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Transcript of Green Materials in Buildings
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TSHWANE UNIVERSITY OF TECHNOLOGY MATERIALS IV 2012 1
Introduction:
Sustainability and today's current drive for "green" ratings in buildings
has sparked a trend in the built environment. Designers, builders and
manufacturers are all trying to collaborate in achieving sustainable
buildings. This research assignment draws attention to various types of
green ratings systems as well as what a green material is, and the
properties thereof, while counterpointing the findings with non green
materials.
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TSHWANE UNIVERSITY OF TECHNOLOGY MATERIALS IV 2012 2
Introduction to Green materials:Through heightened global awareness of our dwindling resources as well as
the importance of the protection there of, we have become more conscious in
the way which we analyse, consider and use materials in our everyday lives.
Some institutes and organizations have developed guide lines, principles
and frame works by which materials can be rated.
Sustainability:
Defined as:
sustainability
Environmental Science . the quality of not being harmful to the environment
or depleting natural resources, and thereby supporting long-term ecological
balance.
(Dictionary.com, 2012)
creating buildings which are energy efficient, healthy, comfortable,
flexible in use and designed for long life
(Foster and Partners, unknown)
materials and construction products which are healthy, durable, resource
efficient and manufactured with regard to minimising environmental impact
and maximising recycling(A. Edwards, 2004).
Differentiation between green and non-
green materials:Differentiating between green and non-green materials involves an
evaluation method which one needs to follow. This method has three steps,
as follows:
Research:
This is the first step to checking whether the material is green or not.
All information from when the material was manufactured, to the technical
data of end product has to be evaluated. Technical data may include
Material Safety Data Sheets, product warranties, recycled content data,
durability information as well as environmental statements, of which there
are many more.
Evaluation:
After the gathering of all the information, it then needs to be evaluated,for example; looking at how much energy was used to manufacture and
transport the product. This step also involves the comparing of similar
types of products according to the environmental criteria.
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TSHWANE UNIVERSITY OF TECHNOLOGY MATERIALS IV 2012 3
There is a technique which incorporates the assessment of a product from
cradle to grave, its full life cycle, called Life Cycle Assessment (LCA).
Taking all the impacts associated with the production and use of the
product into consideration.
Selection:
This step generally involves the use of a green rating system to assess
each product based on specific environmental criteria. Hereby allowing each
product to attain a total score, thus indicating the product with the
highest environmental attributes.
By following this method of finding out how green or not-green materials
are, you will establish which materials/products would be best suited to
the project, striving for a better 'green' rating.
Evaluating green materials:When rating these materials, one needs to do what is known as a life-cycle
assessment, or commonly known as a life-cycle analysis. This is an
assessment of a materials life-cycle from cradle to grave, cradle to gate,
cradle to cradle, gate to gate, well to wheel, economic input output and
or an ecological based LCA.
Criteria by which an LCA should be conducted are set out in the ISO
Standards, ISO 14040 and ISO 14044. ISO 14040 specifies the framework and
principles by which a report on lifecycle assessment studies should be
conducted where as the ISO 14044 illustrates the requirements and the guidelines which are to be implemented when setting up a rating system.
Approximately 3 billion tons of the earths raw materials are consumed with
in building and construction activities which accounts for about 40% of the
total usage in the world.(Spiegel and Meadows, 1999) It is therefore
crucial that rating systems are developed in order for us to make more
informed and conscious decisions when selecting a material for a building.
Green rating system:
Among the vast quantity of green rating systems being designed and
implemented, Greenglobes, LEED, BRE, ATHENA and BEES, are among the top
currently. furthermore not all of these green rating systems are adaptable
to all countries, due to some being country specific. however there are
some which can be globally applicable or rather either, northern hemisphere
and southern hemisphere applicable. For example Australia uses the GBCA
(Green building council Australia) green star system which is applicable
for South Africa.
Some of these green rating systems focus on an assembly of components, for
example, the BRE system which is developed in the United Kingdom or,
ATHENA which is developed in the United States. Each of these green rating
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TSHWANE UNIVERSITY OF TECHNOLOGY MATERIALS IV 2012 4
systems divide each component of the building into categories. These
categories are then divided into different assemblies. In addition to this
BRE provides default system which give ratings for over 1500 different
building materials.
Although these systems are developed in different countries they are still
base on similar criteria which would define the green 'value' of a
material. Even though Green materials can be given a green 'value' or
'rating' the material will still react differently in different geological
locations. Hereby resulting in the variety of green ratings systems we see
developing in various regions.
Ultimately one green rating system would be the ideal solution.
