How cold can your classroom get - legally?

With classroom windows open due to Covid guidelines, Chris Parr looks at the dangers to teachers and pupils of plummeting temperatures

Chris Parr

covid classroom

The government says your windows need to be kept open – but with winter closing in, how cold can your classroom get before it starts causing problems unrelated to Covid-19?

According to the Health and Safety Executive, the minimum temperature in a workplace “should normally be at least 16C” – although if the work in question involves “rigorous physical effort” (like a PE lesson, for example) then the temperature should be at least 13C.

However, these temperatures are “not absolute legal requirements”, the HSE guidance states, and individual schools have a “duty to determine what reasonable comfort will be in the particular circumstances”.

Coronavirus adaptations

The NEU teaching union feels the HSE advice does not go far enough and has lobbied for a minimum classroom temperature of 18°C, which it says is based on “previous standards for schools”.

“The NEU view is that in order to help with the balance between ventilation and warmth, uniform and dress codes should be relaxed to allow staff and students to dress more warmly but, in addition, schools and colleges should where necessary have the heating turned up higher and for longer, starting earlier in the morning, to keep the temperature comfortable throughout the working day,” the union says in its latest guidance

But what actually happens to our bodies as the mercury begins to drop – and what are the main dangers of teaching in a cold environment?

What happens when the body gets cold

“Humans are homeothermic animals, which means our physiological systems act to maintain a core body temperature of about 37C,” explains Shane Maloney, a professor of anatomy, physiology and human biology at the University of Western Australia. “We continually make heat as a by-product of our metabolism, and to keep body temperature constant we need to lose that heat, which we do mostly from our skin to the air surrounding us by convection.”

In colder environments, this heat loss to the environment increases, particularly if air temperature falls and wind speed increases.

“Both of those increase the rate of heat loss by convection and cold rooms increase heat loss by radiation, so letting in cold air puts us at risk of developing hypothermia – a low core body temperature,” Maloney says.

Risks of cold temperatures

Our bodies attempt to stop hypothermia happening by reducing blood flow to the skin – which traps heat in the body’s core – and by generating more heat, mainly by shivering.

So, how much risk are teachers and pupils facing this winter? 

“The proposal to increase the rate of air flow, and especially the rate of clean air flow, into classrooms is a logical strategy that should help to reduce the airborne spread of viruses,” says Andrea Fuller, a professor in the School of Physiology at the University of the Witwatersrand. “But over a cold winter, it will create issues with thermoregulation, especially for young children.”

Because the area of skin across which people exchange heat with the environment is larger relative to body mass in smaller humans than in larger ones, small children lose heat “more rapidly and ‘feel the cold’ more than do teenagers or adults”, adds Fuller.

Pile on the clothes

The main way in which schoolchildren and teachers can protect themselves from heat loss is through wearing thicker clothing, or layers of clothing.

“It’s important to keep narrow body parts well insulated, because they lose heat fast, but doing so compromises dexterity, explains Duncan Mitchell, emeritus professor in the School of Physiology at the University of the Witwatersrand.

“Even with good insulation, a lower skin temperature in exposed areas like the face will still activate cold defence processes and generate a feeling of discomfort. One likely response in children is increased fidgeting, both as a way to distract themselves from the cold but also as a means to maintain movement and dexterity in cold extremities, like the hands and feet.”

In short, behaviour and uniform policies are going to have to be relaxed – a lot. But in the depths of winter, the viability of having children sitting in freezing classrooms is going to have to be very carefully assessed. 

Chris Parr is a freelance journalist

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