Clearview North December 2013 - Issue 145 | Page 56

ENERGYEFFICIENCY

ENERGY EFFICIENCY REQUIREMENTS
CALL FOR ENGINEERED SOLUTIONS
No matter which industry you’re in, the
topic of energy efficiency is hard to avoid;
though it is particularly pertinent to the
construction industry: statistics suggest the
sector is accountable for approximately half
of the UK’s emissions of carbon dioxide.
Jamie Lewis, facades and offsite advisor at
SFS intec, argues that this could be markedly
reduced by implementing more sustainable
and engineered solutions; specifically when
setting windows over external wall insulation
zones.
In the last twelve months, government
initiatives such as the Green Deal and the Energy
Companies Obligation (ECO) have played
an important role in educating householders
of the benefits of energy efficient home
improvements.
The Department of Energy and Climate
Change (DECC) reported that at the end of
October, over 85,000 Green Deal assessments
were completed, but only 57 homes have had
energy saving measures installed since January,
with 505 homes still pending. While this
signifies the scheme’s struggle to process the
assessments with speed, it does highlight the high
volume of homeowners who are keen to improve
energy efficiency.
This has been helped by ECO, which is
driving a large amount of sustainable building
work through the public sector. Specifically,

over 244,000 measures were installed under
this scheme up to the end of August. So, while
the implementation of the Green Deal requires
much improvement, the ECO funding is
booming, and both are successfully raising
awareness and instilling a level of understanding
and knowledge about enhancing eco
credentials.
Out-boarded windows

Over the last 12 months, one measure
which has increased in demand is external wall
insulation (EWI). This method can improve
thermal efficiency and reduce heating costs by as
much as 40%, by minimising a building’s heat
loss and gain. However, many system designers
are still failing to recognise the importance of
correctly positioning the windows over the
insulation zone, instead of simply placing in the
same position. Failure to consider the window
positioning in an EWI application will have a
dramatic negative effect on the windows U-value
which in turn, will lead to condensation and
black mould growth within the building.
Similarly, while thicker window sets provide
improved energy efficiency, triple-glazed units
are much heavier. These additional loads must
be properly calculated in order to reduce the
likelihood of the frame sagging or dropping into
the insulation zone, which can cause damage and
costly financial implications.

Given the fairly infant nature of this
application, many windows which are being
installed over external insulation zones, are
done so using cobbled-together solutions as few
suitable products are currently available. This
can include strips of metal or wood which are
often fitted as a ‘make do’ option. However, this
isn’t an acceptable solution where there are so
many considerations, including the hardware
used, dead and imposed loads of the unit, as well
as the cantilever distance. Indeed, taking such
a rudimentary approach is putting the window
system at real risk of failure.
Engineered solutions

A specifically designed, engineered support
system, which will accommodate the increased
dead and imposed loads acting on the frames,
is imperative to ensure peace of mind and
continued performance.
Made up of jamb and sill brackets, a suitable
solution should be secured from the inner
wall leaf, attaching to the window unit at
numerous vital support points. The brackets
should be specified based on the mass of the
window unit versus the cantilever projection
– ranging between 30mm and 150mm - in
order to establish the dead loads on the system.
Dependant on the cantilever distance, the correct
bracket can be chosen from a detailed datasheet
to ensure the most suitable selection for the
job.
In support of this, the system should meet the
requirements for IFT Rosenheim testing - static
positive and negative pressure with + 2000 Pa,
non permanent additional load up to 800 N on
an open sash and also simulated use with 10,000
leaf/sash movements.
Don’t take the easy way out

Energy efficiency requirements will continue
to drive demand for innovation. As new
applications like EWI begin to grow in
popularity, it is important that the industry
understands the implications and does away
‘make do’ options. Cutting corners only
presents unnecessary risk and performance
will undoubtedly be affected. Specifically, a
tailor-made bracket solution which is tested
and designed to securely fix a window in place
will not only provide performance, but will also
ensure the optimum efficiency of the windows
and building overall.

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DEC 2013

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