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TSHWANE UNIVERSITY OF TECHNOLOGY MATERIALS IV 2012 5
Breeam Rating System:
BREEAM is the green rating system we will focus on for this research
document.
BREEAM (Buildings Research Establishment's Environmental Assessment Method)is the United Kingdom's most commonly used environmental assessment method
for buildings. Having been developed in the 1990's BREEAM has established a
large quantity of environmental research from construction and property
industries, government and building regulators. This information and
research has been translated into a crediting system containing nine
categories, based on construction and in-use performance of the building.
BREEAM rates materials with an overall score which is defined as
'unclassified', 'pass'[C], 'Good'[B], Very Good'[B], 'Excellent'[A] and'Outstanding'[A], see Table 2. This is achieved by giving the credits
weights and then calculating the overall aggregate.
For a building to achieve the 'Outstanding' rating it needs to exceed the
score of 85, see Table 2, while meeting the minimum requirements specified
in table 3 as well as producing an assessment of the building, once in use,
within its first three years. Should this not be met BREEAM will reduce the
rating to 'Excellent'
BREEAM is a generic Method which is customised to accommodate specific
building typologies. There are currently 13 versions of BREEAM including:
Offices Industrial Retail Healthcare Prisons Courts Multi-Residential Schools Code for Sustainable home EcoHomes EcoHomes XB
BREEAM accommodates other projects which can't be categories with their
"BREEAM Bespoke Scheme". Furthermore BRE offers an international scheme for
buildings outside the United Kingdom.
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TSHWANE UNIVERSITY OF TECHNOLOGY MATERIALS IV 2012 6
Table 1. Assessment categories.
Table 2. Ratings
Table 3. Standards
[A]
[A]
[B]
[B]
[C]
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TSHWANE UNIVERSITY OF TECHNOLOGY MATERIALS IV 2012 7
Material:
SummaryRating
ClimateChange
FossilFuelDepletion
OzoneDepletion
HumanToxicitytoAirandWater
WasteDisposal
WaterExtraction
AcidDeposition
Ecotoxicity
Eutrophication
SummerSmog
MineralsExtraction
CostR/m2
TypicalReplacementInte
rval
RecycledInput
Recyclability
RecycledCurrently
EnergySavedbyRecyclin
g
FLAT ROOF: WARM DECK
In situ reinforced concrete slab, vapour
barrier, insulation, asphalt, chippings
C B B A C C A B C C A C
R42.90 25 C A B B
LOW PITCHED ROOFSCoated steel composite roofing system ,
insulation, on steel roof structure
A A A C A A C A A A B A NA 25 C A A B
'TRADITIONAL' PITCHED ROOFS
Polymer/resin bonded slates, battens, sarking
felt on timber roof structure with insulation
between rafters
C C C A C A A C C C B A NA 35 C C C C
Roof Coverings
Flat Roof:
In situ reinforced concrete slab, vapour barrier,
insulation, asphalt, chippings
Natural Rubber- vs. PVC membranes
According to Woolley (2002:99) natural Rubber membrane is the preferred
membrane to use for flat roofing construction, but suppliers are difficult
to locate. Therefore Woolley suggests that the next best sustainable
membrane would be EPDM, because bitumen felts are not an environmentally
preferred option since it has very low durability. Woolley (2000:101) says
that durability and ease of maintenance is essential for a green option.
The following is a green rating of EPDM (synthetic rubber) according to the
BREEAM rating system.
EPDM (ethylene propylene diene terpolymer)
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TSHWANE UNIVERSITY OF TECHNOLOGY MATERIALS IV 2012 8
Summary rating [C]:
EPDM (ethylene/propylene rubber) is an elastomeric synthetic rubber. It has
a relatively low impact in comparison to other membranes and has high
durability and reusability properties. It is quite a simple system which
consists of a single ply rubber that is applied with an adhesive.
Climate Change [B]: G l o b a l w a r m i n g o r g r e e n h o u s e g a s e s
According to Woolley (2000:98), EPDM & Bitumen has a small but still
noteworthy impact on global warming. This is because of oil extraction and
petrochemical refining which are major sources of NOx, CO2, methane and
other Greenhouse gases. It is important to notice that EPMD with
reinforced polyester, has major effects on global warming because of the
polyester production process. Thus it is important to specify your
materials carefully.
Fossil Fuel Depletion [B]: C o a l , o i l o r g a s c o n s u m p t i o n
"The energy required to produce crude oil or natural gas is 3-4MJ kg. The
refining of these raw materials and the formation of polymers takes up
significantly more energy." (Woolley,2002:103). EPMD is one of the
materials which has a smaller impact than most bitumen felts.
