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PHOTOGRAPHS: ROBERT GRESHOFF

ELIZABETH FRY BUILDING PROBE
When natural ventilation was
all the rage, a novel form of
mechanical ventilation was
quietly slipping into Britain:
the Swedish Termodeck
system. One of the first
buildings to use Termodeck
and other Swedish detailing
was an academic facility at the
University of East Anglia. How
has it fared?
BY THE PROBE TEAM

14: Elizabeth Fry
Building
T

he Elizabeth Fry (EFry) Building, occupied in January 1995, is the most recent
low energy building commissioned by
the University of East Anglia (UEA). It is the
last of a group of new buildings on the western
edge of the Norwich campus, which started in
the 1980s and includes the Constable Terrace
student residences and the Queens Building.
For an in-depth details of the building’s
construction, readers should look at the original building analysis ‘Teaching low energy’
(Building Services Journal, April 1995)1.
Basically, the building has a gross floor
area of some 3250 m2 (3130 m2 treated floor
area) over four storeys. Its north facade is on
the site perimeter road, while the south side
faces Constable Terrace across a courtyard/
car park.
The top two floors contain 50 cellular offices for about 70 staff. The School of Social
Work is mainly on the first floor, with the
School of Health Policy and Practice on the
second floor. The lower ground and ground
floors contain lecture and seminar rooms,
bookable by the whole university. For the
conference trade, there are also two dining
rooms and a small catering kitchen on the
second floor.
The position, height and external style of
EFry, including its rendered and concrete
block external finishes, was very much dic-

tated by earlier buildings on the site. Finishes
are of a high quality and more reminiscent of
stylish business premises than most academic
establishments, even though cost levels were
normal at £820/m2. On the north side a curved
projection identifies the main entrance, which
leads to a pleasant narrow atrium reaching up
to roof level. Lecture theatres on the lower
ground floor have their own separate entrances
on the south side.
Construction details
The design team has produced a well insulated, tightly sealed and triple-glazed building
envelope to meet the client’s low energy criteria1. This included double-skin blockwork
walls with 200 mm insulated cavity, and nylon
wall ties to reduce thermal bridging.
All floors including the top floor have exposed structural ceilings made of ventilated
hollowcore slabs. The roof has 300 mm insulation, with 100 mm insulation applied to the
exposed floor soffits of rooms over the upper
ground floor perimeter walkway on the south
side of the building.
The windows use low-E, argon-filled triple
glazing with an inner sealed unit, mid-pane
perforated metal venetian blinds in the outer
cavity, and external protective single glazing.
These were carefully detailed to minimise
cold bridging and air infiltration, and included
BUILDING SERVICES JOURNAL APRIL 1998

a heavy-gauge polythene seal to the inner leaf,
which was beaded and plastered.
These unusual features required clear explanation to the site workers and special checking of critical details before being concealed
by internal finishes. The process benefited
from the previous experience of the UEA’s
Clerk of Works and the co-operation of main
contractor Willmott Dixon. The contractor
was obliged to meet the airtightness specification by pressure testing at the end of construction (see box “BSRIA pressure test”).
The Clerk of Works felt that all went well
generally, but would have preferred stainless
steel wall ties. The weaker nylon ties had to be
fitted at four times the normal density, while
the extra bridges across the cavity meant lots
of extra cutting and scribing of the mineral
wool slabs. The Clerk of Works also thought
the gaps so created may have undermined
any theoretical benefits attributable to the
lower thermal conductivity of the ties.
Servicing arrangement
The designer considered natural ventilation,
but opted instead for the Swedish hollowcore
system Termodeck. As a floor slab, this is
both a structural component and a means of
ducting ventilation through the building2,3.
EFry was the second UK building (after
Weidmuller Klippon Microsystems in West
E20

