NHS Southend hospital is a part of the Mid and South Essex (MSE) NHS Foundation Trust. The trust has ambitious targets when it comes to decarbonising it’s building stock, aspiring to decarbonise by at least 10% by 2025. The three-story Cardigan Building, part of the NHS Southend hospital estate, is the first building to seek optimisation with the help of the Hysopt Software. The building, a 700-bed healthcare facility that houses facilities including maternity, operating theatres, wards, and an IC-unit, serves a population of around 340.000 people.
The Trust had already sought out a heat pump solution to produce hot water and cooling as a low carbon demonstrator project. The building itself, is a stand-alone building with its own boiler house, low temperature water system and gas metering. The system in place had never received any major updates in its almost 27 years of existence. “The building therefore seemed quite a good candidate to be used as a proof of concept for validation with the Hysopt Digital Twin”, testifies Manoj Chohan, head of sustainability at MSE.
The use of Hysopt’s Digital Twin
The Hysopt Optimisation Software was used to as a proof of concept for the initially proposed heat pump installation, by creating a digital twin of the existing installation. The results indicated high operating temperatures, low delta T’s and high pump consumption due to hydraulic imbalances. Manoj explains “At this stage, we were looking at engaging an electric heat pump manufacturer. Hysopt was not only able to model the existing distribution system, but also comment on their recommendations.”
After the review of the current installation and the proposed design concept for the heat pump installation. The Hysopt Digital Twin software showed the following:
- Only a third of the cooling rejected from the domestic hot water production would be recovered to help cool the building in the summer.
- The overall seasonal coefficient of performance was much lower than anticipated (3.3. instead of >5 suggested by the supplier). This identifies a clear performance gap between promised and actual system performances.
- The proposed heat pump solution would deliver an overall carbon and cost reduction of 14%, but with an ROI of 36 years!
Important side note! The lower performance rates are not caused by the heat pump itself but is caused by the way it was planned to be hydraulically implemented into the existing installation.
“Generally speaking, engineers, design consultants or people like myself, we tend to replace “like for like”. That’s the concept, that’s the theory…and that stays with you. With the Hysopt digital twin, you can provide science-based knowhow and evidence to justify, or question suggested options. For me, the added value, is being informed so you can challenge or debate the like for like replacement and put things in that you otherwise wouldn’t or convert the entire system” Manoj explains.
Bringing “choice” to the table
Alternative options were put into the already created digital twin of the system. The option of upgrading the heating installation from a constant to a variable flow was modelled, and a range of optimisation options were offered. The new simulation of the Cardigan building’s heating and cooling system (before the application of heat pumps) showed a potential of 16% carbon savings and 21% annual energy cost savings. All of this with a ROI of 5 years, because of the significantly lower CAPEX investments! How? Because this option entailed only to change a range of pumps and valves and reprogramming the buildings energy management system – not the application of a heat pump.
Manoj continues “We are a hospital. We need to make sure that the environmental conditions are not compromised. We cannot say we put in a smaller pump, so we have less energy costs, but half the building has problems in summer with comfort conditions. The Hysopt design model is quite innovative, because of the engineering and science that goes behind it. Take it from the concept, the design, and the physical installation…giving it then six months and take than the learnings to other buildings in the future.”
Heat pumps: yes or no?
Improving the existing installation through optimising the existing hydraulic installation, was the logical first step to achieve carbon savings within a finite capital budget envelope. This way the Cardigan Building will be optimally prepared for a future integration of heat pumps due to significantly lower operating temperatures. These will make it possible to not only integrate heat pumps for domestic hot water, but also for space heating, thereby creating an opportunity to save a lot more carbon!
Going the extra mile
The NHS’ climate goals are ambitious. John Henry, director of Specialist Services at MSE, explains;” We are very keen on taking innovation forward, not only in carbon and energy reduction, but also in clinical practice and several 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.”
Manoj adds: “For me, it’s putting in plans and equipment that are designed with the Hysopt engineering concept, and ultimately install equipment that will deliver the needed service… all without compromise.” He elaborates; “We have a green plan to become net zero by 2050 that is aligned with national programs. The NHS put it a bit tighter and more ambitious and is looking at 2040 to influence emissions on scope 1 and 2, and eventually 2045 for the entire scope 3 supply chain”.
John Henry concludes: “What this work with Hysopt and its Optimisation Software has done, has put us back in control of our design and commissioning, and in my view, Trusts need to reclaim the informed client role”