Fiddling with the roof, again

With the almost obscene image included here headlining its post, Sourceable presents a longish article

Which Is Greener, White Roofs or Green Roofs?. 

This latest look at roofs discusses a new report by the Lawrence Berkeley National Laboratory, which purports to say white roofs are the optimal choice, both economically and for cooling the globe.  I realise now, that the release of the LBNL report must have been the trigger for the earlier articles on which I have commented recently on this blog.    

To give credit to Sourceable, the piece by contributor Steve Hansen doesn't oversimplify the issues, and in particular gives space to the advantages of vegetated roofs beyond their impact on heat transfer.

"Green roofs are also effective at reducing urban air pollution. According to the U.S. EPA report, Reducing Urban Heat Islands: Compendium of Strategies, a green roof can remove particulate matter (PM), nitrogen oxides (NOx), sulfur dioxide (SO2), carbon monoxide (CO), and ground level ozone (O3)."

But it is interesting that even otherwise robust reports from scientific and government agencies have to be read with the same caution as might be applied to the web's less well credentialed sources. That is what actually triggered my own posts.  An example is the truly punchy part of the LBNL report.  Trying to break out of the limitations of a narrowly economic analysis, the authors cite as an example the potential health implications of roof colour.  I quote (albeit from the press release, not the paper):

"For example, black roofs pose a major health risk in cities that see high temperatures in the summer. “In Chicago’s July 1995 heat wave a major risk factor in mortality was living on the top floor of a building with a black roof,” Rosenfeld said. For that reason, he believes this latest study points out the importance of government policymaking. “White doesn’t win out over black by that much in economic terms, so government has a role to ban or phase out the use of black or dark roofs, at least in warm climates, because they pose a large negative health risk,” he said."

I can't quibble with the statistic, or even with the analysis that led to the conclusion about the deaths in the Chicago heatwave. But as I point out in Roofs in black and white, intemperate conclusions about the scope of regulation are naive and possibly counter-productive.  They display an ignorance of potential alternative roof construction methods, in which dark roof colour can actually be beneficial for summer heat control and passive solar winter heating.

Similarly, the degree to which roof choices might contribute to the urban heat island seems peculiarly prone to ignoring the very obvious information in aerial thermal imagery, the subject of my earlier post Are trees good for you?
So, forgive the disproportionate number of posts on roofs, and enjoy the rush of useful information. It was long overdue.

See:

• U.S. EPA report  Reducing Urban Heat Islands: Compendium of Strategies
• If you have access to a subscription to Science Direct, you can download a full text of the paper from LBL Economic Comparison of White, Green, and Black Flat Roofs In the United States here. Otherwise, go to the LBNL press release here.
• For balance, I need to include a link to the critique of the LBNL study by the EPDM Roofing Association.  Download a copy here, but do check the cute file name!

Economic Comparison of White, Green, and Black Flat Roofs In the United States, - See more at: http://sourceable.net/greener-white-roofs-green-roofs/#sthash.Wo5jkcpY.dpuf

Economic Comparison of White, Green, and Black Flat Roofs In the United States, - See more at: http://sourceable.net/greener-white-roofs-green-roofs/#sthash.Wo5jkcpY.dpuf

Economic Comparison of White, Green, and Black Flat Roofs In the United States, - See more at: http://sourceable.net/greener-white-roofs-green-roofs/#sthash.Wo5jkcpY.dpuf

Which Is Greener, White Roofs or Green Roofs?

Which Is Greener, White Roofs or Green Roofs?

Which Is Greener, White Roofs or Green Roofs?

Good on paper?

I note that Japanese architect Shigeru Ban is this year's Pritzker winner.  In a blog post in June last year, I reflected at length on Ban's energetic promotion of his signature paper prototypes in the inexhaustible 'emergency shelter' domain.  It wasn't a kind reflection, asking whether the work had true value, or whether it was a notably focused polemic of self-promotion.

I am curious what will be said of his work in the flurry of commentary now he has Architecture's equivalent of the Nobel Prize.  I think it is safe to say that Ban has succeeded in maintaining a rhetorical focus, until he stood out from his peers, and has now been duly rewarded.

However, one has to admit, that especially lately, Ban's buildings have taken on transcendental qualities that may have derived from a mastery of an unusual material, but also appeal more broadly to refined aesthetic sensibilities.

