(Yes, I've resorted to a click-baity post title. Sorry! There's a good reason for asking the question, though.)
Some years ago I dealt with a technical question about roof insulation. The precise details are hazy, but don't really matter. All you need to know is that the roofing contractor described his build-up and finished by saying, "It's 0.20 for a roof now, isn't it?"
I politely pointed out that his target U-value was actually 0.18. What I didn't add was that 0.18 was not a new target; it wasn't like regulations had changed the week before. It had been the case for a while. A good while.
(It occurs to me only as I write this that the guy could have been trying his luck. Maybe he knew what he needed to achieve but didn't have enough room to accommodate enough insulation and thought he'd see if I'd agree with his target. The way I remember the conversation, though, I believe it was a genuine enquiry.)
My abiding memory is of coming away with a new-found awareness about just how slowly information can trickle through the different layers of the construction industry. Which brings me to this excellent article:
'Where are my damn learning curves?'
Learning curves in construction
The author, Brian Potter, asks whether learning curves are evident in construction. He suggests they can be, but are rarely evidenced consistently because of how circumstances change - in big and small ways - from project to project. An individual project can evidence learning curves, but the learning doesn't tend to translate to the next site or building.
His conclusions led to some interesting trains of thought.
For example, volume housebuilders have consistently lobbied against previous regulation change, arguing the cost of achieving better standards was too high.
The article suggests costs could have been expected to fall fairly rapidly with improvements in understanding and adapting to the changes. So any 'pain' for the housebuilders (excuse my cynicism) would have been short-lived ... and yet, knowing that learning curves reset so frequently, you wonder whether genuine and widespread improvements would have been achieved anyway.
Suddenly you become aware of how hard it must be to spread and implement knowledge.
If learning curves reset on every project, almost regardless of circumstance, you need an especially committed group of people working together across multiple projects to have even a hope of seeing consistent good results.
Which begs the question: how do you then scale the results that the one group achieves? Anything that disrupts the original group would risk resetting their learning curve, after all...
What does this have to do with Part L 2021?
All of this suggests that frequent regulation changes are a bad idea, because they reset learning curves and exacerbate people always being at different stages of knowledge - like the behind-the-curve roofing contractor I dealt with years ago.
Part L 2021 has been introduced specifically as a stepping stone, intended to help people prepare for the Future Homes and Buildings Standards in 2025. Having a better understanding of learning curves, however, suggests that the benefit of any preparation is likely to be lost when people are left playing catch-up with the next change.
The consultation response to Part L 2021 reflected a widespread feeling that the government wasn't being ambitious enough with the proposals. Now we have another reason for wanting better than this stepping stone offers.
As disruptive as it might have been, it probably would have been better to make one big step change to introduce long-term regulations. That way, everybody could hopefully learn at the same time, developing together - without another impending change a few years later that will reset everything again.
There's something slightly depressing about knowing how easy it is for learning curves to reset, because it's a bit too easy to question whether there's any point changing things at all. At the same time, it can focus our minds on doing things differently to try and ensure an effective transfer of knowledge and learning.
Regulation changes to introduce better standards - including Part L 2021 - are not a waste of time.
But maybe there needs to be a concerted effort to understand this learning curve effect, and apply it to the introduction of new regulations so they are more effective and drive the genuine improvements we all need, and want to see from them.