28
DECEMBER 2013 PRO INSTALLER
PRO PRODUCTS
www.proinstaller.co.uk
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 O bligation (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.
‘Reduce heating costs
by as much as 40%
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 canti-
lever 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.