Mark Smulian takes a look at the University of Leicester’s new Centre for Medicine, which will be the UK’s largest non-residential Passivhaus project to date
Fitting the people and equipment from three departments into a single structure on a constrained site might challenge any construction and design team, but that is what has been going on at the University of Leicester for the past two years.
Not only that, this will be the largest non-residential Passivhaus project in the UK, possibly in Europe, and as a pioneer of its kind will be used to set criteria for future projects that wish to meet this standard.
Leicester expects to open its new £42m medical school this autumn, replacing one that was built in 1975 and later extended with two additional structures.
The new 12,863 sq m Centre for Medicine will be adjacent to the old one and staff have taken the opportunity to redesign how some aspects of their courses are taught with, for example, lecture theatres equipped to show students ‘live’ consultations and medical procedures.
When he first saw the site, Jon Chadwick, of Associated Architects, found some challenging limits to how he could build.
On one side a main road separates the site from the main university campus; on the second side another road runs between it and the old medical school – which is not life-expired as a building and will be converted for other academic uses – and a school on the other two sides.
There was also a protected view up to a war memorial designed by Sir Edwin Lutyens with which to contend.
“This was certainly a constrained site and I think the fact that the building was going to be a demonstration project for a large scale Passivhaus approach was helpful in securing planning permission,” Chadwick says.
Passivhaus is an energy performance standard originated in Germany based on excellent thermal performance and exceptional airtightness.
A definition used by the BRE states: “A Passivhaus is a building, for which thermal comfort can be achieved solely by post-heating or post-cooling of the fresh air mass, which is required to achieve sufficient indoor air quality conditions – without the need for additional recirculation of air.”
Chadwick’s design uses a ground and first floor that cover the whole site, but which then rise to three separate towers of three, five and six floors.
This was both because of the demands of Passivhaus and because of the university’s requirements for its accommodation – a combination of large lecture theatres, laboratories and offices for academic staff.
“We chose the three towers design because of the need to get natural light in and have glazed areas that would help to heat the building, so having three towers gives more surface area.
“It made sense to have the large lecture theatres on the lower floors so the building becomes more private as you go up in height. “There are also some research programmes that are doing things that are acoustically or thermally sensitive, for example, so you do not want those near to where there are large numbers of people. The towers give the upper floors a different feel.”
Some of the academic offices are private and complement large collaborative and shared use areas, though could be converted to open plan were the Centre for Medicine for some reason to change it’s working methods in future.
Everything in the design had to flow from the requirement to meet Passivhaus standards, but even so, Chadwick says:
“From an aesthetic point of view we did not want the architecture to be a slave to the environmental performance.
“Fortunately, Passivhaus is quite flexible and if you’d decide from day one how you are going to build a building then you can do other things that will still produce the right u-values.
“Most criteria on Passivhaus apply to all buildings, so you go for the minimum u-value you can and the best energy performance and air tightness.”
One issue to resolve was that a Passivhaus structure would normally not have much glazing on its colder northern elevation, but the university did not want any staff to have minimally glazed offices so the glazing was used and had to be compensated elsewhere in the design.
Passivhaus techniques require a heat exchanger, and normally one would try to place this under a car park or some other space not also being used for building work.
The tight configuration of the Centre for Medicine made this impossible and so the heat exchanger went under the building itself.
“It meant that piling and underground drainage had to be fitted around it, which made for a technical 3D puzzle for the design,” Chadwick says.
Making all this work required close co-operation with main contractor Willmott Dixon, whose principal surveyor Grant Henderson explains the workings of the heat exchanger.
“There is no gas in the building, energy comes from the heat exchanger basement plant room from which there are 1.6 Kms of pipes for the heating system,” he says.
“The heat exchanger keeps air at 14 degrees underground, which is an effect of what the earth does, so it only needs to be heated up further to 20 degrees inside the building.
“Since there is nothing to compare it to, the data from here will go to the Passivhaus Foundation and form the criteria for future large projects.”
The Centre for Medicine is built on a post-tensioned concrete frame with columns rising the height of the building with the ground and first floor elevations being traditional brick and block construction.
Passivhaus requirements mean there is 300mm of insulation, an unusual degree of thickness, and that even stretches into the ground so that the piles are insulated.
Mechanical and electrical installations are under the floors but insulation running right down columns below the visible floor level to limit any inflow of any cold air.
“It’s to reduce air penetration, as we seek one cubic metre an hour of air penetration, which is very onerous,” Henderson says.
The windows do open, “but it will be a management issue to ensure they are closed after use”, he says.
Other features used to reduce the building’s energy consumption include ‘intelligent lifts’ that permit access only to floors authorised to cardholders, and so do not make unnecessary journeys, a brise soleil and external blinds that will descend automatically when specific levels of heat are reached, to avoid the need for mechanical cooling in the rooms concerned.
There are low-energy LED lights throughout the building and windows will be triple-glazed.
Radiators can be set according to the heat condition in different parts of the building so, for example, those in the eastern side of the Centre for Medicine could be working on a cool day but not those to the west.
There is a hot melt roof, which on the lowest tower at the rear is capped by a green roof that descends to a green wall. The other two towers have ‘brown’ roofs, on which soil is used to create a natural habitat for wildlife.
Leicester is seeking a BREEAM ‘excellent’ status for the Centre for Medicine, and while proud of its design the most important thing about it is of course its potential for training and innovations in medical science.
Explaining why the new building was needed, and in particular the facility to ‘beam’ medical consultations and procedure into lecture theatres, Professor Nick London, head of the medical school, says:
“It is becoming increasingly difficult for all students to see patients with the full range of diseases they need to see during their training.
“By streaming the consultations live in the lecture theatre, our students will receive a much more vibrant educational experience that will replicate real-life practice.”
The new building provides space for the co-location of the university’s medical education, health sciences and psychology departments and in which they can advance applied research in particular into the prevention, detection and treatment of major chronic diseases, including kidney disease, stroke, diabetes and chronic respiratory illness.
As Henderson says:
“This is an interesting project because of the scale of the Passivhaus measures being used, which will guide others in future. “But it’s also good to be working on a medical centre whose work will benefit all of us in years to come.”
Architect: Associated Architects
Main contractor: Willmott Dixon
M&E contractor: NG Bailey
Concrete frame: Metropolitan Developer
Curtain wall: Advance Glass Facades
Brickwork: Keith Walton brickwork
Groundworks: Tim Bates Plant Hire
Glazed screens: Moda
Hot melt roof: Briggs Amasco
Partitioning: L Reynolds
Ceilings: Globe Contract Interiors
Carpentry: CS Mansfield
Floors: Active Flooring
Structural engineer: Rambolls
Passivhaus consultant: Warm
Acoustic consultant: Sharps Redmore
Facade materials: Schuco
Insulation materials: SIG
Facade consultant: Wintech
Client: University of Leicester
Planning authority: Leicester City Council