Pathfinder - St Mary's Hospital, Phoenix Park

Objective

The 2023 Climate Action Plan reaffirmed several targets for public bodies that had been originally introduced in previous iterations of the plan.  These include a requirement that all public bodies must reduce their GHG emissions from burning fossil fuels by 51% by 2030, compared to a 2016-18 baseline.  They must also reduce their electricity emissions in line with anticipated supply-side reductions.  SEAI’s pathfinder programme has been working collaboratively with public sector organisations to develop scalable solutions to meet these targets, for benefit across the public sector and the wider non-domestic sector. 

Under the OPW’s Optimising Power @ Work programme, a Preliminary Energy Audit and Building Management Survey, carried out by Powertherm Consulting Engineers in conjunction with HSE personnel, identified a suite of energy saving recommendations associated with the control and operation of the heating system at St. Mary’s Hospital.  The BMS recommendations were implemented under this Pathfinder project, together with lighting, fabric and pump upgrades, and the installation of a PV system. 

Background

The building to become St. Mary’s Hospital was founded in 1769 as the Royal Hibernian Military School and did not see medical purpose until it was handed over to the Irish Government in 1922.  In 1948, the hospital was transferred to the Dublin Health Authority, and in 1964 it took on the role it provides today.  The 100-bed unit and day hospital were built in 2008, with the 50-bed unit added in 2009. 

The hospital provides residential long stay care and day care services to older persons.  In addition, the hospital has 75 short stay beds, including a 10-bed stroke rehabilitation unit, a 12-bed unit for young persons with physical and sensory disability, a Healthy Aging Clinic, which provides diagnostics and education services, an Ambulance Training Centre, and an Addiction Clinic.  There is also a pharmacy on site that is not part of the hospital.  The site is approximately 32 acres in size. The hospital runs 24/7 and has a large demand for hot water, heating and electricity.  A range of gas-fired boilers and a combined heat and power (CHP) unit supply space heating demands across the campus, with a number of separate boilers meeting domestic hot water (DHW) demand. 

Project Description

The programme of works carried out in this project included modifications to the building management system (BMS) associated with the 50-bed and 100-bed units, commissioning/replacement of the existing BMS for Phoenix Hall, and connecting the three BMS to a front end located in the Maintenance Office.  Alongside this scope, LED lighting upgrades, advanced boiler load control, solar photovoltaic (PV) installations on the 100- bed residential unit and Phoenix Hall building, site-wide cold water and hot water pump upgrades and external insulation wrap of Phoenix Hall were also implemented. 

Performance

Table 1 shows a comparison of projected energy savings compared to actual performance.  Results indicate annual savings of 703,500 kWh of electricity, and gas savings of 2,339,000 kWh gas.  Projected savings were conservative, with actual savings achieved exceeding predictions. 

Two measures in particular delivered significantly higher savings than projected.  Predicted savings associated with advanced boiler control were calculated by a supplier based on the typical savings associated with boiler load control systems.  Actual savings achieved were almost double those projected.  The very high savings are associated with the highly inefficient operation of the boilers before the works were completed; the boilers that were upgraded did not have any controls prior to the works, and were either on, or off and dry cycled regularly, leading to very high wastage.  Therefore, the savings achieved at this site were higher than typical savings associated with these control systems. 

Insights

This project demonstrates the very significant savings which can be achieved through advance boiler load control and appropriate BMS control of heating plant, with the additional benefit of improved comfort levels for building occupants. In particular, it highlights the considerable levels of energy wastage which may be associated with poorly controlled plant. Payback periods associated with works to replace or repair valves, actuators and controllers which were not working were very short, yielding energy savings in excess of those achieved via fabric and lighting upgrades. Targeted audits focussing on BMS settings and controls can often yield significant low cost savings.