Ozone Depletion [A]: G a s e s t h a t d e s t r o y t h e o z o n e l a y e r
According to Woolley (2002:98),Bitumen based EPDM has no negative impact on
the ozone layer, but EPDM with reinforced polyester has major consequences
on the ozone layer.
Human Toxicity to Air and Water [C]: P o l l u t a n t s w h i c h a r e t o x i c
t o h u m a n s
Woolley's research states that (2002:98),oil extraction and petrochemical
refining are major sources of So2, and NOx, which forms acid rain, and the
production of EPDM may have a small but significant contribution to this.
Fortunately this has no negative effect on human health. It is important to
note that EPDM with reinforced polyester is much more toxic than Bitumen
based EPDM.
Waste Disposal [C]: M a t e r i a l s e n t t o l a n d f i l l o r
i n c i n e r a t i o n
It is recommended by ERA (EPMD Roofing Association) that EPMD should rather
be recycled. This is because disposal of EPMD is expensive and harmful to
the environment.
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TSHWANE UNIVERSITY OF TECHNOLOGY MATERIALS IV 2012 9
Acid Deposition [B]: G a s e s t h a t c a u s e a c i d r a i n , e t c .
As mentioned above EMDM has a small but significant contribution to acid
rain.
Eco-toxicity [C]: P o l l u t a n t s w h i c h a r e t o
Woolley states that the polymers and monomers used in EPDM manufacture
cause minimal harm to the environment, but the solvents used for treatment
of the semi-manufactured product can cause harm to human health and the
environment.
Summer Smog [A]: A i r p o l l u t a n t s t h a t c a u s e r e s p i r a t o r y
p r o b l e m s
Research done by the Institute Construction and Environment, has shown that
with bonded systems, installation accounts for the largest relevant
contribution (due to solvent emissions during installation), in the case of
self-adhesive membranes with polyester fleece this can be attributed to the
wash primer. This also refers to the 1.5mm thick membranes.
Minerals Extraction [C]:M e t a l o r e s , m i n e r a l s a n d
a g g r e g a t e s
'The raw material for the membranes is oil, a non-renewable source. Known
reserves of oil and gas equate to approximately 40 60 years respectively
at current consumption.'(Woolley,2002:100).Unfortunately EPDM is dependent
on the use of non-renewable sources.
Figure 1. distribution of summer smog potential
demonstrated on 1.2mm thick membranes.
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TSHWANE UNIVERSITY OF TECHNOLOGY MATERIALS IV 2012 10
cost per metre squares:
The cost of EPDM depends on the installation type. Construction pricing is
starting at around R42.90 per square meter.
typical replacement interval: d u r a t i o n b e t w e e n r e p l a c e m e n t o r h i g h
m a i n t e n a n c e r e p a i r
According to Woolleys' research (2002:103), EPMD is longer lasting than
roofing felt made with blown bitumen. BRE researchers found that EPMD is
one of the most durable polymeric membranes, over greater temperature range
than PVC. According to Jane Andersons' Green Guide to Specification, single
Ply Polymeric membranes can last up to 20 years.
Recycled input [C]: A m o u n t o f e n e r g y p u t i n t o t h e r e c y c l i n g p r o c e s s
When the time comes to replace the EPMD, it is encouraged by ERA (EPMD
Roofing Association) to rather have it recycled. Recycling involves melting
down and reusing the rubber, or cutting it into strips.
Recyclability [A]:M e t a l o r e s , m i n e r a l s a n d a g g r e g a t e s
Woolley explains that (2002:102),EPMD is easily reused when it is loose or
has been mechanically fixed. Recycling is possible by grinding and reusing
the resulting granulate as a filler. This, however, requires a lot of
energy and is a low grade form of recycling.
Recycled currently [B]:
According to an article in Californians Roofing magazine(Evanko,2010:43),
most EPMD membranes are being recycled in the USA, because it is much more
beneficial than disposing it.
Figure 2. recycling of EPMD membranes
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TSHWANE UNIVERSITY OF TECHNOLOGY MATERIALS IV 2012 11
Energy Saved by Recycling [B]: M e t a l o r e s , m i n e r a l s a n d
a g g r e g a t e s
Even though recycling EPMD requires a lot of energy and is a low grade form
of recycling, research done by ERA, a waste management and recycling
company located is the USA, has shown that recycling EPMD is less expensive
than disposing it.
Advantages:
- The rubber is somewhat environmentally friendly with an initially low
energy production.
- Has a long life cycle before it is necessary to replace.
- EPDM can be applied to almost any scale project, and even over anexisting roof or as primary roof.
