Voodoo heliostats

Oh, the magic of the big architectural gesture!!! 

By far the most read of my blog posts are those about Nouvel's iconic carbuncle on the face of One Central Park, here in Sydney.  It is clear that there are a lot of people interested in that big and mysterious heliostat.

But what really amuses me is that it seems to have raised expectations more broadly.  Quite clearly, some people think that such technical gymnastics will also solve otherwise impossible architectural or urban design problems elsewhere.

That heliostat again: enough already.

Now that Jean Nouvel's One Central Park apartment building has been invested with the exalted status of “Best Tall Building Worldwide” by the Council on Tall Buildings and Urban Habitat (CTBUH), it's time to put that infamous heliostat to bed.  Especially as it hardly got a mention in the metaphorical shadow of the breatless claims for the world's biggest, ot tallest green walls by Patric Blanc.

Up front:  The heliostat works as described in an earlier post in this blog.  See the diagrams and descriptions at "Clued in on the heliostat".  And a video here. No, it doesn't do anything to improve winter sun for the apartments at all.

Not only a heliostat

It is the piece of bling that keeps on giving. More than likely the heliostat and the very big green facade will continue to dominate the interest of architects in One Central Park, part of the inner Sydney redevelopment starring John Nouvel and Fosters, as well as a minor cast of local architectural firms. But as I was reminded by an article from John de Manincor, the story of how the development came to be what it is, is much more interesting than the technical details of bits of the building. This post is kind of a first-hand review of that article, so you should read it first here at ArchitectureAU.

Almost no description of the first four years of urban design guidelines, design quality competition, design development and community consultation and negotiations with the city authorities can capture the sheer attrition of trying to realise a large brownfields infill development, experienced by the original proponents of the scheme. 

The sky isn't falling, but I'm clueless

Just a quick update: the penthouse apartments in Jean Nouvel's apartment block, known as Central Park 1 in Sydney, have gone on sale this weekend, offered to buyers locally and marketed also in our increasingly affluent and outward looking Asian region.

But I am not a real estate agent, my interest continues to be the question of just what exactly will the much-vaunted heliostat do?  The image above is from the advertisement, and is just a bigger version of the same rendering I used in my previous post about the subject.

Up till very recently, try as I might, I couldn't find a single reference on-line or otherwise accessible to the average punter, that answers my original question: just how does the winter sun in the middle of the day actually get to the bits of the cantilevered frame, which then are supposed to reflect it down the shaded southern facade (remember, this is the southern hemisphere)?

That changed, slightly, when the company contracted to do the feasibility study and construct the heliostat, local firm Kennovations, released a single page promo/case study.  You still have to be a detective to even begin to figure out what is actually proposed.  Let me try to help, while we all wait with bated breath for the chance to see it in action.

Image: Kennovations

The image at the left is clearly from a 3D analysis of ray-traced reflections.  Not labeled for date or time of day, it doesn't by itself demonstrate a lot, except that such modelling has actually been done.  I wouldn't expect otherwise.

It turns out the consultants are Device Logic, who otherwise specialise in design, installation and commissioning of tracking systems for utility scale solar power plants.

Clue 1:  The rays shown, both directly from the sun, and arriving via the cantilevered frame, are directed at the rooftops of the podium, and of the 'West Building', not at the south face of the taller 'East Building'.

Clue 2:  All along, had we read it carefully, the description of project had said:

"The heliostat incorporates an innovative system of fixed and motorized mirrored panels designed to capture sunlight and redirect it into the retail atrium and onto the landscaped terraces."  

Why did we jump to the conclusion that it was supposed to be a Clayton's solar access in winter for the south facing apartments?

Because every other residential building approved in Sydney has to try to arrange such solar access to 70% of all apartments, under the local model code which gives effect to a State Environmental Planning Policy known as SEPP65.  My consultancy practice is almost entirely devoted to helping architects go through the gymnastics of achieving that compliance.

Now that you are in that frame of mind, you probably look at the renderings slightly differently.  I can't help wondering what the occupants of  the apartments on several floors under the cantilever will think of looking into its underside, and losing the light from the sky?  But look more carefully.

Image: Kennovations

Clue 3:  The cantilevered frame shown in the other images is protruding much more from the facade than the one in the top picture.  I wouldn't immediately jump to the conclusion that the 3D renders are cheating.  Mind you, it's either that, or the frame is motorised to protrude further at key times.  If the latter, I definitely wouldn't like to live under it.

Clue 4:  Now look more carefully at the technical description finally available in the Kennovations pamphlet.  It says:

"Kennovations is contracted to Watpac to Design and Construct  the 42 x 6.2sqm Sun Tracking Heliostats (on the rooftop), the 320 x 1.5sqm Reflector Panels (suspended beneath the main cantilever)."

