low embodied energy materials in sustainable design by lazar petrov

8/2/2019 Low Embodied Energy Materials in Sustainable Design by Lazar Petrov

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Low embodied energy materials in

sustainable design

Bachelor of Architectural Technology and Construction

Management

7th Semester dissertation

Written by: Lazar Petrov Petrov (123953)

Via University College

28th of November 2011


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Title Page:

TITLE of ElectiveSubject report. Trip to China October 2010

AUTHOR(S)

Study number(s)

Lazar Petrov Petrov(123953)

CONSULTANT Jesper Saxgren

DATEHANDED-IN

28.11.2011

Number of

COPIES

2

Number ofPAGES

24

SIGNATURE(S) of AUTHOR(S)

.

All rights reserved Font Verdana, size 12

No part of this publication may be reproduced without the prior permission of the

author(s).

NOTE: This dissertation was compiled as part of the 7th Semester Architectural

Technology and Construction Management degree course.

No responsibility is taken for any advice, instruction or conclusion given

within.


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Acknowledgements

I would like to thank Jesper Saxgren for his guidance during theprocess of writing and the advices he gave me.


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Abstract

This dissertations topic is Low embodied energy materials insustainable design. The goal of the dissertation is to give an overall idea

of what low embodied energy is and define several low embodied energy

materials. As the resources of raw energy and building materials are

running low, we have to find new solutions to the problem. The reduction

of the building industrys energy consumption is of great importance and

low embodied energy is the key to a great success in solving that issue.

The dissertation describes methods of estimating low embodied energy,

such as Life Cycle Assessment (LCA). It also provides information on the

usage of low embodied energy materials and life cycle assessments ashelpful tools in decreasing the negative impact on local and global eco

systems, by lowering the emissions of CO2. The dissertation also includes

a comparison between building materials with low embodied energy, as a

result of which the material with the lowest embodied energy is timber. It

also reflects on the great significance in the differentiation between

renewable and nonrenewable resources and their importance to the

environment.

Key words: embodied energy, embodied energy materials, energyconsumption, life cycle assessment, nonrenewable resources, raw

materials


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Contents:

1. Introduction ................................................................................. 1

1.1 Background information ...................................................................... 11.2 Relevance for the chosen topic ............................................................ 1

1.3 Problem statement and research questions: .......................................... 2

1.4 Delimitation ...................................................................................... 2

1.5 Methodology ...................................................................................... 2

2. The global problem of vanishing raw materials .................................. 3

3.What is low embodied energy? ........................................................ 4

4.How do we calculate the embodied energy of a certain material? ......... 7

5.How would it help to lower the energy consumption in the building

industry? ......................................................................................... 8

6.How can we use a Life-cycle assessment as a tool to define low

embodied energy materials? ............................................................ 13

7.What can we define as low embodied energy materials? ................... 18

7.1 Low embodied energy materials ......................................................... 18

7.2Stones in comparison with other low embodied energy materials ............ 19

8.Conclusion .................................................................................. 27