- EPDM has proven to be hail, wind resistance in excess of 120MPH and great
heat/fire ratings
- Old EPDM roof requiring replacement can often be coated to give the roof
a little more life before you need to redo the whole roof
- Is also available in white
Disadvantages:
- Installation must be done by professionals and can be expensive.
- Recycling is labour intensive
- Is lower in resilience and tensile than natural rubber
- Is not resistant against chemical attack, therefore cot suitable for
applications involving petroleum derivatives.
- EPMD is not recommended as an electrical insulator.
Conclusion:
EPDM is currently the best choice of waterproofing membrane on the market.
It is considered a green material because of its high durability and
reusability. It has a small impact on the environment in relation to other
waterproofing systems such as PVC and Bitumen Felts. Accept for a pitched
roof or natural rubber membrane, EPDM will be your best buy.
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TSHWANE UNIVERSITY OF TECHNOLOGY MATERIALS IV 2012 12
Material:
SummaryRating
ClimateChange
FossilFuelDepletion
OzoneDepletion
HumanToxicitytoAirandWater
WasteDisposal
WaterExtraction
AcidDeposition
Ecotoxicity
Eutrophication
SummerSmog
MineralsExtraction
CostR/m2
TypicalReplacementInte
rval
RecycledInput
Recyclability
RecycledCurrently
EnergySavedbyRecyclin
g
FLAT ROOF: WARM DECK
In situ reinforced concrete slab, vapour
barrier, insulation, asphalt, chippings
C B B A C C A B C C A C
R42.90 25 C A B B
LOW PITCHED ROOFSCoated steel composite roofing system ,
insulation, on steel roof structure
A A A C A A C A A A B A NA 25 C A A B
'TRADITIONAL' PITCHED ROOFS
Polymer/resin bonded slates, battens, sarking
felt on timber roof structure with insulation
between rafters
C C C A C A A C C C B A NA 35 C C C C
Roof Coverings
Low Pitched Roofs
Coated steel composite roofing system, insulation, on steel
roof structure
According to ArcelorMittal (2012), steel roofing is the most adaptable and
effortless to install, roofing option available in South Africa. Due to it
being easier to install, has become the contractors preference.
This versatile material is not only easy to install but is by far the most
cost effective roofing material, as transporting costs are reduced by itsease of transport.
This weather proof product can last for many years if it is properly
maintained and cared for. furthermore the lighter weight of steel sheeting
results in lighter roof construction, opposed to tiles or concrete.
Additionally Steel roofing is available in galvanised sheets, tiles and
coloured sheets.
One of the more "traditional" methods of steelmaking is Basic Oxygen
steelmaking, also known as the oxygen converter process. This process
entails using a (BOS) vessel which holds approximately 280 tonnes of steel,which is then lined with refractories (special bricks) which can tolerate
extreme temperatures.
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TSHWANE UNIVERSITY OF TECHNOLOGY MATERIALS IV 2012 13
Charging then takes place, this is when the furnace is filled with
ingredients in proportions of roughly one fifth steel scrap to molten iron
till it is full.
once the vessel is filled, it is turned up right, while inserting a
component called a lance, this Lance blows 99 percent pure oxygen into the
steel and iron, which increase the temperature to 1700C. Hereby melting
the scrap metal and reducing the carbon content of the molten which aids in
removing unwanted elements.
This is all then followed by a 20 minute blowing cycle, which involves the
feeding of fluxes (burnt lime or dolomite) into the vessel to from slag,
which absorb the impurities of the steel making process.
This id followed by the process of tapping, the vessel is tilted on its
side pouring the steel into a ladle. The steel is further refined by the
addition of alloying materials; with the assistance of argon or nitrogen
gas to ensure mixing; in the ladle furnace. Lastly the steel is removed
followed by the removal of slag which is poured out along with its
impurities.
Another method involving steel making is called Electric Arc Furnace
steelmaking.
Climate Change [A]: G l o b a l w a r m i n g o r g r e e n h o u s e g a s e s
According to the World Resources Institute the iron and steel industrycontribute 3.2 percent of global man made emissions. The iron and steel
industry is large in comparison to all the single industrial sectors and
has one of the largest carbon footprints in this industry. the processes
which involve the mining and transportation of iron ore, the smelting of
that ore into iron in blast furnaces, then turning it into steel mainly
produce the green house gas; carbon dioxide. However, even though the
initial atmospheric impact is high this countered by its ability to be
recycled, see recyclability.