See a slide show of his work at Dezeen at http://www.dezeen.com/2014/03/25/key-projects-by-shigeru-ban/

Famous AND notorious

The late Harry Seidler, of an earlier generation of Australian architects who actually managed to have some measure of world standing, was said to have declared: 

"If you can't be famous, be notorious."

It was a clever strategy which Seidler, brash Viennese refugee, used in his earlier years to bootstrap himself to prominence in his new home, clearly hoping that he would indeed become famous one day.  When he did become sort of famous, he actually did stop making such an effort to be notorious.

Perhaps a similar strategy helps explain why Patrik Schumacher, Zaha Hadid's loyal lieutenant, took to Facebook with one of the more self-serving inane rants about architecture I have read for quite a long time.  I think most people would have passed on his initial castigation of "critics and critical architects" for their agnosia, or form blindness - as predictable marketing of the firm's trademark approach to architecture ..... It was the next installment of petulant imperatives that went viral.

"You need to know someone is looking in order to publicly tantrum."

I guess anyone reading this will have no doubt as to my opinion of such statements.

In my terms, even if you try to reduce architecture's task to an irreducible, it would have to be something like 'form, organisation and codified meaning'.  Perhaps Schumacher would have us believe that 'communicative spatial form' captures my notion of form and meaning, but reading the last four paragraphs of his proto-manifesto makes clear that it isn't so.

As to 'organisation', he is dissembling.  His firm's parametric exercises are mostly just big empty sheds with voluptuous surfaces, under whose redundant volumes and structures simple diagrams of circulation cope adequately with the building program.  Those diagrams mostly work in 2D, and are given a tweak by teasing them out of the single plane with a few ramps.  I hasten to add that I don't think there is anything wrong with such a strategy.  It works, and it liberates.  The crime is to pretend that it's not what you are doing.

But for the moment I don't have the energy to properly set out, at greater length, why I might find Schumacher's approach to architecture quite so offensive.   So I'm referring readers to one of the more accessible commentaries.  I don't always take kindly to the Opinion pages on Dezeen, but the piece by Mimi Zeiger is a pretty good read. 

Access the Dezeen article here.

Choose your own green?

There has always been some suspicion about whether various rating schemes actually delivered reliable guidance about the sustainability credentials of buildings.  

The three major such tools, LEED from the US, BREAM from the UK and GreenStar from Australia are all spawned by the 'property industry' with perhaps three dominant objectives:

• To incorporate as far as possible a comprehensive set of 'indicators' of sustainability;
• To foster 'industry transformation' by creating the incentives for a greater proportion of developments to adopt better standards than the minimum compliance mandated by local authorities; and 
• To maintain self-regulation in the face of likely and imminent government requirements.

Actually, it would be hard to get the industry bodies such as the Green Building Council to publicly admit to the last objective.  But the two other objectives seem reasonable enough, nay, even praiseworthy.  And indeed, there is undeniable evidence that the schemes have had some success.  The chief success, arguably, has been that the ubiquitous 'star ratings' have become the headline marketing tool for premium office buildings as they compete for tenants.

The reliability of these 'points accumulation schemes' in reflecting actual enhanced performance, is worthy of several separate posts, and I won't attempt that discussion here.  Let's just say that whatever may be dodgy in the detail, these ratings only really work if they retain some authoritative comparability between buildings submitted to them.  You have to be at least able to say that you expect Building A to be 'better' than Building B, because it has a higher score using the same criteria.

So it is with some bemusement that in the one week, I have come across two announcements that publicize the credentials of buildings, seemingly flouting that principle.

Australia’s first Green Star hotel on the horizon utilised custom-built rating tool is the heading of an article in Architecture & Design.  At first pass that doesn't seem so problematic, especially if you are aware of the steady rate at which the Green Building Council of Australia has been introducing the building type specific variations of its core rating tool.  The sting for me is buried further into the article, where it points out that "GEOCON (the developer)now has exclusive use of this Green Star rating tool, and Abode Woden has been registered to achieve Green Star certification"  Eh?  So to what is this building being compared?

Once riled, I couldn't help reflect that the thinly editorialised press release also fails to mention the Green Globe rating system, which is the global certification for sustainable tourism. That scheme has been in place for a good ten years. The buildings component of the ratings tool was developed by the then Centre for Sustainable Built Environments at UNSW, but certification requires more than just building ratings, and commits operators to a 'continuous improvement' cycle to maintain the initial ratings for a facility and its operation.

