HVAC SYSTEMS
Chris Davis explained that Hysopt as a business was formed in 2012, initially trading mainly in Belgium and the Netherlands, before entering the UK with its software in late 2018. He said: “Hysopt is short for ‘Hydronic System Optimisation’. The software is based around creating digital models of complex heating and cooling installations, and optimising them for improved performance – whether for a new design, or to optimise the performance of an existing heating and cooling installation. The key aims include reducing energy costs, improving occupant comfort, cutting carbon emissions, and fundamentally introducing performance as a measurable metric in a digital environment, rather than, say, a hospital’s Estates and Facilities team having to rely on trial and error to achieve the optimal heating and cooling solution. “It’s also,” he added, “ about closing the performance gap between design intent and what actually gets delivered. We talk about a number of key elements – including giving people like John an insight into how his system is performing, what the available improvement options are, and the impact of any proposed changes, in terms both of energy and capital cost savings and carbon emission reduction. Equally important is protecting the integrity of the design, i.e. ensuring that the design intent is actually delivered by the contractor.”
Drawbacks of a ‘traditional’ approach Chris Davis said that in ‘traditional’ heating and cooling system design, ‘everything gets designed based on static, peak loads’. He explained: “In contrast, Hysopt allows the design engineer to see how their system will operate and perform at partial load, where it will spend over 99 per cent of its time operating. It is all about understanding how key heating and cooling plant work hydraulically and thermally under partial load conditions, and thus optimising the entire system’s
Active mixing circuit for VT-circuit
Radiator circuits
FCU, heating coils and frost coils
Gas boilers in parallel
Low loss mixing header DHW calorifiers
Figure 1: A model implementation of the heating plant room in the Cardigan Wing using the Hysopt software.
operation.” He added that, particularly with many healthcare clients looking at low carbon technologies – such as CHP or heat pumps – there was now ‘a tendency to take a component-based approach’ – by selecting technology particularly ‘in favour’ at the time. He elaborated: “Take CHP, and 2-3 years ago it made absolute sense, both from an operational cost standpoint – since you can generate cheap electricity, and from a carbon standpoint – as you are offsetting the carbon content of the electricity. However, now that the grid has got much ‘greener,’ CHP makes far less sense from a carbon standpoint, and heat pumps are becoming a more interesting option. They do, however, have their challenges from a technical and operational standpoint; they perform best at lower temperatures; are expensive pieces of plant, and typically in a larger installation such as a hospital, have to work alongside other technologies. That is partly where Hysopt comes in; the software helps users understand how those technologies can be best integrated for both optimal performance and a good balance between ‘Opex’ and ‘Capex.”
The client’s view
John Henry, director of Specialist Services at Mid and South Essex NHS Foundation Trust.
76 Health Estate Journal September 2020
Here, John Henry joined the discussion. He said: “We are a new NHS Trust, formed on 1 April this year from the merging of Southend University Hospital NHS Foundation Trust, Basildon NHS Foundation Trust, and Mid Essex Hospitals Trust. The main hospital sites at Chelmsford, Basildon, and Southend, have thus come together under the auspices of the Mid and South Essex NHS Foundation Trust, which puts us into the ‘top 10’ largest NHS acute Trusts in England. We are very keen,” he added, “on taking innovation forward, not only in carbon and energy reduction, but also in clinical practice and a number of other technology areas. We want to be at the
forefront of low carbon, and I have a plan to take forward a low or zero carbon hospital, and to be leaders on that front. We have taken Southend Hospital as our initial model.”
By way of context, John Henry explained that at the Trust’s Broomfield Hospital site in Chelmsford, his team had been doing some work with a heat pump specialist, and had successfully de- coupled the hospital from the electricity grid. During periods of high carbon consumption, the hospital has a system that works off batteries, takes the site’s full electrical load, and runs the cooling for a data hub, as well as providing domestic hot water to the ward block. He explained: “This work led us to look to do something similar at Southend Hospital. We are currently out to tender for a heat pump system, deploying a similar off-grid system, linking to batteries and solar PV. As part of this strategy, we wanted to look at ‘digital twinning’, running parallel with the heat pump project, and engaged Hysopt to produce a digital twin of our Cardigan Building plant room. We were particularly interested to see how the proposed heat pump would operate and perform.
Changing the current operating mode “Interestingly,” John Henry continued, “the digital modelling showed there was a piece of work to be done before we even consider installing a heat pump, because we discovered that the building’s existing heating and cooling plant wasn’t operating as it should be. In particular, the digital twin identified that if we changed the operating mode from constant to variable temperature running, we could achieve the same carbon reductions for much less capital outlay than via the proposed heat pump scheme. This was a bit of an eye-opener.”
The Cardigan Building’s existing plant
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