So it’s arrived. That week of the year that school business leaders and premises managers all over the UK dread - in the profession, we call it DefCon AirCon. Every year, for on average four days, the temperature in the UK hits the heady heights of 23 degrees or more, sending schools into a literal and figurative meltdown.

It’s the week where site staff and SBLs are assumed to have the powers of Zeus, and to take on personal responsibility for global warming, the natural movement of the universe, tidal flow, seasonal shift and the mixed wool content of a myriad variety of school uniform trousers.

Suddenly, SBLs are expected to find the means to cool an 80-room school with no more than a tissue box, some sticky backed plastic and a paperclip. And as the temperature rises, so do tempers, causing normally brave site staff to scuttle off to their boiler rooms muttering “Hang on, I think there’s a fan down there somewhere, I’ll take a look”, never to be seen again.

‘We’re also hot, even with our hearts of ice’

We know it’s hot, of course we do, we’re also hot, even with our hearts of ice. We know that’s not the same hot as being stuck in a sun-baked classroom with 30 hot teenagers, 30 computers and window restrictors. But here’s the facts on why so many schools are unable to provide air cooling:

1. Air conditioning is hugely expensive to install - on average, about £6,000 for a normal sized classroom.

2. The hidden costs of air conditioning are enormous - they use massive amounts of electricity, need regular servicing and maintenance. The Carbon Trust states that using air con just on those few days per year that the temperature reaches over 28 degrees can cost the same as heating the same space for a year.

3. Reliance on air conditioning creates its own dependency. The more air conditioning we experience, the lower our ability to tolerate changes in climate.

4. The carbon emissions of a typical air-conditioned building are 30 per cent higher than those with natural ventilation (Carbon Trust).

5. Air conditioning only works if the room is sealed. It works by circulating and cooling the same air. This means it also circulates the same germs, bacteria, dust and allergens.

It isn’t cheap

So regardless of those facts, here’s the back-of-a-fag-packet maths:

• Air conditioning installation is around £6,000 per standard classroom

• Running and energy costs for a year might be, say £800 per unit

• A medium-sized secondary school might have 60 classrooms (not including sports halls, assembly halls, canteen, offices, communal spaces, staff rooms etc).

• That’s a total of £408,000 in year one.

• The same medium-sized secondary school might receive approximately £26,000 of capital funding per year. That’s to maintain the entire site. Yes, really.

• Using those numbers, if all we spent our capital funding on was air con, with no roofing, no plumbing, no building works, no fencing, no windows, no refurbs and no flooring, it would take 15 years to install air con in every classroom, by which time, the lack of spend on basic building maintenance would mean the school had fallen down.

We empathise 

So, much as I totally understand the discomfort that excessive temperatures can bring, along with the negative impact on learning and engagement, the options are somewhat limited. And whilst the leading teaching unions might gallantly recommend that schools consider air conditioning their classrooms, it would be equally gallant if they also sought to secure schools the funding with which to do so. Do I sound miffed? I am, sorry, it’s warm in here.

So, of course, we’ll try and provide air con for the worst affected rooms, but do please understand that it’s simply not possible to retro-fit air con to an old building without a massive injection of cash, which we all know isn’t happening any time soon.

In the meantime, here are some additional tricks that may help:

• Keep the blinds down

• Turn lights off

• Keep classroom doors open (if they are not fire doors)

• Minimise the use of computers if possible

• Avoid leaving on projectors and Smartboards where you can.

• Only open windows if the temperature outside is cooler than the heat inside.

• Get hold of a good fan, open the windows, and point the fan out the door.

Apparently, the fan draws the cooler air from outside into the class. Something to do with air forced being out the window causing a drop in pressure in the room, causing air to flow in from another opening, ie, the door. Anyway, that’s what a physics teacher told me and I believed him.

I’m writing this in the hope that by the time you read it, we’ll nearly be out the other side of this hot flush, but if not, let’s work together to stay calm, if not cool, and to enjoy the beauty, randomness and quirks of our uniquely British summer. See you on the beach.

Hilary Goldsmith is director of finance and operations at a large secondary school and tweets at @sbl365