A BLUEPRINT FOR SUSTAINABLE STUDENT HOUSING

Educational institutions have large and complex estates in which many buildings face round-the-clock use. Their building mix is diverse too, from labs to dormitories, libraries to teaching spaces so energy needs are multifaceted and one-sized solutions don’t often apply. Buildings need to be designed to handle the wear and tear of new cohorts of students streaming through year in and year out. The academic calendar is a regimented and regularised one too so there are very specific – and narrow – windows of time in which to make ongoing improvements, to fix things that may break down or close down parts of a building for repairs. It’s why these buildings need to be robust. They also need to last long and stand the test of time.

As hubs of so much activity, academic buildings can also be particularly energy intensive. The Carbon Trust estimates that annual energy costs for the further and higher education sector are around £400 million resulting in 3 million tonnes of CO2 per year. That’s more than the entire carbon emissions of a city the size of Stockholm in a single year. Many institutions have an older building stock designed long before the issue of climate change became a prime concern resulting in energy inefficiencies. Yet we also must recognise that many of our most beautiful examples of architectural heritage are found within universities and colleges. The ivory tower, it turns out, is often draughty. Yet it is precisely the university sector that is primed for innovation and where we test out pioneering ideas in sustainable buildings.

Girton College, founded in 1869, began as a pioneering idea itself: women should be able to go to university. Girton was the first constituent college of the University of Cambridge to admit women and was long an exclusively female college. (Co-education was introduced in 1976 when, in another first, Girton became the first of the women’s colleges to go mixed). The campus is situated at a distance from the city centre, located two miles to the northwest of central Cambridge on Huntingdon Road. Life at Girton revolves around a residential experience that is central to the College’s identity and the daily life for the 1,000 Fellows, students and staff that make up its community at any one time. Looking to the future, the College appointed Allies and Morrison to design its first major residential development in 80 years. It was the third commission the practice undertook at Girton, building upon earlier successes of the Girton Library and Archive and its kitchens and conference centre. The task this time was to design a new building with 50 en-suite bedrooms, gym accommodation and an indoor swimming pool and do so to the highest environmental standards while complementing the architecture of Girton’s existing red brick Victorian buildings.

The building, now open and the winner of several design and sustainable awards, is used year round, as a student residence during term time and as a conference venue during the summer months. The ethos guiding all design solutions was that the building should remain viable for many generations. This was underpinned by a desire to reduce its ecological footprint as much as possible and we translated this into innovations inside and outside the building, above ground and below ground. In an uncertain energy future, all reasonable steps were taken to minimise the need to import energy for operation.

Achieving this steered us to an integrated Passivhaus approach. Air-tightness is pre-eminent, structure and envelope are fixed. Exemplary fabric performance standards were met, resulting in an airtight building. U-values, the measurement of a material’s usefulness in insulating heat, surpass regulatory requirements. The architectural team utilised thermal modelling to minimise the risk associated with thermal bypass. This ensures that the building will avoid summertime overheating and the draughtiness associated with the winter months.

Key to a sustainable building is to design for the long-term. With that in mind, we thought in terms of centuries rather than decades and years. Robust materials were used throughout to minimise degradation and the need for replacement of key elements that could, in future, make it more economic to replace the building than repair it. A long lifetime will necessitate replacement and repair of key elements to maintain performance, which our design attempts to address. Crucially, the air-tightness barrier is designed to be relatively easy to inspect and repair. Services have been made completely accessible from point of entry to final connection. And the new building is extensively monitored and metered such that its metabolism can be interrogated as a ‘living lab’. This allows performance to be improved in an ongoing manner and respond to changing demands, uses and external influences. Finally, we designed not just for today’s climate but for a future climate. The building design was tested against the UK Government’s 2080 high emissions scenario; while we all hope for the best, just in case, the building will be able to withstand the stresses of the worst case global climate change projections.

Furthermore, proportionate and sensible heating controls and central set point management ensure the building is used well whilst offering room-by-room adjustment. Generous day-lighting throughout maximises natural light, minimising the need for electrical lights during daytime. The building’s overall layout itself also contributes to maximising environmental performance in that all of the sleeping accommodation intentionally faces northeast such that the windows are always shaded when direct sunlight is incident on them.

Renewable energy is also a key ingredient. The project maximises the use of on-site renewable energy generation technologies where appropriate. A 190 sqm photovoltaic array has been carefully incorporated into the pitched roof, providing nearly half of the building’s electricity demand. The financial savings against the total cost of the panels gives a simple payback in just over 15 years.

It is noteworthy that all this was achieved in the context of a building that forms the final range of a Cambridge College Grade II*-listed courtyard. The coordination of 21st century services into a 19th century setting with the realistic prospect of continued use into the 22nd century and beyond was demanding. Following completion of the project the College Mistress summarised this success in a letter to the design team – “One of the marvellous achievements of the Ash Court development is that it carries a trace of our Victorian past into the clean lines of an environmentally sustainable 21st century.” Creating a building that fits in with its historic campus is one more way to ensure a building’s longevity. In the field of student housing, it is a strategy we have used not just at Girton but previously also at Brighton College where we designed a BREEAM Excellent new student residence within a collection of Grade II buildings. The new boarding house is contemporary but sits comfortably alongside its Victorian neighbours.