Timber Engineering Europe
WRITTEN FOR "The Olive Press" by TEE October 2008
It's "that" time of the year again - The Big Water Debate! Have we? Haven't we? The tourists are blamed for over
enthusiastic water usage, or the golf courses are wasting it on the grass, solely for the benefit of our fellows with the
funny shoes and sweaters. The poor old farmers don't escape lightly from accusations of waste either. Look around you and
in every direction you will see water being wasted to excess, and nobody seems to notice! I am referring to the millions
of litres - No, lets get it right, billions of litres of water used in concrete construction every year. To give the reader
some idea of the massive use of water in construction, each cubic metre of concrete requires in the region of 176 litres
of water! This does not include the quantity of water required to make the base products of each material either.
Add 176 litres of water to 320kgs of Cement, 600kgs of Sand and 1,200kgs of Gravel and mix it up well, (preferably not
with a shovel - it could take some time) and you have 1 cubic metre of concrete! But, in order to manufacture the
ingredients, once they have been blasted out of the quarry and before they can be used in concrete production a great deal
of water usage is involved.
Embodied energy and embodied water intensity requirements in manufacturing are rarely given much thought. The production
of steel also used in construction has a very high-embodied water intensity level, to add to the usage of water required
in concrete construction.
Taking that figure of 176 litres of water per cube of concrete and multiply by 6, this tells you that each concrete
truck is carrying a minimum of 1056 litres of water. I suppose its something to think about next time you are stuck
behind one. According to one Mr. Peter Gleck (don't ask), he claims that the average daily usage of water in Spain, per
person including bathing, washing, drinking, recreation, (I take it this includes pools) and wastage, is 160 litres daily;
so each truck has enough water to keep nearly 7 people a day! Not impressed? Read on...... .
In 2007 one concrete supply company, Tarmac Iberia supplied over 2.8 million cubic metres of ready-mixed concrete
and 7.8 million tonnes of aggregates, which brought an income of 200 million euros - but, that's nothing compared to the
Spanish Holcim Group who's cash till rang up 660 million euros in sales. These are only two of many! Based on the above
Tarmac Iberia alone used almost 500 million litres of water on just their ready-mix product. It is very difficult
to be 100% accurate with these figures as they vary from source to source and without being alarmist I believe them to be
reasonably accurate and this statement should avoid receiving rebuke or correction appearing in your esteemed organ,
from "Outraged Engineer - Penge".
Construction also creates a separate problem with supply as water can be heavily impacted by residential construction.
Site clearing and grading often cause erosion and polluted runoff. Urban development decreases the percentage of permeable
surfaces, reducing the ability of the land to absorb and filter incoming rain and pollution. And, as population and housing
developments expand, there is demand for more water so it becomes an ever-faster spinning wheel. So, we are the architects
of our own destination - more urbanised construction demands more water use, yet contributes to restricting supply.
We must ask ourselves, why does Iberia continue to use such a product that is so quarry focused and water intensive. Why
use a product in construction known for its unpredictable behaviour in earthquake. Why continue to build homes that
have ridiculously high passage of sound levels and unbelievably high carbon emission levels? Why use a product and
system, which does not allow heat retention in winter and heat regulation in summer, without the use of mechanical
assistance? Why continue to suffer defect in new property as a result of the fabric drying process? The opportunity to
incorporate modern building technology, along with alternative materials and methods, has never been greater. Construction
time and cost can be slashed if modern methods are employed. Many, many other developed countries can supply affordable
housing, using modern technology and incorporating the principles of environmental and responsible material and method
choices. The rest of the world embraces modern methods of construction - why not Spain and Portugal?