PROBE ELIZABETH FRY BUILDING
Malling) to use this technique. By enhancing
access to the thermal capacity of the structure,
Termodeck offers the opportunity for yearround tempering of incoming fresh air.
Due to its innovative nature, detailed monitoring of the EFry Building’s energy and environmental performance between January 1996
and August 1997 has been carried out by
Databuild under a joint BRE/BRECSU contract. The BRECSU’s report is due to be published shortly.
In the offices and seminar rooms, air is
supplied to the hollowcore slabs via stubs
from ducts running above suspended ceilings
in the corridors. After three passes through
the ceiling slabs, the air enters the rooms via
annular soffit diffusers. Return air is extracted
from behind the ceiling cornice and back to
the air handling units (ahus) via the corridor
ceiling plenum.
In the main lecture theatres, the air from the
ceiling cores is ducted down to wall-mounted
displacement terminals. The cores can only
handle one-third of the design maximum air
volume. The rest is supplied from under the
floor, via a damper which is controlled only to
open during occupied hours. Return air is
again via the cornice.
The windows have inward-opening casements, typically 300 mm wide by 1200 mm
high. These are a key element in the mixedmode approach, giving occupants adaptive
opportunity to overcome discomfort.
Four supply/extract ahus are located in
four separate plantrooms on the lower ground
floor. The ground floor seminar rooms and the
first and second floor offices in the west end of
the building are served by ahu A. It has a threespeed fan (respectively for offices only, seminar rooms only and both).
The main lecture rooms are served by ahu
B, which has a cross-flow heat exchanger with

An IT resource room is located directly above the main entrance, and follows the gentle curve of the elevation.
Note the row of annular soffit diffusers connecting directly to the exposed Termodeck slabs.

damper-controlled by-pass. The inverter-controlled variable volume fans normally operate
at low speed, passing air via the hollowcore.
Return air quality is monitored using CO2
sensors, with fan speeds raised and the dampers to the floor voids opened accordingly.
AHU C serves two lecture rooms and an
adjacent computer terminal room. A constant
volume unit, ahu D, serves a variety of accommodation on all floors at the east end.
The heat recovery system for ahus A and D
is based on high-efficiency Regenair heat
recovery units2. These use metal heat exchanger packs to absorb heat from the exhaust air stream.
The airflow between the intake and exhaust ducts is mechanically reversed once a
minute, allowing the pack to impart its heat to

CO2 emissions and electricity consumption data

FIGURE 1: End-use energy breakdown at the Elizabeth Fry Building. Total CO2 emissions of 44 kg/m2/y are
just over half the low-to-medium academic benchmark of 82 kg/m2/y. This is less than half of the ECON 19
good practice benchmark for a type 3 office (96 kg/m2/y), and in the good practice bracket for simple,
naturally-ventilated offices. Conversion factors are gas: 0·2 kg CO2/kWh and electricity: 0·6 kg CO2/kWh.

E21

BUILDING SERVICES JOURNAL APRIL 1998

the incoming air while its twin is being regenerated in the exhaust stream.
Flow reversal (and recirculation if required)
is achieved using a set of fast-acting, mechanically-linked dampers. The system claims to
recover 85% of the available heat, a figure
verified by the monitoring, though the maintenance staff say that it is now closer to 80%,
suggesting that the heat recovery packs may
need cleaning.
Experience has shown that no additional
heater battery power is required at increased
volumes: the occupancy gains and the heat
recovery is enough. In fact, the design heat
loss is only 15 W/m2.
Heating and hot water
Three 24 kW domestic condensing boilers
(with 50% standby/reserve capacity) supply a
65°C lphw circuit to the ahu heater coils.
During the PROBE survey, with outside air
temperatures of 8-9°C, the boilers were not
required all day.
Maintenance staff said that the lecture room
plant always brings on the boilers first, owing
to their less efficient plate exchangers and
periods of low occupancy and internal gains.
The boilers are not sized for the (unlikely)
event of the heat exchangers being out of
service. If they were, they and the heater
batteries would have been very much larger,
more expensive, and almost undoubtedly less
efficient in operation.
The standard Swedish specification for
Termodeck includes low-power – often electric – perimeter heaters in each room. In view
of the milder UK climate, it was decided to
omit them from the EFry Building with a view
to revisiting the decision once the building
was in use.
To date, the UEA has installed six 200 W
electric panel heaters. These are all in rooms
with marginally higher-than-average heat
losses due to greater exposed external surface area, such as the first floor offices above
the ground floor external walkway on the
south side.

