"Thick Skinned", detail of outer skin, Design Hub, RMIT, photo by Bruce Dickson

It seems I was right to raise concerns about the green credentials of RMIT’s new Design Hub. Following publication of my article on Tuesday, Are all green buildings really that green?, RMIT amended the description of the building on its web site earlier today.

In the earlier post, I queried two major claims the University was making about the so-called “smart skin” around the building:

  • “The glass cells track the sun via the building computer automation system to help shade and power the building.”
  • “The building’s ‘smart skin’ is made up of more than 16,000 sandblasted glass cells, which have the ability to harness solar power.”

I pointed out that, as built, (1) none of the so-called “cells” are equipped with solar collectors and (2) none of the “cells” can track the sun – three quarters of them can’t move at all, and the other quarter only rotate on one axis.

RMIT replaced both sentences with the following words, which now describe the building as having:

A double-skin façade with a unique external skin that incorporates glazing disks. The disks in the outer façade have the capacity to be fitted with photovoltaic collectors for harnessing solar power.

These new words remove the incorrect claims (and dropping the pretentious “cells” is a good call; pity “skin” wasn’t dropped too – as the exhibit shows, there’s nothing especially high-tech or “smart” or skin-like about the discs).

However I think portraying “the capacity” to be fitted with PV collectors as a virtue is a stretch. It’s a bit like me boasting my house has “the capacity” for solar sometime in the future because it has a roof! Anyway, why would RMIT retrofit the wall with solar collectors when the disks can’t track the sun? At the very least, the words “in the future” should be added at the end (preferably along with “probably at considerable cost”).

But the important issue is this building was constructed on a premise that isn’t valid anymore. It was conceived on the basis that the external discs could be rotated in two dimensions. That would’ve enabled the discs to track the trajectory of the sun and thereby (a) collect solar power in hot weather via PV units in the discs while simultaneously shading the building from the hot sun, and (b) admit warming sun to fall on the inside wall in cold weather. It was a very interesting idea.

Now that the University’s confirmed the building lacks these capabilities, the question remains whether or not the external wall, as built, offers effective thermal control. On the one hand, the discs can’t be opened to let the winter sun in. On the other, the discs are made of glass that doesn’t have reflective foil, so they can’t shade the building from the hot summer sun effectively. Moreover, there are gaps between the discs that mean 21% of the outer wall doesn’t offer shading, as I discussed last time.

So, there’s reasonable doubt whether the external wall really qualifies in a meaningful way as “green”. RMIT hasn’t responded to the questions I raised on Tuesday about the thermal efficiency and cost-effectiveness of the external wall relative to other solutions that could’ve been used. Nor has the University indicated if it prepared a detailed analysis of the costs and benefits of the wall before committing to the final design.

There’s an architectural issue here, too. That elaborate outer wall is the dominant (and in my opinion rather handsome) architectural expression of this building. The obvious question is: how valid or legitimate is that expression if it isn’t innovative in terms of climate control or, worse, if it turns out that it’s not an especially green solution? These are good reasons for RMIT to respond to the questions I’ve posed.

But the really big question that keeps niggling away in the back of my mind is this: when was the decision taken to do away with the PV collectors and the moveable discs? Was it taken before construction commenced? If so, why wasn’t the entire approach to sun control re-thought? There’s probably a perfectly reasonable answer to this question – so let’s hear it.

More photographs of the Design Hub here.