Hold it!  What does that say? 42 big 6.2sqm heliostats on what rooftop?  Is that what those things are on the West Building roof?  If so, what are they lighting?  If not, why has noone mentioned them before?  Unfortunately, I have no clue that helps me out with answering those questions.

Image: Kennovations

So, now that you are thoroughly confused, but like me, keen to keep going with this game of Cluedo, try this one.

Clue 5:  Thenext image also comes from Kennovations.  It looks like a full scale mock-up of the reflectors.  Is it?  If so, where is it?  I'd love to see it.  Because looking at it, I am even more mystified how the heliostat will work.

In desperation, let's try my favourite trick of analysis.  I call it 'semantic opposites'.  In other words, if something just doesn't want to make sense, look at it the other way around.

Clue 6:  What if the things on top of the 'West Building' are reflectors pointing upwards? Watch architect Bertram Beissel wave his hands around about half-way through this video, produced by the Sydney Morning Herald on-line, then finally, you may find on the Kennovations Portfolio Projects page this well hidden linked graphic different from any previously available.

Now I only get anxious about looking down from my apartment onto an array of mirrors reflecting an optical image of the sun upwards.

I think I am getting close to solving the mystery.  But I think it might be best if I have the patience to  answer all those questions by seeing the real thing - relatively soon, if it's true that the new owners of the penthouses are  able to move in come June 2013.  Keep the fingers crossed that it hasn't all been a monumental con-trick.

For the clues, read:
Kennovations One Central Park Heliostats and Reflectors Case Study here.
Gizmag Cantilevered residential heliostat takes shape in Sydney linked here.

For anyone really interested, there are further technical snippets to be found here. The links include a short amateurish video of wind tunnel testing at CPP's huge boundary layer wind tunnel at St. Peters, Sydney.

EDIT:
Jeremiasz Sieczko has posted an excellent reworking of this attempt to unravel the mystery of the heliostat geometry.  It was too long for a comment, so I have posted it as an independent article length post at Clued in on the heliostat.

 

 

Big gestures

The southern end of Sydney is undergoing a major architectural renaissance, with buildings by several of the world's leading architects.  The developments include the brownfield site of the former Carlton and United brewery, but also the University of Technology precinct on the other side of Broadway, one of Sydney's major road arteries. Partly to satisfy the agenda of the Sydney City Council, partly driven by the involvement of the University, sustainability is meant to be high on the list of priorities.

It is a moot point what, besides some default bolt-ons, is really being incorporated in these high-density developments.  But there are certainly some signature items that make the architectural community and the casual lay observer think that something radical is going on.

On Jean Nouvel's twin residential towers, some of the vertical greenery by Patrick Blanc are being installed, but they have just been upstaged by the lifting into place of the 110 tonne frame of a very large heliostat cantilevered from the 29th floor.

I was involved with an earlier tedious, painstaking, and ultimate pointless attempt to optimise solar access to generate the massing of a larger number of residential buildings on the same site. So I am under no illusions that Nouvel's bold gestures, and Foster's overwhelmingly methodical presentation of their contribution, broke through a previous barrier to the sensible development of this complex piece of Sydney. But that said, I have to work hard to maintain my enthusiasm that either the vegetative facades or the heliostat are anything but distractions.

The planting on the otherwise unrelieved glass curtain walls still produces a somewhat cynical response, to what might be more sensibly scaled and varied ways of living at high density in the city.  Effective passive environmental control, even in Sydney's benign climate – or perhaps especially in this climate – they certainly are not.

The heliostat makes me edgy for another reason.  The renderings have been spectacular, the promise of the night-time display of LED lighting undoubtedly likely to impress.  But for the life of me, I have not been able to find a sensible diagram that actually shows how winter sun angles might interact with the surfaces available for the installation of the mirrors.  The latest image, part of an online announcement on ArchitectureAU after the lifting of the frame, illustrates my point.

It shows the heliostat slung off the bottom of the cantilevered sky garden (complete with swimming pool).  The two-storey depth of the truss is clearly necessary structurally, but as far as I can tell develops exactly the sort of overshadowing of the mirrors, that will make the heliostat least effective in the middle of the day in winter when reflected sun is most needed.  By the same token they will receive the least shade in midsummer, when in Sydney shade in public places is a precious commodity.

But I have learned never to guess the complex 3-D geometries of sun and shade without the benefit of a 3-D model.  I could be wrong.  I just wish the architects would stop publishing renderings of what they hope will happen, and let us have instead some of the evidence which I sincerely hope they have bothered to investigate.