Passivhaus design, originally intended for housing, is being adapted to demanding university and other educational buildings, which have complex needs in terms of occupancy and technology.
Two new buildings are showing the way. In this article we look at one in Vienna, Austria and one in Leicester, England.
Tüwi, a facility Vienna’s BOKU (the University of Natural Resources and Life Sciences), has a new Passivhaus building, situated on its previous location on Dänenstrasse.
It includes a lecture hall for 400 people, the mineral collection with a practice room for 60 people, the Türkenwirt restaurant, a cafeteria, even a farm shop and garden, plus three institutes and the premises of the Austrian Student Union.
It opened in time for the 2018-19 academic year, immediately becoming the first educational building in Vienna to achieve the best quality level in all tested criteria groups in the ÖGNI Platinum sustainability certification (the Viennese certification system).
BOKU sees itself as a “teaching and research centre for renewable resources which are necessary for human life”, and so it is fitting that the building design should reflect latest developments in sustainability.
The building’s development was managed by Bundes Immobilien Gesellscaft, an Austrian quasi-governmental company that manages Austrian publicly owned real estate – the central provider of space for several public sector functions such as schools, universities, prisons, courts and police stations.
At its grand opening ceremony, in an interview with ÖGNI CEO Peter Engert, BIG’s managing director Hans-Peter Weiss spoke of the need to raise awareness of sustainability: “As one of the largest real estate companies in the country, BIG wants to set a good example here”.
Veronika Kaup-Hasler, Vienna City’s councillor for culture and science, emphasised in her speech that it is not just about successful research and teaching, but also about creating a “social space that produces sustainability”.
Designed by architects Baumschlager Hutter Partners, the TÜWI’s heating and cooling is supplied through a heat pump while a solar thermal system supplies some of the hot water and a photovoltaic system some of the electricity. For the remainder, the building is connected to a district heating system.
The striking wooden slats of the façade are untreated larch, providing shading to prevent overheating and glare.
The atrium is landscaped with hanging gardens extending over several storeys, ensuring a pleasant indoor climate. Ecological, non-polluting and PVC-free materials used throughout permit a healthy and comfortable atmosphere.
There are three floors above ground and two basements, plus a rooftop space where students can work under shelter. The entire building is accessible and equipped with comprehensive energy efficiency measures.
The George Davies Centre (formerly Centre for Medicine) at the University of Leicester is much larger, being the largest non-residential Passivhaus building in the UK. It was designed by the practice Willmott Dixon in 2017 and represents the first of a new wave of large-scale, non-domestic, Passivhaus buildings in the UK.
In 2018 it was declared Chartered Institution of Building Services Engineers’ Project of the Year: Public Use, recording a “19” energy performance asset rating, placing it in the “A” category. The judges said: “The standard of the shortlist was incredibly high but the Centre for Medicine had the best performance and will be a tough project to follow. We are impressed with the actual energy performance as well as the application of Soft Landings and post-occupancy evaluation, which provide a great demonstration of best practice for the industry to follow.”
With an internal floor area of just under 13,000 square metres, features include a high level of automation; blinds, ventilation, lighting, heating and cooling are all controlled by the building automation system based on a range of factors, such as external weather, internal temperatures, CO2 levels and occupancy.
A green wall is planted with 75,000 individual seedlings, and blinds on windows track the sun and automatically close to prevent solar gain. Along with thermal mass and other passive-cooling features, it maintains a stable temperature even when temperatures outside reach 30oC.
The roof sports 150 sq m of photovoltaic panels and 1.6 kilometres of Rehau earth tubes supply about 30 per cent of the air entering the building as a ground-to-air heat exchange system. Embedded soffit cooling also helps with energy reduction.
Since completion, energy consumption has reduced to 80kWh a sq m from 500kWh a sq m.
The building looks normal. Instead of the usual Passivhaus trope of more south-facing windows it has a more even distribution of windows.
The upper storeys’ curtain walling was manufactured offsite to assure high precision. The ground and first floor levels use traditional masonry brick and block cavity walls, filled with 300 mm of cavity insulation, plaster and tape.
The project is undergoing a three year learning process to refine its efficiency using a process called Soft Landings that has been developed to ” to ensure all decisions made during the project are based on improving operational performance of the building and meeting the client’s expectations” and is being used here to adapt the building’s management system to user behaviour.
As CIBSE states, “Striking the right balance between automation and user control is key to achieving the design targets”.
The architects work with the university’s facilities management team to perfect the building management system.
Users can override the controls within a defined range – for example for temperature and lighting. The building controls learn
how to compensate for and replicate this.
A year into the Soft Landings program the building achieved an A-rated Display Energy Certificate. “In year two, we are comparing performance against last year’s and aiming to exceed this,” says Willmott Dixon’s Khasha Mohammadian.
“This feedback loop is invaluable in understanding which controls, settings or general design decisions work well and which don’t. The first step in diagnosing a problem is identifying the symptoms – and, to do that, a good metering and monitoring
system is vital.”
Another energy saving opportunity that’s been discovered is to change the lighting monitoring and control system to measure the amount of natural light available when an occupant enters a room and only turn lights on if inadequate daylight is available. Previously it was commissioned to come on when users entered.
Willmott Dixon’s James Elliment says: “The building management system continually monitors CO2 levels in each room and communicates with AHUs to increase or decrease the level of fresh air supply to each room.
“The summer thermal comfort strategy minimises the number of hours when the temperature exceeds 25°C… and gives priority to passive measures such as automatic external shading blinds, openable insulated panels for natural ventilation, roof lights with external shading and exposed thermal mass.”
The development of Passivhaus in academic spheres owes something to the architect Martin Treberspurg (pictured), who was
honoured by being given the opportunity to present his valedictory speech this month at the Tüwi venue, on the occasion of his retirement.
Treberspurg 14 years ago was the first architect to teach at the university and spent the intervening time steering it in the direction of solar and ecological construction, passing his wisdom onto hundreds of students.
With his practice Treberspurg & Partner Architekten, he designed numerous buildings, deepening the connections between comfort, sustainability and ecology and between practice, theory and teaching.
In 2005 he designed Schiestl House (above), the spectacular first passive house in a high Alpine location, and in 2010 one of the first passive houses in Canada on the occasion of the Olympic Games.