You may recall I wrote previously about the alarmed reaction of the U.K. HVAC industry to the new government's systematic "ungreening" of its flagship green-building policies.

I described how the new Conservative administration had halted funding of the Green Deal program of energy efficiency measures and rowed back from its zero-carbon building targets on the grounds of "saving taxpayers money." And I ended with the comment that many in the industry wondered whether the other flagship HVAC policy — the Renewable Heat Incentive — would face a similar shutdown.

At the time, I thought this was not a serious threat. After all, the previous administration boasted loudly that the RHI was "the world's first" subsidy for renewable heating, and it had taken long years to come to fruition.

But things move fast when there is anti-austerity credibility to be gained by governments. Perhaps hardened in skepticism by those years of waiting for the scheme to materialize, those in the renewable heating sector seem less optimistic, and warnings have been raining down from those who fear the worst.

It is the fledgling heat pump sector that feels most in the firing line — and with good reason — as there is evidence already that the uncertainty over the RHI scheme's long-term future is harming the prospects for the technology. The warnings are dramatic — that heat pump technology may "die" if the support from the RHI for its development is not maintained.

For those not familiar, the RHI offers a range of subsidies for renewable technologies, based on a per-kilowatt usage. So for every heat pump, PV panel, biomass boiler or other such heat source installed, the customer stood to receive a payment back on his electricity bills.

Even though there have been no definitive statements about RHI being stopped, there have equally been no positive noises emanating from government that it will guarantee long-term funds. As heat pumps are still a developing technology in much of Europe, those involved feel the financial motivation offered by the RHI, and the assumed "support" from government that comes from being in the scheme, is essential to sustain its take-up (and indeed its credibility) among customers.

Star Renewable Energy, a Glasgow-based firm involved at the large industrial end of the heat pump sector, went public last week with news that this lack of clarity around the future of the RHI had led it to withdrawing from a key project.

The project in north London was projected to demonstrate the viability of harvesting heat from surface water while simultaneously selling cooling to third parties. It was set to receive around 1 million British pounds of subsidy and funding from the government's Department of Energy and Climate Change.

Alongside the obvious impact on Star's business, the company stressed this was potentially a key exemplar of the application of heat pump technology, while providing sustainable heat for homes and businesses in the locality.

"The water-source heat pump was expected to supply cheaper, more eco-friendly heating locally," Star said. "Drawing on heat from the local Regent's Canal, the Islington water source heat pump project would have simultaneously warmed local homes and businesses, as well as cool a local data center server room."

Star said it was on-track to lead Phase 2 of the project, but the potential heat pump funding cuts on the horizon forced it to withdraw from the tender as commissioning beyond March 2016 would have resulted in no RHI application.

David Pearson, director at Star Renewable Energy said he "fears that heat pump technology may die" if the much-needed subsidies are withdrawn on the cusp of what he believes could still be a renewable heat revolution.

"More than 50 percent of the energy we use in the U.K. does not come from wind turbines and solar panels as electricity, but in the form of heat," Pearson said. "With only 1 percent of the expected renewable heat uptake being achieved with heat pumps, funding is essential to promote the acceptance and introduction of large-scale heat pumps in the U.K. market."

Pearson expressed his disappointment about the London project.

"The teams at DECC and the Heat Network Delivery Unit should be commended, and the vision of the Borough of Islington recognized," he said. "We walked away from 1 million pounds in support, and that was a bitter disappointment, especially given the hard work done by the team whose work had shown lower cost, lower carbon and zero local emissions. But ultimately we were unsure of the continuance of the RHI, and this was a factor in our withdrawal."

He said that while Star has delivered over 30 MW of heat pump-driven heat around Europe, the technology is still far from becoming understood in the U.K., so he now was urging the government to ring-fence heat pump funding for heating technology "to allow the technology to be properly understood by customers and the public."

Paul Younger, professor of engineering at Glasgow University, drew attention to the lack of support from government for the heat pump technology.

"As it is so often the case, other countries saw the light earlier than us, and heat-pump technology built on the Clyde is now heating other European cities by extracting thermal energy from their rivers," Younger said. "Meanwhile, our rivers flow by, delivering their renewable thermal content to the open ocean unused — while many people in the U.K. cannot afford to heat their homes."