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E
N
E
R
G
Y


A
U
D
I
T
.



E
N
E
R
G
Y


A
U
D
I
T


C
O
N
T
E
N
T
S
.
 
 Space
Heating
Scatterplots


Sankey
Diagrams.


Control
Charts.


Heat
Distribution
And
Using
The
Data
Logger.


CUSUM
Charts.


Heating
Systems
And
Tariff.


Energy
Use
Compared
To
Degree
Days.


Appliances
Layout.


The
NPI
Calculation.


Recommendations.


Using
The
Bedzed
Benchmark.
 



Energy
Audit
Methodology
Breakdown.



S
p
a
c
e


H
e
a
t
i
n
g



S
c
a
t
t
e
r
p
l
o
t
.
 The
scatter
plots
below
correlate
the
Heating
Degree
Days
data
against
the
Heating
Load
(kWh)
and
 drawing
a
resultant
mean
trend
line
through
the
point
plotted.
The
further
that
the
individual
points
are
 from
the
line
of
best
fit,
the
less
the
heating
system
in
questions’
responsiveness
to
changes
in
External
 temperature.
 Flat
29
had
the
best
correlation
out
of
all
the
flats
assessed.
This
may
be
resultant
from
the
increased
 thermal
mass
caused
by
additional
insulation
on
the
exposed
wall
and
the
cork
flooring
allowing
the
 building
fabric
to
store
heat
for
longer
than
other
flats
would.
 



C
o
n
t
r
o
l


C
h
a
r
t
.
 The
control
chart
is
used
to
see
how
the
actual
energy
consumption
of
heating
compares
to
the
 performance
drawn
in
the
previous
baseline.
It
must
be
noted
that
negative
readings
infer
energy
 efficient
behaviour
and
consequential
savings.
Flats
29
and
38
particularly
show
this
positive
behaviour.


C
U
S
U
M


C
h
a
r
t
.
 Through
 the
 cumulative
 sum
 of
 the
 difference
 (CUSUM)
 Chart
 we
 can
 see
 evidence
 of
 the
 energy
 efficiency
of
a
building.
Here
the
graph
shows
the
patterns
in
monthly
data
over
the
course
of
a
year.
 An
upward
incline
on
the
CUSUM
chart
indicates
that
energy
consumption,
at
that
time,
is
increasing.
 Savings
are
indicated
by
a
decrease
/
a
downwards
slope
in
the
line.
 CUSUM
 are
 helpful
 as
 they
 represent
 the
 overall
 trends
 occurring
 in
 energy
 consumption
 and
 savings
 (here,
in
regards
to
heating).
This
is
particularly
useful
to
notice
fluctuations
of
energy
consumption.
It
is
 beneficial
 in
 this
 instance,
 as
 it
 allows
 the
 author
 to
 alert
 the
 occupants
 to
 act
 upon
 excessive
 energy
 consumption.



Using
 Flat
 38
 as
 an
 example,
 we
 can
 see
 increasing
 energy
 consumption
 between
 the
 months
 of
 September
and
January.
There
is
then
a
decrease
in
consumption
after
this
point
as
the
summer
months
 approach
 and
 the
 need
 for
 space
 heating
 becomes
 considerably
 less.
 This
 is
 a
 normal
 distribution
 as
 heating
needs
decrease
as
it
gets
closer
to
summer.
 
 
 



 E
n
e
r
g
y


U
s
e


C
o
m
p
a
r
e
d


T
o


D
e
g
r
e
e


D
a
y
s
.

 These
 graphs
 are
 used
 for
 comparing
 the
 actual
 space
 heating
 energy
 consumption
 to
 the
 heating
 degree
days
(specific
to
the
locality).
The
red
constant,
dotted
line
shows
the
base
load
of
the
building.
 This
is
a
kWh
figure
is
equal
to
the
lowest
monthly
energy
consumption
of
the
year
in
question.
 This
graph
is
utilised
by
recording
the
points
at
which
the
degree
day
line
exceeds
the
value
/
bar
height
 of
the
energy
consumption.
This
means
that
the
building
is
likely
to
overheat.
In
contrast
however,
if
the
 degree
day
line
is
below
the
energy
consumption
figure,
the
flat
is
in
need
of
additional
heating.

 So
overall
we
can
tell
if
a
system
has
an
efficient
heating
system
as
the
more
efficient
it
is,
the
closer
the
 two
 sets
 of
 plotted
 data
 (energy
 consumption
 /
 degree
 days)
 correlate.


T
h
e


N
P
I


C
a
l
c
u
l
a
t
I
o
n
.

 The
NPI
is
used
as
a
‘yardstick’
to
state
annual
energy
consumption
(kWh/m2/year)
of
a
building.
It
 allows
for
patterns
in
occupancy,
weather
and
exposure
of
the
building.

