8/20/2019 Gpcs 278 http://slidepdf.com/reader/full/gpcs-278 1/4 G o o d P r a c t i c e W L d o British Telecom maintains office refurbishment improvements as part of its energy management programme Telephone House Edinburgh over 40 sustained by close monitoring Refurbishment ed to major Gas heating costs down by Electricity consumption for lighting beats current good practice target Good energy performance and a corporate commitment to energy management savings in building energy costs ‘ nergy efJiciency improvements from refurbishment 99 nd energy management B E S T P R A C T I C E P R O G R A M M E
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G o o d P r a c t i c e
W L
d o
British Telecom maintains office
refurbishment improvements as part
of its
energy management programme
Telephone House
Edinburgh over 40 sustained by close monitoring
Refurbishment ed to major
Gas heating costs down by
Electricity consumption for lighting
beats current good practice target
Good energy performance
and a corporate commitment to
energy management
savings in building energy costs
‘ nergy efJiciency improvements from refurbishment
9 9
nd
energy management
B E S T P R A C T I C E P R O G R A M M E
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H O U S E
ofllce accomm 4dBUm showlng the extenslve
use
of t sk lighting
hone exchange and mainly open p lan
e accom modation for B ritish Telecom (BT).
i n g wa s r e f u r b i s h e d i n t h e l a t e
es, and has been successfully managed
sustain redu ced energy costs as part of BTs
the saving s that can
to
ET'Scorporate commitment to
refurbishment provides better conditions for
t e rs and assoc ia ted
- and g rea t ly
cruciform p lan (see figure 1)
ven-storey wings
in g f ro m a c e n t r a l c o r e , wh i c h i s
y a cen t ra l p la n t room. The
at ion possible. Mechanical air ha ndling
to a uni t that suppl ies
units. The
par t of the refurb ish men t , the f ia t - roof
grade the insu lation to current standards.
U-values were greatly improved by
c h a n g e s a f f e c t i n g e n e r g y
ires an d a
l l in g a b u i l d i n g e n e r g y m a n a g e m e n t
d energy performance was achieved, and
een susta ined, despi te adverse
f a c t o r s s u c h a s h i g h u s a g e o f o f f i c e
e q u ip m e n t , m o d e s t i n s u ia ti o n s t a n d a r d s ,
24-hour operation of some departments, and a
large catering facility
Ga s c o n s u m p t i o n f o r s p a c e a n d DHW
(domestic hot water) heating was re duced by
over 40 to 92 kWh/m* of treated area: this
approx imateiy matche s the 'good p ract ice '
value, and is iess than haif the 'typical' value
Suggested in EEO Energy Consumption Guide
191'1 for naturally-ventilated, mainly ope n plan
office buildings (type 2),
Elect r ic i ty consumpt ion for l ight ing is now
b e t t e r th a n t h e g o o d p r a c t i c e l e v e l [ l l f or
comparable buildin gs, but the h igh density of
office equipment means that overall electricity
consump t ion (91 kWh/m2 o f tr ea ted a rea ,
excluding computer suite) is Still higher than
the Guide's suggested go od practice yardstick
valu e of
61
k W h M
Heating
Two 586 kW conventionai. gas-fired boiiers,
located in the rooftop plan t room, deliver hot
water via zoned circuits
to
perimeter convector
heaters throughout the building. The ent ire
system is monitored and cont ro l led by the
BEMS, which is programmed to allow each
o f f i c e t o b e h e a t e d i n a c c o r d a n c e w i th
predicted occupancy times. Heat levels are set
by room temperature sensors which control
diverier valves in the water supp ly circuit.
A branch distribution circuit provides heating
for the can teen's a ir h andi ing uni t , and for
convectors in the g round fioor reception area.
Domestic hot water
Two
87.6
kW direct-fired gas boilers for DHW
suppiy have replaced the original calorifiers in
the rooftop plant room. Another, similar boiler
is installed in the ground f loor kitchen, and
supplies DHW for this area. Neither system
uses central hot water storage.
Catering
E le c t r i c i t y a n d g a s a r e u s e d i n k i t c h e n
equipment, in a telephone operator's rest r w m
catering facility, and in drinks vending machines
that are iocated throughout the building.
