Comment
January 2005
In
the 2005 December edition of the ASLA journal,
Landscape Architecture, the editor Bill Thompson
made comments regarding the design and construction
industry’s contribution to global warming.
See the online article via the AILA
news pages
Neil
Hobbs, an AILA National Councillor, responds:
embodied
energy
A
few local observations on what targets we should
be aiming at – including “How WSUD
may increase greenhouse emissions”.
The
local market for material suppliers is, like all
markets, being taken up by the larger players.
Historically clay was dug and fired for brick and
tiles at the clay pit site – a couple of
Sydney examples - Homebush
Brick Pit, (now a frog habitat), and St Leonards
brick pit (closed in the 1940’s – now
a waste transfer station) and so on. The bricks
were used locally – the yellow/white St Leonards
bricks are still seen in lower north shore buildings
(Kioloa circa 1880, in Union Street North Sydney,
and Homebush bricks were used almost exclusively
in Haberfield and
surrounding areas. Closer to home, the Yarralumla
Brickworks supplied bricks for Canberra, even
to the point of being transported to the Old
Parliament House site by a light railway. Very
energy efficient!
Much
like the dominance of Coles and Woolworths in retail
markets, now brick and clay product manufacture
is centralised, requiring the transport of raw
material to the brickworks, then further transportation
to the building site. The major manufacturers have
multiple pits and kilns, but their marketing material
makes no reference to the place of origin, so that
a brick purchaser in Melbourne can choose from
bricks made in Rockhampton Qld, or from down the
road – for no discernible price penalty.
I understand that a Queensland manufacturer transports
vast quantities of pavers to the west coast of
the USA – thank you, free trade agreement.
Don’t
get me wrong, I appreciate the choice of materials – one
does tire of red brick – but I do worry at
the seemingly needless movement of material up
and down the coast. Some material suppliers in
Melbourne find it inefficient to break a journey
to Sydney in Canberra – so that our order
goes past us, gets unloaded, then reloaded, then
makes the journey back to Canberra, effectively
doubling the 700 kilometre journey.
A
recent public area refurbishment project we were
involved with included the eminently sensible idea
of reducing urban stormwater runoff, while helping
to provide deep root zones and watering for street
trees – but have the WSUD initiatives come
a too high a price?
The
project involved replacement of existing impermeable
car park paving with porous paving over graded
subgrades to allow for ground water percolation.
We also provided deep planting preparation for
deciduous trees, including structural soil. Excess
water remains drained off to the existing stormwater
through subsoil drains.
All in all, a very positive initiative – however
-
Construction
process was as follows:
- Strip
bitumen and recycle – local recycling depots
are well patronised – a tick for this:
- Excavate
for new subgrades, re-use filling within local
environs – another tick;
- Place
quarried material, in various grades, and compact
with rollers, quarried material was required
because a recycled product will not have the
matrix of facet shapes and sizes to hold together
while retaining voids for percolation. This scores
a minus for the quarried product, but a plus
for the increased water percolation potential – on
balance equal;
- Placement
of various geotextile fabrics – synthetic
products, oil based, very high embodied energy
use ;
- Supply
and place porous paving blocks – manufactured
in Adelaide SA, presumably from reasonably local
materials, then transported to Canberra by road,
unloaded at a depot, then picked up and taken
to site in small loads – surely the energy
to transport the material will add to the potential
environmental payback time for the WSUD benefit.
Who can calculate this?
Should
Landscape Architects be concerned about this?
Should
we be concerned at the crates of imported granite
and stone that can land in Australia for not
much more than the price of a basic, locally
produced precast concrete paver?
And
this is only for paving material....
(
a response or follow-up? - email web<<at>> aila.org.au)
