Categories: News, Article, Press

Opinion piece from the GSHPA;

You may have recently read an article published in the Telegraph on the 14th March 2023; Heat Pumps Wont Work in Old Homes, Warns Bosch.

There are two aspects to the Telegraph report which quoted Vonjy Rajakoba, MD of Bosch UK, (and which was subsequently picked up by other media outlets). The first is what was actually said, and the second is why it was said and by whom.

Let’s tackle the technical aspect of the comments first. It is vital to recognise that the building has no idea where the heat comes from. Therefore, any building will leak heat regardless of source, and all buildings and all heat technologies will benefit from a degree of energy efficiency or building fabric improvements. At this point in time, society has to decide between leaking lower cost, very high carbon heat (gas), or slightly more expensive, increasingly low carbon heat (electrification with a heat pump). Over time, the spark gap, the difference between the retail price of gas and electricity, will continue to reduce, so even the cost argument will ultimately evaporate.

Buildings with higher energy demands may require higher flow temperatures in the radiator systems in winter, but there are two new factors in play here. Firstly, our industry has a growing range of High Temperature (HT) units available which can be a direct replacement for boilers operating at high temperature. Secondly, Building Regulations now requires new build and retrofit replacement heating systems to be designed for a flow temperature of just 55°C, to ensure that boilers do, indeed, operate largely in condensing mode, so delivering the oft voiced high efficiencies. Conveniently, 55°C is a perfectly reasonable design flow temperature for a replacement heat pump system, especially when operating under weather compensated controls.

The Energy Systems Catapult has just published its Interim Heat Pump Performance Data Analysis Report from the recent government sponsored Heat Pump Demonstrator programme. Apart from reporting steadily improving efficiencies (over previous trials) this programme could not identify a dwelling for which there was no individual heat pump solution, be it air source, ground source or hybrid (a combination of a heat pump and a fossil fuel boiler). Interestingly, this parcel of work also reports that HT heat pump systems were marginally more efficient than lower temperature systems, so there was no overall efficiency hit from needing slightly higher winter flow temperatures.

The National Trust is turning to heat pump technologies as its members increasingly reject the burning of biomass fuels. Bath Abbey, surely one of the leakiest buildings in the UK, is now heated with a water source heat pump system.

It’s also important to recognise that this technology is not just for large properties with extensive budgets, the Listed Property Owners Club could, I’m confident, cite many examples of small cottages and houses which have successfully displaced oil, LPG or gas with heat pumps. Several of our members have also carved out significant market segments in period and Listed properties.

On the question of space, indeed, some heat pump architectures do require more space, potentially both inside or outside the home. But there are many ways of mitigating against this. The Bosch comments refer uniquely to domestic air-source heat pumps, but this is only one approach to the decarbonisation of heat with heat pump technology. In the rare instances where homes may be unsuitable for an external device, these could be served with an internal ground source heat pump, or via a heat network that will almost certainly end up being driven by a centralised commercial heat pump, even if not from the outset. On space for a hot water cylinder, yes, this can be a challenge for homes which currently have a combination boiler (frequently the least efficient devices); but here, again, there are space saving technologies, such as phase change storage devices ( which have the potential to reduce volumes by 75%.

Moving to the source of the statement, Worcester Bosch is, itself, now bringing heat pumps to the UK market. However, all of their current UK manufacturing facilities are geared to producing condensing boilers and the senior management want to get as much out of that investment as they possibly can, by extending the life of those production facilities until legislation forces them into a change of tack. Exactly the same happened with the migration from non-condensing boilers to condensing boilers in 2003-2005. The division of the overall business that deals with heat pump sales in the UK is currently small. Whilst it obviously has a different view, its influence is modest. For Mr. Rajakoba, it’s the group performance that counts.

By comparison, it’s worth looking at the public position taken by Vaillant and Grant. Vaillant has been a long term manufacturer of both boilers and heat pumps, and is now investing in new heat pump production facilities in the UK. Its marketing campaigns now give equal weight to heat pumps and boilers. Grant is probably the largest UK manufacturer of oil fired boilers which it recognises will be first in line for legislation being the highest carbon factor fuel. Consequently, its promotion of its heat pump offering is very advanced.

We also specifically highlight some examples of heat pumps working in older properties on our website that include a Victorian farmhouse, a grade 1 listed row of terraced houses and remote 18th century Welsh dwelling.

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