ISG finds the right chemistry at Imperial College

Construction acrobatics were required to squeeze the complex mass of services for a seven-storey chemistry laboratory at Imperial College London into the inflexible footprint of a new build office block. Stephen Cousins reports.

It looks like an incredible water park ride. The giant reinforced plastic tubes, each around 1m in diameter, snake in and out across a seventh-storey rooftop, then plunge, vertiginously, through holes in the floor on a thrilling journey into the darkness below.

But slip on your trunks and jump down these pipes and you could be in for a shock – they are connected to giant whizzing fans that suck up clouds of toxic fumes from chemistry laboratories on the floors below.

This curvy plant installation is part of a major £61m fit-out being carried out by ISG to create a new home for Imperial College London’s renowned Department of Chemistry, on a regeneration site in White City, west London

The 25,500 sq m Molecular Sciences Research Hub (MSRH) project is highly technical and features one of the most densely packed fume cupboard installations in Europe, a state-of-the-art nuclear magnetic resonance (NMR) suite, four laser laboratories and a 250-seat lecture theatre where researchers will watch projections of live chemical experiments in 3D.

The resulting spaghetti of wires, cable trays, ventilation ductwork and other equipment is being crammed into a building originally intended as an office block, with shallow ceiling voids, just three service risers, and a concrete frame and foundations with limited load-bearing capacity.

Alasdair Higgs, project director for ISG’s Engineering Services unit, tells CM: “We are used to technically challenging buildings, but this project has really made us think on our feet; everything has been driven by the spatial fit and coordination of services and the need to manage the daily work cycle. It gets very congested out there with multiple trades for multiple services.”

Post-apocalyptic approach

Approaching the site from White City tube station takes visitors north along a 500m-long access road through a dilapidated urban area, characterised by abandoned concrete lots and rusting steel-framed warehouses, including the former home of Unigate Dairy. The air reverberates with the drone of cars and lorries crossing the six-lane Westway flyover overhead.

But walk to the other side of the flyover and a very different scene emerges, one of sleek contemporary architecture and frenetic construction activity, as Imperial College’s new 10ha White City Campus is gradually brought to life.

The MSRH is ISG’s second project on the site, having kicked off the redevelopment in 2012 with four “grad pads” to the north of the campus. The new project stands next to a recently completed office for tech startups, known as the I-HUB, and opposite an arrow-shaped residential tower currently being constructed by Laing O’Rourke.

It is surprising to learn that the college’s future plans for expansion – to be implemented over next decade or so – cover an area of  circa 40ha, including  the brownfield land along the access road.

The MSRH will provide space for up to 800 research scientists, clinicians, engineers and businesses, who will tackle challenges in areas such as energy, healthcare and sustainability. Floors one to six will feature large open-plan laboratories and rooms for writing up experiments. The two basement levels will house specialist laboratory space, including the NMR suite and a suite of laser and low electric noise laboratories, plus the lecture theatre and an energy centre.

The flues are craned on to the roof

The building was originally designed as flexible office space for the Department of Public Health, but in January 2014, during construction of the shell and core by main contractor Laing O’Rourke, the client had a change of heart. The Department of Chemistry had outgrown its existing premises in South Kensington so Imperial College made the decision to change the brief entirely and convert the office into laboratory facilities.

Architect Sheppard Robson and services consultant Hoare Lea were employed to work up the redesign. ISG was awarded the design and build fit-out contract in August 2015. Over a 12-month pre-construction phase it worked with the consultants, the client’s project manager Turner & Townsend, M&E contractor MJ Lonsdale and structural engineer Curtins, to develop the detailed design and programme of work.

Light touch

ISG tried to work within the limits of the existing structure and minimise alterations to reduce disruption and improve sustainability. In combination with energy-efficient heating, lighting and ventilation systems, plus improvements made by Laing O’Rourke during the original build, the project is targeting BREEAM “Excellent” certification.

“There hasn’t been a lot of cut and carve, only the waste materials are from areas we punched through the slabs to create new service risers,” says David Gray, divisional director of ISG’s Engineering Services business. “We have mostly worked with the loadings provided, with no requirement for new piles or underpinning.”

Some external walls had to be moved to create room for external plant, a new level was added to create space inside the double-height basement and new foundation slabs for the NMR suite and lecture theatre were created in the basement.

A BIM diagram showing the complex arrangement of extract flues

Researchers in the NMR suite will study the behaviour of tiny radioactive particles. Strict anti-vibration requirements raised concerns given the close proximity to the Central Line, the overground railway and flyover.

