Energy efficient bio-based natural fibre insulation

The demands on the buildings we use are changing. Reducing the energy used to heat our houses and offices is a priority and thermal insulation can help to achieve this aim. However, improvements in sound insulation, thermal mass, indoor air quality and the prevention of condensation are also becoming priotities within the construction sector. What solutions can be developed to meet these new priorities? One possible option is the wider use of innovative insulation materials that are made from renewable, bio-based resources. These products offer the potential of improving a buildings thermal performance as well as meeting these new challenges. In addition these new materials can also store CO2 and help reduce global warming potential.
This project looked at ways to improve the technical performance of commercially made bio-based insulation materials. A key technical development was the collection of data on the functional performance. Performance was measured under a number of practical and theoretical hygrothermal scenarios where humidity and temperature were altered to replicate winter and summer conditions in wall and roof applications.
Improvements in technical performance were achieved by developing new prototypes that were tested against standards. Successful prototypes were then manufactured at full scale by the consortium partners. Successes included an improvement to the existing products and resulted in the introduction of a new insulation material to the UK market.
The project demonstrated the effeactive ability of natural insulation materials to buffer moisture. This ability helps to contribute to the control of indoor air quality. Condensation in buildings is an area for growing concern as buildings become more airtight. This can potentially lead to a build up of moisture levels if there is inadequate ventilation. Understanding and quantifying how insulation materials perform in this respect is one key performance indicator. During the project moisture related properties were measured including water absorption and resistance to vapour diffusion. Comparative hygrothermal testing of bio and non bio-insulations was undertaken to determine the likelihood of interstitial condensation in the interfaces of insulation materials. During these tests it was observed that condensation occurred much earlier with mineral wool insulation than with bio-based insulations. It was found that the bio-insulation reduced the water vapour pressure by adsorption and/or absorption and this prevented condensation. Further tests simulated conditions found in loft spaces and walls. Again experimental work indicated that bio based insulations could cope with damp environments and were able to reduce the moisture in the air.
The project results indicate that bio-insulation can play an active role in reducing humidity levels and thereby decrease the risk and degree of condensation, whether in walls or lofts. Experimental work has also shown that conductivity measurements do not give an accurate indication of actual performance. The project partners gained an insight into how insulation behaves in-situ and under conditions found in buildings. These results suggest that under dynamic conditions bio based insulations can outperform conventional synthetic materials.
Air quality in buildings is another area of increasing concern. Some building materials may be contributing to the composition of volatile organic compounds (VOCs). There is evidence to suggest that bio based insulation materials made from wool may help to improve the indoor environment. During the project, test data was gathered on the ability of wool fibres to selectively absorb VOCs such as formaldehyde. Further work in this area is continuing with the consortium partners.
The market development study also identified the barriers to the greater use of bio based insulation materials. Legal issues such as planning controls, building details, supply chains and technical performance were all considered. This information will be used to develop improved channels to market with better promotion of the uses of bio-based insulation materials.
This study also identified that the key barrier was the lack of credible, non-commercial sources of reliable information. This project will address this issue by extensive publication of all the test data resulting from the project and this will be made available on line and will be publicly disseminated. Another output from this project is the consortium have been instrumental in establishing a new not-for-profit cross-sector organisation called The Alliance for Sustainable Building Products (ASBP).. Through the ASBP it is hoped that a technical committee will be formed to look at the standards for ‘green building products’.
The consortium believes that for the Government to really deliver on targets of carbon neutral buildings by 2016 (as set out in the Code for Sustainable Homes) then a dramatic improvement is needed. The use of better and more sustainable materials is critical and natural fibre insulations can help to achieve these aims.