prefabricated walls and facades, in three cities in the Pays de la Loire region: Nantes, Guérande, and Angers.
Off-site construction: a field of application for the cellulose insulation
Off-site construction involves manufacturing all or part of a building’s components in a factory before transporting them to the construction site for assembly. This approach is particularly common for prefabricated walls and facades.
In the four projects presented here, the “ cellulose insulation ” is part of the wall systems manufactured by Sybois. It is combined with other components, including exterior cladding, windows and doors, and roller shutters.
For those in the construction industry, these projects demonstrate that bio-based insulation can be integrated into industrialized construction solutions, in both renovation and new construction projects.
Housing Renovation: Two Projects in Nantes and Guérande
Renovating the existing housing stock involves working with an existing building, its limitations, and the project’s objectives. In Nantes and Guérande, two renovation projects illustrate how the “ cellulose insulation ” has been integrated into prefabricated walls and facades.
1. Les Bretonnières in Nantes: 88 housing units renovated using prefabricated construction
How can a housing complex be renovated while improving its energy efficiency and residents’ comfort, without requiring them to leave their homes during construction? This is the challenge that Nantes Métropole Habitat took on with the renovation of the La Bretonnière apartment complex, located in the Nantes Erdre neighborhood.
Built in 1984, this 88-unit residential complex underwent an energy-efficiency renovation from September 2024 to July 2025. The project marks Nantes Métropole Habitat’s first initiative carried out using the EnergieSprong approach, which relies in particular on industrialization and prefabrication to accelerate building renovations.
In this project, Igloo’ cellulose insulation s are integrated into the walls and facades prefabricated at the factory by our partner SYbois. It is thus part of a construction solution that combines bio-based insulation with large-scale energy-efficient renovation.
Prefabricated facades designed for the existing building
The renovation primarily involves installing exterior thermal insulation on wood-frame facades. The insulation panels are custom-made based on 3D scan data and then attached to the exterior of the buildings.
This off-site approach allows a large portion of the components to be prefabricated in a factory before being installed on-site. At La Bretonnière, it made it possible to carry out the work while the building was occupied: tenants were able to remain in their homes throughout the project, while on-site work was limited in duration and minimized disruption.
The composition of the facades combines several components:
- 200-mm prefabricated walls + fiber;
- Igloo " cellulose insulation " insulation;
- Class 3 Douglas fir siding;
- Cybel PVC Windows and Doors;
- Roller shutters.
Beyond the insulation, the architectural project was the result of a collaborative effort with the architectural firm Floret-Scheide. The pre-weathered Douglas fir siding, the interplay of solid and openwork slats, and the composite siding elements at the entrances all contribute to giving the buildings a fresh new look.
A collaboration among stakeholders in industrialized renovation
The success of an off-site renovation project depends on the coordination of the various parties involved. Nantes Métropole Habitat serves as the project owner; Floret-Scheide acts as the architect; and Alteresco, a subsidiary of Altyn, is the general contractor responsible for design, construction, and operations under a comprehensive performance contract.
Alteresco regularly collaborates with SYbois on facade design. This partnership between renovation contractors and a manufacturer of prefabricated walls illustrates the importance of collaborative efforts in developing industrialized solutions tailored to the constraints of existing buildings.
“This renovation has allowed us to balance energy efficiency, user comfort, and architectural quality. It serves as a concrete example of ALTERESCO’s ability to implement, in partnership with Nantes Métropole Habitat, industrialized and replicable solutions.”
Energy performance at the residential level
The Nantes Métropole Habitat press kit highlights a significant change in the average energy consumption of housing units: it dropped from 286 kWhEP/m²/year before renovation—corresponding to energy class E—to 64 kWhEP/m²/year after renovation, corresponding to energy class B.
The report also notes an 80% decrease in CO₂ emissions, from 67 to 13 kg CO₂ eq./m² of gross floor area per year.
These results pertain to the entire energy-efficiency renovation program, which includes several measures: exterior thermal insulation, replacement of windows and doors, insulation of the attic and the ceiling above the parking garage, improvements to the ventilation system, and upgrades to the heating system. They therefore cannot be attributed solely to cellulose insulation.
For Igloo France Cellulose, this project illustrates one key point in particular: the “ cellulose insulation ” can be integrated into prefabricated facade systems used in ambitious energy-efficient renovation projects, beyond its traditional application in unused attic spaces.
To learn more about this energy-efficiency renovation project, the goals of the EnergieSprong initiative, and the results achieved, see the Nantes Métropole Habitat press kit.
Download the La Bretonnière press kit (PDF)
2. Bois Rochefort in Guérande: 72 renovated housing units with prefabricated bio-based facades
In Guérande, the Bois Rochefort apartment complex also demonstrates the potential of the Igloo cellulose insulation in large-scale energy-efficiency renovation projects. Built in 1969 and renovated in 1992, this 72-unit apartment complex underwent a comprehensive renovation led by Habitat 44 as part of the EnergieSprong initiative.
