Commercial buildings can reduce workplace overheating by improving ventilation, maintaining HVAC systems, reviewing glazing and shading, upgrading lighting, checking roof and insulation performance, managing heat-generating equipment and planning maintenance before summer heatwaves arrive.

The key areas to check are:

• ventilation

• air conditioning and HVAC

• windows and opening controls

• blinds, shading and glazing

• roof condition

• insulation and heat gain

• lighting

• plant rooms and server areas

• meeting rooms and enclosed spaces

• staff welfare areas

• maintenance records

• heatwave response plans

For facilities managers, landlords and business owners, the priority is not just cooling the building when it becomes hot. The priority is understanding why the building is overheating and what can be improved before the next heatwave.

Why Workplace Overheating Is Becoming a Bigger Issue

UK commercial buildings were traditionally designed around keeping heat in during colder weather.

That is now only part of the challenge.

Hotter summers, more frequent heat alerts and changing working patterns mean buildings also need to manage excess heat. Offices, schools, hospitality venues, healthcare sites, large venues and older commercial properties can all struggle when ventilation, shading or cooling systems are not suitable for current conditions.

Overheating can affect:

• staff comfort

• productivity

• concentration

• meeting room use

• customer experience

• pupil learning environments

• plant and equipment performance

• indoor air quality

• maintenance demand

• energy use

• workplace complaints

For many organisations, the question is no longer whether a building looks presentable. It is whether the building remains usable during hotter weather.

Is There a Maximum Workplace Temperature in the UK?

There is no single legal maximum workplace temperature in the UK because workplaces vary widely.

A commercial kitchen, office, warehouse, school classroom and plant room all have different conditions and risks.

However, employers still need to manage workplace temperature and keep conditions reasonable. Where heat becomes a risk, practical steps may be needed to protect people, maintain comfort and reduce disruption.

This is why facilities teams should treat overheating as a building management issue, not just a seasonal inconvenience.

Suggested external links to embed:

• HSE workplace temperature guidance

• HSE workplace ventilation guidance

• Acas hot weather at work guidance

The First Building Question: Where Is the Heat Coming From?

Before spending money on upgrades, identify why the building is overheating.

Heat can come from several sources:

• solar gain through windows

• poor ventilation

• failing or undersized air conditioning

• old lighting

• poor roof insulation

• poorly controlled heating and cooling systems

• heat from equipment

• enclosed meeting rooms

• server or comms rooms

• crowded spaces

• flat roofs

• lack of shading

• windows that do not open safely or effectively

The cause matters because the solution may not always be more air conditioning.

Sometimes the better first step is maintenance, shading, improved controls, ventilation review or reducing heat gain.

1. Ventilation: Check Fresh Air Before Adding More Cooling

Ventilation is one of the most important checks in any overheating review.

Poorly ventilated workplaces can feel stuffy, hot and uncomfortable, especially in enclosed rooms or areas with high occupancy.

Areas that often need attention include:

• meeting rooms

• classrooms

• staff rooms

• kitchens and tea points

• open-plan offices

• reception areas

• corridors

• toilets

• changing areas

• hospitality spaces

• gyms and studios

• internal rooms with limited windows

What to check

• is there enough fresh air?

• are vents blocked?

• are filters clean?

• do windows open safely?

• are mechanical systems working properly?

• are rooms being used by more people than originally planned?

• are internal rooms getting enough airflow?

• do users complain about stuffiness?

• are there smells, condensation or stale air?

Ventilation should be reviewed before relying entirely on cooling systems.

Related service: Commercial HVAC and Ventilation

2. HVAC and Air Conditioning: Service Before Summer Pressure Hits

Air conditioning and HVAC systems are often expected to perform hardest when they have been maintained least.

A system may appear to work during mild weather but fail during a heatwave.

Common issues include:

• blocked filters

• dirty coils

• poor airflow

• ageing equipment

• incorrect controls

• poor zoning

• refrigerant issues

• noisy operation

• uneven cooling

• plant running inefficiently

• systems not matching current layouts

An office may have been reconfigured over time, with more meeting rooms, call rooms or staff areas added. If the HVAC system was not adapted with the layout, some rooms may overheat while others remain comfortable.

