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.
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