Warming and cooling systems in British homes

For decades, plumbing and heating professionals have focused primarily on keeping buildings warm. But rising summer temperatures, better-insulated homes and changing customer expectations are broadening that role towards year-round indoor comfort. According to the World Meteorological Organization, the past decade was the hottest on record. As a result, more than 92% of existing homes are at risk of overheating during extreme heatwaves by 2050. Equally, 90% of NHS buildings in England are susceptible to overheating and 66% of UK classrooms are at risk of heat-related cognitive impairment, rising to 92% by 2050.

Unsurprisingly, manufacturers are reporting significant demand for climate control technologies. “We’ve been selling air-to-air heat pumps for over a decade,” explains Martyn Bridges, director of external affairs at CIPHE Industrial Associate Worcester Bosch. “They’ve never been a primary product line, but over the last couple of years the growth has been meteoric. Sales of air-to-air heat pumps have increased by around 300% this year alone.”

Government regulations

Prolonged periods of extreme heat are becoming increasingly common, while modern homes are built to ever-higher insulation standards. The Future Homes Standard, ongoing Part L changes and tighter Microgeneration Certification Scheme (MCS) requirements are all pushing the industry towards lower-carbon, lower-temperature systems and smarter, connected controls.

In England, Part O of the Building Regulations requires designers to reduce the risk of overheating in new homes – via measures such as limiting solar gain, providing adequate ventilation and enabling heat to escape naturally – before considering mechanical cooling. “Fabric must always be considered first,” says Chris Reilly, director at Zeuner. “It will not always be a complete solution and mechanical systems may also be needed, but we must be responsible about total emissions – even if it doesn’t suit our business.”

Passive measures like insulation and exterior shading can reduce a building’s cooling demand by 80%, but Bridges believes that isn’t enough. “Current regulations are contradictory,” he says. “Heat pump funding is available under the Boiler Upgrade Scheme, but the government wants people to explore other ways of keeping properties cool.”

Retrofits don’t currently have to meet Part O, which means installers are increasingly responding to homeowner demand rather than regulatory requirements, but growing concerns about overheating mean requirements should evolve as building regulations are reviewed. Many domestic air-to-air heat pumps can also be installed under permitted development, provided they comply with conditions.

Richard Soper, CEO at Unico System UK, believes the future lies in fully integrated, multi-function HVAC systems. “They will have a significant role to play,” he says. “They help in compliance with Parts L, F and O of Building Regulations and Awaab’s Law for social housing repairs. Plus, they ensure that the air we breathe indoors is free from unacceptable humidity levels and unhealthy airborne contaminants.”

Installer opportunities

While there are many installers operating in the boiler replacement market, there are far fewer qualified in domestic climate control. For many, the prospect of additional training might not appeal, but the transition might be less daunting than they expect.

“You need knowledge of refrigerant handling and different jointing techniques, which you can learn on an F-Gas training course, but competent engineers already have many of the core skills,” says Bridges. “We’ve seen a big rush on F-Gas qualification training courses – ours are heavily subscribed, with waiting lists.”

Reilly believes that where there are skills gaps, installers can collaborate with the companies that understand the systems. “This is the most immediate route to business expansion,” he says. “Businesses will gain a greater understanding through exposure to the technologies and learn how to better navigate management and safety issues. They will also gain a clearer understanding of the right questions to ask when speaking to clients.”

For Daniel Jackson, training manager at CIPHE Industrial Associate Daikin UK, competent installers will need strong foundations in heat loss calculations, low-temperature system design, hydraulics, and commissioning and controls. “Engineers will need a grip on the whole system, rather than individual products,” he says. “They will also need to interpret performance data and explain unfamiliar tech to customers.

“There’s a wider need for consistent, recognised standards,” he adds. “The City & Guilds Assured Daikin Altherma heat pump training gives installers an independent way to show they meet a consistent standard.”

Soper suggests beginning with HVAC solutions, as they are easier to install, simple for residents to operate and give complete indoor climate control. “Those able to offer expertise in this area will be at an advantage,” he says. “Installers must shift from a standard wet plumbing mindset to considering the potential for whole-house environmental solutions, as these present a significant opportunity to diversify and potentially build a more profitable business.”

Connected technologies require a particular set of skills. “These include whole-house system design and heat loss calculations, how insulation and air tightness affect heat retention and ventilation needs, and integration with heat pumps,” adds Soper. “Proper training is, of course, essential to correctly install, commission and maintain any HVAC system.”

Installation practicalities

The biggest consideration is selecting the right climate control system for the property. While homeowners may assume a heat pump automatically provides cooling, not all systems are designed to do so effectively. Air-to-air heat pumps, for example, are purpose-built for both heating and cooling. When specifying air-to-air units, installers should consider:

• room size and heat load to ensure correctly sized indoor units

• outdoor unit location, taking account of planning requirements, noise limits, maintenance access and airflow

• indoor unit positioning to provide even air distribution, while avoiding draughts directly onto occupants

• condensate drainage, ensuring water produced during cooling can discharge safely

• electrical capacity, particularly where multiple indoor units are connected to a single outdoor unit, such as integration with heat pumps.

For Rick Clarke, product manager at CIPHE Industrial Associate NIBE Energy Systems, the success of any heating and cooling system starts long before the equipment is installed. “Engineers should consider how the property is used, the level of insulation, the type of heat emitters already installed and whether cooling is genuinely required,” he says. “It’s also important to set realistic expectations. Cooling from a heat pump is designed to deliver steady, comfortable indoor temperatures, rather than the rapid blast of cold air associated with traditional air conditioning. When properly designed, the result is a more comfortable home throughout the year, with excellent energy efficiency.”

