Reviewed: Glasshouse structures

The life sciences building at the University of Bristol is a state-of-the-art growing facility for horticultural research, Sally Drury discovers.

GroDome: University of Bristol greenhouse facility built on the roof of life sciences building offers views over city - image: HW
GroDome: University of Bristol greenhouse facility built on the roof of life sciences building offers views over city - image: HW

When the University of Bristol commissioned the construction of its new life sciences building, it also started work on a research hub and knowledge spar. Step through the doors into the central atrium and you enter an inspirational space surrounded by five storeys of laboratories, teaching rooms and computer facilities. There are eight "suspended" pods for breakout meetings and a SkyLounge with space to hold 120 people.

Overall, 2,000 people worked on the project, including 28 architects from 10 countries. The resulting building and surrounding area, complete with living walls, have been rated BREEAM "excellent". Rainwater is collected from the roof to flush the toilets and the building is said to save enough electricity to power 650 houses.

But from a horticultural viewpoint, the best bit is at the top. On the roof Unigro constructed a purpose-built greenhouse facility to provide research-quality growing space for all sorts of plants. It is here, with some of the best views over Bristol, that horticultural greenhouse manager Tom Pitman spends his day.

"It's a fantastic addition to what we already have and will take us well into the 21st century," says Pitman as he surveys the growing chambers in the GroDome. He recalls the 1950s-built greenhouses of his first job. "They had cast-iron heating pipes and a massive boiler that had to run for hours before you got any heat out of it." No such inconvenience here. Whatever the plants want, be it heating, cooling or water, they get immediately.

Fully contained unit

Standing beneath the curved roof of the GroDome you get a feel for what is going on. It is a fully contained unit, 22m wide and restricted by planning to a height of 3.8m. It is built with 90x90mm box steel and clad with 10mm twin-walled polycarbonate sheets for insulation while maximising natural light.

If the rest of the life sciences building expands and contracts, the GroDome must expand and contract with it, while maintaining its negative air pressure. Specified to take wind speeds of up to 140mph, the structure feels robust and resilient. The level of light transmission is high and it spreads well through the house due to the high quality of the polycarbonate sheeting.

Inside the GroDome there are six growing compartments ranging from 15sq m to 40sq m, each with independent temperature and lighting controls to allow researchers to mimic winter growing conditions in summer and vice versa, or to mimic tropical conditions as required.

The environments are uniform in each compartment. The curved roof helps to keep temperature consistent. As air travels over the curve it loses velocity and falls back to the crop. A tiny breeze moves the ears of barley just a little - the air velocity never fluctuating by more than a metre per second across the growing environment. Carbon dioxide supplementation is circulated via the fan coil.

Benches are kept wet for irrigation purposes. This means some condensation collects on the fan coils but because the set point for the cooling water is changing all the time there is only a small amount and this is collected in drums and treated. A crossover heat exchanger handling unit ensures that all the air taken out of the building warms or cools the air coming in, adding to the efficiency.

Containment areas

The GroDome, and each compartment in it, is a high-level containment area operating under reduced air pressure, each compartment exceeding the quarantine and containment requirements for Defra plant health. The negative air pressure is around 45-50 pascals and is adaptive - when one door is opened, the rest of the building reacts and the air-handling system ramps itself up to maintain the pressure while also maintaining the temperature coming into the building. Since much of the research involves plant pathogens, the air - like the water - is treated. To ensure that no pathogens escape, all exiting air is passed through a high-energy particulate air filter box.

There are blinds in the new house to reduce light pollution at night and also for use in the event of the cooling system failing during the day. Currently 600W high-pressure sodium lamps are used for lighting because when the building design began back in 2011 it was thought that LEDs were not the right offer. But technology has moved on since then and now Unigro research and development director Angus Padfield is of a mind that future houses will use LEDs to keep cooling loads and running costs down.

The whole facility is controlled by a building management system, rather than conventional greenhouse controls, so it can be configured exactly as required. Pitman can look at the system from anywhere in the building or at home. In the GroDome a touchscreen details the building plan and environmental conditions in each chamber. It is as simple as working a smartphone - no manual needed. From here he has temperature control, regardless of climatic conditions, and is able to set exact required temperatures from 18 degsC to 35 degsC.

Much of the research focus is on plant development, using Arabidopsis thaliana as a model for other plants. But there is also work on major crops such as wheat, looking at a variety of agronomic traits such as the genes controlling grain quality. The GroDome provides the perfect environment, with Pitman having seen tillering in wheat plants where previously he had not achieved any. When it comes to pathogen work, plants in the GroDome are so healthy that sometimes it can be difficult to get inoculants to take hold.

Construction challenge

Building a greenhouse on top of a five-storey building is not without its difficulty, especially when the five-storey building is being built at the same time, and explains much of the £800K total cost. "It's not like a large build in a Lincolnshire field where you can go where you like and put things up on a timescale that suits," says Padfield. "We had to fit into everyone else's time slot. The meetings and paperwork were quite onerous."

The process began with road closures while one crane lifted another crane onto the roof to erect the steel structure. "There had to be room on the roof for the crane," Padfield explains. "When the steel was completed the crane had to lowered, so we had to finish with our crane before the main contractor took his crane away. It has been a challenge."

Much of the equipment was later transported in the service lift, once that was operational. Today the lift is used for all supplies - composts, pots and plant material. But Pitman does not mind. "It's like another world," he concludes.

Reviewed This Issue

Life sciences building and GroDome, School of Biological Sciences, University of Bristol


Tom Pitman, horticultural greenhouse manager, School of Biological Sciences, University of Bristol

Tom Pitman has spent his entire working life in horticulture, starting with a job maintaining the grounds around a convent in the Knowle area of Bristol. After a short spell in a garden centre he moved to Long Ashton Research Station, where he worked in the glasshouses for 23 years. When Long Ashton closed, he was appointed senior horticulturist and then botanical house manager for the science centre @Bristol. In June 2007 Pitman started work as horticultural technician in the University of Bristol's School of Biological Sciences experimental glasshouses. With the construction of the new life sciences building, including a new GroDome, he was appointed greenhouse manager for the school.

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