The second announcement was in Sourceable, touting "the first residential building of its size to be certified under a ‘six-leaf’ sustainability rating by the Urban Development Institute of Australia (UDIA)".

Who?  What?  The UDIA turns out to be “Australia’s peak representative body for all segments of the urban development industry”.  In other words a lobby group.  Their EnviroDevelopment certification turns out to be, in their own words, “a scientifically-based branding system designed to make it easier for purchasers to recognise and, thereby, select more environmentally sustainable homes and lifestyles”.  Digging further  yields “An EnviroDevelopment license is valid for a period of 12 months from the date of approval by the EnviroDevelopment Board of Management. However, certification and use of the logo suite is only granted after the licencing agreement and statutory declaration has been signed by both parties and all fees have been paid”. 

Of course, I downloaded the EnviroDevelopment Technical Standards .  I found a very nice checklist template under six useful categories, which referred sporadically to earning points……but nowhere did I find any indication of the number of points you have to earn to gain certification.  I guess the kindest interpretation is that if there isn’t a minimum score for compliance, unlike with LEED or GreenStar, a developer can’t be accused of chasing the easiest points.  All-in-all, I couldn’t quite work out why this scheme is really needed, given that its general thrust and detailed checklists are so hauntingly similar to GreenStar.

I have felt for some time that established ratings had lost any meaningful influence on the design process.  But these two announcements seem to suggest we had reached the point where you can either find at will a whole new ratings scheme to credential yourself under, as long as you pay the license fee, or, I suspect, invent one to suit yourself.  I am now waiting for a breathless announcement about a project, ‘branded’ with some sustainability certification to which I can’t even find any google search links. 

the first residential building of its size to be certified under a ‘six-leaf’ sustainability rating by the Urban Development Institute of Australia (UDIA). - See more at: http://sourceable.net/brisbanes-sustainable-residential-tower-set-commence-two-week-sell/#sthash.8umYOciA.dpuf

the first residential building of its size to be certified under a ‘six-leaf’ sustainability rating by the Urban Development Institute of Australia (UDIA). - See more at: http://sourceable.net/brisbanes-sustainable-residential-tower-set-commence-two-week-sell/#sthash.8umYOciA.dpuf

the first residential building of its size to be certified under a ‘six-leaf’ sustainability rating by the Urban Development Institute of Australia (UDIA). - See more at: http://sourceable.net/brisbanes-sustainable-residential-tower-set-commence-two-week-sell/#sthash.8umYOciA.dpuf

Roofs in black and white

The current issue of  the Australian on-line magazine The Fifth Estate features a Special report: the case for white roofs by Cameron Jewell, and the byline:

With externalities including an increase in the urban heat island effect, peak electricity demand and climate change, is it time to ban black roofs?

The best thing about the article is that it draws together in one place most of the conflicting considerations in choice of roof colour, and even to some extent, roof material. The worst thing is that it is missing perhaps the most important variable: the construction of the roof.

The issue with roof colour is the absorption of solar radiation. In any climate where summer overheating is an issue, the solar radiation absorbed rather than reflected has the same effect as raising the outside temperature, and therefore the temperature difference between outside and inside with which any insulation under the roof then has to deal.  The equivalent rise in temperature is known as the SolAir fraction, and can be very significant in the total cooling loads.

But this is only true if the roof is mainly relying on reducing the heat flow by conduction. It becomes less important if the roof system has low emissivity cavities which are effectively ventilated to the outside.  In an ideal version of such a roof, the ‘inside’ face of the cavity would be barely warmer than the temperature of the ventilating air, and therefore the effect of the solar radiation would be effectively neutralised, regardless of the roof colour.

In some other countries, such ventilated roofs are commonplace, even usual. It is important to understand that we are not talking about a ventilated attic of the kind to be found on a typical Australian pitched roofed house. Rather, the ventilated cavity is directly under the roofing material, with the low emissivity achieved by a downward facing foil faced membrane. The cavity is then formed by a rigid sheet lining, supporting the second of the ‘double sarking’ layers, this time with upward facing foil. The secret to the arrangement is to leave an unobstructed air path that will turn into an efficient buoyancy driven air stream, inducing intake at the low point and exhausting hot air at the ridge. This is achieved by the primary battens supporting the roofing running up the slope of the roof, rather than across the slope.  And of course it works best with roofs that are simple gable shape.

