Buildings as ‘urban mines’
On the same vein started by Ali wrt sustainability – a short read from the ‘lefties’ at the Guardian that I found interesting:
The construction industry accounts for 60% of new materials used, a third of waste and 40% of the carbon emissions. A few countries are starting to turn construction into a circular process, with ideas such as ‘building passports’ detailing every component for future re-use; ‘building elements as a service’, with ownership retained by the manufacturer and buildings never truly ‘owned’; and old buildings being ‘mined’ for useful materials.
In my (short) experience so far in a city based Phase 3 – the lack of space means that many of the projects are ‘re-imaginings’ of a current, in-situ structure. That being said, the place is gutted and, with a Client focus on ‘going green’, replaced with facades and services to achieve 6-stars (GreenStar). In this way Sydney is slowly upgrading its ‘old’ stock (bear in mind many of the buildings are less than 50 years old, modern Oz is young!) and improving its green profile.
Has anyone found this to be a trend in other major cities, or indeed wider? I get the impression that Europe is leading the way.
For those with experience with the RSME refurb – did they consider sustainability, or was it a ‘lick of paint’ for those old, drafty buildings?
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Good shout David. Taking the first last so to speak, the refurbishment discussions about Denison Block were pretty wide ranging and a dream sheet of energy saving measures was drawn up for consideration by the Authority. When the costs started to come in during the tender stage, the value engineering started; this was code for cutting out the nice to have stuff you can’t afford or aren’t required by JSP 315, not the way it can be run where benefits to both parties are supposed to be identified.
The result was that the biggest energy saving consideration was deemed to be during the winter, as the building (despite persistent requests), did not qualify for mechanical cooling under JSP 315. Therefore, they concentrated on the U value of the facade and the energy efficiency of the control systems for the heating (the boilers were out of scope as they also powered the workshop). Interesting technology like trick glass, phase changing ceiling tiles etc were then dropped, although the brise solei were allowed to be kept as a nod to the rubbish orientation of the building. Effectively what happened was the specification was dropped to ensure compliance with L2B and JSP 315, but little more.
Where buildings are being built speculatively for a landlord, or for sale or rent directly to tenants, the whole Greenstar, LEAD, BREEAM stuff kicks in commercially because these qualifications can help to burnish the credentials of the companies you are trying to attract into doing business with you. This effect should become even more powerful across the market as (if) the public push for companies to become more environmentally responsible.
As engineers of course, we have a professional responsibility to push this agenda in all of our work, but the reality is that the accountants generally have the final say about how forward leaning you can be in this area of design, over and above the requirements of legislation. Very frustrating, but hopefully on the process of changing.
With regard to the age at which buildings are currently being pulled down and rebuilt in London (only listed aspects of buildings seem to be retained), John Moran ran a really good CPD session on demolition in the museum. The director of the demolition company giving the talk noted that you knew you had been in the business a while, when you had got to the stage in your career where you were pulling down the buildings you had constructed as a junior engineer. He reckoned this time span was typically 25 – 30 years. If he is correct, Sydney seems to be hanging onto its building stock longer than London.
Anybody have any thoughts on why this might be?
I came across this concept last year but it was introduced as Buildings as Material Banks (BAMB) rather than mines. In theory it is the right way to think about things but as always there are obstacles to overcome:
– The material passports require fully mature BIM processes for every single building, far beyond any measures I’ve seen in action so far. The record keeping requirements for this are huge and, despite my Ph2 project aiming for top marks on LEED and BREEAM, there is no way they are close to that level of BIM maturity.
– There are only so many times you can re-use the same material before it becomes worthless as an engineering material so the cycle can’t be a perfect loop (but every little helps on this front). In-situ concrete for example can only be realistically removed from a site as rubble but pre-cast may have more scope for re-use.
– How do you recycle or reuse foundations? If you want a bigger building you will often need ‘bigger’ or at least different foundations. Is it more sustainable to replace existing foundations to get more on your site (triple bottom line) or restrict yourself to the capacity of what is in place?
On the up side, there is a lot of innovation focussing on sustainability (increasingly used in the environmental sense) so maybe we will see progress towards this – Hanson (cement company) even mooted the possibility of ‘renting’ concrete by the cube i.e. you ‘buy’ it from them but they get first refusal on the demolition rubble at the end. I’ve also got a blog coming up on an new pile type that you can get excited about Dave.
In my experience of London there is a huge amount of work in re-cladding existing frames or making use of lightweight materials to increase capacity (i.e. add a couple of new floors to a tower block) but equally demolition remains big business.
I won’t ask how you ended up reading the Guardian but it is interesting.
I defer to your current site experience Tom. My observation was based on walking past a couple of sites in Westminster on the way to the IMechE HQ.
A new term I cam across was ‘Cut and Carve’ modifications; re-engineering building structures to accommodate changes. This appears quite popular in London.