Palmerston North Hospital, particularly over the past quarter of a century, has led the way in managing these large, expensive energy systems.
The hospital is the largest user of New Zealand’s EECA Crown Loan programme, which allows DHBs to access funding for energy projects without using normal capital funding.
The hospital’s first EECA project began 25 years ago, managed by Technical Services Engineer Warren Crawley.
The hospital was able to reduce its electricity consumption by 15 per cent by installing high performance reflectors into all its light fittings, and by cutting the number of light tubes by half.
Warren said: “The project’s co-benefits were a reduction in air conditioning demand as there were fewer ‘heat producing’ tubes, and we also got rid of toxic PCB and PCN chemicals.”
When the hospital’s engineering services were contracted to Spotless Services in 1994 the approach to energy management became more strategic and the emphasis went on to predicting how much energy would be needed well into the future, and where and when it was needed.
Further projects reduced heating energy requirements of the hospital and laundry by more than 30 per cent, and allowed the hospital to decommission its third coal-fuelled boiler.
Recently the hospital’s boiler burners were upgraded. Funding from EECA allowed “economisers” to be fitted to the boiler flues, which preheat water using waste heat, saving three to four per cent of gas consumption on site. Variable speed drives were also fitted to pumps and fans to reduce electrical consumption.
In 2012, the first stage of a sophisticated energy monitoring system was installed. Warren said: “This system combined with local weather conditions lets us measure the efficiency of our heating and electrical systems. This has many benefits including the ability to identify if a building is ‘out of tune’. For example, perhaps the wrong chiller is being used to provide air-conditioning for the level of cooling demand.
“Overall, I believe our greatest energy efficiency achievement was the construction of the clinical records building, which is the most energy efficient building on the hospital campus, and it was built at the same cost as a conventional building.
“It is south facing, minimising the cooling required, and its location adjacent to a hot service tunnel provides low running costs as it uses the tunnel’s waste heat. The intake air for the air conditioning is naturally pre-cooled by drawing air from under the building rather than from the roof. It is also an exceptionally efficient building shell protected from the external environment by an insulating barrier.”
The hospital’s electricity supply, not surprisingly, has been subjected to increasing demand. Back in the early 1990s the hospital’s emergency power supply was provided by three diesel generators, one feeding each of the three substations built in the early to mid-1970s.
By the late 1990s electrical demand had increased to the point where the generators had to be “synchronised” to optimise their capacity.
The redevelopment of the site in the early 2000s saw the most significant change in electrical demand – which increased by 25 to 30 per cent. A fourth generator had to be added to the emergency generator system.
Warren said: “This successfully provided emergency power until it became obvious in 2011 that electrical demand was still increasing. Plus two of the oldest generators were creating maintenance challenges - we were having to repair parts on site as there were no spares.”
In 2016, the oldest generators were replaced and a new fuel system put in. The last 1970s vintage generator will need to be replaced in the early-mid 2020s as electrical demand and age finally take their toll.
The current challenge is the replacement of the 11,000 volt and 400-volt core electrical systems which date back to the late 1960s.
The chilled water system, which provides the cooling in hospital buildings, is also facing capacity. This was particularly evident during last summer with its high temperatures.
Over the next 25 years the infrastructure is going to have to match the increasingly technical and fast changing clinical environment. Reliability is paramount in a hospital, with no tolerance for failure. Staying at the forefront of energy management will be critical.
- Written by Paula McCool