Scheduled for completion in November 2025 and to be inaugurated in June 2026, the project combines energy efficiency improvements, architectural renovations, and housing upgrades. Its goal is to reduce energy consumption, improve residents’ comfort, and keep utility costs under control, all while allowing residents to remain in their homes during construction.
Prefabricated, insulated facades made of Igloo- cellulose insulation
At the heart of the project, new prefabricated wood-frame facades were installed from the exterior. The components were designed and manufactured in a workshop before being assembled on site, in accordance with the principles of off-site construction.
For this project, our partner SYbois incorporated the “ cellulose insulation ” into the prefabricated walls, alongside the other facade components:
- 200-mm walls + fiber;
- Igloo " cellulose insulation " insulation;
- Douglas Melodik Siding;
- Cybel PVC Windows and Doors;
- Roller shutters.
The renovation of the facades is accompanied by architectural changes to the residence, while meeting the requirements of a comprehensive energy-efficiency renovation.
2,738 m² of renovated facades thanks to off-site prefabrication
ALTYN's press kit states that the project involved 2,738 m² of facades, with 216 prefabricated panels designed in the workshop and then assembled on site.
The installation of the facades took five months, with a planned rate of six panels installed per day. This industrial approach is designed to ensure high-quality workmanship, reduce the duration of on-site work, and minimize disruption to residents.
This approach illustrates the benefits of prefabrication for renovation projects: a significant portion of the work is completed in advance, while work on the existing building is organized to maximize efficiency.
A comprehensive renovation with significant energy savings
In Bois Rochefort, improving energy efficiency isn’t limited to the facades. The program also includes the modernization of heating, domestic hot water, and ventilation systems, as well as the replacement of windows and doors and various interior renovations.
The project also includes a communal wood-fired heating system fueled by pellets and 355 rooftop solar panels, covering an area of 710 m².
According to ALTYN’s press kit, the renovation is expected to reduce energy consumption by 70 percent. The document also notes that the new wood-fired boiler system will cut annual CO₂ emissions by approximately 110 metric tons compared to previous levels.
These results pertain to the overall renovation program and the upgrades to its facilities. They cannot be attributed solely to cellulose insulation.
An environmental approach that goes beyond the choice of insulation
The Bois Rochefort residential complex exemplifies an environmental approach that combines several strategies: bio-based materials, prefabrication, the circular economy, and logistics optimization.
The press kit notes, among other things, a waste sorting rate of over 80 percent, a reduction in waste of nearly 90 percent thanks to the use of off-site prefabrication, and a share of 80 percent of materials sourced from the Greater West region.
These figures reflect a commitment to reducing the project’s environmental impact on several levels. In this context, the integration of the cellulose insulation into the prefabricated facades is one component of a broader renovation strategy.
For Igloo France Cellulose, Bois Rochefort serves as yet another example demonstrating that the “ cellulose insulation ” can be integrated into prefabricated wall systems in ambitious multi-family housing renovation projects.
This project, like the one at La Bretonnière in Nantes, highlights the synergy between bio-based insulation materials, industrialization, and the expertise of construction professionals.
Download the Bois Rochefort press kit (PDF)
These two renovation projects illustrate a common principle: incorporating bio-based insulation into prefabricated facade components in large-scale renovation projects.
New Construction: Two Student Housing Complexes in Angers
The Igloo “ cellulose insulation ” is also being used in new construction projects. In Angers, two student housing projects carried out by Angers Loire Habitat illustrate this alternative application.
3. Belle-Beille Sciences: 154 student housing units
The Belle-Beille Sciences program involves the construction of 154 student housing units in Angers, in the Maine-et-Loire department. The project has a total facade area of 1,140 m².
Sybois' prefabricated walls incorporate the Igloo cellulose insulation into a system that combines several components.
Composition of walls and facades:
- 170 mm walls + Weather;
- Igloo " cellulose insulation " insulation;
- Rockpanel siding;
- Cybel PVC Windows and Doors;
- Roller shutters.
The project was carried out for Angers Loire Habitat, with Rolland & Associés serving as the architect and OTELI as the engineering firm.
This case study, in turn, demonstrates how the Igloo “ cellulose insulation ” can be incorporated from the design phase of new buildings intended for student housing.
4. Belle-Beille Lettres: 210 student housing units
Also in Angers, the Belle-Beille Lettres project involves the construction of 210 student housing units. Carried out for Angers Loire Habitat, the project has a total facade area of 1,650 m².
