Regulating the performance of cladding is the answer. And as for spandrel with an insulated backpan, that still doesn't hold a candle to the performance of a more sophisticated solution with a proper back-up wall. Legislation that requires better performance targets for cladding systems would both increase the quality of the glazing systems employed on projects that require a high degree of glazing and would also enable architects to use more solid-wall systems for better performance on projects where the architecture requires more solid area and punched-out windows. There is a great interest in doing more such buildings at the architectural level but the client/developer has become accustomed to using window wall and getting them to budge and adjust their pro-forma to account for better glazing or for solid cladding systems is... next to impossible.
Re: rewriting the legislation on a regular basis based on advances in cladding systems: the changes in building science and the marketplace only happen so quickly. And legislation should respond to advances in building science. Given the prominence of real estate development and buildings in terms of economic and environmental impact, it's an entirely worthwhile endeavour. The government already tests and approves particular systems and materials for use here, so a lot of the work is already done. Nobody is saying that we need to require developers to use the very latest, most cutting-edge solutions. But the outdated and very low-ranking window wall and spandrel crap we're seeing everywhere would easily be the first to fall below the cut-off for system performance and longevity.
What is madness to me is the 60/40 rule because it's a lazy legislation that results in exactly what we've seen as a result. Developers want all-glass because they've become accustomed to having one contractor handle all of the envelope. Any solid parts of a facade become spandrel glass.
Specifying a particular level of performance would enable architects to spec better systems and to explore more options for the cladding of a building. We need to get away from glazing behind a default, and as a result, copious spandrel cladding. But even when an architect tries to spec something other than glass, the client will push them back to it.
As for having the public put pressure on developers to make better choices; that's valid and important but there will never be enough pressure or interest from the public to make a sustained, meaningful difference. And even in many cases where there is pressure, developers are going to rationalize their choices in order to make their millions. The opinion of the public and even the uninformed purchasers, is largely irrelevant, so long as they can sell their units.
Stricter and more sophisticated building-code legislation has worked in many other countries and it would work here. It's getting these changes past the lobbyists and homebuilders associations that is the tricky part.