ELIZABETH FRY BUILDING PROBE
Control issues
The EFry Building was initially fitted with a
basic system of stand-alone controls and sevenday programmers. After completion it soon
became apparent that the system did not enable the maintenance team to understand
how the various systems behaved.
In addition, a number of teething problems
were identified, including slab temperature
sensors fitted near the inlets to the hollowcores
instead of near the outlets as specified.
Aware that in a thermally stable building
any reported comfort problems would come
too late for corrective action, the UEA opted to
incorporate EFry into a new Campus-wide
Trend bems system. Replacement Trend outstations feed data back to a supervisor pc in
the Estates and Buildings Division offices.
The new bems has allowed the control
strategy and settings to be fine-tuned and
simplified. During winter and summer the
system maintains a core temperature set-point
of 22°C. There is no winter/summer switch.
Heating plant can operate during the summer
if conditions demand, although the extremely
stable temperatures mean that this has rarely
happened in practice.
For heating there is a 0·5°C deadband below the 22°C set-point, heating being enabled
if the core temperature drops below 21·5°C.
During hours of occupancy, there is full fresh
air with heat recovery if heating is required,
the heater batteries only operating (with a 15minute delay) when heat recovery alone is
insufficient. If heating is required outside occupancy hours, the ahus operate on full
recirculation.
For cooling, the deadband is 1°C above the
22°C set-point. During occupied hours the
ahus operate on full fresh air, but during
unoccupied hours after 22.00 h the fans will
operate if core temperatures are above 23°C,
and when outside temperatures are at least
2°C less than the core temperature.
The facilities team has learnt that the original strategy to provide boost preheat to the
slab overnight in winter was seldom necessary. This simply resulted in surplus heat
being expelled by the ahus the following day.

rated blinds under photoelectric control. During the PROBE survey the blinds remained
closed despite overcast external conditions,
possibly because control of the blinds may
have been overridden by the occupants.
Energy analysis: electricity
EFry is a non-residential academic building,
so the most appropriate yardsticks to benchmark total energy consumption values are in
the EEO Yellow Book Introduction to energy
efficiency in further and higher education5. The
only relevant yardsticks available for an enduse breakdown of electricity consumption are
those in ECON 19 for offices.
While the EEO Yellow Book benchmark
for electricity consumption places low at below 75 kWh/m2 and high above 85 kWh/m2,
the EFry Building falls between the ECON 19
type 1 (naturally-ventilated, cellular) and type
3 (air-conditioned, open-plan). That said, a
type 3 office is more instructive as monitored
summertime conditions in EFry are equivalent to or better than an air-conditioned office.
The treated floor area of EFry used as offices
amounts to a third of the total, so the office

benchmarks should be used with discretion.
Total electrical consumption in 1997 was
191 MWh or 61 kWh/m2/y. Consumption
was unchanged on the 1996 usage and about
5% up on the figure for 1995, probably due to
increased occupancy and equipment levels.
The figure of 61 kWh/m2 /y is 20% below the
good practice figure for academic buildings of
75 kWh/m2/y, and under half that used in a
good type 3 office.
End-use breakdown at EFry (figure 1) has
been calculated using the normal PROBE
reconciliation technique, but where available
actual consumption data for loads monitored
by Databuild.
Fans, pumps and controls account for about
18 kWh/m2/y, nearly all of this attributable to
the fans. The heating and gas-fired hws comprises just one set of run/standby circulating
pumps each of 550 W and 275 W respectively
which, together with an estimated 1200 h of
full-load boiler operation per year, contribute
to a consumption of less than 1 kWh/m2.
Fan consumption is about 18 kWh/m2, half
that of a good type 3 office, despite the considerable number of slab night-cooling hours.

Results from the occupant satisfaction survey

FIGURE 2: Overall satisfaction with comfort conditions at the Elizabeth Fry Building.

Lighting design
Most room lighting is by high frequency
fluorescents concealed beneath the ceiling
cornice, normally on both the corridor and
the window walls.
However, the penalty of this indirect lighting is reduced efficiency, with relatively high
installed power densities of between 15 and 30
W/m2, as against a good practice office standard4 of 12 W/m2.
Desktop illuminance levels of 420 lux were
measured with lights on and blinds raised,
with measured levels of 310 lux with the
blinds lowered. This suggests a typical lighting efficacy of around 7 W/m2/100 lux, as
against a good practice standard of 3 W/m2/
100 lux. In offices, manual pull switches have
replaced the original wall switches which became obscured by filing cabinets.
A south-sloping rooflight in the entrance
foyer atrium has motorised external perfo-

FIGURE 3: Occupant satisfaction with the building’s health, management and control strategies.