The construction of the prefabricated walls follows the same principle used for Belle-Beille Sciences:
- 170 mm walls + Weather;
- Igloo " cellulose insulation " insulation;
- Rockpanel siding;
- Cybel PVC Windows and Doors;
- Roller shutters.
The project involves the same project owner, Angers Loire Habitat; the same architect, Rolland & Associés; and the same engineering firm, OTELI.
With its two residential complexes in Belle-Beille, the “ cellulose insulation ” demonstrates its involvement in new construction projects for student housing.
Four initiatives, one shared goal: to diversify the applications of the cellulose insulation
These four projects provide a concrete way to gauge the diversity of projects in which the " cellulose insulation " can be used.
| Production | Location | Project Type | Program | Facade area |
|---|---|---|---|---|
| Les Bretonnières | Nantes (44) | Rehabilitation | 88 housing units | 4,315 m² |
| Rochefort Woods | Guérande (44) | Rehabilitation | 72 housing units | 4,097 m² |
| Belle-Beille Sciences | Angers (49) | New Construction | 154 student housing units | 1,140 m² |
| Belle-Beille Letters | Angers (49) | New Construction | 210 student housing units | 1,650 m² |
In total, these projects comprise 524 housing units and 11,202 m² of building facades, on which the Igloo cellulose insulation e is integrated into prefabricated wall systems.
These figures illustrate the wide range of possible applications: two apartment renovation projects and two new construction projects for student housing.
Why incorporate the " cellulose insulation " into an off-site construction project?
A bio-based insulation material made from recycled materials
Igloo “ cellulose insulation ” is made from selected fibers derived from recycled paper, which is itself made from wood. Igloo “ cellulose insulation ” is certified with the “Bio-based Product Gold Label (89–90%) + French supply chain + recycled.” The paper used in “ cellulose insulation ” comes 100% from France. Igloo wadding is manufactured in France at the two Iso Green Group plants (in Vendée and Hérault). The “ cellulose insulation ” continues to store biogenic carbon (originally captured by the tree) throughout its entire lifespan.
1 kg of cellulose insulation stores 1.37 kg of CO2.
A dense loose-fill insulation material
Igloo “ cellulose insulation ” is available in bulk. It is this form that allows it to adapt to all the specific requirements of off-site construction, regardless of the width and thickness of the prefabricated elements. There is no cutting or material waste. Furthermore, when blown into walls within enclosed cavities, the density of Igloo “ cellulose insulation ” ranges from 48 to 60 kg/m³. This high density ensures superior thermal performance and long-term durability.
Integration into prefabricated components
Projects carried out with Sybois demonstrate the potential for combining the Igloo cellulose insulation with factory-manufactured walls and facades. This approach makes it possible to consider the use of bio-based insulation materials in industrialized construction projects, whether for new construction or renovation.
As with any insulation solution, the choice of method must be evaluated based on the wall’s composition, the project’s requirements, and the applicable technical specifications.
Igloo' cellulose insulation : From Attics to Walls—New Opportunities for Professionals
Igloo' cellulose insulation s can be used in a variety of construction projects, beyond just insulating unused attic spaces.
For architects, engineering firms, project owners, and construction companies, these projects serve as concrete examples of how bio-based insulation can be integrated into prefabricated walls, both in new construction and in renovation projects.
At Igloo France Cellulose, we are convinced that the development of bio-based insulation also depends on a wide range of applications and on collaboration with stakeholders in the construction industry.
Frequently Asked Questions About In-Wall cellulose insulation
Can the " cellulose insulation " be used for anything other than an unused attic space?
Yes. The “ cellulose insulation ” can be integrated into the insulation of floors, roof slopes, and walls using various certified systems and construction methods. The projects presented in Nantes, Guérande, and Angers, for example, demonstrate its use in prefabricated walls for multi-family housing.
Can the " cellulose insulation " be used in new construction?
Yes. The “ cellulose insulation ” can be integrated into prefabricated wall systems for new student housing construction projects, such as the Belle-Beille Sciences and Belle-Beille Lettres projects here in Angers. But it can also be easily combined with on-site construction—whether using wood-frame and/or traditional construction methods—in walls, unused attic spaces, and sloped ceilings.
Can the " cellulose insulation " be incorporated into prefabricated facades?
Yes. The four projects presented use off-site components that incorporate cellulose insulation insulation. The walls are combined with various facade components, depending on the characteristics of each project.
What types of buildings are involved in these projects?
Many types of buildings are involved: single-family and multi-family residential buildings, offices, schools, and so on. The case studies presented here cover, for example, two types of projects: the renovation of multi-family housing and the new construction of student housing.
Who should I contact to explore the possibility of installing the " cellulose insulation " within the building?
The choice of an insulation solution depends on the construction system, the wall composition, and the site constraints. The Igloo France Cellulose teams can guide you to the technical information best suited to your project.