Fossil Fuel Depletion [A]: C o a l , o i l o r g a s c o n s u m p t i o n
The mining process of steel entails burning a large quantity of fuel by
both vehicles, to get the ore out of the ground and into the furnace, and
by the furnace to smelt the ore for further refining. These fossil fuels
are not sustainable in any way, the fuel for the vehicles which is usually
Diesel is either derived from coal, or oil, both non-renewable energy
sources. Furthermore most mines have over head power cables which these
large mining vehicles need to connect to additional power, this uses even
more electricity which to is generated by fossil fuel. Additionally the
furnace then burns fossil fuels to smelt the ore in the refining process,once again further depleting fossil fuels. however the quantity of steel
output for the quantity of energy input is quite good, resulting in a
substantially low quantity of fossil fuel burned per square meter of steel.
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TSHWANE UNIVERSITY OF TECHNOLOGY MATERIALS IV 2012 14
Ozone Depletion [C]: G a s e s t h a t d e s t r o y t h e o z o n e l a y e r
As stated under Fossil Fuel depletion, the mining process of steel entails
burning a large quantity of fuel by both vehicles, to get the ore out of
the ground and into the furnace, and by the furnace to smelt the ore for
further refining. These two process both cause the emission of harmful
gases into the atmosphere with is detrimental to the Ozone layer, as it can
take between 20 to 120 years for these gases to deplete to a point where
they no longer damage the ozone layer.
Human Toxicity to Air and Water [A]: P o l l u t a n t s w h i c h a r e t o x i c
t o h u m a n s
Although many chemicals are used in the production of steel one in
particular has been recognized as being harmful to humans. Hexavalent
chromium is a genotoxiccarcinogens compound which increases the risk oflung cancer due to chronic inhalation.
Waste Disposal [A]: M a t e r i a l s e n t t o l a n d f i l l o r
i n c i n e r a t i o n
"The world steel industry produces about 780 Mt of crude steel and
simultaneously approximately 300 Mt of solid wastes products are also
produced. Thus an average of about 400 Kg of solid by products is generated
in the steel industry per tonne of crude steel. Major share of this (70-80%) consists of Blast Furnace Slag and basic Oxygen Furnace Slag. These
wastes are an ecological hazard" (Department of Science and Technology,
GOVT, of India, 2003)
Even though there is such a high waste quantity from the production of
crude steel, this is not perceived as a bad thing, solely due to the fact
that these by products of the production process can be used to create
other products, resulting in a 100% material utilization.
Water Extraction [C]: M a i n s , s u r f a c e a n d g r o u n d w a t e r
c o n s u m p t i o n / p o l l u t i o n
The manufacturing processed of crude iron uses water in the early stages of
the production line, where the coke that has been burned needs to be cooled
by water. This quenching of the coke contaminates the water with coke
breezes and other components. However these contaminants can usually be
removed by filtration, thereafter either being used in other manufacturing
processes or it can be released. Regardless of the ability to purify the
water, this process still requires large volumes of water.
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TSHWANE UNIVERSITY OF TECHNOLOGY MATERIALS IV 2012 15
Acid Deposition [A]: G a s e s t h a t c a u s e a c i d r a i n , e t c .
Acid rain is caused by two main sources, namely sulphur dioxide (SO2) and
oxides of nitrogen (NOx). A by-product of combusted fossil fuels containing
sulphur is sulphur dioxide. The smelting of metal sulphate ore, in iron and
steel production, which produces pure metal; cause the release of sulphur
dioxide.
Eco-toxicity [A]: P o l l u t a n t s w h i c h a r e t o x i c t o t h e
e c o s y s t e m
As stated under, Water Extraction, the main pollutant involved in the
production of steel is the contamination that takes place in the water used
to cool the coke. BREEAM identifies that the water is purified to remove
these pollutants resulting in water which can be released without the
degradation of natural elements.
Eutrophication [A]: W a t e r p o l l u t a n t s t h a t p r o m o t e a l g a l
b l o o m s , e t c .
The effect that steel production has on eutrophication is relatively
minimal, due to the fact that the chemicals which would have an effect,
such as phosphate, is part of the slag which is collected for use in the
cement industry, or even in fertilizer. There is however a possibility
that water run-off from farms using this fertilizer can have a minor effecton eutrophication.
Summer Smog [B]: A i r p o l l u t a n t s t h a t c a u s e r e s p i r a t o r y
p r o b l e m s
During the mining process of the iron ore large volumes of dust is
deposited into the air, especially during the explosions used to break
apart dense rock formations. These dust clouds combined with the fumes of
all the running vehicles do create summer smog. Additionally the
manufacturing process where the ore is smelted by fossil fuel, further adds
fume output into the environment, even though it is released in a
controlled manner after having been purified to a degree, this does add to
the overall summer smog effect.
