HOSPITAL ENERGY SYSTEMS
energy plant, from which services such as steam, chilled water, and hot water are distributed. It is not uncommon on many hospital campuses to find buildings and plantrooms that are 40 to 50 years’ old, and still vital to the function of the facility. Careful consideration is needed when deciding whether to maintain and electrify these nodes, or to decentralise the energy generation around campus to achieve the all-electric solution. Whichever option is chosen, significant planning, design, and implementation, will be required to ensure that there is no impact on the clinical, functional, or system resilience, and this doesn’t happen overnight.
Swapping out gas for electricity What are the effects on maximum demand if we swap out gas for electricity? Removing natural gas from a hospital necessitates an increase in electrical demand – the systems are still required at the end of the day (see Table 1). By breaking down the gas demand into respective systems, we can calculate what the corresponding electrical load per system would be. For example, the heating portion of the boilers would be replaced by a heat pump. Taking into account the losses of the boiler, and the coefficient of performance of a typical heat pump, we get the corresponding electrical demand to replace the gas- fired system.
It is important to review each system individually, because the respective electrical-based technology would have a different electrical-to-heat energy conversion, which affects the overall demand. Taking the summation of these systems, we can calculate roughly a 30 to 40% increase in electrical energy consumed. Obviously, this will vary on a case-by-case basis, but generally the figure is consistent. The figures in Table 1 were taken from a Melbourne hospital.
Considering when the peaks and additional load will occur In terms of a maximum demand, we have to consider the existing peaks, and when the additional load will occur. Incidentally, when these figures are run through an IES model, it shows that the increased maximum demand is around 40% also, but the peak demand now occurs in winter, not summer. What are the effects on the local
infrastructure? The Victorian grid is already struggling with capacity in the CBD. Every project nowadays seems to require upgrades to local infrastructure for even the smallest of increases. An increase of 25% per site is therefore no mean feat, especially for existing category 1 hospitals. For our example hospital, the
February 2023 Health Estate Journal 23 ‘‘
If we focus in on the energy usage by HVAC systems, this typically accounts for a whopping 65% of the total energy consumed by a hospital. This isn’t too surprising when considering the amount of ventilation and associated treatment of this air, but is still a very large proportion
maximum demand would increase from 9.5 MVA to around 13.5 MVA. Not only would this mean multiple and expensive sub-station upgrades, but it would also require careful planning to ensure continuity of supply. Having one of the two mains supplies offline for an extended period is a significant risk to the clinical services – how will this be managed? The above is also assuming that there
are not further upgrades required outside of the site to support this. Often, this is not the case. So, who is going to pay for these upgrades? This is not to say it cannot be achieved, but the planning and implementation goes far beyond the typical upgrades for a commercial premises. The flowchart in Figure 3 highlights a few things to consider during the planning and implementation of removing natural
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