Anyone who has followed the description so far will realise that the system, ironically, works best if the roof sheeting is dark, because that will provide the necessary heat to drive the ventilation.
So what about winter, when it would be good to benefit from the extra heat absorbed by the dark roof? An additional elaboration of the system switches over to capturing the warm air in the cavity, and pulls it into the house interior. Admittedly, this may require a fan, but the fan power is small compared to the heating obtained.

OM Solar system Japan

In case anyone thinks the description is fancifully theoretical, it is in fact essentially the type of roof construction employed in Japan, parts of Europe, and of North America. Only the last bit, the winter heat capture is a relatively recent development, as exemplified by the Japanese OM Solar system, which gathers so much heat from a typically small Japanese house roof, that it also puts a heat exchanger in the loop to provide the prodigious amounts of hot water needed to support traditional Japanese bathing habits.

Summer daytime operation

So why don’t we build such roofs in Oz? Because we traditionally used to think it’s for those wankers overseas, while we can save heaps doing away with the plywood sheeting, and even sarking under the tiles. Well, the time has come to look again at what those wankers are doing, why they are doing it, and to spend a little more on building energy efficient smaller houses, rather than the world’s biggest poorly built homes.

Oh yes. And then you can have your black roof and feel good about it.

Inconvenient women

The issue of the participation and fate of women in architecture just doesn't seem to want to calm down.  That it is a reflection of the greater societal problem is hardly an explanation, nor a consolation.  In my opinion, it is actually a special case, and all the more a disgrace.

I say this because in Architecture, unlike in most other endeavours, there is the the added and all-important consideration of attribution, of authorship of projects that were in any case always collaborative.  Where a female judge, if she fought her way to that eminence, will always have her name tied to her judgements used as precedent, an important female architect can have her contributions erased from history in favour of her husband or male partners, by the persistent misogyny of the profession.  And it is willingly aided and abetted by the populist media.

All this was just now brought to mind by the controversy around the BBC using a group photograph from which Patty Hopkins was literally airbrushed, to make a more cosy image of Norman Foster, Richard Rogers, Nicholas Grimshaw, Terry Farrell and her husband, Michael Hopkins, and thereby to appropriate exclusively for these 'boys' the credit for initiating the most influential movements in post-WW2 British Architecture.

It is better to read the coverage by the Architects Journal, including comments by a number of contemporary women architects, than for me to attempt a summary.  I comment rather from my position as someone who has taught literally thousands of architecture students, and not irrelevantly, as the father of cherished daughters. 

I started studying at University of Sydney in 1966, with eight women out of the sixty seven commencing architecture students.  I started teaching there five years later in 1971, just a year or two before the proportion of women in the intake first exceeded 50%.  With the exception of a couple of years at the then newly founded architecture program in Canberra, every year for the last forty four of my academic life, I have taught more women than I have men.  I can testify that (reflecting the general trends in secondary and tertiary education) the girls outperformed the guys most of that time.  I sent entries to formal student competitions, and turned many studios into live projects that were less formally, but still externally judged.  Over the years, the women were over-represented in the premiated projects.  Experiencing all this, it's been doubly hurtful for me to watch the demoralisation and the loss to the profession of most of these talented individuals, as their numbers thinned quickly after graduation. But this is all old news.

Where my personal experience comes to bear on the events that triggered this post, is that I started teaching at the height of the feminist push.  Its towering figures like Germaine Greer and Anne Sommers were barely older than I, and had not long left Sydney.  Other women of fearsome intelligence, who happened not to have turned their PhDs into foundational feminist manifestos, argued and partied and for a brief time tolerated my presence in their midst. As a consequence, I can say with my hand on my heart that I took the principles of equality very seriously, and always pedantically referred to the iconic architectural couples and partnerships by both names.  Denise and Robert, Peter and Alison or Maxwell and Jane may as well have been siamese twins joined at the hips.  Admittedly, we knew less of Wendy or Patsy, but had we known, we would have been just as careful.

We did this because we recognised that if we did not, or female students would have to fight their battles all over again.  Along the way, it even appeared to become fashionable to accuse the big boys of ruthless appropriated authorship, most scurrilously that Wendy rather than Norman Foster was responsible for the seminal ideas of the Willis Faber and Dumas Building in Ipswich, or the Sainsbury Centre.......

