Snow has fallen in many parts of the UK in the past day, and as a result, hundreds of schools have closed this morning (Monday, December 12).

The Met Office has issued yellow weather warnings for areas impacted by snowfall, including the South East, West Midlands and the North East of England.

Whilst schools usually close after heavy snow because of the difficulties in actually getting in, there are some questions related to how cold the temperature would have to be to shut schools.

This applies to the temperature inside buildings rather than what it is outside.

Whilst the Government recommends not letting the temperature fall below 16C in work environments, is it the same for schools?

How cold does it need to be for schools to close?

According to the National Education Union: "Until October 2012, legal requirements which specified the minimum temperatures which had to be maintained in school classrooms were set out in the Education (School Premises) Regulations 1999."

READ MORE: When is it too cold to go to work?

Where there was "a normal level of physical activity associated with teaching" the minimum temperature was recommended to be 18C.

In areas where there was "a lower than normal level of activity" like sick rooms, or a higher level of activity, like gyms, then the minimum temperature was 21C and 15C respectively.

However, these regulations were replaced by the School Premises (England) Regulations 2012 and they do not specify minimum temperatures for any parts of a school.

Despite this, the NEU still recommends that a minimum temperature of 18C be kept.

Ultimately though it is up to the school itself to make the decision on whether to close if temperatures inside were unable to be maintained at that level.

The NEU added: "The NEU does not expect its members to continue to work in situations in which the legal requirements concerning the health, safety and welfare of employees and others are not being met."