How reversible heat pumps can combat overheating
Tim Mitchell from Klima-Therm explores the challenge of overheating and how the latest generation of advanced reversible heat pumps can provide low-carbon, year-round climate control – keeping commercial buildings cool in summer and warm in winter while reducing carbon emissions.
The UK is just emerging from the hottest summer on record, according to the Met Office. Great British summers, which were once comfortably warm and more likely to result in soggy picnics than heat stroke, are now regularly hitting record breaking temperatures. Heatwaves of 40°C are no longer exceptional events but the new normal that we must plan for.
The CCC makes it clear in the 2025 Progress in Adapting to Climate Change report that the UK is not prepared for the rising risk of extreme heat. The report highlights that current action in the built environment is far behind where it needs to be, with too many homes and workplaces at growing risk of becoming uninhabitable in hot weather. This position is echoed by the UK Green Building Council (UKGBC), which warns in its Climate Resilience Roadmap that overheating is not being adequately addressed across much of the built environment.
Overheating is now one of the most pressing risks facing commercial property managers, occupiers and designers. With regulations focused on reducing heating demand, adaptation to higher temperatures remains underdeveloped. Buildings that were designed to keep heat in are increasingly struggling to keep heat out.
However, technology is moving quickly. The latest generation of reversible and polyvalent heat pumps are opening up new possibilities for creating low-carbon, year-round climate control that can respond flexibly to the shifting demands of a changing climate.
The impact of overheating
Overheating not only causes discomfort among building occupants, it also impacts performance. A 2006 meta-analysis by the Lawrence Berkeley National Laboratory suggests that workplace productivity begins to decline notably when indoor temperatures exceed 23–24°C. By the time temperatures reach 30°C, performance can fall by nearly 9%, creating serious knock-on impacts for businesses that rely on concentration, collaboration and decision-making. In sectors such as healthcare, overheating can have critical consequences for both patients and staff.
There is also a reputational and compliance dimension. Organisations are under growing pressure from employees, investors and regulators to ensure that workplaces are safe, sustainable and resilient. A building that cannot provide a comfortable working environment risks becoming a liability.
Traditional air-conditioning has been the default response, but its energy use and environmental impact are increasingly at odds with net zero goals. What’s required is a solution that tackles overheating without compromising decarbonisation.
The role of reversible heat pumps
This is where advanced polyvalent reversible heat pumps come in. At their core, these systems operate on the same principle as conventional heat pumps – they move heat rather than generate it, which makes them far more efficient than combustion-based systems. But reversible models go a step further. With the ability to switch seamlessly between heating and cooling, and in some instances provide both functions at the same time, they provide year-round comfort from a single integrated system, reducing capital expenditure, simplifying maintenance, and crucially, lowering operational emissions.
The latest innovations are making the benefits of these systems even more compelling. Advances in variable-speed compressors, inverter-driven fans and low-GWP refrigerants are pushing efficiencies higher than ever before. The newly award-winning UniPack-P range from Rhoss, for example, can produce hot water up to 72°C and cold water from -10°C to 20°C, ensuring optimal performance in diverse climate conditions.
Another key advantage of reversible heat pumps is flexibility of integration. Many models are designed for installation alongside existing HVAC systems – such as fan coils, chilled beams or underfloor heating – or incorporated into newbuild designs where they deliver even greater efficiency. Flexibility and extended operating limits make these heat pumps well suited for commercial applications where multiple thermal needs exist.
HVAC innovation leading the way
The message from the CCC and the UK Green Building Council is clear. Overheating is already affecting our buildings and our lives, and without urgent adaptation, the risks will only grow. The good news is that the technology we need to meet this challenge already exists.
Advanced reversible heat pumps offer a practical, low-carbon, future-ready solution that addresses both sides of the thermal comfort challenge – cooling in the summer, heating in the winter – with outstanding efficiency.
If we are serious about climate resilience, HVAC solutions that provide year-round temperature control should be the gold standard, sitting at the heart of building and retrofit strategies, supported by policy and embraced by designers, contractors and building managers alike.
Klima-Therm is exhibiting at elementalLONDON, the UK’s leading event for advancing the efficiency of buildings, on 19-20 November at Excel, London. To register for your free ticket, click here.
