Refurb Projects - November 2018

EDUCATION INFRASTUCTURE
Balancing performance with user comfort –
Passivhaus as a living case study
THE multi-million-pound
George Davies Centre
(formerly Centre for Medicine)
at University of Leicester – the
largest non-residential Passivhaus
building in the UK – has continued
to scoop awards for its size and
complexity, being recognised across
the higher education sector and the
UK as a whole.
Developed in Germany during
the early 1990s, Passivhaus is the
world’s leading fabric first approach
to low energy buildings. It’s
excellent thermal performance has
reduced the university’s energy bill
for its new teaching and medical
research facility. However, ‘with
great performance comes great
responsibility’ claims Willmott
Dixon’s James Elliment who worked
on the project.
He said: “This pioneering project
for the higher education sector has
attracted the attention of a number
of institutions around the country as
they are continually challenged to
reduce their environmental impact.
Achieving Passivhaus standard is not
easy and it requires absolute buy in
from the customer, but the benefits
of adopting it are significant.
“At Willmott Dixon we have been
working with University of Leicester
to deliver a three-year soft landings
programme for George Davies
Centre. A year after the project’s
completion we achieved an A-rated
DEC, showcasing just how effective
the building’s credentials have been
in action.”
From a green wall featuring
75,000 individual plants to CTB
blinds that track the sun and
automatically close to prevent solar
gain, this highly intelligent building
presented very real challenges to the
team that delivered it. For example,
the industry standard for air
tightness is 5m3/hr/m2, but
Passivhaus requires five times less
than that.
PASSIVHAUS AS A SOLUTION TO
THE PERFORMANCE GAP
“Despite many buildings achieving
high energy performance ratings the
reality can be quite unpredictable, as
day-to-day usage is very different to
that laid out in tests – sometimes as
much as 200 to 500 per cent
according to CIBSE’s Zero Carbon
Hub.
“As part of the soft landings
process we are actively monitoring
and tracking energy usage, taking
corrective action, such as for
controls and equipment, carrying
out reviews with the customer
ahead of full occupation, and
conducting workshops with
building’s users to further reduce
energy and close the performance
gap of the building. It’s been a
learning curve for the whole project
team, as we are working with a
living and breathing building, which
supports and underpins the work of
so many people.”
With state-of-the-art, heating,
cooling and ventilation systems, the
building’s intelligent energy
efficiencies include a ground-to-air
heat exchange system, external
blinds for active solar shading and
embedded soffit cooling. With
Passivhaus only being previously
applied to domestic buildings,
sourcing air handling units (AHUs)
that met the needs of a building of
this size and complexity, as well as
Passivhaus requirements, was
challenging. Working jointly with
the mechanical and electrical
services contractor, Willmott Dixon
created 10 fully bespoke AHUs,
which were BSRIA-tested to ensure
certification to the required
standards.
Speaking of the project’s success,
James said: “Gaining the Passivhaus
certification is so challenging that
many buildings aim to achieve it but
fall slightly short due its finer
complexities. However, as George
Davies Centre shows, the
environmental benefits are
outstanding and worth perseverance
and dedication.
“In fact, George Davies Centre is
over five times more energy efficient
when compared with other higher
education buildings, as its total
energy consumption per annum has
been 61.2 kWh/m2 and has a DEC
rating of 59, while the higher
education sector average is at 320
kWh/m2 (according to DEC data*).
“The efficiencies in George
Davies Centre’s design have allowed
the university to close old and
inefficient buildings earlier and
extend the hours of usage at George
Davies Centre beyond its usual
operating hours. This has reduced
carbon emissions across the campus
and means users get access to a
more comfortable environment.”
STRIKING A BALANCE
“Through the three-year soft
landings process we have been able
to really understand how to use the
building as efficiently as possible.
Part of this has involved working
very closely with the building’s users
to educate them about how the
building functions – explaining why
the lights automatically dim, how
the radiators know when it is too
cold and when blinds close
themselves, so that the building can
perform to its optimum levels.
Without this education the
performance gap and payback
period grow, which is something we
have worked to avoid.
“The real challenge for our team
has been finding the balance
between efficiencies and comfort
for the building’s users. For example,
the ultra-intelligent lighting system,
which monitors natural sunlight in
20 NOVEMBER 2018, REFURBISHMENT PROJECTS