 Highest
Annual
Energy
Use:
Flat
38.

 Lowest
Annual
Energy
Use:
Flat
10

 This
unit
(Flat
10)
does
not
use
the
under‐floor
heating
and
uses
an
electric
heater.
Internal
temperature
 readings
also
confirmed
that
Flat
10
maintains
a
lower
temperature
band
than
the
other
flats
there
 requires
less
energy
to
heat
the
flat
to
optimum
temperature
 



 

 
 

 

 Actual
Energy
Use
 
 Weather
Correction
 
 Exposure
Correction
 
 Occupancy
Correction


Building
Annual
Energy
Use
(kWh/m2/year)
 
 
 Flat
10
 Flat
29
 
 
 Electric
 Electric
 

 
 2780
 7905


Corrected
Energy
Use
 
 NPI
kWh/m2/year
 
 

 



 Flat
38






Flat
50
 



Electric
 



Electric
 


13338


9572


1362


393


14496


1557


1498


433


15946


1713


3792


6277


13603


9521


3792


6277


13603


9521


72
 



158
 



236
 



197
 



















U
s
i
n
g


t
h
e


B
e
d
z
e
d


B
e
n
c
h
m
a
r
k
.
 Bedzed
stated
that
they
consumed
34.4kWh/m2/year
in
2007.
 When
comparing
Bedzed
to
Thackley
End,
it
was
noted
that
Thackley
Ends
lowest
case
study
flat
energy
 consumption
 doubles
 that
 of
 Bedzed’s.
 A
 result
 of
 considerable
 cause
 for
 heat
 losses:
 limited
 building
 fabric
 insulation,
 single
 glazing
 and
 cold
 bridging
 via
 means
 of
 the
 window,
 it’s
 frame,
 and
 the
 continuing,
thermally
unabridged
concrete
slabs
and
block
work.
 There
is
definitely
ample
opportunity
to
improve
Thackley
End‘s
energy
efficiency.



S
a
n
k
e
y


D
i
a
g
r
a
m
s
.
 The
Sankey
diagrams,
as
shown
below,
show
how
annual
energy
consumption
is
distributed
between
 base
loading
and
heating
load.
The
lowest
energy
consumption
months
was
taken
as
the
base
load
(as
 shown
in
energy
use
compared
to
degree
days
graphs).

 The
Sankey
diagram
shows
Flat
38
to
have
a
very
high
base
load
and
low
heating
load.
It
is
presumed
hat
 this
is
an
anomaly
caused
by
the
resident
changing
their
fuel
bills
from
3
to
6
months.
Therefore,
when
 the
bill
figure
was
divided
by
6(
to
get
a
monthly
figure
for
CUSUM
/
Control
charts)
the
same
energy
 consumption
figure
was
given
for
each
month.
Therefore
odd
findings
ensued,
most
notably
with
the
 base
load
being
greater
than
the
heating
load
(under
normal
circumstance
this
ratio
should
be
the
other
 way
round).
 
 



 



H
e
a
t


D
i
s
t
r
i
b
u
t
i
o
n
.


L
o
g
g
e
r


D
a
t
a
.
 
 In
these
diagrams
we
can
see
the
heat
distribution
within
the
 flat
types.
The
key
relates
to
the
temperatures
measured
by
 the
loggers
(ranges
from
minimum
to
maximum
recorded).
 Temperatures
were
recorded
between
12
noon
to
2
pm
in
 the
day.
 Evidence
of
heat
loss
through
the
exposed
walls
was
 recorded
from
temperature
being
of
a
lower
recording
when
close
to
said
exposed
wall.
Although
with
 double
/
triple
glazed
units
in
their
flats,
Flats
29
and
10
still
proceeded
to
lose
heat
through
the
 exposed
walls.

 During
the
analysis
period
the
loggers
also
recorded
some
 extremely
high
temperatures
in
the
flats,
and
as
high
as
250C
 in
some.
Due
to
high
levels
of
glazing,
extreme
peaks
in
 temperature
can
be
recorded
in
the
day
as
a
result
of
solar
 irradiance.

This
glazing
can
also
cause
heat
loss
issues
in
 winter
months.
 



H
e
a
t
i
n
g


S
y
s
t
e
m
s


A
n
d


T
a
r
i
f
f
.
 Thackley
 End
 flats
 were
 built
 with
 underfloor
 electric
 heating,
 however
 few
 of
 these
systems
sill
work.
So,
some
occupants
have
installed
storage
heating
and
 electric
heaters
to
cater
for
their
thermal
needs.

 Predominantly
 residents
 use
 the
 Economy
 7
 tariff
 which
 is
 utilised
 by,
 and
 preferable
 to,
 night
 storage
 heaters.
 This
 is
 because
 it’s
 tariff
 is
 structured
 and
 priced
 differently
 in
 regards
 to
 time
 of
 day.
 Electricity
 costs
 are
 significantly
 reduced
in
the
evenings
and
so,
to
reduce
energy
costs,
storage
heaters
are
used

 to
retain
energy
for
heating
the
flat
at
a
useful
time
in
the
day
/
evening.