A trench around the floorplate isolates the NMR suite from main structure and doubles up as void for services distribution. For the slab, ISG had to identify the correct density and type of concrete that would simultaneously minimise vibration and loading on the existing foundations.

ISG worked closely with Curtins to design a foam concrete slab with a 300mm topping of higher density traditional concrete.

Tight fit

The office layout offered an opportunity to depart from convention and create a series of open-plan laboratories covering an average of 60% of the floorplate, on levels one to six, with the remaining space given over mostly to write-up space.

The open-plan environment should be more conducive to interaction and collaboration and able to accommodate a much large number of fume cupboards than a conventional lab – up to 78 per floor.  However, the shallow ceiling voids, measuring less than 1m deep, and lack of service risers, raised coordination issues for the vast amounts of ventilation ductwork and cables required.

Services needed to be coordinated into a tight space

Gray says: “In a purpose-built lab environment ceiling voids would measure 1.6m to 2m deep. We had to work incredibly hard to coordinate all the cable runs and ducts. In some areas it is so congested you can’t even see the slab soffit.”

Exposing the services in the ceiling made it possible to add a valuable 150mm of space. Meanwhile, four new risers were punched through the existing floor slabs, each measuring 4m by 2m, to create space for large air supply handling units that push air into the labs, plus extract ventilation ducts.

Fume cupboards in a typical lab are connected to a single extract system, but here groups of fume cupboards connect to common header ducts in each of the risers and common banks of fans that ramp up velocity depending on the number of fume cupboards in operation.

All services were modelled and clash detected in 3D in Revit, to improve coordination and resolve spatial fit issues. Laing’s O’Rourke’s original 3D model for the base build was combined with new cloud point survey data to get an accurate picture of as-built construction.

“Designing this project traditionally would have cost us more time and money as some clashes would not have been identified until we were on site,” says Gray. “The model was used during design review meetings and as part of the approvals process, projected on a big screen to walk client and consultants through the installation.”

Logistical battle

The large amount of kit on the project, which includes 333 fume cupboards, 2,000m of fibre optical cable, 400,000m of data cable and 45,000m of pipework, threatened to create bottlenecks.

“Getting people to produce that quantity of fume cupboards in the timespan we have was difficult,” says Gray. “The only way we could get it done to fit the programme was to start manufacture early and store the units in facilities off site.”

Imperial’s 10ha White City Campus site is next to the Westway flyover

Most large items of equipment, including two 10-tonne chillers, had to be lifted through a single narrow opening on the roof, using a 700-tonne crane with a 70m-radius fly jib, positioned at the back end of an adjacent site. Smaller items enter via a temporary goods lift running up the facade.

ISG’s team had just three weeks to lift, co-ordinate and install all major plant and equipment on the roof, with deliveries arriving roughly every 10 minutes. A critical moment came in February, when the crane had to lift two banks of eight 20m-long extract flues, used to channel air up from the water park-style extract ducts below. Assembled using 1m sections, these were attached to the crane, but the lifting was winded off several times as Storm Doris swept through the country.

Walking through the building today, the air is alive with intriguing industrial noises, such as the mechanical drone of extract fans and a strange unidentified gurgling in one of the laser labs, as engineers start work on the onerous task of commissioning equipment.

The fit-out is expected to complete next spring, ready for Imperial’s first cohort of researchers to begin their experiments, each one unaware of the fascinating experiment carried out on the building they work in every day.

Sock it to ’em

An innovative “roll grill” design for fresh air distribution in the laboratories will help reduce downtime compared to the use of traditional “sock” filters

Displacement ventilation in traditional laboratories pushes supply air through a sock diffuser, a form of inflatable filter that must be periodically removed, cleaned and reinstalled.

Removing socks means shutting down a lab for health and safety reasons. The Molecular Sciences Research Hub has up to 78 fume cupboards on a single level, potentially causing major disruption.

“If we had 40 socks to change per floor it could mean closing the floor down for a day or two at great cost,” says David Gray, divisional director of ISG’s Engineering Services business.

The solution was to incorporate a new form of horizontal displacement ventilation, known as a roll grill, that pushes out air through numerous penetrations in the sides of the cylinder.

Concerns that the velocity of air from the system would create turbulence and alter air containment in adjacent fume cupboards resulted in revised designs for some of the roll grills, which feature special nozzles that jet some air away from the sides of the cylinder.