Minerals Extraction [A]:M e t a l o r e s , m i n e r a l s a n d
a g g r e g a t e s
Iron ore, which is used to manufacture steel, is the earth's fourth most
abundant rock forming element, forming as much as 5% of the earth's crust,as stated by USGS, (2012) This reduces its sustainability impact as it is
so abundant, respective of its quantity, iron ore isn't always found in
solid rock formation. Due to iron's rusting properties, layers flake off
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TSHWANE UNIVERSITY OF TECHNOLOGY MATERIALS IV 2012 16
and disperse, even still these rusted particles can be collected and used
in the production of steel.
Recyclability [A]:M e t a l o r e s , m i n e r a l s a n d a g g r e g a t e s
Steel is a very easy material to recycle as it can easily be melted into a
new product of almost any type. This ability gives it a good rating as the
life cycle of steel is essentially infinite as it doesn't degrade to a
point where it can no longer be recycled
Energy Saved by Recycling [B]: M e t a l o r e s , m i n e r a l s a n d
a g g r e g a t e s
As stated above steel is an easy material to recycle, however, the
recycling process does require that the material is re-melted in a furnace
again. This re-melting requires fossil fuel once again, and results in the
emission of pollutants, even though it does all of this, energy is saved as
the metal does not need to be mined and refined again, it merely needs to
be melted and processed into a new product.
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TSHWANE UNIVERSITY OF TECHNOLOGY MATERIALS IV 2012 17
Material:
SummaryRating
ClimateChange
FossilFuelDepletion
OzoneDepletion
HumanToxicitytoAirandWater
WasteDisposal
WaterExtraction
AcidDeposition
Ecotoxicity
Eutrophication
SummerSmog
MineralsExtraction
CostR/m2
TypicalReplacementInte
rval
RecycledInput
Recyclability
RecycledCurrently
EnergySavedbyRecyclin
g
FLAT ROOF: WARM DECK
In situ reinforced concrete slab, vapour
barrier, insulation, asphalt, chippings
C B B A C C A B C C A C
R42.90 25 C A B B
LOW PITCHED ROOFSCoated steel composite roofing system ,
insulation, on steel roof structure
A A A C A A C A A A B A NA 25 C A A B
'TRADITIONAL' PITCHED ROOFS
Polymer/resin bonded slates, battens, sarking
felt on timber roof structure with insulation
between rafters
C C C A C A A C C C B A NA 35 C C C C
Roof Coverings
'Traditional' Pitched Roofs
Polymer/resin bonded slates, battens, sarking felt on
timber roof structure with insulation between rafters
Polymer or resin bonded slate roofing is typically found on roofs in the
United Kingdom. 90% of Europes slate originates from slate quarries in
Spain. Other, significant slate industries are located in Wales, Great
Britain, North America and Brazil.
The process of quarrying slate is an evasive procedure, opening huge spans
of ground to be used as quarry pits. This means that trees which had
occupied the area need to be felled. When slate was quarried in the past
in small surface quarries it was done by hand using hammers and chisels.
The finishing process of slate used in roofing required heavy machinery
called punchers and trimmers and today high speed diamond-plated saw blades
and laser levels have meant precise cuts and reduced waste. The puncher was
a machine that would take the finished piece of slate and punch one or two
holes in the top edge so that it could be fastened to a roof. The trimmer
was a machine that takes a piece of slate and lobs the uneven edges off so
that it makes a perfectly square or rectangular piece of roofing slate.
Both of these machines were used in manufacturing roofing slate. Other
machines that were developed include the sawing machine and the planer. The
sawing machine is the first machine that the slate gets to after it is
quarried out of the pit. This machine chunks the large piece of slate into
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smaller pieces, easily able to be handled. The slate planer is a machine
that is used right after the sawing machine. This machine automatically
trims the edges of the irregular block of slate and makes the surface
smooth. After the plaining machine, the slate is then placed on a large
iron disk, on which it is ground smooth.
Although technology has improved the sawing of slate, in quarry processing,
explosives are used in the initial stages. This is in order to break apart
the stone. There are fewer employees as compared to quarries of the past.
This is because technology has been able to expedite practices such as
transporting slate from the quarry to the processing building. Slate
quarries have damaged and degraded vast plains of landscape.
The impact of the quarrying stage of slate has an adverse effected the
environment. Exhaust from machinery is produced and let into the air; air
pollution from machinery, water pollution due to use for cooling purposes
and the juxtaposition of waterways next to quarries, and the degradation of
the surrounding landscape by felling trees and digging up the ground all
can be attributed to the quarrying processes. Waste is another
environmental problem.
