Facilities managers and managing agents across the UK are being warned to prepare for another period of extreme summer temperatures, with climate experts signalling the potential return of a strong El Niño weather pattern and the UK Climate Change Committee (CCC) calling for urgent action on overheating in buildings.

For the FM sector, this is no longer just about occupant comfort. Overheating now presents a genuine operational, compliance and business continuity risk, particularly for offices, residential blocks, schools, healthcare environments and mixed-use developments. The CCC is calling for maximum temperature rules for workplaces to incentivise businesses to deploy cooling technologies to protect workers' health.

The latest warnings come as the CCC states the UK was ‘built for a climate that no longer exists’, with future heatwaves expected to exceed 40°C more regularly by 2050.

The HVAC Pressure Point

When temperatures rise suddenly, HVAC systems experience immediate strain. Buildings that appear to operate normally during average conditions can quickly suffer from:

• Reduced cooling efficiency
• Increased plant failures
• High-pressure alarms and system trips
• Occupant complaints
• Indoor air quality deterioration
• Increased energy consumption
• Poor BMS response or control instability

Older systems are particularly vulnerable, especially where maintenance backlogs, dirty coils, poor ventilation balancing or outdated controls already exist.

For facilities managers, reactive maintenance during a heatwave is costly and disruptive. The priority now should be proactive readiness.

Why This Summer Could Be Different

The Met Office has identified developing El Niño conditions in the Pacific, which historically contribute to elevated global temperatures and more extreme weather patterns.

Some forecasters are warning that a ‘super El Niño’ could intensify heatwave conditions across Europe and the UK over the next 12-18 months.

Combined with already rising baseline temperatures, the result could be prolonged periods of overheating across commercial and residential buildings.

The CCC Warning: Indoor Temperatures Must Be Actively Managed

In its latest climate adaptation reporting, the UK Climate Change Committee has urged Government to introduce maximum indoor temperature guidance for buildings such as schools, hospitals and workplaces. The committee also highlighted:

• Heat-related deaths could rise significantly
• Most UK homes are likely to overheat
• Hospitals, schools and care facilities require active cooling strategies
• Existing adaptation plans are currently inadequate

This is a major signal to the built environment sector. Expectations around overheating risk management are increasing, and building operators may soon face tighter scrutiny around occupant welfare and thermal comfort standards.

What Facilities Managers Should Be Checking Now

Before temperatures spike, now is the time to carry out targeted HVAC and building performance checks.

1. Verify Cooling Plant Capacity

Ensure chillers, condensers, VRF systems and split systems are operating efficiently and capable of coping with peak load conditions. Key checks include:

• Refrigerant pressures
• Condenser cleanliness
• Fan operation
• Compressor performance
• Temperature differentials

2. Review BMS Setpoints and Strategies

Many buildings still operate seasonal settings that are not optimised for sudden heat events. Review:

• Cooling schedules
• Night purge strategies
• Deadbands
• Occupancy-linked controls
• Simultaneous heating and cooling conflicts

3. Check Air Handling Units and Ventilation Rates

Poor airflow becomes far more noticeable during high temperatures. Inspect:

• Filters
• Belt conditions
• Damper operation
• Fresh air rates
• Sensor calibration

4. Inspect Critical Areas

Certain spaces overheat first and should be prioritised:

• Comms rooms
• Plant rooms
• South-facing offices
• Lift motor rooms
• Residential top floors
• Healthcare treatment spaces

5. Assess Tenant Complaints Data

Historical reactive callouts often reveal recurring overheating issues before they become major failures. The following patterns can help identify vulnerable zones:

• Hot/cold complaints
• Out-of-hours callouts
• Portable AC requests
• Fan usage

6. Test Emergency Response Procedures

If cooling systems fail during extreme heat, do teams know:

• Escalation procedures?
• Contractor response routes?
• Temporary cooling plans?
• Occupant communication processes?

Preparedness now reduces operational disruption later.

Energy Performance vs Occupant Comfort

One of the biggest challenges facing building operators is balancing Net Zero objectives with occupant wellbeing. The CCC has acknowledged that passive cooling measures alone may not be sufficient in future UK summers. This means facilities teams must increasingly focus on:

• Smarter controls
• Efficient cooling technologies
• Demand-led ventilation
• Zoning strategies
• Predictive maintenance
• Real-time building analytics

The answer is not simply ‘more cooling’ but better-managed cooling.

A Wake-Up Call for the Industry

The FM sector is moving into a new operational reality where overheating resilience becomes just as important as winter resilience. Buildings that are not prepared will likely experience:

• Increased tenant dissatisfaction
• Operational downtime
• Rising maintenance costs
• Energy inefficiencies
• Compliance and wellbeing concerns

For managing agents, there is also reputational risk. Occupiers increasingly expect buildings to remain safe, comfortable and operational during extreme weather events.

Final Thoughts

The warning signs are already here. Climate advisers, the Met Office and the wider building industry are all pointing toward hotter, longer and more disruptive summers ahead. For facilities managers, preparation cannot wait until the first heatwave alert arrives. Now is the time to:

• Stress-test HVAC systems
• Optimise controls
• Identify overheating risks
• Strengthen maintenance strategies
• Ensure buildings are operationally resilient

Because when temperatures rise suddenly, building performance is tested instantly.

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