Flgure Typical floorplan
Lighting
T h e b u i l d i n g s h a p e a l i o ws d a y l i g h t to
most areas. Ar t i f ic ia l l ight ing in the of f ice
a c c o m m o d a t i o n i s m a i n l y b y r e c e s s e d
t w in a n d q u a d r u p le f l u o r e s c e n t t u b e s ,
c o m p l e m e n t e d b y c o m p a c t f i u o r e s c e n t
d o wn i i g h t e r u n i t s a n d d e s k l a m p s u n d e r
individual controi.
These units usually p rovide adequ ate lighting
by themselves, ailowing main area ligh ting to
b e left off altogether. Central access areas in
mOSt of f ic es, an d
ail
to i le ts , have com pact
fluorescent down lighter units.
Building energy management system
A BEMS. installed dur ing the refurbishment,
mon i to rs and la rge ly con t ro ls a l l hea t ing ,
cooling and mechanical ventilation systems in
Telephone House - t also monitors systems in
other BT buildings n Scotland.
There are weather-compensated daily heating
programmes for 29 zones, and data handiing
programmes aliow detection of trends through
quick ana lysis of monitored informa tion.
Mechanical ventilation and
air-conditioning
The ventilation system which serves the dining
r o o m h a s a h e a t e r b a t t e r y t o wa r m t h e
incoming fresh air, served by low pressure hot
water from the spa ce hea ting system.
The compu ter suite, an d areas where solar and
off ice equipment heat gains are highest, are
coo led b y Small, self-contained air-conditioning
units. Elsewhere, cooling and natural ventilation
is achieved b y manually opening the windows.
Analysis
of
nergy consumption
and cost
Figure 2 shows a breakdown of annual energy
u s e a n d c o s t s , b a s e d o n m o n i t o ri n g fr o m
Oc t o b e r 1 9 9 0 t o Se p t e m b e r 1 9 9 1 ( 2 5 2 6
degree-days). D uring that t ime, the buiiding
consume d abou t 978
000
kWh of gas and
1.4 million kWh of electricity, co sting
f1
232
and f66 704 respectively. About 31
o
total
e lec t r ic i t y i s used in t he compute r room,
leaving a balance for offices of 961 940 kWh.
The total energy Consumption for the building
is slightly in excess of ' g w d pract ice' leve lsl~l.
This is mainly due to the extensive use o f small
power loads for office equipment -w hic h has
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TELEPHONE
H O U S E
Energy cost (pencelft2n
50 Services
i : : ; : ; / : : : , : ; ~ ;;:,:.:
: : : : : : : : : : : : :
. . . . . . .
ating
w
Hotwater Cooling
w
Fans,
pumps, controls
Offlce
equipment
Flgure2 Annual energy use and cost for Telephone House, Edinburgh
Refurbishment bulldlng, eam Building detalls Fabrlc U-values following
architect: Purpose-built office and telephone exchange
Wshment Wh2K)
Cove1 Matth ew Partne rshi
accomm odation, completed in 1973 and
refurbished in 1988.
Heatlng and ventilatlng contractor:
James Scott Ltd Floors.
......
Energy manager:
Gross floor area:
Arthur Nicholson
Treated floor area:
(brick-cavity-concrete block,
1.6
lnrl uninsulated):
Roof
O
m2
(including suspended c eiling
lO 60 8m * and insulation): 0.45
Suppliers
There may b e other suppliers of similar energy
efficient equipment in the market.
Nett floor area: 8462 m2 Windows
Computer suite
(include d in above):
Typical numb er of occupants:
Typica l hours of use:
(Some areas, eg computer
suite. are always occupie d)
etai sliding frames with sliding sec ondary
azing and internal blinds): 2.9
Energy efficiency in offices. A technical
ide for owners and single tenants, Energy
onsumption Guide 19. London, EEO, 1991.
Natural ventilation in non-domestic
180
ildings. ERE Digest 399. 1994.
resulted in a microcomputer on every desk.
However, the gas consum ption is considerably
better than 'typical' offices of this type, and the
electricity use is comparable.
Heating
66.0 kWh/m*
6.1
plsq
l l
Heating energy use is very low despite only a
moderate standard of building insulation and
24-hour operation of some departments. This is
due
to
the applica tion of appropriate controls
to
suit the high internal equipment hea t gains.
W
Hot water
7.4
kWh/m2
0.7 Plsq ft)
Hot water energy use is small for a building of
this size with catering kitchens an d distribution
mains operational throughout the year. The
absence of a centrai hot water storage facility
(with associated standing heat losses) is a
major con tributory factor.
