How energy-resilient is your estate?

With over 40 years’ electrical engineering experience, of which much of the last 20 have been spent advising NHS Estates managers, it’s clear to me that there are wide variations in the condition of healthcare estates. Some estates have modernised, but there are many where critical resilience relies on the performance of 40- or 50-year-old electrical equipment. While this equipment was well designed and built, and has remained reliable well beyond its designated life, the availability of spares and the skilled personnel to maintain it are becoming scarcer, and the risk of critical failure increasing. This in turn presents a greater risk to staff and patient safety, that is fast becoming untenable.

As we move towards Net Zero Carbon, and become ever more reliant on electricity, the grid will come under growing pressure countrywide, so it is essential that healthcare estates can cope with the increased electrical loads that come with decarbonisation, as well as with power supply disruption. The increasing risk of more frequent cyberattacks on hospitals, such as the incident on 3 June which severely affected services at some major London hospitals — described as ‘one of the most serious in British history’ — reinforces the need for hospital infrastructure to be self-sufficient, resilient, and resistant to such attacks.

So, what can be done? The modern hospital estate needs electrical infrastructure that:

• Can provide resilient standby power supply to 100% of clinical facilities (historically this was only 30%);
• Can ensure resilience in times of disruption to the primary supply;
• Has the capacity to accommodate embedded renewable generation (e.g. solar PV);
• Has capacity to supply electric powered plant installed to achieve decarbonisation of heating and cooling, and
• Has the capacity to supply EV charging systems for operational vehicles, and possibly staff and visitor vehicles.

Determining the capacity of the electricity supply that will be required to meet these various drivers requires a number of steps, which are closely linked into the stages of a decarbonisation plan. Let’s look at each of these points in turn.

1: What must be done to provide a resilient standby power supply to 100% of clinical facilities?

Historically, hospital electricity distribution has been classified as essential and non-essential — the latter supplied from the incoming grid supply, with the capacity to supply 100% of the load. This would provide the normal supply to the essential distribution, which could supply 30% of the load, and would have a changeover arrangement to a secondary supply, typically standby generators sized only for this purpose. However, this no longer offers sufficient resilience for modern clinical care requirements, where there is increasing reliance on electrically powered systems and devices. NHS England’s Health Technical Memorandum (HTM) 06-01 provides good clear guidance on governance and risk management steps that Trusts should adopt to determine risk to patients from supply loss, and the appropriate clinical risk grade for each department within the hospital. It also addresses and grades risks to business continuity due to supply loss.

The role of the Electrical Safety Group

The HTM advocates the Electrical Safety Group overseeing the governance of this. Some Trusts have established a standing Electrical Safety Group, whereas others form one as needed. While the group’s membership can be adjusted to address circumstances at hand, it is certainly beneficial to maintain a standing group that regularly reviews all matters set out in the HTM.

Undertaking risk assessments will determine the appropriate risk grades for each department, forming a firm basis for designing the electrical infrastructure. A practical overview of each building and the entire site is necessary to establish a distribution strategy, considering potential future changes in use. For instance, providing a lower-risk supply to only one or two departments might be impractical if these departments may be converted for higher-risk use later. By applying this process rigorously, it can be determined which buildings on a site will receive 100% secondary supplies.

2: How can you ensure resilience in times of disruption to the primary supply?

The primary supply to a hospital, often referred to as ‘grid’ or ‘mains’, is generally a high or low voltage connection from the Distribution Network Operator (DNO). Typically for a larger hospital site, the supply will be at high voltage, and a ‘switched alternate’ supply comprising two cables entering the site will be requested to improve resilience.

In the event of local network failure, the DNO can switch the supply to another part of its network; typically, the DNO will aim to do this within three hours of the failure. It is well worth the effort to build relationships with the DNO and gain sight of the single line diagrams for their network to fully understand how the network is configured upstream of the connection. If there is a power failure, there is a greater opportunity for resilience if the connection is on an interconnector between two separate sub-stations.

One robust solution agreed upon for the University Hospital of North Tees in Stockton-on-Tees in County Durham comprised two ring main units connected by a cable, with the DNO routinely using this as the open point on its interconnector between two primary substations, thus providing greater resilience (see Figure 1).

The two switched alternate supplies are connected to the new hospital intake switchboard, from which a ring main feeds three sub-stations that serve the main clinical buildings. Each sub-station has a five-panel switchboard equipped with unit protection to enable the ring to operate closed, and any single fault in the ring to be automatically switched out without loss of supply. This feeds two 100% transformers, each feeding an LV switchboard, equipped with automatic changeover to the secondary supply and a manual interconnector. The two streams are labelled ‘Red’ and ‘Green’, with clear colour coding to provide an intuitive awareness for operators that is quite distinct from the previous Essential and Non-Essential systems that it replaces.