So I don't quite know where things went wrong again.  Perhaps it would have been possible for Robert Venturi to refuse the Pritzker unless the award committee also inscribed Denise Scott Brown.  Those kinds of awards don't happen by opening an envelope on the night (He would have been a brave man gambling quarter of a million dollars).  But the real point is that the award committee didn't think of it themselves.

And so here we are today, where we not only erase from history the contributions of women architects, we are actually willing to erase them physically?!?

Are trees good for you?

Of course they are.  I firmly believe that.  Obviously, so do advocates of urban forests. Oh, yes, I am one of those.

Advocacy for increased attention to tree scale planting in cities, for the establishment of viable urban forests, is at least a generation old.  And even though rarely adopted as a coherent policy by cities during that time, there has nevertheless been a distinct trend for the public and private domains to acquire significantly more green fuzz.

Paddington, Sydney 2012

It is quite enlightening to compare old aerial photographs of 'inner ring' suburbs of a city like Sydney, with recent images.  It becomes clear how little greenery featured in these places when they were a dense matrix of unregulated industry and predominantly worker housing, strung together by tramways and above ground electricity and telephone wiring.  In contrast, gentrification also seems to bring a commitment to transforming bare streets to treed, and small gardens to intensely planted havens.  In particular, not so many people these days seem to share the former suburban phobias about gutters blocked by leaf litter, so they don't maintain personal vendettas against trees taller than three meters.

Paddington, Sydney, 1947

But lately there also seems to be a more concerted push towards urban forests, driven by a loose conception that greening the city will help do away with the so-called 'urban heat island effect'.

The latest such initiative I have come across is from Melbourne, Australia, already one of the worlds most livable cities.  The article is on Sourceable.net, and may very well have some of the usual baggage of journalistic oversimplification, but I suspect that the point I am about to tease apart is not one of them.

Thermal image of inner Melbourne

As almost always, the key image in the argument for the putative benefits of a green canopy is an aerial view as a 'false colour' thermal photograph.  The image supporting the Melbourne press releases is the prettily coloured one I reproduce in this post.  What you are meant to see is that all the parklands show up as reassuringly blue-green cool, in contrast to the warm yellow-reds of all the concrete and asphalt of buildings and roads.
 
But now look more carefully.  Look for all the coolest surfaces, the ones in the most intense blues.  I am not really familiar with Melbourne, but I can tell by the shapes that the coolest surfaces are in fact the metal roofs of the sporting venues, and indeed of the large industrial and warehouse sheds.  Now, I don't know too much more about the total heat balance over time, of these lightweight roofs as opposed to the grass and canopies of the areas of vegetation.  But I am sure my reading of the pretty picture is not going to be popular with the people who would like it to be self-evident, that literally greening the city will by itself make the urban heat islands go away.

Most readers of my blog would be familiar with my obsession with looking more carefully at data and imagery, particularly when looking for evidence of technical performance.  Well, this is one more example.  In fact, US research suggests that simply extending green surfaces by way of street planting and vegetated roofs makes far less impact on the city's average albedo than we would hope.

Which is not to say that a lot of the other benefits of trees in cities are not worth it for their own sakes.  I'd rather a shaded street sidewalk to walk along than to bake in the merciless sun of a Melbourne summer, I'd rather the leaves overhead cooling and humidifying by transpiration the microclimate under them.  But to capture that correct depiction of what happens, you need to show thermal images of the street at pedestrian level.  It would be just as compelling as the misinformation of the thoughtlessly chosen and misleading aerial.

Read the Sourceable.net article here.

To see another similar aerial thermal image, with exactly the same issues, see the ones of Sydney, here.  But if the reader is interested, this page also links to other microclimate monitoring by the City of Sydney.  If really, truly interested, take the trouble to go to the UNSW link and download the full report of the pilot project
Micro-Urban-ClimaticThermal Emissions: in a Medium-Density Residential Precinct.  Don't be put off by the poorly written report itself, and spend your time instead on the comprehensive literature and methodology review in Appendix 1.

Micro-Urban-Climatic Thermal Emissions: in a Medium-Density Residential Precinct - See more at: http://www.be.unsw.edu.au/sustainability-and-climate-change-adaptation/projects/thermal-impact-designed-environment-urban-heat#sthash.Y6relWBT.dpuf

Thermal Impact of the Designed Environment on the Urban Heat Island - See more at: http://www.be.unsw.edu.au/sustainability-and-climate-change-adaptation/projects/thermal-impact-designed-environment-urban-heat#sthash.Y6relWBT.dpuf