Designing Timber issue 10 for online - Flipbook - Page 60
———— SAFE SCHOOLS FOR THE FUTURE ————
←
Burry Port
school was the
昀椀rst Passsivhaus
school in
Wales. Clad in
Welsh larch, its
elliptical 'pod'
building uses
the 'Bretstapel'
method. This
uses short
lengths of
softwood timber,
held together
with hardwood
dowels, to form
a solid timber
panel - thus
allowing the
use of Welsh
Douglas 昀椀r and
Sitka spruce; ©
Leigh Simpson.
↙
is often viewed as an
unnecessary cost, but it is
vital for achieving intended
performance levels.
Form factor e昀케ciency
in school design
UNDERSTANDING
E昀케cient form factors in
school design can enhance
energy performance. Form
factor is calculated by
dividing heat loss area (HLA)
by treated 昀氀oor area (TFA).
A lower form factor indicates
better energy e昀케ciency
and reduced heat loss;
advantageous in achieving
Passivhaus standards.
However, a low form factor
need not be a barrier to
creativity. Creative designs
can still achieve high
performance levels while
optimizing construction
costs and embodied carbon
impacts: the case study
schools show a wide variety of
design creativity.
The timber frame
system
project team can also deliver
more cost-e昀昀ectively. The
construction costs of the
primary schools have been
benchmarked against industry
averages. The 昀椀ndings
highlighted the importance
of learning from experience
to the project team: schools
completed up to 2015 started
above industry averages but
were subsequently optimized
to be nearly 20% below
average costs.
The role of Passivhaus
certi昀椀cation
Safe Schools argues that
Passivhaus certi昀椀cation is a
de昀椀ning factor for maintaining
ambitious targets and
ensuring high performance.
Thirteen out of the seventeen
case study schools achieved
certi昀椀ed Passivhaus status.
The Passivhaus standard
has speci昀椀c performance
targets for heating demand,
airtightness, and primary
energy use. These ensure
comfort and operational
performance in the school
buildings.
There is a qualitative
di昀昀erence between certi昀椀ed
projects and those merely
following Passivhaus
principles: certi昀椀cation
DESIGNING TIMBER
60
NOV/DEC 2025
The case study schools utilize
an e昀케cient and scalable
timber frame system. The
Larsen truss is an established
design which pairs two
sawn softwood timbers with
plywood plates for insulation.
It can be constructed by
small teams or by automated
manufacturing, and its use of
timber is economical, enabling
the construction of multiple
schools with the same amount
of material.
Maybury Primary School, the
case study building for the 昀椀re
research, utilised the Larsen
truss system for external walls,
and select CLT internal walls to
provide racking stability.