BUILDING SERVICES JOURNAL APRIL 1998

E22

PROBE ELIZABETH FRY BUILDING
Installed fan power for the two main ahus is
5·2 kW for ahu A (three-speed) and 7 kW for
ahu D (fixed speed). This amounts to a total
of 12·2 kW, providing a supply volume of 5·5
m3/s, equating to a specific fan power of 2·2
W/litre/s. This is similar to the ECON 19
good practice level of 2 W/litre/s, though
well above the low-energy target of 1 W/litre/
s. Commissioning results confirm this figure,
with specific fan powers of 2·2 and 2·3 W/
litre/s respectively for ahu A (at high speed)
and ahu D.
The two ahus serving the lecture theatres
have a total installed power of 10·4 kW and
supply rates of 3·2 m3/s, giving a specific fan
power of 3·3 W/litre/s at full speed. In practice, the variable speed drives on these ahus
ensure that the fans rarely operate at more
than half speed (and usually less).
The significant energy saving potential of
variable speed drives is revealed from the
individual fan consumption monitored for
BRECSU. Equivalent annual full-load operating hours (calculated by dividing the annual
fan consumption by the installed fan power)
for the fixed-speed ahu D is 4300 h.
As expected, this is longer than the total
occupied hours of 2500 h/y due to considerable hours on during summer nights for slab
cooling, in addition to shorter periods topping-up the heating during unoccupied periods in winter.

The ahus with variable speed drives serving
the lecture theatres run for only 130 h and 600
h at full-load equivalent, despite running all
2500 occupied hours and for night cooling.
The fan laws and efficient drives offer huge
energy savings with variable speed control.
At 26 kWh/m2/y, lighting consumption is
similar to a good type 3 office, but nearly
double that for a good type 1 cellular office.
Installed lighting loads are at typical (for a type
3 office) rather than good practice levels, averaging 20 W/m2 in offices and 12 W/m2 in
corridors.
Total consumption reflects the long operating periods of lighting in circulation areas
which is manually key switched during security rounds at the start and finish of each day,
together with the unnecessary lighting of unoccupied seminar and lecture theatres.
Some use of daylight or occupancy-sensed
light switching in communal areas and lecture
theatres could reduce the lighting consumption significantly. This was cut from the original specification.
The catering kitchen on the first floor is
used relatively infrequently to prepare refreshments and serve meals (cooked elsewhere).
The staff common room includes an electric
hot water boiler for making tea and coffee, and
many offices also have kettles. Hence the
electricity use for catering is 5 kWh/m2/y.
The six 200 W retrofitted electric panel

DESIGNERS’ FEEDBACK
From our point of view, we are of
course extremely pleased to see the
combination of very low energy use
and good comfort conditions coming
out of the PROBE investigation, write
Andrew Ford and Richard Brearley1.
Elizabeth Fry is one of those buildings
where everybody's efforts have
combined in a positive manner.
The idea of low energy was
introduced powerfully at the very first
design team meeting. A panel of
independent experts assembled by
Fulcrum openly discussed all the
issues with the architect and the rest
of the design team.
From this point on, the design team
understood the issues and took on
board fully the design implications of
the desire to achieve comfort without
air conditioning.
These ideas included keeping the
building surfaces very close to normal
room temperatures, and the avoidance
of any very high or very low
temperature heat sources.
Easily reached openable windows
were also regarded as vital to provide
contact with the outside. This is as
important for the sound of birds and
voices as it is for fresh air and control
over temperature.
Avoidance of draughts, accidental
air leakage, good thermal insulation

E23

and limiting excessive glazing were
also major objectives.
From the services engineer’s
perspective, it was important to
restrain from installing anything that
might be avoided and keep everything
to the minimum size calculated for the
building rather than the plant.
Termodeck allows this because of its
immense capacity to even out
fluctuations.
Termodeck, two years study and
monitoring by BRE plus regular
feedback sessions between users,
designers and monitoring contractors
enabled faults to be identified. It also
ensured that energy use fell constantly
from its initial very low level with no
inconvenience of the occupants due to
the nature of the heat sources.
The most serious problem we faced
was the capital savings made at the
project’s inception. This removed the
front-end control interface which
subsequently limited feedback on the
controls. Such feedback is essential in
a building whose inherent
characteristic is to respond to changes
over days, not minutes.
1

Richard Brearley Dipl Arch RIBA is an
architect with John Miller + Partners,
and Andrew Ford CEng MCIBSE is a
partner at Fulcrum Consulting.