What to review

• service history

• filter condition

• room-by-room comfort

• plant age

• system capacity

• zoning

• controls

• thermostat locations

• meeting room cooling

• enclosed office spaces

• ventilation noise

• energy use

Planned HVAC maintenance should happen before summer, not after complaints start.

3. Windows, Glazing and Shading: Reduce Heat Before It Enters

Many commercial buildings overheat because of solar gain.

This is especially common in:

• south-facing offices

• glazed meeting rooms

• reception areas

• converted buildings

• classrooms

• top-floor offices

• buildings with large windows

• older properties with limited shading

Cooling a space becomes harder if direct sun is constantly heating the room.

Practical checks

• are blinds working?

• is shading suitable?

• does glazing create glare and heat gain?

• can windows open safely?

• are window seals damaged?

• are staff keeping blinds open during peak heat?

• do certain rooms overheat at specific times?

• are meeting rooms placed in high-sun areas?

The most effective solution may be a combination of shading, ventilation, controls and maintenance rather than one single upgrade.

4. Roofs and Upper Floors: Do Not Ignore Heat From Above

Top-floor offices, school classrooms, hospitality spaces and older buildings can overheat because of roof performance.

A roof issue may not only cause leaks. It can also affect internal comfort.

Checks should include:

• flat roof condition

• roof insulation

• rooflights

• damaged coverings

• void temperatures

• water ingress

• poor ventilation in roof spaces

• reflective surface condition where relevant

• plant located on roofs

• access for maintenance

Roof defects and poor insulation can make a building harder to cool and more expensive to operate.

Drone surveys can help inspect roof condition, gutters, rooflights and high-level areas with less disruption.

Related services:

• Commercial Roofing Services

• Drone Survey and Reports

5. Lighting: Old Systems Add Unnecessary Heat and Cost

Lighting is often discussed as an energy issue, but it can also affect heat.

Older lighting can contribute to internal heat gain, especially in offices, schools, corridors, retail spaces and hospitality environments.

Modern lighting upgrades can improve:

• energy efficiency

• comfort

• lighting quality

• zoning

• controls

• meeting room performance

• staff experience

• building presentation

What to check

• old fittings

• inefficient lamps

• lights left on in unused areas

• lack of occupancy sensors

• poor zoning

• heat build-up in enclosed rooms

• glare on screens

• emergency lighting condition

Lighting upgrades often work well alongside refurbishment, decoration, ceiling works or electrical improvements.

6. Meeting Rooms: The First Spaces to Become Uncomfortable

Meeting rooms are often the first spaces where overheating becomes obvious.

They may be:

• enclosed

• heavily glazed

• occupied by several people at once

• full of screens and equipment

• used with doors closed

• poorly ventilated

• poorly zoned for cooling

A room that is comfortable when empty can become hot and stuffy within minutes when occupied.

What to check

• airflow

• cooling

• meeting room size

• occupancy

• screen and AV heat

• lighting

• door position

• acoustic requirements

• whether the room is used for long meetings

• whether remote calls require doors to stay closed

Meeting room overheating can damage how people feel about the whole office.

7. Staff Kitchens, Tea Points and Welfare Areas

Kitchens and welfare areas can become hot because of appliances, boiling water, dishwashers, fridges and poor airflow.

They are also important because staff often use them to recover, take breaks and access drinking water.

Checks should include:

• ventilation

• appliance heat

• fridge ventilation gaps

• dishwasher steam

• hot water equipment

• lighting

• waste areas

• access to drinking water

• comfort during breaks

• proximity to desks or meeting rooms

If the kitchen overheats, smells or becomes unpleasant, staff may avoid using it.

8. Schools and Public Buildings: Heat Can Disrupt Daily Operation

Overheating is not only an office issue.

