What’s More Expensive: Heating a School, or Losing a Day of Learning?

School budgets are under pressure. Energy bills, maintenance costs and competing demands on limited funding mean that every investment needs to be carefully considered.

But when it comes to overheating, are we accounting for the full cost?

The financial impact of running a school building is relatively easy to identify. Energy consumption can be measured, bills can be compared and maintenance expenditure can be tracked. The consequences of classrooms becoming too hot are less straightforward to quantify.

Yet temperature matters. When teaching spaces overheat, the effects can extend beyond physical discomfort, affecting concentration, classroom conditions and the ability to learn effectively.

So, when schools are deciding where to direct limited resources, there is an important question to consider: what is the cost of not addressing overheating?

The cost we can see

For schools, energy is already a significant consideration. Heating, lighting and operating buildings all come with a cost, while older buildings can present additional challenges when it comes to maintaining comfortable internal conditions.

As temperatures rise, keeping classrooms comfortable creates another set of challenges, particularly in buildings that were not designed for today's climate.

This creates a difficult balancing act. Schools need to provide suitable environments for pupils and staff while managing budgets responsibly. But focusing only on the immediate cost of an intervention can make it difficult to see the longer-term cost of leaving a problem unaddressed.

Overheating is a good example.

A school might know that a particular classroom becomes uncomfortable during warm weather. It might receive complaints from teachers, notice that windows are regularly opened or use temporary measures such as fans.

But these observations only tell part of the story.

They do not necessarily show how often the problem occurs, which rooms are most affected or how long temperatures remain elevated.

The cost we don't always count

The impact of overheating is not always reflected in a school's financial accounts.

A classroom that becomes too hot may still be operational. The lesson continues, the building remains open and there may be no obvious financial loss attached to that particular period.

But that does not mean there is no consequence.

Research has highlighted the relationship between indoor temperature and cognitive performance. As temperatures rise beyond comfortable levels, concentration and task performance can be affected.

For a school, that matters.

A lost period of effective learning cannot be treated in quite the same way as an additional item on an energy bill. But if pupils are struggling to concentrate because their learning environment is uncomfortable, there is a wider cost that is much harder to measure.

This is why the conversation around overheating needs to extend beyond “How much will it cost to fix?”

It also needs to ask:

“What does it cost if we don't?”

Not every classroom overheats in the same way

One of the challenges with overheating is that it is not necessarily consistent across an entire school.

Two classrooms in the same building can experience very different conditions. Orientation, glazing, ventilation, occupancy and equipment can all influence how a room responds to heat.

A classroom on one side of a building may remain comfortable while another becomes uncomfortably warm for several hours.

This means that looking only at a building-wide temperature, or relying on occasional spot measurements, can hide important differences.

A single reading can tell you what is happening at that moment. It cannot necessarily tell you whether a room has been overheating for several hours, whether the problem happens regularly or whether another space is experiencing an even greater issue.

What can temperature data tell us?

Twinview's Too Hot to Learn? report looked at temperature data collected by Twinview sensors across 105 teaching spaces in three UK schools.

Across the monitored period, more than 5,000 hours of classroom time were recorded above 24°C.

The findings illustrate why measurement matters.

Rather than relying solely on anecdotal reports of classrooms feeling too warm, temperature data can show when conditions change and where those changes are occurring.

It can help schools understand:

• Which teaching spaces are most frequently affected
• When temperatures begin to rise
• How long rooms remain above a particular threshold
• Whether certain areas of a building are consistently more affected
• Whether conditions change following an intervention

This does not mean data alone will solve overheating. Decisions around shading, ventilation, room use or building improvements require consideration of the building, its occupants and available budget.

What data can do is provide evidence to support those decisions.

Making informed decisions

When budgets are limited, schools need to understand where investment could make the greatest difference.

If temperature data shows that a small number of classrooms consistently experience higher temperatures, this can help estates teams investigate those spaces more closely rather than treating the entire building as though it has the same problem.

Ongoing monitoring can also help assess whether an intervention has actually improved conditions.

The process becomes:

Measure. Identify. Act. Review.

Instead of responding to overheating only when it becomes uncomfortable, schools can build a clearer evidence base around what is happening inside their buildings.

So, what's more expensive?

There is no simple calculation that can put a price on a lost day of learning and compare it directly with the cost of improving a school building.

But that does not mean the question is not worth asking.

As the climate changes, schools are likely to face increasing pressure to keep teaching spaces comfortable during warmer periods. Understanding how buildings are actually performing will become increasingly important.

The first step is not necessarily to spend more.

It is to understand more.

By collecting reliable temperature data, schools can identify which spaces are affected, understand when overheating occurs and build a clearer picture of where action may be needed.

Because when budgets are limited, better information can help ensure that investment goes where it can make the greatest difference.

And perhaps the real question is not whether it costs more to heat a school or lose a day of learning.

It is whether we can afford not to know what is happening inside our classrooms.

Want to understand overheating in your school?

Read Twinview's Too Hot to Learn? report to explore what real temperature data collected across UK schools can reveal about classroom overheating.