LOW CARBON SOLUTIONS Cooling in a changing climate
As the conversation around climate change moves from prevention to adaptation, Steve Molloy, sustainability & commercial solutions manager at Daikin UK, looks at how building services engineers can meet the growing demand for mechanical cooling while still working towards decarbonisation
T
he extreme heat, drought and wildfires experienced across Europe this summer have marked a noticeable shift in the discourse around climate change. The United Nations Environment
Programme (UNEP) has warned that exceeding 1.5°C of global warming is now widely assessed as unavoidable under current policies and near-term trajectories. Within its report, UNEP urges global policymakers to prioritise decarbonisation efforts, in a bid to reduce the climate ‘overshoot’ and gradually bring temperatures back down below the 1.5°C threshold. However, it recognises that this period, perhaps decades long, will require significant adaptations in what it describes as a phase of “coping and containment”.
In the UK, this comes against the backdrop of the Climate Change Committee’s (CCC) recent publication A Well-Adapted UK, which states that the UK is “built for a climate that no longer exists”. The landmark report, published in May, advocates for greater use of both active and passive cooling measures in public buildings, particularly in those intended for vulnerable populations such as care homes and schools. For building services engineers, a pragmatic
approach will mean balancing the increased requirement for mechanical cooling with the ongoing imperative for low-carbon solutions.
Changing expectations
Occupant attitudes are also moving in this direction. Daikin’s second World Air Survey, which gathered responses from 1,200 air conditioner owners across 12 cities around the globe between late May and early June this year, found that 86.5% of respondents feel their
area has become hotter over the past five years, and 84.1% say the period in which they use air conditioning has become longer. More than a third (36.1%) said they had made
greater use of cooled public buildings and commercial spaces to escape the heat. Non- domestic buildings are increasingly acting as places of refuge in hot weather, so how they perform in extreme conditions is a growing consideration.
Rising demand for cooling inevitably raises concerns about energy consumption and peak electricity demand. The World Air Survey found that 64.4% of respondents sometimes limit their use of air conditioning because of energy costs or power supply constraints. That figure underlines a point that is central to the UK’s approach: cooling must be efficient if it is to be affordable, equitable and compatible with a decarbonising grid. This is where system selection becomes crucial.
A reversible heat pump provides heating and cooling from a single, electrified technology, avoiding the need for separate fossil-fuel heating plant and standalone chillers. As the carbon intensity of UK electricity continues to fall, the operational emissions associated with both functions fall with it. Cooling delivered in this way can support, rather than undermine, decarbonisation efforts provided the system is correctly sized, well controlled and properly commissioned.
Mechanical cooling is not, however, a substitute for good passive design. Shading, glazing ratios, thermal mass and ventilation all reduce the load a system must meet, and the most resilient buildings pair a fabric-first approach with appropriately sized plant.
Designing for the climate ahead
HVAC equipment specified today will typically remain in service for 20 years or more. If it is designed using current weather data, it will spend much of that life running in noticeably warmer conditions than it was sized for. Assessing overheating risk against future weather files, such as those set out in CIBSE TM49 and applied through TM52 and TM59, gives a more realistic picture of the loads a building will face over its lifetime.
Equipment selection should reflect this. Engineers should check that outdoor units can maintain capacity and efficiency at elevated ambient temperatures. Plant should also be positioned to avoid heat build-up and discharge air recirculation, which can cut performance just when it is needed most.
6 BUILDING SERVICES & ENVIRONMENTAL ENGINEER NOVEMBER 2026
Allowing headroom in electrical infrastructure, and engaging early with the Distribution Network Operator, will also help avoid costly constraints later in the project or in future refits. Controls deserve equal attention. Zoned, demand-based operation integrated with the building management system ensures cooling is delivered only where and when it is needed, which is particularly valuable in buildings with variable occupancy, such as schools. For offices, hotels, retail and education buildings, Variable Refrigerant Volume (VRV) air-to-air heat pump systems offer a practical and efficient route to integrated heating and cooling in new-build construction. Direct expansion systems require only two energy transfer steps and respond immediately to changing indoor conditions, which is a compelling advantage in buildings where solar gain, occupancy and IT loads can shift rapidly. Heat recovery configurations allow simultaneous heating and cooling in different zones, recapturing rejected energy and redistributing it where needed, with measurable efficiency benefits in mixed-use buildings. Compact refrigerant pipework and a self- contained installation make VRV systems straightforward to integrate structurally, and the industry’s ongoing shift towards lower GWP refrigerants like R-32 makes them particularly suited for projects seeking BREEAM, LEED or WELL certification.
Hot water temperature has historically been a constraint on heat pump specification in healthcare and other settings where Legionella control is critical. Advances in high-temperature heat pump technology now make it possible to achieve the required storage temperatures without resorting to fossil-fuel backup, although careful attention to system design and cylinder sizing remains essential. Moving forwards, the challenge for building services engineers will be around delivering cooling without compromising decarbonisation goals. By combining passive measures with efficient electrified systems, designing for future climate conditions and making greater use of heat recovery, cooling can become part of a building’s wider energy strategy rather than an additional demand on it. As the UK adapts to warmer summers, this integrated approach will become increasingly important. Designing systems that can respond to changing conditions while making efficient use of energy and recovering heat wherever possible will help ensure buildings are resilient, comfortable and fit for the climate they will face over the decades ahead.
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