Another project to upgrade the high voltage infrastructure at the Royal Hospitals in Belfast, the largest hospital campus in Europe at the time, was conceived out of several years’ liaison with the DNO, which had a long-term aim of replacing the historic 6.6 kV distribution system in the area with an 11 kV system. Ultimately, the catalyst for this happening was the Royal Victoria Hospital Belfast’s (Figure 4) requirement to increase capacity, which led to the DNO establishing a new primary sub-station (Figure 5) on land leased from the hospital to provide the new 11 kV supply. The Trust had the foresight to specify that each new transformer installed on the site during redevelopment projects was dual wound, with primary windings for both 6.6 and 11 kV in readiness for the expected project implementation. This reduced the number of transformers and length of cable to be replaced once the project proceeded. Condition assessment of remaining cable using partial discharge mapping and Tan Delta testing was adopted to inform further cable replacement. Only once the new 11 kV supply was established and proven did the final phase of voltage changeover proceed. For each ring, the open point was moved to allow each substation to be changed over to the new 11 kV supply, and the transformer winding changed.

Changeover on a Sunday

To suit the criticality of the hospital services fed, only one substation could be changed over each Sunday. So, once started, the process was irreversible, and lasted several weeks, during which reduced resilience was mitigated by provision of temporary generators and additional on-call staff to ensure that supplies could be quickly restored. The changeovers went smoothly, with no unplanned interruptions to supply.

Resilience in the secondary supply is also needed to account for breakdown and maintenance. The mainstay of secondary supply remains the standby generator; while alternative fuels are being developed for internal combustion engine generators, diesel remains the most readily available and reliable way of assuring this. It is important to consider the design of standby systems — whether to have several to serve single buildings or parts of a site, or a single system to serve the whole site.

At North Tees, two 2.5 MVA generators were provided in the new Energy Centre to provide N+1 support to the whole site. Both primary and secondary distribution systems were duplicated, reducing the risk of calling on the generators to start for an internal distribution failure. The arrangement also allowed paralleling for mains restoration and online load testing of each generator in turn. To assure resilience, CHP and solar PV arrays are automatically disconnected when standby generators are in use, which also avoids fault level issues.

Tertiary supplies

Additionally, tertiary supplies, which are provided by uninterruptible power supplies (UPS), are only required for the highest risk grade departments. Selecting locations for UPS in already busy areas can be challenging to ensure that conditions for good battery life are maintained. Large ventilation plant rooms, often above operating theatre departments, are locations where it may be possible to achieve acceptable temperature conditions by ventilation alone.

Finally, cybersecurity risks are a growing concern as more components — such as CT scanners or CHP units, connect to the internet for remote diagnostics. Increasingly, internet-connected devices may be embedded in equipment without it being obvious to the casual observer. So, it is important to obtain assurance from the manufacturers about the security of these connections and their compliance with NHS protocols for accessing IT networks. This approach will need to be developed to assess and manage the introduction of Artificial Intelligence into functional safety and safety-critical systems. This is an evolving area to watch.

3: What can be done to ensure your estate has the capacity to accommodate embedded renewable generation such as solar PV?

There are very few hospital sites with sufficient spare land to install a solar farm or a wind turbine. Other forms of renewable generation have been experimented with, but haven’t matured into reliable technology. In most sites, space is at a premium, making building-mounted PV panels the most practical systems to install. On a hospital site operating 24/7, the electricity generated during daylight from PV is usually used on site, and it is unlikely that any excess will arise, so there is no advantage in exporting excess or having battery storage to store it for later use. Where the healthcare site focuses on outpatients, and only operates on weekdays, it may be desirable to consider battery storage to save energy generated at the weekend for use the following week.

Except for the smallest installations, it will be necessary to make a G99 application for each PV installation. The need for early engagement with the DNO cannot be overstated — such is the pressure on the National Grid that it cannot be assumed that a connection can be accommodated straight away.

4: Decarbonising your estate, and preparing to meet the requirements of Net Zero Carbon

Thermal energy for hospitals is traditionally produced in a central boiler house or energy centre using fossil fuels. Many hospitals use combined heat and power (CHP) to make more efficient use of the fossil fuel and reduce overall energy costs. With advances towards Net Zero Carbon, the carbon savings from CHP are no longer as attractive, and do not compete with the carbon content of grid electricity. Carbon-free alternative methods of producing thermal energy use electricity to a greater or lesser extent depending on the system chosen.

These factors point towards an increasing requirement for electrical capacity.

Implementing a decarbonisation plan

Determining this capacity will require the application of a decarbonisation plan such as the TGA Net Zero Carbon 10-point plan (see Figure 9), which works through the stages to minimise energy demand by installing energy-efficient components and improving the building performance through fabric improvements, etc. Exploring the detail of how to apply the decarbonisation plan is worthy of a separate future article. Nevertheless, it is also important to take account of the need for appropriate ventilation, infection prevention and control measures, and the growing need for cooling. The resulting thermal energy capacity required may well be less than the existing capacity, but either way it will be rigorously arrived at, and should include capacity for future growth and agreed climate data.

The next stage is to select the method of thermal energy production, which will be influenced by site conditions. For instance, not all sites are suited to ground source heat pumps. If air source heat pumps are favoured, is there space for centralised plant, or is decentralised plant favoured; is there a continuing requirement for steam generation and — if so, is this to be decentralised? All these considerations will lead to decisions about the nature and arrangement of thermal plant, and, therefore, the electrical capacity and distribution that will be required.

