Designing a Sustainable Future
In all our discussions on sustainability in building, the major focus is on how to reduce energy consumption by the occupants of the buildings that we architects are now designing. However, we must also see that this is only one part of a much bigger picture which includes such issues as:
- longevity – how long our buildings will last
- carbon emissions in the manufacture of the building materials we specify
- thermal mass
- the ability of the parts of demolished buildings to be recycled
- thermal movement
|Longevity||Carbon Emissions in manufacture||Thermal Mass||Ability to be recycled||Thermal Movement|
|Traditional materials and construction|
|Solid Masonry wall (brick or stone in lime mortar) min 1' 6" thick up to 6 storeys with dry lining insulation||A||A||A||A||A|
9" outer skin of brick or stone in lime mortar
3" cavity plus insulation
9" inner skin of brick or block
|Slate or tile roof on timber rafters (with insulation)||A||A||-||A||A|
|Timber windows with Secondary glazing||A||A||-||A||A|
|Modern materials and construction|
|Steel on RC frame with brick or glass cladding, in excess of 8 storeys||C||C||C||C||C|
4" outer skin of brick in cement mortar
3" cavity & insulation
4" block in cement mortar
|Glass wall double or triple glazing||C||C||C||C||C|
|Concrete slab, flat roof, screed with asphalt||B||C||-||B||C|
|Timber flat roof, plywood with roofing felt||C||A||-||C||B|
|Aluminium double glazed windows||C||C||-||C||C|
|PVC double glazed windows||C||C||-||C||C|
The table illustrates these issues at the top. On the left-hand column are various types of traditional and modern construction. Let me briefly take you through them.
1. First, longevity. It is no use building a structure with zero carbon emissions when occupied, but only has a life of a few decades, because the whole process of rebuilding is very expensive in environmental terms. You can build a caravan with a high insulation rating, but if it only lasts 20 years, the environmental consequences of its disposal and remaking, will be considerable. It will be seen on the attached table that modern steel frame construction gets a C rating as many of such buildings are demolished after 40 years, whereas all properly constructed traditional buildings, of the sort described in the top of the table, all get an A rating, and with normal maintenance will last indefinitely.
Therefore to demolish traditionally built houses, which could easily be refurbished, is environmentally damaging. The embodied energy in each of such houses is equivalent, (according to the Building Research Establishment) to 4000 gallons of petrol – enough to send a Ford Mondeo round the earth five times. Those fossil fuels have already been burnt and the CO² is already in the atmosphere. So why repeat the process?
2. Second, we ought to consider the expense, in environmental terms, in the manufacture of the materials we specify. Here again, stone, brick, lime mortar, slate and timber all get an A rating whereas steel, reinforced concrete, large areas of glass, aluminium, and pvc get a B or a C rating. Stone is already in the ground and simply needs to be cut out and transported to site, whereas the energy consumed in producing modern materials is phenomenal.
And double glazing – contrary to what is said, is doubly harmful for two reasons: First, it encourages architects to build entire walls of glass when they should build solid walls with smaller windows; and second, the seals on double glazing units are guaranteed for only 5 years! So the environmental cost of frequent re-glazing is unsustainable. Even some Modernist architects acknowledge that an insulated brick wall with punched windows would beat a glass wall hands down in the energy saving stakes.
3. Third, thermal mass. Traditional buildings are solid and heavy in weight; whereas modern buildings are light and brittle. Many of us have noticed that when we go into a large traditional church in Italy in the middle of the summer, the building is pleasantly cool; this is because its thermal mass evens out the seasonal and daily variations, whereas thin lightweight walls do not have the thermal mass to achieve this.
As you all know, air conditioning is the major consumer of energy in hot climates. I have recently built a house in Texas with thick walls and high ceilings and it has already been noticed that the air conditioning requirement is very considerably lower than with modern stick construction of thin walls with no thermal mass.
4. Fourth, ability to be recycled. Buildings today which only last a few decades have to be demolished. Demolition produces a lot of material that has to be transported to a licensed tip, not to mention the problems of disposing of new materials like asbestos and worn out refrigerators. Traditional buildings are constructed in lime mortar and therefore they can be taken apart and reused, and the lime will enrich the soil. In the past many old buildings were often built of the materials from the remains of older buildings particularly bricks, stone and timber. This was necessary because in those more thrifty times all materials had to be transported by horse and cart and thus there was an added incentive to use the materials that came to hand.
5. Thermal movement. The traditional materials, brick, stone, lime mortar are all virtually inert to changes in temperature and therefore have an A rating, whereas modern materials like reinforced concrete, steel, glass, aluminium and pvc get a B or C rating. This is because they have such a high co-efficient of thermal expansion that they require expansion joints at regular intervals. This is the main cause of their short life span, because the expansion joint (filled with mastic which breaks down under sunlight) cannot protect the building from driving rain and water ingress.
We architects are a major cause of the problem, which cannot be solved by our homage to environmental issues with flow diagrams showing air movement etc. Our buildings – particularly skyscrapers – are environmental disasters. Over the last 50 years, we have built cities totally dependent on steel, reinforced concrete and plastics. We think nothing of burning up the resources of the earth to service our buildings which become higher and wider and deeper – all more and more dependent on artificial light, air conditioning, lifts and transport. In our profligate use of oil and gas we design temporary buildings of inferior materials which have to be replaced at regular intervals which cannot be recycled. We have therefore produced an unsustainable and precarious environment.
So where do we go from here?
There is an alternative, which has worked and proved itself over 4000 years – it is called Traditional Building Construction: solid masonry, modest height, pitched slate and tile roofs, smaller windows. It is beautiful and sustainable, it is the architectural expression of every civilised age.
But it has been rejected.
Sir David King (the British Government’s Chief Scientific adviser on sustainability) has said - "we need a complete change in the way we approach building design, a culture change in the way we live and use our resources, a radical change of attitude from architects and the public.”
Leon Krier has said, "Either we go on as we are and face collective suicide, or make a Copernican return to cut our environmental problems to manageable sizes. In such circumstances it is either mad or criminal not to change course."
We are not designing cars or aeroplanes or armaments which have to be replaced every 20 years to keep up with our competitors. We are designing permanent homely places where people want to dwell in our towns and countryside.
Is it not about time we began to think the unthinkable, to reject the whole Modernistic system of building and begin to realise that the only way forward is to look back and rediscover what our forefathers handed down to us. Only then will we have any chance of producing an environment which will be sustainable and worth passing on to our grandchildren.