Schools and education buildings can be particularly affected because of:

• high room occupancy

• older buildings

• south-facing classrooms

• limited cooling

• flat roofs

• large windows

• halls and studios

• changing patterns of summer heat

• limited maintenance windows

Hot classrooms, halls and staff areas can affect concentration, comfort and daily planning.

For school estates teams, overheating checks should be combined with wider summer maintenance planning.

9. Older and Historic Buildings: Balance Cooling With Building Fabric

Older buildings can overheat in different ways.

They may have:

• thick walls that store heat

• poor ventilation routes

• limited window opening

• conservation restrictions

• roof void heat build-up

• older glazing

• outdated services

• limited plant space

• difficult retrofit conditions

For these buildings, the solution often needs to be considered carefully.

A simple air conditioning installation may not be suitable without understanding building fabric, heritage constraints, electrical capacity and long-term maintenance.

Suggested external link to embed:

• Historic England overheating in historic buildings guidance

10. Heatwave Planning: What Facilities Teams Should Decide in Advance

A heatwave plan does not need to be complicated.

It should answer practical questions before hot weather arrives.

Who checks the building?

Decide who monitors temperature complaints, ventilation issues and system performance.

Which spaces overheat first?

Identify meeting rooms, top floors, classrooms, kitchens or reception areas that struggle.

What can be adjusted quickly?

This may include blinds, windows, controls, fans, room use, occupancy and working patterns.

What requires contractor support?

This may include HVAC servicing, ventilation checks, electrical works, roof inspections or shading improvements.

What needs long-term investment?

This may include new HVAC, LED lighting, roof works, insulation, controls or refurbishment.

The goal is to stop every heatwave becoming an emergency.

Commercial Building Overheating Checklist

Use this as a starting point:

✓ Review rooms that overheat most often

✓ Check HVAC service history

✓ Clean or replace filters where required

✓ Review ventilation in enclosed spaces

✓ Check windows and opening controls

✓ Inspect blinds, shading and glare issues

✓ Review lighting and heat gain

✓ Check roof and top-floor conditions

✓ Inspect plant rooms and equipment areas

✓ Review meeting rooms and call rooms

✓ Check staff kitchens and welfare spaces

✓ Confirm drinking water access

✓ Review fire doors and escape routes if layouts change

✓ Plan summer maintenance before heatwaves

✓ Keep records of complaints and repeated issues

Common Mistakes to Avoid

Mistake 1: Waiting Until the First Heatwave

By then, contractors may be busier and solutions are more likely to be temporary.

Mistake 2: Assuming Air Conditioning Alone Will Fix Everything

Cooling systems help, but shading, ventilation, controls and building fabric also matter.

Mistake 3: Ignoring Meeting Rooms

Small enclosed rooms often become the most uncomfortable parts of the building.

Mistake 4: Not Maintaining Existing HVAC

Poorly maintained systems are more likely to fail when demand is highest.

Mistake 5: Forgetting Roofs and Glazing

Heat gain through roofs and windows can undermine internal cooling.

Mistake 6: Not Recording Problem Areas

If the same rooms overheat every summer, they should be prioritised for improvement.

How BTS Can Support Heatwave-Ready Building Upgrades

Barry Turner and Son Ltd supports commercial clients across London and the South East with practical building upgrades and maintenance works that can help improve comfort, ventilation and resilience.

Relevant projects:

• Aylesbury Office Refurbishment and Commercial Fit Out

• Sutton Office Refurbishment and Glass Partitions

• Office Refurbishment Project Heathrow

Final Thoughts

Workplace overheating is becoming a more important building management issue across the UK.

For commercial landlords, facilities managers, schools and business owners, the best approach is to act before hot weather exposes weak points in the building.

That means reviewing ventilation, HVAC, windows, shading, roofs, insulation, lighting, staff welfare areas and the rooms that overheat first.

Barry Turner and Son Ltd can support commercial building maintenance, office refurbishment, HVAC, ventilation, electrical upgrades, roofing, drone surveys, decoration and wider improvement works across London and the South East.

To discuss building upgrades or maintenance planning, visit Commercial Services or request a Free Quotation.

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