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Harnessing Air Source Heat Pumps for Commercial DHW Applications

With around 40% of UK greenhouse gas emissions being accounted for by heating, cooling and lighting the built environment, it is clear that either new construction or refurbishment of existing properties is going to become increasingly important throughout the public sector as it takes the lead in the Government’s initiative to achieve net-zero by 2050.

The practicalities of achieving this are incredibly complex, but much has been staked on the application of Air Source Heat Pump (ASHP) technology to deliver sustainable space heating and, in particular, domestic hot water (DHW). The technology is certainly valid, being relatively low cost to secure and easy to install. Within the domestic market it is also highly effective, but for commercial sites it does have its limitations, in terms of generating the necessary high temperatures for regular legionella flushing (a minimum of 60°C) and achieving efficiencies great enough to impact a property’s energy consumption and thereby deliver cost savings.

When assessing the efficiency of ASHP technology, we calculate the ratio between the electricity invested to run the ASHP and its output, this is the coefficient of performance or COP. The COP can be influenced by several factors including the energy needs and energy efficiency of a property, quality of hot water and heating system installation, and once operational, the management of system output. As a gauge, Adveco’s current generation of high-performing FPi commercial ASHPs, due to variance in seasonal external temperature and heating flow temperature, can achieve a COP that ranges from 2.9 to a very high 4.7. 

Since 2015 the wholesale price of electricity has climbed 20%, yet gas prices over the same period are down on average 15%.  The difference between the wholesale market price of electricity and its cost of production using natural gas provides us with the spark spread. At the time of writing the spark spread is calculated to be 5.7. As a result, even the best commercial ASHP system currently available will exhibit a maximum COP lower than the necessary 5.15 to start delivering greater savings. Water temperatures are also typically too low in isolation, with dependable temperature at best reaching 55°C. It is also worth considering that the latest generation of commercial gas boilers will exhibit even greater efficiencies, for example, Adveco’s MD boiler range can achieve a NET combustion efficiency of 106%. 

So where does this leave us? The Government has recently announced a £350 million package targeting carbon emissions, of which £139 million is to be dedicated to the cutting of emissions by supporting carbon capture and storage (CCS) and crucially, the transition from natural gas to clean hydrogen power. This means gas has a long-term role to play in achieving net-zero, and especially for refurbishment projects opens the door to harnessing ASHP as part of a hybrid system approach.  

Whilst new builds will consider a combination of direct electric water heater and ASHP, extant gas infrastructure when packaged in combination with an ASHP and control system presents an attractive alternative for commercial refurbishment projects. The hybrid approach retains and offers better compatibility with existing gas heating distribution systems and the thermal demands of higher heat loss buildings, meaning less adaptation is required. Where bespoke system design is required to meet the particular needs of a commercial project, the availability of two heat sources to meet the DHW demand of a property is extremely advantageous and means the heat pump can be reduced in size, such as the compact FRYO-9Pi, when compared to the capacity of a pure electric heat pump system.

It gives a property the versatility of switching to the gas boiler at time of network peak, or on the coldest of days to meet peak demands, which helps reduce operational costs while maintaining higher water temperatures demanded by commercial operations. 

Although a hybrid approach will not be carbon zero, given that the heat pump does not completely replace an existing heating or DHW system, but hybrid ASHP systems can help organisation meet their carbon targets in the coming decades as hydrogen technology matures and delivers true sustainability for commercial applications. 

www.adveco.co

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