Understanding the Challenge of Air Source Heat Pumps (ASHP)
Commercial organisations face a somewhat unfair challenge as they are held by the Government to be leaders in the move to control and reduce carbon to achieve net-zero by 2050, yet are limited by the technology options that the Government is showing active support for. The current drive, without a doubt is to push Air Source Heat Pumps (ASHP) to the exclusion of other technologies. Neither high-efficiency gas boilers with ultra-low emissions nor proven sustainable systems such as solar thermal have received much love in the latest round of grants supporting the commercial sector. In particular, the decision not to provide support for those opting for hybrid solutions that bridge the technology gap in the most cost-effective manner shows a focus on the finish line, but a failure to grasp the actual challenges the commercial sector faces right now. So, what are the options with ASHPs, and what is a realistic path to take today?
Unfortunately, we cannot control the weather, but despite that, ASHP technology does still present an opportunity to significantly improve the efficiency of buildings across the commercial sector. Because an Air Source Heat Pump is reliant on the ambient air, the Coefficient of Performance, or COP, is going to be affected by both the source and supply temperatures. The heat provided is at a much lower temperature, so a heating system will be required to operate at low temperature for optimum efficiency and may have to be kept on for a longer period to be fully effective. Such a system could well require a significant upgrade to a building’s electrical supply and heating infrastructure. However, to maximise the ASHP efficiency, the lowest possible flow temperature needs to be achieved, and that requires a building to be highly efficient in terms of heat loss. When working with new builds, the ability to drive high efficiency in the thermal performance of the fabric of a structure means a well-designed commercial heat pump system is more than capable of providing all the heating needs for a business and, in the long term, represent good value for money in savings from reduced energy bills, as well as helping commercial premises bring down that all-important carbon footprint.
But in isolation, this demand for low heating temperatures and low water usage will be impractical for many businesses, especially when retrofitting a property, which can highlight the limitations of ‘pure’ ASHP systems. This becomes particularly obvious when ASHP is to be deployed for the provision of hot water, especially if there is a large daily demand. Domestically we would expect a minimum storage temperature of 50oC, but this rises to 60oC minimum for commercial environments. This has a considerable impact on the ASHP’s running efficiency and therefore the running costs. Additionally, by generating hot water at 50oC and not 70oC, the storage volume will have to be considerably larger than that associated with a typical gas boiler. To achieve necessary water temperatures requires greater considerations of space planning and type of hot water cylinder the system will require.
With early to market performance of heat pumps falling below expectations, and a higher capital cost relative to the conventional gas boiler alternative the uptake of ASHP in commercial business on the gas grid had, until the drive to achieve net-zero, been limited. Now commercial operations are actively seeking to use ASHP, but are still running up against these same issues, which is why, with the current capabilities of ASHP technology, a hybrid approach for commercial applications remains attractive. Both in terms of installation and operation, whilst still gaining the all-important running cost savings and reduced carbon emissions.
In part 2 we explore how a hybrid approach can deliver significant value from ASHP technology
Read about Adveco’s compact commercial FPi ASHP range