Transcript What should you think about when deciding where to site

Choosing building materials
straw bale
clay (click for more)
copper
stone
metals (click for more)
Plastic (click for more)
bamboo
wood (click for more)
sand
Can I reduce the environmental impact of my building
by choosing materials carefully?
materials
The construction of buildings uses a huge
amount of materials.
We need to try to work out the impact of different,
commonly used building materials and try to decide
which is the most appropriate for our building….
soil (click for more)
wood (click for more)
stone
sand - to make glass
limestone – makes cement – to make
concrete (click for more)
iron ore – to make steel (click for more)
clay and calcium silicate – to make bricks
oil – plastics (click for more)
What are the materials issues?
What’s the embodied energy of the possible
materials I might use?
How much of the material is left – am I
depleting already scarce resources?
Is it a renewable or non-renewable
material?
What is the thermal mass of the material?
Embodied energy
The embodied energy of a
material is the amount of energy
that has gone into
● extracting it
● producing it
● transporting it to the site.
It’s like the amount of energy
‘locked up’ in the material.
Can you use existing materials?
Rocks used as a shower
wall, a wagon wheel used as
a window frame.
http://www.greenhomebuilding.com/localmaterials.htm
materials
How much of it is available?
Scarce
Plentiful
Is it available on the site? Or
locally?
As well as being
scarce, how much
energy do they use in
production?
Will it require a lot of energy
to process?
Can they be re-used/
recycled?
Questions to think about:
Oil for plastics
Clay
Other metals (eg zinc)
Earth
Lead used on roofs
Straw bale
Stone
Copper – for pipes
materials
How much is left of each material on the planet?
Years left of different materials assuming current rate of use
materials
Materials can be categorised in different ways.
- renewable / non – renewable
- plentiful / scarce
Examples: Stone is plentiful but not renewable. Oil is non-renewable and
scarce.
Renewable
Non-renewable
These are materials which will be replenished
naturally. How plentiful they are depends on how
much land we have available to grow them, and
how fast they grow.
These resources
shouldn’t be used faster
than they can be
replenished.
Examples:
These are materials which are available in
finite quantities, ie once we have used them all
up, there will be not be replenished.
Examples:
Plastics
(from oil)
Bamboo: very fast
Corrugated
plastic
growing but not
indigenous to the UK
Steel
Hemp:
Wood: as long as you
replant it, it is
renewable
Very fast
growing
in the
UK.
(from iron ore)
When using non renewable or scarce
materials (such as plastic and metal)
there are some questions to think about:
●
Can it be used as little as possible?
• Can it be re-used, or recycled afterwards?
●
●
Is it really vital to use it?
Can another more readily available or more sustainable
material be used instead?
What’s thermal mass got to do with material choices?
Thermal mass is the ability of a material to absorb heat energy. A lot of heat energy
is required to change the temperature of high density materials like concrete, bricks
and tiles. They are therefore said to have high thermal mass. Lightweight materials
such as timber have low thermal mass. The lower the thermal mass, the better.
Winter
Allow thermal mass to absorb heat during the
day from direct sunlight or from radiant
heaters. It will re-radiate this warmth back into
the home throughout the night.
Summer
Allow cool night breezes and/or convection
currents to pass over the thermal mass,
drawing out all the stored energy. During the
day protect thermal mass from excess
summer sun with shading and insulation if
required.
http://www.theyellowhouse.org.uk/eco-prin/princip.html#p5
Thermal mass at CAT
The internal wall of this building
is made of rammed earth which
has a high thermal mass.
It warms up when the sun hits
it.
At night, or when the
temperature decreases, the
heat stored in the wall comes
out, keeping the building at a
more constant temperature,
and reducing the heating
demand.
Woodman’s Cottage, Sussex
What’s good about Ben Law’s house?
http://www.channel4.com/4homes/ontv/granddesigns/houses/S/sussex_woodman-5.html
Ben’s house….
- Uses materials with low 'embodied
energy‘ i.e. local, have not travelled
long distances and do not require
large amounts of energy to produce
- Re-uses old materials (e.g.
newspapers)
- Use recycled materials (e.g. front door)
- Minimizes waste (e.g. rainwater
harvesting)
Olympia’s house in Peru
• In 1990 an earthquake in Alto Mayo, North Peru destroyed
3000 houses and damaged 5000 more
• The affected houses were earth-based structures that were
unable to withstand tremors – walls cracked and collapsed.
• The builders were unaware of a traditional technology (called quincha) that had
built-in earthquake resistance.
• Practical Action, a development charity, worked with local people to develop
earthquake resistant housing.
Olympia and quincha mejorada
• Olympia Guerra was one of people affected who
became involved in designing and making new homes
• Quincha mejorada (improved traditional homes) used
the following improvements
• concrete foundations (greater stability)
• tar-treated columns concreted into the ground
(protected against humidity)
• vertically woven canes in the walls (greater
strength)
• roof beams and roofing materials nailed down
(wind resistance)
• use of wires to tie beams and columns (protect
against earth movement)
All the materials were available locally and cheaply
The results
• In 1991 a second tremor hit the same region
• 9000 further homes were destroyed or damaged
• all 70 new quincha mejorada homes survived
• 4000 further homes were built plus schools and community
centres, using the same quincha mejorada techniques
So, how did you do?