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HVAC SYSTEMS


Software accurately models ‘real-world’ performance


A software system which helps heating and cooling system designers make more accurate engineering calculations using ‘dynamic simulation’ to show how their installation will perform under ‘real-world’ conditions has enabled the Mid and South Essex NHS Foundation Trust to arrive at an engineering solution which should reduce the annual carbon footprint of one of its key clinical buildings by 16 per cent, and cut its energy costs by 21 per cent, with payback in around five years. The Trust has been considering installing a heat pump for the Cardigan Building at Southend Hospital, but the Hysopt software’s modelling suggested that a more effective, and considerably less costly, first step, would be to optimise the building’s existing hot water and cooling systems’ operation – by replacing and reconfiguring key components, and switching from constant to variable flow heating. HEJ editor, Jonathan Baillie, reports.


Hysopt is a spin-off from the University of Antwerp, and the Hysopt software recently deployed at Southend Hospital was developed – ‘based on years of research’ – to enable engineers designing new, or reconfiguring existing, HVAC installations to optimise HVAC installation performance ‘on a large scale’. Hysopt explains that the software – already deployed on over 150 ‘large-scale’ heating and cooling projects – is designed to enable building owners and heat network operators to reduce their energy consumption, carbon footprint, and maintenance costs, ‘by hydraulically optimising the heating and cooling system down to the finest level of detail’. There are four key stages: n Firstly, the ‘intuitive’ software uses a model library of pre-programmed hydraulic circuits to build a visual representation or ‘digital twin’ of the installation. Existing and new installations ‘can be perfectly integrated into one new design’.


n Next, it optimises the hydronic installation’s design ‘by always calculating the right equipment with the most suitable parameters’. Hysopt uses ‘advanced algorithms’ to calculate all the installation components automatically.


n The software then simulates ‘how the installation will behave’, by subjecting it to variable conditions – such as the weather, occupancy profiles, and control strategies. ‘Dynamic simulations’ enable engineers to evaluate the design’s energy consumption, thermal comfort, and control behaviour.


n Finally, when the calculations have been made, the engineer or end-user can compare Key Performance Indicators for different hydronic designs from an economic (savings, investment,


74 Health Estate Journal September 2020


The Cardigan Building at Southend Hospital.


payback period), ‘ecological’ (CO2 emissions), and comfort standpoint, and then choose the system design to best meet their needs. As a software- as-a-service system, the Hysopt software is accessible from any device with an Internet connection; users pay a ‘one-time project fee’ calculated on the basis of full-load output power.


Rationale for use


Hysopt says of the typical rationale for using the software: “For existing buildings, the objective is often to improve comfort levels, and to reduce annual energy costs, especially where HVAC installations are a mix of components of all ages and conditions. In new buildings, there is often a need to validate M&E designers’ design proposals, presenting an opportunity to optimise Capex investment, as well as to lock in long-term energy cost and carbon savings.”


Hysopt reports that ‘across projects in


Issues with the ‘traditional’ approach to HVAC system design


Hysopt argues that without digital design and simulation tools, the ‘traditional approach’ to HVAC system design can lead to: n Incorrect sizing: It says studies show that using ‘traditional static-load and rule-of-thumb approaches’ to system sizing can result in oversizing of 50- 95%, and poor performance at partial load. This takes up valuable space, increases capital and energy costs, and decreases occupant comfort.


a wide range of market sectors, including healthcare and education’, end-users have, on average, seen: n A 30% annual fuel cost saving. n A 10% Capex saving on new installations.


n Return-on-investment in under three years in 75% of projects.


n A 52% annual energy cost reduction on CHP installations.


©Mid and South Essex NHS Foundation Trust


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