HEATING, VENTILATION & SERVICES FOCUS
The natural choice
Neil Turner of Ecological Building Systems looks at why sustainable insulation offerings present a natural choice for selfbuilders
N
atural insulation materials are experiencing a resurgence as self-builders are increasingly seeking sustainable materials that can offer similar performance, but with lower environmental impact. here are many performance benefits associated with natural insulation materials, which are becoming more widely known. These include low thermal diffusivity, which results in a reduction in summer overheating due to high specific heat capacity, high density and reasonable thermal conductivity. In addition, natural insulation materials like wood fibre can lead to a reduction in airborne acoustic noise and greater moisture diffusion openness, otherwise known as breathability. In addition, they have better carbon profiles than many other insulation materials. ood fibre insulation is currently experiencing a resurgence. An excellent insulator, it is made from post-industrial recycled wood chips, which may otherwise go into landfill and is suitable for a wide range of internal and external applications, as long as it is above ground level.
Natural insulation has a very low cradle to end of life Global Warming Potential (GWP) of 93.36kg CO2
equivalent/m3 .
ood fibre insulation can also often be recycled at the end of life and when these impacts are taken into account (Section D of the life cycle assessment) Gutex Multitherm, for example, has a better than carbon zero GWP rating of -91.94kg CO2
equivalent/m3 .
WHAT IS NATURAL INSULATION? Natural insulation materials originate purely from renewable resources and, as such, they have a significantly lower carbon footprint and a higher sequestered biogenic carbon content compared to conventional insulation options, such as foam or mineral wool. Its environmental credentials are undeniable. ith woodfibre insulation, when converting these waste wood chips into insulation, all of the sequestered biogenic carbon is locked into the building (1kg of dried timber can sequester 1.8kg CO2
Eq/kg). At the end sep/oct 2024
ED rating for the natural fibre insulation product (Section D of the life cycle analysis according to EN15804).
of their useful life, these materials can often be recycled, contributing to a more circular economy and further boosting the Global Warming Potential (kg CO2
/e)
THERMAL REGULATION The thermal mass and humidity- regulating properties of natural insulation can play a crucial role in maintaining comfortable indoor temperatures and reducing the risk of moisture-related issues in a home. Compared to many other insulation materials, natural fibre insulation possesses a high specific heat capacity, which when combined with a relatively high density and reasonable thermal conductivity allows the absorption and storage of large amounts of thermal energy. This thermal mass can play a crucial role in mitigating overheating during the summer months, providing a more stable and comfortable indoor environment.
By choosing an insulation which is naturally able to store large amounts of thermal energy, self-builders can benefit from a high level of comfort all year round.
Natural insulation materials also help with acoustics, by absorbing sound waves, which reduces the transmission of noise between different spaces within a building. The lower density natural insulation products have excellent airborne noise reduction properties and the higher density products can be used to reduce impact noise reduction. It is the low dynamic stiffness and porous fibre structure, plus natural insulations inherent density that reduces airborne and impact noise and improves acoustics within a home.
BREATHABILITY
One of the main characteristics of natural insulation materials is their breathability (low moisture vapour diffusion resistance) and high moisture sorption/desorption properties. his provides more fleibility in designing building elements as there is no requirement for highly moisture vapour resistant barriers, which makes them a good solution for solid masonry construction. It also prevents the build-up of moisture within the building envelope, reducing the risk of interstitial condensation, mould, rot and other related problems. In combination with an effective ventilation system, natural insulation also contributes towards
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