 The
 thermostats
 in
 some
 of
 the
 flats,
 in
 particular
 flat
 38,
 showed
 that
 the
 residents
had
little
control
over
switching
the
heating
on
and
off.
As
noted
in
the
 late
 Occupant
 Survey,
 the
 occupant
 at
 Flat
 38
 mentioned
 this.
 When
 the
 Economy
 7
 is
 working,
 they
 have
 no
 control
 over
 the
 heating
 level,
 using
 the
 thermostat.
Also,
having
the
under‐floor
heating
turned
off
in
the
day,
can
result
 to
 uncomfortably
 cool
 temperatures
 in
 the
 early
 evenings
 before
 the
 heating
 turns
on.
 Therefore
it
seems
it
may
be
beneficial
to
change
occupants
onto
a
green
energy
 tariff
 as
 this
 may
 lead
 to
 occupants
 being
 able
 to
 control
 their
 heating
 at
 all
 periods.
 In
the
images
on
this
place
we
see
how
radiator
systems
and
under‐floor
systems
 distribute
 heat
 differently.
 Radiator
 systems
 (pictured
 in
 the
 plans
 to
 the
 right)
 create
 pools
 of
 thermal
 irradiance
 around
 the
 radiator
 source.
 This
 gradually
 heats
the
air
n
the
space.
There
is
a
lot
of
localized
temperature
difference
in
the
 room,
and
thermal
delight
can
be
very
different
dependant
on
your
positioning.
 Under‐floor
heating
systems
(pictured
below)
heat
the
space
from
floor
level
upward,
radiating
through
 the
 air
 and
 heating
 the
 space
 evenly.
 By
 putting
 a
 gentle
 heat
 sources
 also
 at
 the
 point
 where
 we
 physically
connect
with
the
room
(our
feet)
the
perceived
comfort
becomes
much
greater.
Under‐floor
 systems
 seek
 to
 store
 heat
 also
 in
 the
 building
 fabric,
 to
 slowly
 radiate
 heat
 throughout
 the
 day.
 Radiator
systems
however,
do
this
but
to
a
much
lesser
 degre e
 of
 succe ss.
 



A
p
p
l
i
a
n
c
e
s


L
a
y
o
u
t
.
 
 
 
 
 
 
 
 
 
 
 
 These
 diagrams
 show
 the
 locations
 and
 appliance
 types
in
the
case
study
flats
analysed.
 Flats
 with
 a
 large
 number
 of
 appliances
 and
 electrical
 goods
 will
 have
 a
 resultant
 high
 plug
 load
 /
 energy
 demand.
 This
equipment
also
 transpires
 heat
 throughout
 it’s
 use,
 which
 can
 further
 increase
 internal
 temperatures.
This
can
be
undesirable
to
the
flats
due
to
their
 relatively
small
size
and
current
problematic
solar
gain.
 Flat
10
(pictured
left)
had
the
highest
recorded
plug
load



















 of


the
Thackley
End
case
study
flats.


This
graph
shows
the
appliance
loads
for
the
individual
flat Flat
10
has
the
highest
appliance
energy
use
whilst
Flat
40
 least.



R
e
c
o
m
m
e
n
d
a
t
i
o
n
s
.
 No
Cost
Measures.
 Changing
 the
 electrical
 suppliers
 to
 an
 energy
 efficient
 company.
 Examples
 of
 these
 are

 Ecotricity
and
Green
Electricity
UK.

 However
 research
 must
 be
 carried
 out
 when
 changing
 electricity
 companies,
 due
 to
 some
 companies
charging
more
for
using
Economy
7
tariff
during
peak
times
than
for
standard
tariffs.



 Low
Cost
Measures.
 Fix
 the
 system
 of
 thermostatic
 controls
 to
 allow
 better
 localised
 control
 of
 the
 heating
 for
 occupants
 with
 under‐floor
 heating.
 As
 well
 as
 being
 a
 practical
 solution
 this
 improves
 the
 wellbeing
of
the
occupant.



 Medium
Cost
Measures.
 Upon
 exhaustion
 of
 current
 appliances,
 replacements
 should
 be
 A
 –
 if
 possible
 A+
 rated
 for
 energy
efficiency.
These
will
save
on
energy
consumption
and
resultant
costs.
 Replace
 existing
 stock
 of
 single
 glazed
 /
 steel
 framed
 windows
 to
 double
 glazing
 to
 reduce
 excessive
heat
losses.
 
 
 
 



2008 Research Paper - P.O.E. Energy Audit. Energy Audit (Part 02)