NBT Woodfibre Insulation for Environmental Education

Natural Building Technologies’ (NBT’s) natural woodfibre insulation systems have been used in the construction of a centre for environmental and ecological education in Sheffield. Part of the Hallam City Learning Centre and sited in the grounds of Notre Dame High School, the Hallam Environmental Learning Centre (ELC) provides a flexible space to study the wildlife within the school’s garden, pond and surrounding woodland. The centre is used primarily by students from local primary and secondary schools, and is also available for use by members of the wider education community of Sheffield, the Universities and local ecology and wildlife groups.

Designed by Burnell Briercliffe Architects, the ELC sets a fine example of sustainable and energy efficient building, achieved through the creation of a high performing external envelope using NBT’s natural woodfibre insulation systems. NBT’s Diffutherm system was used to insulate the external walls of the centre and NBT’s Pavaroof system was used to insulate the roof.

The Diffutherm system features NBT Diffutherm woodfibre boards, fixed in a continuous layer around the outside of the building and finished externally with a mineral based thin render applied directly onto the woodfibre. The boards are fixed to timber studs, which are infilled with NBT’s Thermafleece sheepswool. A layer of OSB is incorporated for racking strength and air-tightness, and, along with the studs, is fixed to the external face of the oak structure. The bays between each of the oak members in the wall construction are infilled internally with either rendered Diffutherm or Thermafleece-insulated built up panels, leaving the oak structure exposed on the inside of the building.

The Pavaroof system features NBT’s Thermafleece sheepswool between the rafters and NBT Isolair woodfibre boards over the rafters, which radically reduces thermal bridging through the timber. The roof of the ELC is finished with traditional cedar shingles.

Being manufactured from over 95% recycled timber, drawn from FSC approved sources, NBT Diffutherm and Isolair woodfibre insulation fulfill the sustainability requirement for the ELC, whilst simultaneously delivering ultra high levels of thermal performance. Indeed, their application within NBT’s high performing systems achieved U-values of 0.17W/m2K for the ELC’s roof, and an average of 0.15W/m2K for its walls. These woodfibre boards also provide high thermal mass, which helps to regulate overheating during the summer months.

In addition, NBT’s woodfibre boards offer the benefits of being fully breathable, thereby ensuring that any moisture that gets into the roof or wall structures does not condense within the insulation itself, but instead, is expelled harmlessly to the external atmosphere. Without this capability, there is a risk of formation of interstitial and internal condensation forming, leading to degradation of the building structure and/or mould growth that is a proven health hazard.