1. Cheshire Oaks – Eco Store
This sustainable flagship store opened in late 2012, and was designed to have a minimum environmental impact and to provide the lowest Carbon footprint of any store in Marks & Spencer estate. The challenge to all designers, installers and OEM’s was to produce a finished product that met this aspiration whilst constructing one of the largest out of town stores in the chain.
An accompanying package of obligations made by M&S included –
- Environmental plans and promises for changes in the transport infrastructure.
- BREEAM Excellent status.
- To create more than 350 local jobs on completion.
- To complete an independent POE assessment of the installation and its operation as a true reflection on the target to objective success of the scheme.
2. Project Description
The brief was to design a refrigeration system using wholly natural refrigerants and followed a specific installation that offered a sympathetic approach to the wooden substructure of the core building construction.
Using Hydrocarbon primary refrigerants and CO2 sub critical pumped secondary cooling circuits the installation was completed by a dedicated team of installers from A1 refrigeration and was supported through design and site commissioning by Emerson Retail Solutions.
A1 Refrigeration completed the scheme in line with the stringent demands of the brief and optimised the engineering developments that were taken in to the scheme, in both the Central Plant structure and the display cases and may form part of other applications to this awards process.
3. Technology Utilised
Using a Hydrocarbon primary refrigerant to cool a CO2 fluid secondary cooling medium to the sales floor, the system has a total natural refrigerant charge of 120kg divided across two central plant systems. 50% splits in each central system provide additional resilience to support the cooling in the event of any single item failure.
A cascade CO2 sub critical cooling system supports the Frozen Food demands in the store. All plant systems are close coupled in a grouped arrangement on the north side of the building to ensure minimum solar impact and to ensure the system can be run at the lowest system differentials possible
whilst protecting from operational risk.
Low temperature differential case mounted heat exchangers overcome the cold aisle affect via heat recovery from the central plant without any elevation of system operating characteristics. Pumped system differential controls ensured minimum pump power for the secondary fluid with a saving
on the pump benchmark of -80% Pabs. The independent 3rd party auditors reported that as a whole the refrigeration system has a profile compared to the benchmark of -43% Pabs.
High resolution monitoring has been installed for all controls and gas detection and provides full off site visibility for ongoing maintenance and support of the systems operating characteristics throughout the life cycle of the plant.
4. Health and Safety
The highest standards were set for construction and post construction health and safety, with site access constraints a major consideration throughout. All plant areas were controlled throughout with formal Permit-to-Work controls initiated once the systems were charged with Hydro Carbon.
Contract staff, and subsequently store staff received a high level of training throughout the project to repeatedly identify the H&S demands and operational mechanics of the systems.
The construction period was extensive and required long term plant protection from both the construction trades and the environment, with A1 Refrigeration providing an on-site presence throughout the construction period to successfully protect both of these aspects. This was demonstrated during the safe movement of 5Tonne plant modules on rolling skids over a distance of more than 80 metres, due to site constraints.
A very high standard of the general construction health & safety for the installation was required to meet the criteria set for this high profile project, with further consideration taken to the operation and safety of the plant post construction. All operatives required training and certification in order to enter plant areas, with an introduction to store staff. Full considerations were looked at during design with the impact in limiting the quantities of refrigerant within individual systems. Installation of refrigeration services at high level within basket supports brought up other challenges due to the nature of the construction of the ceiling with ‘Glulam’ beams limiting the space available.
5. Client Satisfaction
Both the client and main contractor have expressed their satisfaction with the quality delivered by both the installation site team and back up they received through A1 Refrigeration Installation’s commitment in the completion of the project, this is shown by the glowing testimonials received.
6. Environmental Benefits
The integrated nature of the sales floor cooling and under cabinet heating system maintains a 17-18ºC aisle temperature and limits the impact on the staff and customers of the refrigeration of product. The development of cabinet air profiles helps reduce the air losses from the display cases to support the general environmental quality of the sales floor.
7. Repeatability of Techniques
The lessons learnt especially in relation to Hydro Carbon primary cooling, have allowed developments in specification and design that make the system more commercially acceptable and considerably less sophisticated in terms of the management of this refrigerant.
Also, the advances in pump technology have helped reduce the parasitic load of the system considerably with the overall system efficiency per kW of cooling now comparing favourably with a standard system. As a learning store the remote technical support is ongoing, with the process of independent Post Occupancy Evaluation continuing to ensure that the lessons learnt are comprehensive and any success is measured to enable future sites to benefit.
Cheshire Oaks has been a success in setting new benchmarks for his type of system in both design and installation practices for the industry. The willingness of the client to support system evolution and new commissioning standards has provided a model which can be rolled out to future sites without a major cost burden and with a life cycle operating profile significantly reduced from a conventional chemical refrigeration system.