Industry urged to rethink waste heat as part of net zero HVAC push

HVAC experts warn that megawatts of usable heat generated from cooling equipment such as refrigeration plant in supermarket estates is going to waste each year. This waste heat, with more collaborative thinking across the HVACR sector, could help support the country’s ambitions for lower carbon and net zero buildings.

The comments were made during a recent BESA webinar focused on the role of heat recovery in cooling systems and the role that utilising this energy could play as part of building decarbonisation strategies. It included a look at how supermarket retailer Tesco was currently looking at making use of waste heat.

Graeme Fox, BESA’s head of technical, said that significant amounts of waste heat was currently being generated by larger scale commercial and industrial cooling systems that could offer new ways of providing more efficient and cost effective heat.

He said, “Much of this, with a little bit of joined up thinking, could be recovered and used to supply heat for heat networks or social housing built near to those non-domestic buildings.”

“The building services design consultants need to work more collaboratively with refrigeration consultants, rather than in their more traditional siloes, so that we can harness ejected heat and help our built environment become truly carbon neutral.”

Tesco research

Phil Hozer, Tesco’s group refrigeration engineering manager, spoke during the webinar about how the retail giant has conducted research looking at ways of better using waste heat generated in its stores.

Mr Hozer said that initial testing had indicated that much more study was needed around the heating demand of individuals stores. This would need to consider a range of factors other than purely looking at the basic store size and location.   Other factors expected to be included in future studies would look at the basic building structure of a store and how cold air retrieval solutions and the types of mechanical ventilation are being used.

He added, “We’ve actually started a knowledge sharing hub with the University College of London (UCL) to look at this in a bit more detail.”

Mr Hozer said a major challenge identified by the retailer around rethinking waste hear was based on the integration of HVAC and refrigeration controls to ensure different systems were being efficiently sued together, while also taking into account seasonal changes in demand.

He said that many stores have shown demand for heat functions in summer months.

Mr Hozer added, “So the integration of the heat demand signal in particular with refrigeration controls is still problematic.”

“In the short-term, I see that the refrigeration controls will operate some of the pumps and control things such as the buffer vessel temperature and then we will endeavour to omit the need for the heat demand signal to give us greater control of the refrigeration systems efficiency. This will protect the refrigeration system’s core functions.”

In the longer-term, Mr Hozer said he believed that the closer and more effective integration of heating and cooling systems in its estates and across the wider HVACR industry was inevitable.

Heat pump role

He added that another consideration for the retailer in the planned integration of heating and cooling demand across the company was the issue of the types of refrigerant being used in heat pumps across its estate.

Mr Hozer said that typically, the lower flammability R32 refrigerant was expected to be used for the heating systems. This option still had a “relatively high” global warming potential (GWP) of 675 that would require a need to consider alternative lower GWP options going forward with Tesco looking at natural refrigerant for its operations, Mr Hozer added.

He said, “I see a lot of refrigeration plant managers moving into that sector and offering CO2 heat pumps, at least in the short-term.   Longer-term. I guess there will be a change in the market.”

Tesco said that it was also looking at aligning the company’s HVAC and refrigeration replacement programmes that Mr Hozer said would increasingly have to be considered simultaneously.

Mr Hozer said, “We’re somewhat bound by existing policies related to service life write down periods. To try and help this alignment, we have since last year been fitting heat recovery as standard to our refrigeration plant – whether it’s used or not.”

“Effectively this is making it ready for a future boiler replacement and decarbonisation project.”