Winner - ACEI 2012 President's Award for Excellence in Innovation
Sustainable Energy Innovation Award Winner 2012
Tesco Ireland has retained J.V. Tierney & Co. to provide consulting engineering services for many of their retail outlets countrywide. Projects include Refresh Stores, New Stores and Express Outlets, with Services Values up to €1.2m per store. Works on many outlets have been ongoing since 2009 and throughout 2010 and 2011, from locations such as the Merrion Centre in Dublin, to Roscrea, Celbridge, Galway, Wexford and all around the country. J.V. Tierney & Co.’s award-winning specialist designer subsidiary, JVTE, have deployed some of our most innovative engineering designs for the Tesco Store in Cabra, Dublin, in order to achieve a ‘Zero Carbon Rated Retail Outlet’. This is the first Carbon Neutral store in Ireland with a gross floor area of 5,502m2. The overall Project Value for Tesco Cabra is €25.5 million.
In the harsh economic climate we live in, J.V. Tierney were delighted to be given the opportunity by Tesco Ireland to put forward environmental friendly solutions and, in the testing of these, we acted as full Mechanical, Electrical, Sprinkler & Environmental Design Consultants.
We utilized thermal modelling software to assess the stores predicted performance. We used this information to set out the challenge to be met in order to ensure the store achieved Zero Carbon status. J.V. Tierney worked with the Design Team & Tesco Carbon/Environmental Teams to deliver on this challenge.
The major difference between a typical Tesco Store and the Zero Carbon Store in Cabra is the ability of the building to operate as a naturally ventilated building when conditions allow. From the computer simulations modeled, we were able to demonstrate that this contributed to a significant reduction in the energy demand. Another major impact on a store’s energy consumption is the lighting. In Cabra, there are a number of large rooflights installed evenly across the sales floor allowing natural daylight to aid lighting on the sales floors. The same principle was applied in the staff areas. The use of natural lights allows us to dim the buildings lighting throughout the day to achieve Tesco’s required lighting levels. The effects of this natural light are seen in the model and give a reduction of approx. 18% on the lighting load.
The Store Space Heating, Cooling and Electricity demand is met using a bio-diesel Combined Cooling, Heating and Power Plant (CCHP). From the results of the model simulation, we were able to analyse the heating, cooling and electrical loads for each part of the building throughout the year. The CCHP engine runs on a 50/50 mix of Tallow and Waste oil sourced in Wexford, Ireland. The CCHP will provide electricity for the store, heat for the AHU’s and heat to drive the absorption chiller providing cooling for the sales floor AHU when required. The graph below shows the comparison of Electrical and Thermal load for a typical 2006 store V’s Cabra ZC Store.
A DALI lighting controls system was supplied and commissioned to allow us to optimize the lighting controls to meet our carbon reduction strategies; Daylight controlled dimming, use of PIR/Photocell sensors, zonal switching and ensuring that all lights are dimmed as necessary to meet our design targets and reduce power consumption & increase lamp life.
The two level carpark under the building is lit using LED lighting. The LED lighting has reduced the energy consumption of the car park lighting by 50% and the lamp life has increased by 2 ½ times compared to a standard fluorescent lamp. To further reduce the energy usage the lighting is being separated into zones which are controlled via a time clock and PIR sensors. Additionally LED fittings were installed for the fridges and freezers on the shop floor further reducing the electrical consumption throughout the day.
An air tightness target of 3m3/m2/hr @ 50Pa was set for the new store. The actual test achieved a rating of 0.53 m3/m2/hr @ 50Pa. This assists in reducing the thermal load on the building.
Wind Catcher Ventilators together with the BMS system provide natural ventilation to the space when conditions allow.
Rainwater harvesting is installed to reduce the potable water demand.
To achieve the Zero Carbon status a bio-diesel CCHP unit to provide heating, cooling & electrical power to the building is installed. The CCHP will provide all the heating, cooling & electrical generation for the building and the Tesco will be exporting surplus electricity to the ESB grid. The bio fuel for the system is being supplied by Green Bio-Fuels Ireland.
The CCHP combined with the carbon reducing measures ranging from high specification glazing, building air tightness, LED lighting, eliminator doors on freezers, cold aisle retrieval, global control of lighting, etc combine to give Tesco a building which will help them realize their aim of cutting Carbon emissions from their stores over the coming years.