BUILDING SERVICES JOURNAL APRIL 1998

heaters account for 0·2 kWh/m2/y, while the
local electric water heaters account for 1·7
kWh/m2/y. The estimated electricity consumption of office equipment is 8 kWh/m2/y.
Each office has a pc and a printer, with two IT
rooms providing a total of 25 pcs for students.
Office equipment densities are generally
low. Over the whole treated floor area, average installed load density is 4 W/m2, much
less than might be expected in a type 3 office.
There is no mechanical refrigeration at
EFry, the extended operating hours of the
fans to achieve night cooling of the Termodeck
being the closest comparison. Despite this,
comfortable conditions are achieved with typical office internal heat gains of about 40 W/m2
(considerably more than this in the lecture
theatres and seminar rooms when occupied).
Interestingly, using data from Databuild’s
technical report, the coefficient of performance (heat removed/electricity input) of the
additional night ventilation used for fabric
cooling can be estimated as 5·8. This strategy
also benefits from using night rate electricity,
which is both cheaper and less CO2 intensive.
Energy analysis: gas
Office areas are normally occupied between
08.00 h and 18.00 h weekdays, but the building is open for use between about 07.00 h and
23.00 h depending on the security rounds.
Seminar and lecture theatres can be booked
up to 22.00 h, seven days a week. All cleaning
takes place between 18.00 h and 21.00 h.
Booking sheets are used by the Estates
team to adjust plant time schedules via the
bems supervisor for the week ahead. Lecture
theatres are generally only used during normal hours, while seminar rooms are regularly
used during evenings and weekends.
Unfortunately, EFry does not have pulsed
output utility meters and so cannot be monitored automatically. However, manual weekly
meter readings have been taken since the
building was occupied in January 1995.
Gas is used for space heating and hws in the
main toilets and the catering kitchen. Unusually (and commendably) the gas supply to the
hws boiler is separately metered.
As far as the EEO Yellow Book is concerned, low annual gas consumption would
be below 185 kWh/m2 and high above 220
kWh/m2. During the 1997 calendar year, actual heating gas consumption at EFry was 96
MWh or 31 kWh/m2 /y. Gas used for hws
generation was 4·2 kWh/m2/y. Normalised
for standard weather conditions of 2462 degree days, the gas used for heating in 1997
was 33 kWh/m2/y.
The total normalised gas consumption for
1997 was 37 kWh/m2/y, which is one fifth of
the academic building low benchmark, under
half the lowest ECON 19 good practice benchmark5. Exemplary by any standard.
Gas consumption for heating has fallen
significantly since the EFry’s occupation, demonstrating the benefit of fine-tuning. The normalised figures for 1995 and 1996 were 73
kWh/m2/y and 53 kWh/m2/y. Gas for hot
water has reduced since occupation from 5·6
kWh/m2/y in 1995 and 4·9 kWh/m2/y in

ELIZABETH FRY BUILDING PROBE
1996, despite an increase in building usage.
Water consumption during 1996 and 1997 has
remained steady at about 880 m3/y (280 litres/m2/y). If attributable only to the 70 office
staff, this equates to a maximum of 12 m3/
person, which is comparable to good practice
office use of 10 m3/person/y.
The true figure will inevitably be less than
12 m3/person, due to the variable number of
other building users. The UEA has also installed some urinal flushing controls.
The occupant survey
Analysis of the survey results concentrates on
the office staff responses, which can be compared to the BUS dataset benchmarks, writes
Adrian Leaman. Questionnaires were completed by a total of 41 staff members. Respondents were a mix of administrators, academics
and researchers, 50% of whom work a five-day
week at EFry.
An unusually high proportion of people are
partial occupants of the building. A high proportion (51%) of staff had been at their present
workstation for less than a year, while 31% had
been in the building for less than year. Some
76% of staff have a window seat, which reflects
the cellular office environment.
EFry stands out in achieving exceptional
conditions across a wide variety of key criteria. On overall comfort, winter and summer
air quality and lighting, the occupancy scores
are the highest in the Building Use Studies
(BUS) dataset (figures 2 and 3). In all other
criteria EFry comes in the top 20%. It is only
the second building in the PROBE studies to
achieve better overall comfort in summer than
winter. Another PROBE building – Gardner
House – has radiant cooling, but its airtightness problems affected winter conditions more
than in summer.
The high air quality scores and good summer freshness at EFry seem to demonstrate
the benefit of full fresh air ventilation, but
without the penalty of high gas consumption.
There were some comments of smells and
smoke drifting from room to room, possibly
owing to eddies in the return air ducts.
Exceptional lighting scores add weight to
the argument that indirect lighting and electric light levels of 300-400 lux are well liked by
most occupants. The wide range in adaptive
opportunities to adjust electric and daylight
levels (confirmed by the high perceived control of lighting) must also contribute.
Such high scores raise eyebrows. The overall score for comfort is exceptional, but this
may be slightly helped by the cellular layout,
which offers privacy, security and control.
Statistical analysis also reveals that parttime occupants rate conditions more highly
than full-time occupants of buildings, though
not enough to negate the findings. Scores
from the full-time staff at the EFry building are
also very high.
There are some problems, though. Sun
glare through the perforated blinds was reported on the south side, with gloomy ceilings
when the lights were off. When lights are on,
the cornices reflect on computer screens. The
electric lighting and daylight are easily con-

