Technical Paper 9 Slim-profile double glazing - Historic Scotland

Results
The
South‐
and
West‐facing
windows
were
affected
by
solar
radiation,
therefore
analysis
of
the
data
from
Charlotte
Square,
Flat
1/4
Archibald
Place
and
37
Lauriston
Place
was
carried
out
using
night‐time
data
only
with
the
LORD
software
[3].
The
 centre‐of‐pane
 U‐value
 estimates
 are
 given
 Table
 2.
 Figure
 2
 compares
 the
 measured
values
with
the
manufacturers’
specification.
The
results
show
that
the
glazing
units
exhibit
a
 range
 of
 values,
 from
 1.0
 W/m 2 K
 for
 the
 vacuum
 glazing
 to
 2.8
 W/m 2 K
 for
 one
 of
 the
Slimlite
 glazing
 units
 and
 the
 Supalite
 glazing.
 
 Note
 that
 the
 U‐value
 of
 single
 glazing
 is
about
5.5
W/m 2 K.
Figure
2:
Measured
centre
of
pane
(COP)
U‐values
compared
with
manufacturers’
specifications
There
 is
 higher
 uncertainty
 on
 the
 U‐values
 measured
 on
 the
 West‐facing
 glazings
 during
March
 2010,
 particularly
 the
 Supalite
 glazing
 used
 in
 37
 Lauriston
 Place,
 since
 there
 were
less
 data
 available,
 which
 excluded
 the
 influence
 of
 solar
 radiation,
 due
 to
 increasing
 day
length.

The
uncertainty
on
the
other
measured
values
is
5‐7%.
Generally
 the
 manufacturer’s
 specification
 tends
 to
 overestimate
 the
 performance
 of
 the
glazing
 unit,
 except
 for
 the
 Pilkington
 energiKare
 Legacy
 vacuum
 glazing
 and
 the
Slenderglaze
unit.
The
 vacuum
 glazing
 is
 effective
 as
 the
 evacuated
 gap
 prevents
 convective
 heat
 transfer
between
 the
 two
 panes.
 However,
 heat
 is
 transferred
 through
 the
 small
 support
 pillars
separating
the
panes
and
the
edge
seal.
The
performance
of
the
gas
filled
units,
whilst
not
as
effective
as
vacuum
glazing,
is
generally
better
than
the
unit
filled
with
air.
The
performance
of
the
individual
glazing
type
depends
on
the
following:
7