Part L 2025: What about Wales?

Paul Bainbridge, Technical Director

Paul’s Greenprints   

We could preface this piece by saying, “If you don’t intend to build or buy a house in Wales in the coming six months, look away now.”, but that would be a shame, because there’s some information in this blog that perhaps shows signs of where the construction industry across the UK might be headed in the next 5 to 10 years.

You see, whilst we’ve blogged previously about the excitement of the England Part L 2025 consultations and approved documents (and how they affect our clients as well as the construction industry as a whole), we know that so many of you will have been reading through that piece with great interest whilst also thinking, “This is all well and good, but what about Wales?”

As if pre-empting your anticipation, here we are, because at the time of writing, Wales have indeed announced their own consultation on the Part L 2025 regulations – and what that looks like for their house builders and home buyers in the coming phases.

Largely, the Welsh consultation is similar to England’s regulations, what with the plan to make use of air source heat pumps as the primary heat source for future homes, to utilise PV on roofs to equate to 40% of the ground floor building area, and the proposal to eventually move away from the SAP to the HEM calculation when it’s the right time to do so. But there are some differences to the consultation, as well. Two of them, in particular.

Interestingly enough, these two differences (or modifications, if you will) were previously considered for England’s Part L 2025 regulations, but were dropped early-on in the consultation. So put simply, what the Welsh are doing here is potentially quite pioneering. Read on.

Firstly, they’re removing the Dwelling Energy Efficiency Rate (DEER) and replacing it with the Energy Use Intensity metric (EUI). This means that they’ll be measuring (or attempting to measure) both regulated and unregulated energy use (and subsequent efficiency) in all future homes their house builders build. The idea behind this is that it will protect homeowners or occupants from high regulated fuel bills. Here at The FES Group, we genuinely don’t know how (or if) that would work, but that’s the intention behind this thinking, and we’ll be the first to report on its success if it does indeed work well in practice. In truth, if it does if fact work well with Wales having been the test case, then it wouldn’t be a surprise at all if England go on to follow in their neighbour’s reduced carbon footprints.

The reason the team at The FES Group impose a healthy dose of cynicism around anything to do with the use or cost of energy in future homes, is because with unregulated energy use being just that, it’s pretty difficult to, well, regulate. In other words, whilst EPCs may give potential home buyers an idea of what their new home in question will cost to run for all things regulated energy (heat, light, and hot water), they don’t really do anything to paint a picture of what it will look like when you throw in your unregulated usage. For example, no metric or system can possibly know how often you make toast in a day (though apparently using the kettle is a regulated given – this is Britain, after all). Similarly, it doesn’t know if you’re going to have a midlife crisis and set up a home gym that powers up a treadmill, cross-trainer, and a his-and-hers set of rowers. Neither does it know to what extent you’re making use of work and entertainment stations in your home on a daily basis, eg, TVs, gaming devices, computers, Meth Labs, etc. This is before we even look at how many people live in the dwelling and how often they’re physically present in there, regardless of their pastimes, hobbies, and behind closed doors behaviours. We try not to judge.

At The FES Group, we like to think that all the work we do – and the blogs we write – benefit everyone, but in our opinion, commenting on proposed energy usage only really benefits the builder (especially if they’re looking to green-up their stats and credentials in the face of ESG or applications for funding). The problem really is that the industry doesn’t know and can’t prove what a ‘good’ metric truly looks like anyway. We may have theories and inclinations, but until a benchmark has been set, we can’t really measure anything or make any claims. In summary, a swap from DEER to EUI under Welsh regulations could prove to be a really interesting test case.

So that’s one difference to the England Part L 2025 that’s proposed under Welsh regulations, but we mentioned there was talk of another. This one comes down to the alterations in fabric specifications – so the doors, floors, windows, and walls. In short, our Welsh workfellows are calling for a relaxation on fabric values.  Having said that, Wales were always more stringent than England with their values and ratings anyway, so this relaxation merely serves to bring them back in line with everyone else. The consultation claims that there’ll be a relaxation on limits and values, which very much ties in with our piece on The Point of Saturation, given the fact that once you hit a certain point with the changes you make to fabric specification in the hope that it’ll be more energy efficient, you actually hit a wall (pun intended) where it makes incredibly little difference financially considering how much money the modification costs you the first place.

The other point to note here is that the proposed relaxation for the walls actually comes in alongside the Welsh proposal to tighten values for the windows. Now, walls obviously cover larger areas than windows in a standard build, and so therefore it appears we would indeed be looking at a net reduction, but this is something the team here at The FES Group are keen to do a little more research on. We’ll keep you posted when we have an update.

To add to all of this, our friends in the West have also thrown in an outlier that we feel affects direction of travel for any future regulations and compliance in the construction industry as a whole – regardless of geography. They’ve done this by proposing multiple options for how their Part L 2025 regulations could work.

Option 1 – pretty much the same as the England Part L 2025, albeit with the replacement of the DEER and the relaxation of fabric specifications on walls, as discussed already in this blog.

Or…

Option 2 – all of the above, plus the inclusion and focus on Mechanical Ventilation Heat Recovery, including the requirement for an Air Pressure Test score of 1.5. This is a score, in our opinion, that seems a tad… insane. We imagine there’ll be a few Site Managers who are beyond nervous at this entire notion, as the rating would be classed as ‘ultra air-tight’ (if not, as we claimed in the previous sentence, ‘insanely air-tight’). But despite the fact that this is very much a stretch notion, leaving Option 1 as the preferred route of travel, this inclusion does indeed still push us to look in the direction of moving towards whole-house ventilation strategies. This would be helpful for house builders when dealing with Part O regulations, as the system would indeed help with comfort cooling as well as tackling overheating. Ideally, however, an Air Pressure Testing rate of 3 would be much more achievable and ideal, and would crucially move the construction industry in a more positive direction to support homeowner wellbeing (providing everything related to the MVHR is installed properly by the house builder and operated properly by the owner or tenant, of course).

If you’re still reading our blogs in the next 5 years – and we really hope that you are – then we’ll most likely cover all of this as it transpires.

Overheating? Hot off the press.