Oftice equlpmeni
36.2
kWhlm2
16.8 plsq
ll
Th is h igh f i gu re i s l a rge iy a t t r i bu tab le to
desktop compu te rs , p r i n te rs , p io t te rs and
copiers, as well as desk lighting and personal
fans, etc. There is approximately one PC or
terminal for evely person and this is unlikely
to
change in the near future.
Many of these units are continually switched
on The buiiding is open 24 hours a day for
shift work, therefore computers are used for 24
hours.
T h e o f f i ce e q u i p me n t i s m o s t ly e ve n i y
d i s t r i b u t e d a b o u t t h e b u i i d i n g , a l t h o u g h
Some areas have a higher concentration and
ca n e xp e r i e n ce e xce ss i ve l y h i g h sp a ce
temperatures during warmer weather.
These areas have been equipped with local
packa ged air-conditioning units w hich results
in an increase in energy consumption.
Caterlng 26.0 k W m 2
23 /sq
It
gas and
3.9 pbq
ft electric)
The gas figure (18.9 kWh/m2) and electricity
(7.1 kWh/mz) are high in comparison with other
offic es. This is large ly due to the extensive hours
of occupancy of the building and the avaiiability
of hot meals and snacks, six da ys per week.
w
Cooling
7.1
kWh/mz
3.1
p/sq
fl)
The cooiing load has increased significantly
a l o n g w i t h t h e g r o w i n g a mo u n t o f o f f i ce
equipment during the life of the building, and
cooling equipment has been required in areas
of h igh concentration of VDU terminals, etc.
Fans and pumps
2.2 k W h W
0.4 plsq
ft)
Energy consumpt ion is low for the size o f
bu i ld ing an d re f lects the m odest extent o f
systems instalied.
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E N C Y I N O F F I C E S
~
Llghtlng
28.0
k2
[ .5 plsq
n)
i th
Miscellaneous
8.0 kWh/m*
ma de up of vacuu m c ieaners ,
nce equipment and l if ts, telecoms
ced ene rgy
m these improvements
pant and computer density were deait with
echanica l vent ila t ion. In i t ia l advers e
n tempe red b y fami l ia r ity o f use.
er lights have a rating of
W, opposed to 112W for a typica l luminaire.
the co mpletion of the refurbishm ent, the
e l i -contro lled bu i ld ing wi th
73p per
of these
are sustained by BT s corporate
to
energy management.
pens ated zone control of the heating
s f u l . T h e zo n i n g a n d
b i n e d t o a vo i d t he
or the whole bui lding to b e
cost-effective manner and allows the heating
h a low energy expenditure. A
not overheat.
13.5 p/sq It)
nates
on the measurement
of
area
oss To ta l bu i l d in g a rea me asu red
inside extern al wails
t Gross area less com mon areas
a n d a n c i l l a ry sp a ce s A g e n t ' s
lettable floor a rea
oth r
areas (eg stores).
nd
directly
heated
Downllghtera to central
core
areas
The add i t i on of secon dary g laz ing has
improved the bu ilding's insulation and comfort
standards for a modest investment. The fioor
to ceiling height of
2 .4
m with a pian width of
12.5 m are wi th in good pract ice i imi ts for
natural ventilation. BRE Digest 399121 confirms
t h a t t h i s w i d t h t o h e i g h t ( r a t i o 5 : l )
approximates the rule of thumb for cross-
venti lating b ui ldings with moderate to high
heat gains.
Economical l ighting is achieved by install ing
efficient luminaires and lamps throughout the
bui ld ing. Th is low insta i led power ioad is
augmented by menuai and automatic controls,
and good management.
Table 1 compares the total electricity and gas
use with typical figures for a medium-sized,
Type 2, naturally-ventilated, open pian building
(Energy Consum pt ion Guide 191 1). It also
shows the impl ied s avings t ransla ted in to
reduction of
CO,
emissions.
The total Oz savings of 19 kgim2 represent
an ann ual saving for the o ffice of 201 552 kg.
Main concluslons
The low energy consumption for heating has
been achieved in spite of the fact that the
thermal characteristics of the 1970s structure
are relatively poor. The effectiveness of zone
controls to take full advantage of internal heat
ga ins has been a ma jo r fac to r i n th i s
performance.
At Telephone House the comm on and wasteful
p rac t i ce o f open ing w indows to a i l ev ia te
