Brown Thomas: Energy Optimisation of HVAC and BMS
Brown Thomas, situated in the heart of Cork City, is a high-end department store catering to a large clientele. The building has four floors, three of which are open to customers, with a total sales floor area of roughly 5,300 m2. The Energy Efficiency works in Brown Thomas Cork were funded jointly by Sirus Group and SEAI. Brown Thomas incurred zero upfront costs, nor any risk. The initial 20% of the total project capital cost was provided by SEAI under the Better Energy Workplace (BEW) Programme 2012. The remaining 80% of funds were provided by Sirus under an ESCO type contract.
The building is presently served with conditioned air from five roof-mounted air handling units (AHU). Originally, the AHU’s were operating at fixed volume airflow during store opening hours. The total AHU motor electrical load is 129kW. In addition, there are two chillers providing CHW to AHU cooling coils which have a combined electrical load of over 250kW, which includes the associated pumping loads. Sirus carried out the following during this energy optimisation project:
- Initial Energy review;
- Energy consumption analysis;
- BMS optimization;
- Modifications of HVAC;
- Installation of sub-metering;
The average daily HVAC electrical load, prior to project implementation, was approximately 1,500 kWh. Since implementation of the efficiency programme in late November 2012, the average daily HVAC load has been reduced to 484 kWh, resulting in an average daily saving in the region of 1,000 kWh per day. The BMS optimisation of the HVAC system prioritises free cooling and utilises a temperature dead band to achieve significant energy savings from reduced fan power and chilling power. Total electrical energy savings of 910MWh were achieved over the three year duration of the Energy Optimisation project in Brown Thomas Cork. These energy savings have removed 445 tonnes of carbon emissions from the environment.