FIGURE 4: The air leakage rate of the Elizabeth Fry Building plotted on the BRE/BSRIA database.

BSRIA pressure test
The Elizabeth Fry Building (EFry) was
initially pressure tested by the BSRIA Fan
Rover in December 1994 to check that the
airtightness met the performance criterion for the building, writes Tom Jones.
The building was required not to exceed 1 ac/h at a test pressure of 50 Pa. The
test result then was 0·97 ac/h @ 50 Pa
(equivalent to 4·2 m3/h/m2 of envelope
area), which met the criterion.
For the PROBE study, the BSRIA replicated the 1994 pressure test on Sunday 8
February 1998 in order to establish the
current airtightness and identify any features leading to reduced airtightness.
The building was tested with all ahus
sealed. The building volume was given by
the UEA to be 13 280 m3, and the envelope
area 3107 m2. The test revealed a slight
deterioration in performance, with an air
leakage index of 6·53 m3/h/m2 at 50 Pa
with the external doors unsealed, and 6·23
m3/h/m2 with external doors sealed (figure 4). This included sealing the air handling plant and external doors with polythene sheet and tape.
Although higher, the figure compares
well with the BSRIA’s recommendation
that airtightness of a low energy building
should be better than 5 m3/h/m2 at 50 Pa.
To investigate the possible sources of
the deterioration, the BSRIA also conducted a full smoke test of the building.
Smoke was observed egressing:
M at stairwell roof level at both ends of the
building;
M from the access hatch to the roof;
M around the windows;
M at door thresholds and from the revolving door;
M into the tank room on the roof (it is
believed that the lift shaft ventilates into
this room).
Smoke emitting from the windows was
from around the frames and the opening
light of the windows. This air leakage is
greater than would be expected for tripleglazed windows and for a building with an
BUILDING SERVICES JOURNAL APRIL 1998

Air leakage through an end stairwell.

Air leaking through the seals of the revolving door
serving the main entrance.

airtightness specification of less than 5
m3/h/m2.
The air change rate for this type of
building with spring temperatures and an
average wind speed would be expected to
be less than 0·15 ac/h. This degradation of
the air seal is likely to increase this air
change rate to 0·22 ac/h.
The BSRIA has undertaken measurements on 14 office buildings which have
been constructed with an airtightness
specification of less than 5 m3/h/m2 @ 50
Pa. The average value for all was 5·7 m3/h/
m2, while the average value for the top ten
of these buildings was 4·1 m3/h/m2, the
same as the airtightness value achieved by
the EFry Building back in1994.
The average for office buildings tested
by the BSRIA without an airtightness specification was 21·8 m3/h/m2, with the worst
being an air-conditioned office building at
40·1 m3/h/m2. The best office building
tested was 2·78 m3/h/m2, and the best
superstore was 1·65 m3/h/m2.
Tom Jones runs the BSRIA Fan Rover. This
pressure test was carried out as part of the
BRE/BSRIA/Building Services Journal
collaboration on improving building airtightness.

