Return to Website

Number Watch Web Forum

This forum is about wrong numbers in science, politics and the media. It respects good science and good English.

Forum: Number Watch Web Forum
Start a New Topic 
View Entire Thread
Re: Modern computer modelling

Another strange feature of modern computer modelling is its very lax attitude towards modelling work actually being valid. Here's an example I noticed from a couple of months ago where modelling of buildings for energy efficiency is reported as not necessarily bearing much relation to reality:

energy efficiency modelling

Extract from the article:

"The difference between how much energy a building is predicted to use and how much it uses in reality has been known in the industry for decades, and is dubbed the ‘performance gap.’ But architects and engineers have traditionally blamed the problem on faulty construction, or unexpected use after completion - such as owners leaving too many lights on.

However David Coley, Professor of Low Carbon Design at the University of Bath, said the real problem stemmed from the practice of building modelling, which is not ‘fit for purpose.’

“It’s a serious scandal,” he said. “It affects all new buildings as well as the refurbishment of older ones.

“When one school in Plymouth was rebuilt, the energy bills for a month ended up costing the same as for an entire year in the old 1950s building.

“The problem is nobody checks that the building is performing as promised. There is very little regulation. They can't be sued. It’s like a surgeon not being bothered about whether their patient lived or died.

“The impact of the inaccuracies of building modelling professionals has severe financial and environmental implications for both the government’s global warming targets as well as building owners who are purchasing homes and other buildings that are sold to be energy efficient but in reality are not.”"

I think the origin of this requirement to model buildings for evaluation of energy efficiency came from the "Energy Performance Certificate" idea that was introduced in some UK legislation about ten years ago, and going further back than that, it comes from some EU directive (and further back than that it will have been the result of lobbying by "Big Green"). This Wikipedia article describes the Energy Performance Certificate idea:

Energy Performance Certificate

I would argue that there is not much point in trying to model the buildings if this work cannot really be done properly. The legislation should not have been introduced until there was sufficient confidence that energy efficiency of buildings could be modelled satisfactorily.

This Energy Performance Certificate idea may have contributed to the recent Grenfell tower block fire event in London. The new cladding (or "siding" as I believe it is called in other countries) for the tower block was probably introduced mainly for cosmetic purposes to help maintain high local property prices. But the Energy Performance Certificate legislation is likely to encourage somebody to think it might be a very good idea to incorporate insulating material into the cladding construction, which unfortunately increased the fire risk for the building. There is a possibility that the Grenfell tower block was in reality not that much more energy efficient than it was before the cladding was installed, even if it got a much improved rating on its Energy Performance Certificate, as the modelling activity is a bit suspect.

Re: Modern computer modelling - by Brad Tittle - Jul 12, 2017 7:54pm