City University Test Cells case study
Info box:
Client:
City University London
Architect:
Rivington Street Studios
Completion date:
September 2020
Value:
£3m
Form of contract:
JCT Design and Build Contract
2016
Key Points:
ATEX/DSEAR compliance
Complex structural and services work
Occupied University Building
The Brief
The Thermo-Fluids Research Centre is part of the School of Computer Science, Maths and Engineering (SMCSE). The Engineering Laboratory consists of 16 Test Cells used for research projects and is located in the basement of Tait Building which is a major teaching and student facility within City’s Northampton Square campus. The facility allows for the direct connection of experiments to a dedicated exhaust system which is managed by SMCSE.
The project’s aim was to upgrade the Test Cells in terms of fire safety, electrical supply, room air supply and extract ventilation systems, an extended BMS control system and interface with existing building Fire Alarm and IT systems.
Neilcott was appointed to develop and complete technical design and installation in strict accordance to Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR).
The Scope
Upgrading of the Test Cells was vital to provide fit for purpose facilities to meet the needs of the University’s national and international collaborations over a wide range of engineering sectors, enabling research towards reduction of emission from combustion engines, better utilisation of fuels, improvement of the efficiency of a vast range of fluid machinery and design of new engineering concepts for energy utilisation. The facility provides an important revenue stream for the University, therefore programme was of critical importance to bring the improved Test Cells on-line as soon as possible.
To expedite the programme an enabling works package was undertaken during technical design development which consisted of:
- Survey/validation of existing fabric & services installations
- Connection of free issue LV panel and circuit boards to CUL energy source
- Stripping out, making safe and isolating of any asbestos
- Stripping out of redundant fabric and services where practical
- Installation of transit blocks and effective cable management to comply with DSEAR, eliminating escape of gases where cables transit through walls/ceilings
- Design and installation of ventilation system capable of achieving 80 air changes per hour with sophisticated specialist control system to vary extract ventilation in-line with the requirement of each experiment.
- Threading ductwork from the basement up five floors through occupied university to fans located on the roof
- Laserlock security access
- Located adjacent to and directly under lecture theatres, stringent acoustic performance standards were required internally and externally
- Extensive cutting of the concrete structure to create new service routes was required, potentially causing disruption within the live education environment through noise, dust, vibration and reverberation
- Safe management of construction activities and interface with the public within an occupied university building
The Challenges
The nature of experiments being undertaken within the Test Cells, where engines are tested 24/7, produce potentially explosive atmospheres requiring all sources of potential combustion to be eliminated through an appropriate ATEX rating. This was the critical issue and impacted all aspects of design, specification, installation and commissioning.
The Solutions
Specialist DSEAR consultant to achieve ATEX – To ensure compliance with DSEAR regulations, Neilcott employed a specialist engineer to work with client, end users, technical consultants and the Neilcott team from design to commissioning. Through a series of design team meetings we explored how the client would use the Test Cells in order to determine the risks involved and the ‘worst case’ scenario. All specifications of materials, components and installation requirements had to be capable of withstanding the worst case scenario.
Test Cells requirements were defined into 3 categories:
- ATEX zone 1 – offering the highest protection for the most onerous experiments
- ATEX zone 2 – for undertaking less onerous experiments
- Non-ATEX rated cells – for experiments not using fuels
The DSEAR specialist compiled and agreed detailed specifications and installation standards to achieve the required ATEX rating, including sealed units for sockets/ lights, field unit camera, stainless steel blades within VAV units and fans to eliminate the risk of sparks or static buildup causing ignition of explosive gases. Secure access controls were installed to prevent unauthorised access.
Detailed specifications and Employer’s Requirements were provided for M&E subcontractors and we required both mechanical and electrical subcontractors to use the same Compex registered electricians to ensure a cohesive approach and intricate understanding of the whole process to ensure compliance throughout.
Attention to detail was paramount with meticulous cable management; each socket and cable was individually tagged and marked at each exit and entry point through walls/ceilings enabling individual isolation. Transit Blocks were used to achieve an atmospheric airtight seal around each cable to avoid any possibility of fumes escaping and provide proper fire separation.
Compex registered electricians worked in pairs with one installing cables and the other verifying correct installation. For each cable within each Test Cell a complete catalogue of installation and testing evidence was provided, including photographs. This was reviewed and signed-off by the DSEAR consultant to achieve the relevant ATEX rating and formed an integral element of the detailed O&M Manuals provided for each Test Cell.