Controls are the brains of a heating system, yet they are often underutilised or poorly commissioned. “Design controls in from the start, rather than treating them as an add-on,” advises Jackson. “Check sensor positioning, set weather compensation against the building’s actual heat loss, agree operating schedules with the customer, and test the system under realistic conditions.”

Handover matters just as much. Engineers must walk the customer through the app or thermostat, show them the settings that count and follow up to fine-tune anything that isn’t working as expected.

Connected tools can allow the system to be monitored and adjusted remotely, helping installers optimise performance without needing to return to site. “A well-designed system can still underperform if the controls aren’t properly commissioned or the customer doesn’t know how to use them,” says Jackson.

Retrofit considerations

While some reversible air-to-water heat pumps can circulate chilled water through existing underfloor circuits, the reality is more complicated. Floor temperatures must remain above the dew point to prevent condensation forming on them, so only lightly cooled water can be circulated, limiting the system’s ability to reduce room temperatures in extreme heat.

Chilled water can also lead to condensation forming on radiators, which is why many manufacturers still recommend treating heating and cooling as complementary but separate systems. Existing boilers or air-to-water heat pumps remain responsible for wet heating, while dedicated air-to-air heat pumps provide rapid, responsive cooling, as well as supplementary heating during colder seasons.

Reilly, however, believes that systems should involve the least amount of equipment: “A system can be simple and intelligent,” he says. Heat pump systems can offer heating through traditional radiators, hot water through storage vessels and cooling via fan coils, all using one heat pump unit.

“Heat pump systems can achieve incredible efficiencies, as they will produce a hot and cold output at the same time,” he adds. “Multiple systems mean more energy input, more parts to fail and more maintenance.”

Ultimately, the right approach will depend on the property, its existing heating system, how it is used and the level of cooling required. For example, retrofit HVAC installations in older properties can also present specific challenges for installers. “There are often planning restrictions,” explains Soper. “Installers need to assess which climate control solution is most practical, while meeting the budget, the owner’s design aspirations and providing the all-year-round levels of comfort that have been specified.”

Heat loss from older properties can also be an issue, and a careful calculation of the full thermal dynamics of the building is essential. “Small-Duct, High Velocity (SDHV) systems are frequently selected for older properties, as they offer flexible installation,” Soper says. “Compact air handling units can be put in ceiling voids or airing cupboards, for example. Discreet room outlets take up minimal space and are quiet.”

Integrated ducted climate control systems distribute conditioned air throughout the property via concealed ductwork and are far easier to install during construction than as a retrofit. For most homes, adding dedicated air-to-air units alongside the existing heating system remains the simplest, most practical and cost-effective route to year-round climate control.

Some heat pumps are capable of providing active or passive cooling when paired with compatible emitters, such as underfloor systems or fan coil units. “However, this isn’t simply a case of switching on cooling after installation,” Clarke explains. “Proper system design, hydraulic considerations and controls all need to be evaluated to ensure efficient and reliable operation.”

Ventilation and humidity

New-build properties are highly energy efficient, better insulated and more tightly sealed than ever before, trapping contaminants and polluted air inside. “Tight construction can also result in overheating and high levels of humidity,” says Soper. “If not addressed effectively, this will have a detrimental effect on indoor air quality and impact the health of occupants, especially those with respiratory ailments.”

Overheating can also occur during cooler months, when strong winter sun rapidly raises internal temperatures. “Ducted air systems can respond within minutes to changing room conditions, whereas underfloor heating and, to a lesser extent, radiators, respond much more slowly,” he continues.

Some systems are highly responsive and this fast reaction to temperature changes lowers the risk of overheating, helps to maintain occupant comfort and reduces energy wastage.

Misconceptions and impact

From concerns over energy use and installation complexity to confusion about where systems are best suited, misconceptions about climate control can prevent customers from exploring solutions that may be right for them. For installers, separating fact from fiction is key to building confidence and helping customers make informed decisions.

“We’ve noted, at times, irresponsible messaging,” says Reilly. “But heat pumps are a tried-and-tested technology and the dominant means of heat production in places like Scandinavia. People need the right information on how to best select these products and that’s on specialists, manufacturers and the government.”

The availability and versatility of all-in-one solutions is still not widely recognised, either, says Soper. “End users and professionals often still think in terms of decoupled equipment for heating, cooling, ventilation, air filtration and moisture control,” he says. “But low- carbon, integrated solutions are readily available and gaining in popularity.”

For Clarke, cooling alone won’t encourage more people to fit heat pumps. “Greater public understanding, high-quality system design, skilled installers and long-term policy certainty remain the biggest factors in increasing uptake, along with the rebalancing of electricity costs.”

Preparing for the future

As domestic cooling becomes more commonplace, customer expectations will evolve. Today, engineers are expected to service heating systems; in the future, they may also need to maintain cooling equipment.

NIBE’s training combines hands-on learning with technical guidance. “Installers gain access to technical support, training opportunities and extended warranty benefits,” explains Clarke. “As demand for integrated heating and cooling solutions grows, CPD will play an increasingly important role in helping installers deliver systems that perform as intended.”

The increase in demand, additional training opportunities and the relatively few installers operating in the market suggest that cooling could represent one of the industry’s biggest growth opportunities over the coming decade – providing installers equip themselves with the right skills. “Engineers need to get comfortable talking to customers about performance, not just products,” says Jackson. “Homeowners want to know what a system will actually deliver in running costs, comfort and reliability.”

The installers who can confidently handle that conversation will be the ones who win the work.

Find a CIPHE-approved training centre for F-Gas courses at https://www.ciphe.org.uk/professional/careers--trainees/find-an-approved-training-centre/