Such a poor article -- not worth reading

The first 6 paras, above the first 2 body pics (as it appears on my m/c anyway) is spot on - a real issue that we constantly highlight on GBF, apart from throwing in 'planners' (note the small p - so not denoting 'The Planners'?). Thereafter, what's the Bath Univ man saying?

The problem is not 'building modelling' - it's the complete lack of same, instead reliance on prescriptive Building Regs compliance, OK weakly informed by SAP calcs which everyone knows are unrealistic.

Is it the latter (and even worse rdSAP, for retrofits) that the Bath Univ man is aiming at? Anyone looked up David Coley lately, see what his research piece is really saying?

...the 'performance gap' has been discussed years ago.
IMO it results from buildings (both domestic and non-dom) not being built to spec, with corners cut, no effective on-site inspections, and building down to a price, rather than up to a standard.

Yes, everybody agrees that there is a performance gap and that there are many reasons for it. What this research claims is that in addition to all the reasons that have been discussed for years there is another one, namely the incompetence of many building modellers.

Certainly

We have a sealed box we want to keep nasty stuff out of, to protect occupants

We also have no windows to stop any effects of blast

Every litre of air that the occupants need is treated through HEPA filters and other active filters that can grab the particularly toxic external atmosphere

So, we need enough air to meet occupant demands - about 10l/s per person - we also have to keep the building at 40Pa above external ambient pressure - so the latter dominates the airflow requirements - particularly as we "leak air" via the access lobbies to prevent ingress of "stuff"

The more the building leaks, the more air we have to supply (at great cost) - so we have a pretty airtight building - our dynamic simulation shows that to be the case - as it also shows the cooling demands with full occupancy and the design day external condition (it's a UK location, so not that onerous but higher than the design summer year or test reference year at the location) - the cooling demands are modest given that it's fabric and internal gains - no windows

When we switch the model to Part L compliance mode however, it's an epic fail - so we have examined every relevant aspect of this - cooling efficiency, fan efficiency etc - and the only variable left is the building airtightness - if we allow it to drop from target as I indicated the model moves closer to Part L compliance - clearly it's actually expecting infiltration to provide some sensible cooling

The model is a fully certified product approved by DCLG for Level 5 SBEM outputs

So, we are perfectly happy that the Dsim is telling us accurately what will actually happen - we've proved it several times by a variety of methods including a % of longhand calcs undertaken by some pretty competent engineers - but the algorithms embedded in the Part L compliance part of the software throw a wobbly and tell us it's a fail - until we make it more leaky

You probably aren't as surprised as us that the leakage influences the cooling so much (in Part L world) - in the Dsim proper, it has the exact opposite effect as we predicted - more airtight, less cooling demand (build tight, ventilate right)

I think the other effect going on is the actual air flow rates versus BR compliance air flow rates (we are at about 3 times that required for "occupancy" )

Keep in mind this is just an office building (albeit with a bigger than normal data room) - the Part L output is definitely being unduly influenced by the "tight" building - so for compliance we need to let the building leak much more - which we do for the Part L BRUKL document - the actual design is much more airtight - we just don't tell BC that (yet)

So - my comment that some modelling for "compliance" will give perverse results compared to reality

More generally, there is a whole load of crap input into models to get through Part L that will never, ever be achieved on site

regards

Barney

Posted By: tonyVery interested to see the planners being talked about, they are involved and badly need to improve

You mean The Planners, rather that just someone planning a scheme (e.g. Architect/Manager/Modeller)?

If so, how on earth should they be involved? Sure they're required to support allegedly 'sustainable' development and individual buildings, but surely get crossed wires when trying to micro-manage ways and means to that (a la Merton BC).

That's what Building Regs are for, and how govts should enforce the technicalities of building.

If Dun Laoghaire mandates PH https://passivehouseplus.ie/news/government/dublin-local-authority-makes-passive-house-mandatory-in-historic-vote , surely that's not to be enforced by the Planning system, but by Building Regs?

Yeah but I'd hate Planning Officers to try and enforce that - horses for courses. If all Applicants knew that after Planning they'd have to jump thro the hoop of e.g. PH standard, like in Dun Laoghaire, then they'd get the 'too much glass' etc (esp compact floor plan/envellope) sorted before making a Planning Application that they'd be sure to get refused at Bldg Regs.

You're saying that Planning system should enforce what Bldg Regs isn't written to do, and doesn't enforce properly anyway.

The trouble with that Tony is that I don't think hair shirt attitudes will get us anywhere, and the British love a dormer, and an open fireplace, and bi-folds, and... and...

Best to work out how to design best performance in, so long as the requirements are "reasonable". And there's the battle-line.

I've been re-watching the Adam Curtis documentaries The Century of the Self over the past few nights. I highly recommend it as an insight to the motives of the "demos" especially the compromises the Clinton and Blair government had to enact to at least make some progressive change.

Posted By: Ed DaviesAnd it's OK to kill off people in the third world to get those, of course, particularly as they won't be affected for a few decades.

This is the quality of trenchant truth that some of us were backing J Corbin to speak - no such luck, sadly.

Yes but you wouldn't have even got the free token measures if they hadn't been elected.