Canadian Consulting Engineer

National Institute for Nanotechnology

The National Institute for Nanotechnology (NINT) at the University of Alberta in Edmonton is dedicated to research in physics, chemistry, engineering, biology, informatics, pharmacy and medicine. Esta...

October 1, 2008   Canadian Consulting Engineer

The National Institute for Nanotechnology (NINT) at the University of Alberta in Edmonton is dedicated to research in physics, chemistry, engineering, biology, informatics, pharmacy and medicine. Established in 2001, NINT is operated as a partnership between the university and the National Research Council of Canada.

The institute is constructed as two physically independent buildings: a seven-storey conventionally constructed concrete tower, and an adjoining single-storey wing of “characterization suites” which house some of the world’s most sensitive high-resolution characterization microscopes.

The stringent requirements for vibration control, the prevention of electromagnetic interference, and other environmental controls for the characterization suites made NINT’s design and construction very different from that of ordinary buildings. With a construction cost of $48 million, the gross building area is 20,370 square metres.

Some of the earliest technical work on the project was done by experts to characterize the site and conduct field measurements of ground vibrations, electromagnetic interference (EMI) and radio frequency interference (RFI). Compounding the challenges, an existing underground utility tunnel runs through the heart of the NINT site. In the final design, the utility tunnel is encapsulated within the basement of the NINT main building.

After identifying the site’s “sweet spot,” i. e. the area with the lowest levels of ambient vibration, the architectural planning evolved so that the most sensitive characterization labs would be located in a structurally separate building wing located at this sweet spot.

Isolating vibrations through structural design

Vibration isolation slabs were required for the characterization suites. In the field of vibration control there is debate regarding whether smaller thick slabs or thinner multi-room slabs provide the best performance. At NINT, four test slabs were constructed during the schematic design phase: a 300-mm thick slab-on-grade, a 300-mm thick slab-on-grade with special damping admixture, a 900-mm thick raft, and a 900-mm raft on piles. In order to save money, the test slabs were located within the footprint of the characterization suites and now form a part of the finished construction.

The tests confirmed that a 900 mm raft on piles gives the best performance, at a level of VC-E or better. The steering committee therefore was able to decide that an expensive proposed air-spring supported inertia slab was unnecessary –a major cost saving.

The majority of the ground floor is dedicated to the Class 1000 clean room and nanofabrication facility, and the high-end characterization suites. These were all located to avoid vibrations from nearby vehicular traffic and from other occupants working within the building. Aside from the vibration-isolated slabs in the characterization suites, the structure uses slab-on-grade in the clean room, and a concrete slab-and-beam system for standard labs in the super- structure main building.

In order to control EMI from stray ground currents that might circulate through the reinforcing steel, the steel reinforcing bars in the slab-on-grade floors are coated with epoxy.

Protecting the instruments’ environment

The sources of electric fields are electrical conductors, transformers, panel boards and motors. One of the mitigation strategies for reducing electromagnetic interference in the NINT facility was to locate instruments a distance away from these large magnetic bodies. As well, rigid steel conduit rather than the typical bus-duct risers was used near sensitive areas, while panel boards and distribution centres were mounted back-to-back to provide a degree of cancellation of net magnetic fields. The electrical rooms were laid out with minimal wall-mounted devices, with most devices mounted on racks in the centre of the room. This strategy allowed for walls to be shielded in the future, if required, without undue difficulty.

The sensitive electron microscopes require a quiet and stable environment where air motion and pressure variations do not affect the quality and resolution of their images. It is also critical for these instruments that space temperatures are maintained within 0.1C variation over a one hour period.

Adding to the challenge was the need to remove a large amount of heat — some 15kW — generated by the electron microscopes without creating drafts or excessive air movement. Radiant stainless steel panels circulating chilled water were mounted on the walls and ceilings to cool the space without using air supply.

Completed in January 2007, the building is designed to LEED Silver standards and has many sustainable features. Its estimated energy consumption is 40% less than ASHRAE requirements.

Name of project: National Institute for Nanotechnology, Edmonton

Award-winning firm (prime consultant, architecture, structural, interior): Cohos Evamy integratedesign™, Edmonton (Jim Montgomery, P. Eng., Jeff DiBattista, P. Eng., Doug McConnell, Donna Clare, Tim McGinn, P. Eng., Jim Goodwin, Neil Robson, P. Eng., Cameron Franchuk, P. Eng., Michelle Sigurdson, Gerald Murnane

Project owner/client: University of Alberta, National Research Council of Canada

Other key players: Hemisphere Engineering (mechanical engineering), Stantec (electrical engineering), HDR (specialty laboratory consultant), Colin Gordon & Associates (vibration and acoustic consultant), Vita Tech Engineering (EMI consultant)

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