Optimising ventilation – Upon strip out of existing services it became clear that the new 9m long x 2.5m x 2.5m supply air handling unit would not fit within the ground floor corridor location originally specified. We explored alternative locations to find a suitable location within the first floor plant room, enabling access for appropriate maintenance, undertaking required ductwork re-design to accommodate this.
Considerate Constructors – Installation of the new ventilation system required access outside of the relatively self-contained project site area to install ductwork within vertical risers and ductwork and fans on the roof. Good working relationships built up with City’s Property & Facilities department, operations and maintenance teams enabled prompt approval of task-specific RAMS compliant to City safe working procedures to gain the required Permit to Work beyond site boundaries. Due to the location of vertical risers within stairwells, these works were undertaken out of hours, agreeing suitable times for works on the roof around student movements.
Acoustic performance – Internal fans, due to their high performance to provide the required maximum 80 air changes/hour were procured/manufactured within an acoustic enclosure to provide the required acoustic rating and ductwork required attenuation. New doors and windows to each Test Cell were acoustically rated to minimise the acoustic break out of an engine running, manufactured with bespoke glass thickness to meet stringent requirements.
Break out of noise into areas outside of the Test Cells from new equipment was required to be assessed and if required works carried out to minimise the breakout through new partitions to Room C318 –Lecture Theatre +C54 Eye Test lab, outside the curtilage of the site.
Roof fans and ductwork needed to comply with Planning restrictions in terms of max break out noise. Therefore roof fans where manufactured in side an acoustic rated “box” and external ductwork was acoustically wrapped.
Acoustic assessments and compliance was resolved with an Acoustic Consultant who carried out validation testing and provided additional information/design to ensure compliance with the ERs, providing necessary reports.
Enhancing useability and access – Each Test Cell had 4 access panels within the roof soffits to enable engines to be lowered in place. These were made from precast concrete which were enormously heavy, extremely cumbersome to use and could no longer meet the required 60 minute fire rating (even new using the same methodology). We developed a timber alternative using a single panel, complying with all fire, acoustic, durability performance requirements as well as able to withstand maintenance access loads and structural stability when lifitng off or moving around.
Minimising disruption whilst cutting concrete – The Test Cells were located adjacent to and directly below working lecture theatres, therefore noise, dust and vibration disruption was a key consideration in planning and managing works. Liaison with the University enabled agreement of ‘quiet periods’ where noisy works were not permitted. Working methods were selected to minimize impact from reverberation and vibration, particularly around the extensive cut and carve operation to open holes for new services routes within the concrete structure. Diamond drills were used to cut into the concrete to minimise noise on 60 (500x500mm) holes within the Test Cells alone!
Innovative structural support solution – Openings created for the new services required additional structural support to the ceiling. The usual methodology of steelwork support was not feasible therefore our in-house structural engineer used an innovative system of bolting and resin bonding steel plates to the existing concrete slab around and adjacent to the new holes being formed to reinforce the new services openings. This method of substituting the reinforcement which had been cut out was also utilised when the new 1100x 500 holes were formed in the structural soffit above the Test Cells to form the holes for the supply air ducts.
Laserlock system – Experiments within the ATEX rated Test Cells required use of industrial grade lasers to evaluate results at an atomic level. Stringent H&S requirements are required for safe operation to avoid access during use which could result in blindness. A Laserlock door access control system was specified to prevent access whilst the laser is in use. The original installation method did not meet ATEX requirements, therefore we worked with the University and supplier to develop standard operating procedures and installation methodology that enabled compliance, setting the Laserlock system up to operate in such a way that it would turn the laser off if a person tried to enter the cells whilst the laser was operating unless an authorized access code is entered to by-pass the system. The laser lock system includes mag locks to the doors, blinds to the glass which interlocked to the system, so the system would not allow the laser to operate until all the blinds were pulled down to cover any vision panels or windows to the cells.
Stringent H&S standards – As with all works within occupied buildings and on live education sites (£60 mannually), H&S is our highest priority. We managed a detailed collaborative planning process to understand how the building and site is used on a daily basis to inform segregation strategy, site set-up, construction methodology, sequencing of works and transport, materials handing and waste management protocols. We sensitively manage works to maintain efficiency around University operations e.g. avoiding deliveries during peak periods, limiting noisy works during key periods for adjacent lectures and exam periods.