E24

PROBE ELIZABETH FRY BUILDING

The PROBE 14 Team comprised Mark Standeven,
Robert Cohen, Bill Bordass and Adrian Leaman.
The PROBE Team extends its thanks to Martyn
Newton and Norman Buck of the UEA Estates and
Buildings Division for their help during the PROBE
site visits, and to BRECSU for access to the
Databuild monitoring reports. Thanks also to Tom
Jones and Nigel Potter at the BSRIA for conducting
the pressure test and air leakage audit.
References
1
Bunn R, ‘Teaching low energy’, Building Services
Journal, 4/95.
2
Bunn R, ‘Termodeck: the thermal flywheel’,
Building Services Journal, 5/91.
3
Winwood R, ‘Termodeck: in-use performance’,
Building Services Journal, 11/97.
4
Energy Consumption Guide 19: Energy efficiency in
offices, 1998 edition (in press).
5
EEO Yellow Book: Introduction to energy efficiency
in further and higher education, Department of the
Environment, 6/94.
PROBE is a research project conducted by Building
Services Journal and managed by HGa Consulting
Engineers. The PROBE research is co-funded under
the Partners in Technology collaborative research
programme run by the Department of the
Environment, Transport and the Regions.

E25

Key design lessons
PHOTOGRAPHS: BILL BORDASS

trollable in most rooms by manual switches,
dimmers and mid-pane venetian blinds.
Though relatively low on the satisfaction
scale, the score for noise is within the top 5%
of the buildings on the BUS database. This
must also reflect the comparatively quiet nature of cellular offices. Although there is evidence of noise breakout from the offices to the
corridor, it seems that the closed door is
generally adequate to contain normal noise
levels, at least within the offices.
Perceived control over heating is lower
than the benchmark – not unexpected as
there are no radiators or anything to adjust
(except windows and doors). The Termodeck
system maintains very stable temperatures so
the consequence of lower control is only important when discomfort occurs. This can be
relieved by responsive action, as at EFry where
a handful of perimeter panel heaters were
fitted in the affected rooms. Winter temperatures are regarded as being on the cool side.
The mechanical ventilation seems to work
well in the background, with on-demand boost
from openable windows. However, some offices had only one window and a few occupants commented that it was not always possible to use it without causing draughts –
more choice would have been preferable.
Discomfort of some sort was reported by
72% of staff, which is not the lowest but still
much better than benchmark (84%). Only 28%
had ever requested a change to the heating,
cooling or lighting systems: a very low figure,
also indicating high satisfaction levels.
EFry is one of the rare buildings where
users give it unprompted praise – “I love it. It
combines a sense of tranquillity with aesthetic delight”.
By any standards the occupant survey results are excellent, one of the best seen by
BUS in over ten years of similar studies. EFry
is thus likely to become a role model for future
building design and management

Energy performance at EFry is
excellent. High levels of insulation,
an airtight envelope and triple-glazing obviated the need for perimeter
heating. Highly efficient heat recovery has shown that internal gains
within such a well insulated building envelope are often sufficient for
the heating requirement, even on
full fresh air.
Ventilated hollowcore slabs have
produced very stable and comfortable temperatures (winter and summer), as good or better than those
in air-conditioned buildings.
without the use of mechanical cooling. Avoidance of
conventional heating and
cooling services has helped
this low energy approach
to be built within normal
UK academic budgets.

The total normalised gas consumption for the
Elizabeth Fry Building in 1997 was measured
at 37 kWh/m2/y, one fifth of the academic
building low benchmark.
The heat recovery
systems for two of
EFry’s air handling
units use highefficiency heat
exchangers. These are
claimed to recover
85% of the available
heat, a figure verified
by the monitoring.

Construction supervision by the client, the design team and the contractor, along with careful detailing and specification, ensured
that the pioneering design was not
compromised. Special attention was
paid to making the design requirements clear to the contractor, and
critical details such as window reveals were inspected before concealment by wet trades.
Controls were initially a problem,
proving insufficient for monitoring The rooflights above the stairs show a slight
and operating the building. The tendancy towards air leakage.
UEA decided to install a site-wide
bems, and co-operation between the
building’s managers, the controls
specialist and the design team produced a well-configured, userfriendly system with a simpler control strategy: you need to know more
to be able to do less.
Aftercare Careful and persistent
commissioning and handover during the first two years of occupation Some areas were initially underheated, like
has ensured that design intent has this first floor corner room above a walkway.
been fully achieved in practice. This
is in stark contrast to many buildings, which proves the value of “sea
trials” for buildings of any originality or complexity.
Occupant comfort is exceptional.
The provision of good ventilation
without major fluctuations in temperature, modest electric lighting
levels and the opportunity to fine
tune local conditions has ensured Note the clear and concise labelling of the
that users are rarely uncomfortable. building controls.
BUILDING SERVICES JOURNAL APRIL 1998

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