Climate Change [C]: G l o b a l w a r m i n g o r g r e e n h o u s e g a s e s
Fewer chemicals are used in the mining process of slate, roughly 90% to 95%
of the materials removed from the slate quarry pits are considered slag, or
waste. The slag from slate is not quite as harmful as the slag from copper
or calcium (marble composite) waste.
Exhaust from machinery is produced and the explosives used in the initial
quarrying of stone are released into the air, exhaust fumes, predominantly
carbon dioxide and carbon monoxide are considered greenhouse gases and
thus the process of slate quarrying is not ecologically and environmentally
green in terms of the uncontrolled and unrestricted release of these
gases into the atmosphere and because slate is found in many locations
around the world and in vast quantities, the magnitude of the slate mining
industry and the greenhouse gases released in terms of this factor are a
small indication of the industrial scale of the consequences.
Fossil Fuel Depletion [C]: C o a l , o i l o r g a s c o n s u m p t i o n
Technology has been able to expedite practices such as transporting slate
from the quarry to the processing building since the period of hand
quarrying, which occupied less land then open, machined quarries. The
puncher is a machine that would take the finished piece of slate and punch
one or two holes in the top edge so that it could be fastened to a roof.
The trimmer is a machine that takes a piece of slate and lobs the uneven
edges off so that it makes a perfectly square or rectangular piece of
roofing slate. Both of these machines were used in manufacturing roofing
slate.
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The heavy machinery used in the quarrying of slate from quarry pits
and the various conveyor belt and water pump facilities available
on quarry sites consume vast amounts of fossil fuels to operate and
this greatly impacts the depletion of fossil fuels globally as an
industry.
Ozone Depletion [A]: G a s e s t h a t d e s t r o y t h e o z o n e l a y e r
The use of explosives is still common practice in the initial quarrying
process to aid in the breaking apart of the stone. These explosives lead
to dust clouds and the subsequent release of gases that are fired in the
process. Exhaust from machinery is produced at an expedited rate and let
into the air in an uncontrolled fashion.
Human Toxicity to Air and Water [C]: P o l l u t a n t s w h i c h a r e t o x i c
t o h u m a n s
Many effects happen when quarries operate for a certain period of time and
then after that they close. One of the most formidable problems is that the
quarry pit fills up with water, creating an artificial pond in its place.
This can be a problem due to the various amounts of pollutants that have
been used in the extraction process of the slate in these mines and are now
allowed to be washed away and are diluted into a artificial water source.
This water source may along the line contaminate water sources utilized in
human-use.
Waste Disposal [A]: M a t e r i a l s e n t t o l a n d f i l l o r
i n c i n e r a t i o n
Although fewer chemicals are used in the mining process, roughly 90% to 95%
of the materials removed from the slate quarry pits are considered slag, or
waste. Where there are old abandoned mines, the waste is often left which
alters the landscape. The slag from slate is not quite as harmful as the
slag from copper or calcium carbonate (marble composite) waste, which isalso exported.
Water Extraction [A]: M a i n s , s u r f a c e a n d g r o u n d w a t e r
c o n s u m p t i o n / p o l l u t i o n
An ideal slate quarry has little glacial material, river deposits, or
disintegrated slate. A supply of water is also a must in order for the
quarry to run efficiently, as it prevents the slate from becoming brittle.
Brittle slate is prone to over-breakage and a waste of usable or viable
slate. This steady supply of water is an initial stage of water pollution,
the water pollution is due to water used for cooling purposes and the
juxtaposition of waterways next to quarries.
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TSHWANE UNIVERSITY OF TECHNOLOGY MATERIALS IV 2012 20
Acid Deposition [C]: G a s e s t h a t c a u s e a c i d r a i n , e t c .
Air pollutants present in the mining of slate are caused mainly by the
extraction processes, controlled explosions, and the exhaust fumes. The
extent of the industry and size that quarries are capable of reaching
before they are eventually abandoned and the amount of the released gases
before that could happen means the likelihood of SO2 being released and
over time causing acid-rain is much greater.
Eco-toxicity [C]: P o l l u t a n t s w h i c h a r e t o x i c t o t h e
e c o s y s t e m
Stagnant water which pools in closed quarry pits is mixed with the slate
slag which was left; slag is culpable of water contamination. These
reservoirs can then potentially mix into established water sources and the
micro-ecosystems which inhabit those water sources suffer from pollutantexposure and contamination.
Eutrophication [c]: W a t e r p o l l u t a n t s t h a t p r o m o t e a l g a l
b l o o m s , e t c .
