Extensive survey of an existing & fully operational private hospital within the UK to establish energy savings achievable through the installation of a comprehensive wireless sensing system throughout the building to feedback additional Temperature, Co2 and Occupancy data into the existing BMS equipment to facilitate ongoing energy and CO2 savings.
The VT Pumps were operating at 100% speed for 16hrs per day, 7 days per week for 29 weeks costing the client £3,326 per annum in electricity and 9.7 tonnes of Carbon. The CT Pumps were operating at 100% speed for 24hrs per day, 365 days per year costing the client £8,649 per annum in electricity and 25.3 tonnes of Carbon. 3 Theatre AHU Supply Fans were operating at 100% speed for 16hrs per day, 6 days per week for 50 weeks costing the client £14,256 per annum in electricity and 41.4 tonnes of Carbon. The Theatre Extract Fans were running 24 hours per day, 7 days per week, 52 weeks of the year. These fans were operating at 100% speed for this amount of time costing the client £8,649 per annum in electricity and 25.2 tonnes of Carbon.
Wireless Sensing Solution
The installation of 13 combined sensors (temperature & Co2) throughout the ground floor of the hospital building. This provided the BMS with data about individual areas of the hospital tailoring the control of the associated HVAC plant to operate optimally. In addition to the environmental sensors, 5 wireless occupancy sensors within the operating theatres area were installed. These sensors inform the BMS when areas are occupied/unoccupied and make changes to plant operation accordingly.
VT & CT Pump Replacement Variable Speed Drives (VSDs)
The supply and installation of new Variable Speed Drives (VSDs) onto the VT Pump (5.5kW x2) andCT Pump (5.5kW x2) pump sets. Instead of operating these pumps at full speed, their operation was optimised based upon the new smart operation of the BMS system supported by the new data stream from the wireless sensor installation. The speed was reduced to around 80% (mean value).
Theatre AHU Supply Fans
Applied two new measures of speed reduction control – Co2 sensing to only run the AHU Supply Fans as required to maintain the air quality within the theatres and Absence Detection to indicate when the Theatres are unused reducing the speed to around 75% (mean value) with an additional 2 hours per day of shut-down time.
Theatre Extract Fans
Under our new smart operation of the Theatre AHUs this reduced the required speed to around 75% (mean value) with an additional 6 hours per day of shut-down time (shutting down the fans at night, etc).
Conclusion and Results
The initial extensive energy usage and equipment survey on the existing system performance outlined significant potential energy savings. The equipment installed proved a huge success in reducing the ongoing running costs and reducing CO2 emissions. This was all achieved with no interruption to the operation of the hospital during the project duration and has resulted in optimised comfort temperature control in all areas of the hospital covered by the project. Ongoing savings in energy consumption could be as much as £25,000 with CO2 reductions of 65 tonnes and a payback of under 2 years.
- VT & CT Pump Replacement Variable Speed Drives (VSDs) element of the project providing a saving of £4,221 and 12.3 tonnes of CO2 per annum.
- Theatre AHU Supply Fans element of the project providing a saving of £11,220 and 27.0 tonnes of CO2 per annum.
- Theatre Extract Fans element of the project providing a saving of £7,163 and 20.9 tonnes of CO2 per annum.
- Total Annual CO2 emissions reduced by 65 Tonnes.
- Total annual project saving £24,227.00.
- Project payback less than 2 years