5: Ensuring capacity to supply electric vehicle charging systems

Hospitals have been familiar with electric vehicle fleets for many years, with electric tugs being used to haul trolleys for supplies and waste through corridors and service tunnels. It is a natural step to adopt electric vehicles across the rest of the fleet. While EV technology has advanced, the operating principles remain similar. Scheduling charging during lower demand periods will minimise the additional capacity needed. Establishing the working hours required of each element of the fleet, and the optimum location for stabling and charging, are key.

Decarbonising travel to work is an important part of the overall NHS decarbonisation programme, and Trusts are incentivising staff to adopt electric vehicles for their own use. It therefore makes sense to provide facilities for staff to charge their vehicles while at work. This could be essential for staff who may not have a charging facility at home; for instance if they only have on-street parking. Assuming that the car will be left in the parking bay, plugged in for the full duration of the working shift (e.g. 8 hours), lower capacity chargers can be installed.

Managing charging and bill energy usage

Systems and technology are available to manage charging and bill energy usage with parking charges through staff payroll. While navigating employee benefit taxation implications, the charging tariff could incentivise carbon-reducing behaviours, such as car-sharing. If adding electric vehicle charging pushes the site’s overall demand beyond the desired rating, the system can be managed to operate within available capacity. Providing EV charging for visitors is beneficial for reducing the hospital’s carbon footprint. However, as visitors usually park for shorter periods, higher capacity fast chargers might be needed, which increases additional capacity requirements.

The charging tariff can be used to manage demand, although one measure that might be undesirable in hospital settings would be imposing penalties for leaving the car parked in the bay once it has become fully charged, because if the visitor is delayed in leaving the hospital that would seem very unfair. Trusts will also wish to consider whether providing EV charging to members of the public is a non-core business area that they wish to venture into (no hospital that I can recall owns an on-site petrol station).

Striking a careful balance

So, caution is advised in drawing a balance between providing a convenience for visitors and helping to reduce the carbon footprint (visitors may be stressed and welcome that convenience — particularly during the current transition period when EV charging infrastructure is not fully developed), and/or becoming embroiled in a complex non-core activity.

Budget and timetable are always likely to be major influences on what can be done and when. However, it is a good professional approach to take time to stand back and consider what would be done in an ideal situation if these were not issues. This exercise will help develop a masterplan that represents the ideal solution for the estate and serves as a guiding principle. From it, we can identify affordable, urgent actions without compromising the overall vision.

The masterplanning stage is when the system architecture will be decided, and it is at this early stage that it is important to consider the cybersecurity implications of introducing levels of automation or monitoring versus the security of not having critical equipment connected to the internet to minimise vulnerability to attack.

Here are some examples of what our NHS clients say:

Richie Speight, assistant director of Estates at North Tees & Hartlepool NHS Foundation Trust, said: “The replacement of the electrical infrastructure was essential to avoid failure. The increased capacity and improved resilience realised by the project have enabled several improvements for patients, including new imaging facilities that would not otherwise have been possible, as there was just not enough power available before the project.”

Nigel Keery, head of Estates Operations for the Belfast Health & Social Care Trust, said: “The HV upgrade Project at the Royal has stood the test of time since it came into operation 12 years ago. The increased capacity has enabled the continuing development of the site, including the recently completed Maternity Hospital redevelopment.”

The latest solutions on the horizon for Estates managers

My approach, after 40 years’ experience, may be more cautious than others, but the reliability of hospital electricity supplies is paramount. Not only does the hospital need to be able to operate in the event of power disruption, but it is also likely to be busier than usual, because if the lights have gone out, more accidents will happen. Therefore, using tried and tested reliable technology does seem like a sensible starting point.

Nevertheless, there is emerging technology that, once tried and tested, might become suitable for use in the healthcare setting in time. For instance, even when decarbonisation of primary supplies has been completed, conducting standby diesel generator tests will still be necessary, and will release a relatively small amount of carbon that would have to be offset.

Emerging technologies

So, one technology to watch is whether alternative, equally reliable methods of standby generation will emerge. In this context it is important to measure emerging technology against the standard that is currently applied, which is to provide 100% supply to the agreed areas of the estate for 200 hours (just over eight days) without fuel resupply. Diesel fuel is readily available as B7 (up to 7% biofuel content), but hospital engineers will want to be assured that older engines can use this fuel, and to consider the impact of reduced shelf life — e.g. do you have to use more to keep it refreshed, thus ending up releasing more carbon? Will fuel with a higher biofuel content (up to B100) become readily available, and — if adopted — will new engines be required, or will modifications suffice? Will green hydrogen become sufficiently abundant and reliable?

To avoid further adding to the electrical demand of the site, green hydrogen might be best made off site, but stored on site for 200 hours’ autonomy. This is just one area of technology development. There are many others that space precludes discussing here; but let the conversation continue.