One of the most formidable problems with slate quarrying is that the quarry
pit fills up with water once the quarry closes down, creating an artificial
pond in its place. Various amounts of pollutants have been used in the
extraction process of the slate in these mines are now allowed to be washedaway and are diluted into a artificial water source. This water source may
along the line contaminate succeeding water sources and water sources which
are a necessity for living organisms and ecosystems. These micro-ecosystems
are altered and damaged by the contaminants.
Summer Smog [B]: A i r p o l l u t a n t s t h a t c a u s e r e s p i r a t o r y
p r o b l e m s
The initial stages of slate quarrying includes the use of explosives to
break apart dense rock formations, these explosions cause massive dust
clouds and the release of exhaust fumes in the running of the slate quarry
machinery, transport and pump plants, these dust clouds and exhaust fumes
however do not contain much VOCs and the impact of them in the formation of
summer smog is of a low-medium environmental impact.
Minerals Extraction [A]:M e t a l o r e s , m i n e r a l s a n d
a g g r e g a t e s
The process of slate quarries and mining of slate in general has littleimpact of the mineral resources extracted globally. The definition of slate
is as follows A fine-grained, foliated metamorphic rock that develops from
shale breaks into flat sheets (Chernicoff& Whitney, 2002). Shale is
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TSHWANE UNIVERSITY OF TECHNOLOGY MATERIALS IV 2012 21
sedimentary rock composed of detrital sediment particles which is less
than 0.004mm in diameter. The formation of slate comes about when the
shale, which is below ground, becomes compressed and heated to great
temperatures and pressures that change the rock from weakly bonded shale to
a very strong slate. Because of the formation of slate from clay and
relatively small amounts of other minerals and metals present in the stone
when it form in large quantities, the slate can be removed without
extracting precious metal ores and minerals from the ground. Iron ore may
be present in the slate, which would give the slate a reddish colour, but
because of the rareness of this phenomenon, the impact of, specifically,
the slate mining industry in the extraction of iron ore is minimal.
Figure 4. Manufacturing Process: Quarrying. Figure 5. Manufacturing Process: Transport.
Figure 3. Slate mining quarry in Vermont.
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Figure 6. Manufacturing Process: Factory Figure 7. Manufacturing Process: Sawing.
Figure 8. Open pit slate mining staged explosion.
Figure 9. Water collection in open slate mining pit.
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Conclusion:
As seen in rating these 3 materials/systems it becomes evident just how
much is considered by BREEAM when they give a material/system a 'rating'
this is a superior method of rating buildings/structures as it doesn't just
focus on the green principles of the building. BREEAM defines the greenvalue of a building through the consideration of every material/system
applied to the structure, giving it closer depiction of a true green value
of a building/structure.
Ultimately one green rating system would be the ideal solution. However
this can only be achieved by the collaboration of vast information, giving
each material a rating based on all the different geological locations.
Making this an immense task. Even then the user friendliness of such a
system would be a challenge as the quantity of data that would need to be
selected by users (designers, etc...) would be complicated or quite aprocess due to the vast quantity of choices that would be available.
Therefore, BREEAM is a very good starting point in the aim towards a
powerful green rating system.
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Bibliography:
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TSHWANE UNIVERSITY OF TECHNOLOGY MATERIALS IV 2012 25
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Table 001.
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Table 002.
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List of Figures:
Figure 1:
EPDMROOFS. (2010),distribution of summer smog potential demonstrated on 1.2mm thick
membranes.[ONLINE]. Available at:
http://bau-umwelt.de/download/CY24b0f8f9X1345afc005dX4d8/EPD_ALW_2010211_E.pdf
Figure 2:
EPDMROOFS. (2010),recycling of EPMD membranes.[ONLINE]. Available at:
http://www.epdmroofs.org/press/pressdocs/Carolinas-roofing-article.pdf
Figure 3.
UNKNOWN. (2006), Slate Mining[ONLINE]. Available at:
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ng.jpg [Accessed 29 May 2012].
Figure 4.
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[Accessed 29 May 2012].
Figure 5.
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[Accessed 29 May 2012].
Figure 6.
UNKNOWN. (2011), Factory[ONLINE]. Available at:
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[Accessed 29 May 2012].
Figure 7.
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Figure 8.
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C8DEM/0.jpg [Accessed 29 May 2012].
Figure 9.
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http://upload.wikimedia.org/wikipedia/commons/thumb/a/a9/Delabole_slate_quarry.jpg/450px-
Delabole_slate_quarry.jpg [Accessed 28 May 2012].