ASK THE EXPERT


Looking ahead at the commercial HVAC trends in 2026


BSEE: Hi Tim, Happy New Year. What’s your main prediction for commercial HVAC in 2026?


With the new year firmly underway, we caught up with Tim Mitchell from Klima Therm to discuss what’s on the horizon for commercial HVAC systems and the trends that will be driving specification in the year ahead


Tim Mitchell: There are lots of ongoing challenges for the commercial buildings sector, most of which we’re closely involved with one way or another, such as minimum energy efficiency standards, decarbonisation and indoor air quality. One of the key issues for commercial buildings in 2026 is the proposed acceleration of the F-gas phasedown, which will perhaps force more radical solutions when replacing legacy systems as traditional relatively high GWP refrigerants fall out of favour and are even considered deleterious material by some developers. Specifiers must ensure new systems use life-time compliant refrigerants and are designed for long-term maintenance and efficiency. But the big issue for me is climate resilience. Globally, 2024 was the hottest year on record and in 2025, temperatures also reached extreme highs, bringing climate change to the forefront of planning decisions. The Climate Change Committee has advised that buildings should be built to withstand a minimum 2°C temperature rise by 2050, with the possibility of 4°C by 2100 for long-life commercial buildings. It is no longer good enough to design buildings based on historical climate data, we need to be designing for the future now.


BSEE: What practical changes do building managers and designers need to consider?


TM: The old model of switching from heating mode in winter to cooling mode in summer is becoming obsolete. With milder winters and more extreme summers, overheating is emerging as one of the most urgent risks in commercial buildings. Research by Rhoss and the Polytechnic University of Turin revealed that buildings designed for high energy efficiency through superior insulation are now facing a paradox— they’re excellent at keeping heat in during winter, but that same characteristic means they struggle to expel heat in summer, especially in buildings with high internal heat loads.


BSEE: So, what’s the solution?


TM: The solution lies in more sophisticated, flexible HVAC systems that can respond dynamically to changing demands. Polyvalent (4-pipe) heat pumps, for example the


UniPACK-P and UniPACK-P EXP range from Rhoss, mark a significant step forward in sustainable heating solutions, with the ability to provide heating and cooling simultaneously to different zones. Unlike reversible systems that switch seasonally between modes, polyvalent systems can recover heat from cooling processes and redirect it elsewhere in the building. This makes them particularly valuable in hospitals, universities, leisure centres, mixed use developments and hotels.


BSEE: The UniPACK range is relatively new to the UK market, isn’t it?


TM: Yes, we launched it in August 2024, and the response has been excellent. The soon- to-be-expanded range currently comprises eleven sizes covering cooling capacities from around 50 to 160kW, available in both high efficiency and super-silenced versions. What’s particularly impressive is the extended operating limits—the units can produce hot water up to 72°C even with external air down to minus 12°C, and cold water from minus 10°C to 20°C with external air up to 50°C. They run on R290 propane refrigerant, which has a negligible global warming potential of just 3, compared to R410A whose GWP is 2088, and also achieve exceptional seasonal performance with low temperature SCoP up to 3.86 and medium temperature SCoP up to 3.28.


HR: What about buildings that don’t have such complex, simultaneous heating and cooling demands?


TM: For those applications, our Rhoss POKER290 range offers an excellent reversible solution. The range comprises high-temperature, air-cooled heat pumps that also run on propane, and they’re incredibly versatile. They can generate temperatures up to 75°C with outdoor air as low as minus 20°C, and in summer mode, produce cold water for air conditioning or chilled water down to minus 10°C. The modular design is brilliant too—you can connect up to four units via our Rhoss integrated electronic dynamic sequencer, covering a capacity range from around 48 to 190kW, with full system redundancy for ultimate reliability.


HR: Retrofit projects present their own challenges. How are high-temperature heat pumps changing the game there?


TM: Historically, one of the biggest barriers to heat pump adoption in older commercial buildings has been temperature limitations. Many legacy systems were designed around radiators and domestic hot water circuits requiring 70 to 80°C supply temperatures. The POKER290 delivering up to 75°C, and our UniPACK-P reaching 72°C, means organisations can decarbonise through phased refurbishment without ripping out existing infrastructure. For even more demanding applications, we have the Rhoss FullFLOW range, which we launched in November 2024. These are non- reversible heat pumps with stepless or inverter screw compressors that produce hot water up to 85°C. They come in seven sizes covering heating capacities from around 400 to 1,000kW, and they’re ideal for hospitals, large residential buildings, hotels, and industrial applications.


HR: What problems might we see due to F-gas regulations in 2026, and how can buildings remain compliant?


TM: Over the next 25 years, any HVAC systems using HFCs will need to be upgraded to compliant alternatives, but it is wise to consider replacement sooner rather than later. We are already seeing supply issues pushing up costs for legacy refrigerants and the cost of repairs and maintenance associated with older systems soon outweighs the upfront costs of replacement or retrofit.


All our key ranges—the POKER290, UniPACK-P, and UniPACK-P EXP—use R290 propane, which offers very low global warming potential and excellent thermodynamic performance. R290 requires less energy to reach and maintain desired temperatures than fluorinated gases, meaning lower power consumption and fuel bills. It’s non-toxic, works with low compressor discharge temperatures that extend compressor life, and unlike some HFOs, it doesn’t break down in the environment into trifluoroacetic acid or other harmful substances. For the FullFLOW range, we use optimised, low GWP refrigerants like R1234ze or R515B. The key message for 2026 is that natural


refrigerants are no longer the alternative— they’re becoming the default choice, and they’re futureproofing installations against increasingly stringent F-gas legislation.


HR: What’s your final advice for building managers and designers as we move through 2026?


TM: The Paris Agreement targets will be exceeded; we need to start planning for that inevitability today. Every design decision, whether for new build or retrofit, must prioritise adaptability and resilience alongside efficiency. The technology is there, but success depends on understanding how different solutions interact for your specific building type, occupancy patterns and existing infrastructure. Engaging with experienced specialists early in the design process will ensure that your buildings perform reliably not just for the next 10 years, but for the decades to come.


https://klima-therm.co.uk/ 12 BUILDING SERVICES & ENVIRONMENTAL ENGINEER FEBRUARY 2026 Read the latest at: www.bsee.co.uk


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40