A heated classroom debate

The heatwaves of Summer 2026 exposed a challenge that many educators have quietly been grappling with for years. More than 1,000 schools reportedly altered timetables, introduced early closures or made other operational changes as classrooms became increasingly uncomfortable during prolonged periods of high temperatures.

The immediate priority was, quite rightly, protecting pupils and staff. Schools relaxed uniform rules, increased hydration breaks, moved lessons into cooler areas and adapted sporting activities. The Department for Education's guidance encourages exactly these practical measures while keeping schools open wherever it is safe to do so.

Those actions helped schools respond to an exceptional summer. The bigger question is what happens when ‘exceptional’ summers become the ‘usual’.

Overheating is emerging as an issue that affects the learning environment over the long-term.

A multipurpose place 

The climate is not the sole cause. The role of the modern school has changed significantly over the past two decades.  

Buildings are used for longer hours, often serving local communities well beyond the school day. Classrooms are equipped with interactive displays, laptops and digital learning technologies that improve education but also introduce additional heat into teaching spaces.

Many schools also provide specialist facilities such as ICT suites, catering classrooms and sports spaces, each with their own environmental requirements.

All of these things increase energy use and add to the internal heat gains in school buildings.

And this is happening as schools are expected to reduce carbon emissions, improve energy efficiency while delivering healthy environments for both pupils and staff.

Faced with hotter summers, there is a temptation to see conventional air conditioning as the obvious solution. The reality is more nuanced.

Keeping cool

Recent debate has highlighted concerns that widespread installation of conventional cooling systems could increase energy demand and contribute to higher outdoor temperatures in dense urban areas if applied without careful consideration.

The Department for Education’s Technical Manual for the design and construction of school and college buildings and outdoor environments (Employer’s requirements) sets out clear requirements and constraints for cooling in school buildings.

The TM says that use of full mechanical comfort cooling should be avoided (with some exceptions for SEND accommodation), but ground source heat pumps (GSHPs) or air source heat pumps (ASHPs) can be used to deliver peak ‘lop’ cooling. This is also required for kitchen areas.

A design-first approach 

However, the most efficient cooling begins with good school design with a focus on passive measures. Solar shading, improved building fabric, effective natural ventilation and careful management of solar gain all help reduce overheating before mechanical systems are considered.

Where additional cooling is required, it should form part of an integrated building services strategy rather than being treated as a standalone response to a hot summer. This is where heat pump technology changes the conversation.

Schools have traditionally viewed heating and cooling as separate building services, often delivered by different systems (if mechanical cooling is installed at all).

Modern heat pumps provide an opportunity to think differently by delivering efficient heating during colder months while also providing cooling when higher indoor temperatures begin to affect comfort and concentration. In many applications, they can also contribute to domestic hot water production, reducing reliance on multiple systems across a site.

Broader objectives 

That integrated approach supports the wider objectives many schools are already pursuing through refurbishment programmes: reducing operational carbon, simplifying maintenance and improving long-term building performance. Rather than installing equipment that only addresses a few weeks of hot weather, schools can invest in systems that provide value throughout the year.

Temperature is only one part of creating effective learning environments. Indoor air quality has become an increasingly important consideration as schools improve insulation and airtightness to reduce energy consumption.

Fresh air supports concentration and wellbeing, but simply opening windows is not always practical, particularly where buildings are located close to busy roads or where outdoor temperatures are already high.

This is referenced in the DfE Technical Manual, which also says that where a ventilation unit provides mechanical supply and extraction, “it shall have heat recovery”.

MVHR systems such as Mitsubishi Electric's Lossnay range introduce fresh air while recovering heat from outgoing air, helping schools maintain good indoor air quality without unnecessary energy loss. Combined with CO₂ monitoring, ventilation can respond automatically to changing occupancy levels, creating healthier classroom environments while supporting energy efficiency.

Climate-ready classrooms

The discussion following the 2026 heatwaves should not be reduced to whether every classroom needs air conditioning. A more useful question is whether today's schools are prepared for the climate in which tomorrow's pupils will learn.

Mitsubishi Electric believes that the answer lies in taking a whole-building view. Combining low-carbon heating, carefully considered cooling and effective ventilation allows schools to create healthier, more comfortable learning environments while supporting their wider sustainability ambitions.

The DfE’s Technical Manual sets out clear requirements for heating and cooling systems for the education sector, so it’s vital to work with a manufacturer with experience in this field – Mitsubishi Electric’s specialist team can help to ensure you find the right technology for your needs.

Because ultimately, the purpose of a school building is not simply to provide shelter. It is to create an environment where every pupil has the best possible opportunity to learn whatever the weather outside

Mike Egan is Business Development Manager