At current rates, it will take 1,250 years to replace every gas central heating system in the UK with an Air Source Heat Pump.
According to the HSE, there are around 130,000 engineers on the Gas Safe Register.
If switching a house over from gas central heating (GCH) to an ASHP takes two engineers two days - which is probably something of an underestimate - how long would it take if all 130,000 of them worked on it as a project together?
There are around 20 million homes with GCH. Working flat out, 5 days a week, these 130,000 engineers could theoretically convert them all from to ASHP installations in about two-and-a-quarter years (that's the equivalent of each pair of engineers completing 2.5 conversions a week).
Sounds brilliant, doesn't it? In a little over two years, we could fully decarbonise home heating.
Except, of course, it's ludicrous to think that (a) every homeowner with gas central heating would opt to change to ASHP in this time frame - especially considering each refit would cost around £7,000 to £11,000 according to the Energy Saving Trust (£140 to £220 bn in total); and (b) that all 130,000 engineers would simultaneously be available to do the work (bearing in mind holiday and sickness absence rates plus the fact that there will always be a proportion of engineers that remain on the register for a short time after retiring etc).
How does it actually look at the present rate of GHC to ASHP conversion?
According to a February 2018 report by the National Audit Office, there have been just 78,000 domestic renewable heat installations out of a 2020 target of 513,000. It says that, based on current take-up rates, we might see 111,000 by then.
That suggests growth of around 16,000 new installations a year.
Projecting forward at that rate, it would take 1,250 years to completely phase-out GCH in homes...
As sad as it sounds, that's probably much more realistic than the pie-in-the-sky notion that 130,000 engineers could convert all GCH to ASHP in just over 2 years.
But it's worse than that because swapping GCH for an ASHP may actually also cost people more money to heat their homes - they offer savings compared with oil boilers, LPG, coal and conventional electric storage heaters, but not necessarily if you currently heat your home with mains gas using a half decent boiler.
Why is all this important? Because there are too many fracking opponents out there telling us we don't need shale (or indeed any) gas to heat our homes because we have renewables.They are talking what's known in engineering circles as "complete and utter crap". Don't fall for it and make sure you call them out on it!!!