List of figures

List of references
http://c/Users/Lazo/Desktop/DISSERTATION/LOW%20EMBODIED%20ENERGY%20IN%20SUSTAINABLE%20DESIGN.docx%23_Toc309893881http://c/Users/Lazo/Desktop/DISSERTATION/LOW%20EMBODIED%20ENERGY%20IN%20SUSTAINABLE%20DESIGN.docx%23_Toc309893882http://c/Users/Lazo/Desktop/DISSERTATION/LOW%20EMBODIED%20ENERGY%20IN%20SUSTAINABLE%20DESIGN.docx%23_Toc309893883http://c/Users/Lazo/Desktop/DISSERTATION/LOW%20EMBODIED%20ENERGY%20IN%20SUSTAINABLE%20DESIGN.docx%23_Toc309893884http://c/Users/Lazo/Desktop/DISSERTATION/LOW%20EMBODIED%20ENERGY%20IN%20SUSTAINABLE%20DESIGN.docx%23_Toc309893885http://c/Users/Lazo/Desktop/DISSERTATION/LOW%20EMBODIED%20ENERGY%20IN%20SUSTAINABLE%20DESIGN.docx%23_Toc309893886http://c/Users/Lazo/Desktop/DISSERTATION/LOW%20EMBODIED%20ENERGY%20IN%20SUSTAINABLE%20DESIGN.docx%23_Toc309893887http://c/Users/Lazo/Desktop/DISSERTATION/LOW%20EMBODIED%20ENERGY%20IN%20SUSTAINABLE%20DESIGN.docx%23_Toc309893888http://c/Users/Lazo/Desktop/DISSERTATION/LOW%20EMBODIED%20ENERGY%20IN%20SUSTAINABLE%20DESIGN.docx%23_Toc309893889http://c/Users/Lazo/Desktop/DISSERTATION/LOW%20EMBODIED%20ENERGY%20IN%20SUSTAINABLE%20DESIGN.docx%23_Toc309893890http://c/Users/Lazo/Desktop/DISSERTATION/LOW%20EMBODIED%20ENERGY%20IN%20SUSTAINABLE%20DESIGN.docx%23_Toc309893890http://c/Users/Lazo/Desktop/DISSERTATION/LOW%20EMBODIED%20ENERGY%20IN%20SUSTAINABLE%20DESIGN.docx%23_Toc309893891http://c/Users/Lazo/Desktop/DISSERTATION/LOW%20EMBODIED%20ENERGY%20IN%20SUSTAINABLE%20DESIGN.docx%23_Toc309893891http://c/Users/Lazo/Desktop/DISSERTATION/LOW%20EMBODIED%20ENERGY%20IN%20SUSTAINABLE%20DESIGN.docx%23_Toc309893893http://c/Users/Lazo/Desktop/DISSERTATION/LOW%20EMBODIED%20ENERGY%20IN%20SUSTAINABLE%20DESIGN.docx%23_Toc309893894http://c/Users/Lazo/Desktop/DISSERTATION/LOW%20EMBODIED%20ENERGY%20IN%20SUSTAINABLE%20DESIGN.docx%23_Toc309893895http://c/Users/Lazo/Desktop/DISSERTATION/LOW%20EMBODIED%20ENERGY%20IN%20SUSTAINABLE%20DESIGN.docx%23_Toc309893896http://c/Users/Lazo/Desktop/DISSERTATION/LOW%20EMBODIED%20ENERGY%20IN%20SUSTAINABLE%20DESIGN.docx%23_Toc309893896http://c/Users/Lazo/Desktop/DISSERTATION/LOW%20EMBODIED%20ENERGY%20IN%20SUSTAINABLE%20DESIGN.docx%23_Toc309893895http://c/Users/Lazo/Desktop/DISSERTATION/LOW%20EMBODIED%20ENERGY%20IN%20SUSTAINABLE%20DESIGN.docx%23_Toc309893894http://c/Users/Lazo/Desktop/DISSERTATION/LOW%20EMBODIED%20ENERGY%20IN%20SUSTAINABLE%20DESIGN.docx%23_Toc309893893http://c/Users/Lazo/Desktop/DISSERTATION/LOW%20EMBODIED%20ENERGY%20IN%20SUSTAINABLE%20DESIGN.docx%23_Toc309893891http://c/Users/Lazo/Desktop/DISSERTATION/LOW%20EMBODIED%20ENERGY%20IN%20SUSTAINABLE%20DESIGN.docx%23_Toc309893891http://c/Users/Lazo/Desktop/DISSERTATION/LOW%20EMBODIED%20ENERGY%20IN%20SUSTAINABLE%20DESIGN.docx%23_Toc309893890http://c/Users/Lazo/Desktop/DISSERTATION/LOW%20EMBODIED%20ENERGY%20IN%20SUSTAINABLE%20DESIGN.docx%23_Toc309893890http://c/Users/Lazo/Desktop/DISSERTATION/LOW%20EMBODIED%20ENERGY%20IN%20SUSTAINABLE%20DESIGN.docx%23_Toc309893889http://c/Users/Lazo/Desktop/DISSERTATION/LOW%20EMBODIED%20ENERGY%20IN%20SUSTAINABLE%20DESIGN.docx%23_Toc309893888http://c/Users/Lazo/Desktop/DISSERTATION/LOW%20EMBODIED%20ENERGY%20IN%20SUSTAINABLE%20DESIGN.docx%23_Toc309893887http://c/Users/Lazo/Desktop/DISSERTATION/LOW%20EMBODIED%20ENERGY%20IN%20SUSTAINABLE%20DESIGN.docx%23_Toc309893886http://c/Users/Lazo/Desktop/DISSERTATION/LOW%20EMBODIED%20ENERGY%20IN%20SUSTAINABLE%20DESIGN.docx%23_Toc309893885http://c/Users/Lazo/Desktop/DISSERTATION/LOW%20EMBODIED%20ENERGY%20IN%20SUSTAINABLE%20DESIGN.docx%23_Toc309893884http://c/Users/Lazo/Desktop/DISSERTATION/LOW%20EMBODIED%20ENERGY%20IN%20SUSTAINABLE%20DESIGN.docx%23_Toc309893883http://c/Users/Lazo/Desktop/DISSERTATION/LOW%20EMBODIED%20ENERGY%20IN%20SUSTAINABLE%20DESIGN.docx%23_Toc309893882http://c/Users/Lazo/Desktop/DISSERTATION/LOW%20EMBODIED%20ENERGY%20IN%20SUSTAINABLE%20DESIGN.docx%23_Toc309893881


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List of figures:

Figure 1. Initial embodied energy into an office building.................................. 6

Figure 2. Embodied energy statistics of concrete ............................................ 7

Figure 3. The global usage of energy resources .............................................. 8

Figure 4. Illustrating positioning of recycling factories ..................................... 9

Figure 5. Illustrating the usage of non-renewable energy resources for

transportation of raw materials in Norway................................................... 11

Figure 6. Showing the main flow of the LCA. ................................................ 14

Figure 7. Illustrating the flow of materials to produce a concrete element........ 15

Figure 8. Illustrating examples of the usage of stone in buildings in the past and

an example of the life span of limestone constructions. ................................. 20Figure 9. Embodied energy comparison....................................................... 23

Figure 10. Weight of materials per cubic meter............................................ 24

Figure 11. Plan of a small building used as an example for wall construction

comparison.............................................................................................. 27

Figure 12. Showing the results of mindless cutting of forests and replanting of

forests .................................................................................................... 26


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Low embodied energy materials in sustainable design

VIA University College, Horsens, Denmark, November 2011 1

1. Introduction

1.1 Background information

This dissertation was written as a part of the final semester of the

education as Bachelor of Architectural Technology and Construction

Management.

The dissertation briefly explains about low embodied energy and its

usage in sustainable design. It provides information on materials with low

embodied energy and it presents methods of defining them. The

dissertation gives an overview of how low embodied energy can help in

the decrease of the building industrys energy consumption.

In addition the dissertation gives information on the main idea of an

Life cycle assessment and how it could be used as a tool to define low

embodied energy and low embodied energy materials. It also includes a

comparison between different low embodied energy materials and their

impact on the environment.

1.2 Relevance for the chosen topic

In the modern world, architecture has a greater focus on preserving

the environment and its resources. Knowing that most of the non-

renewable energy sources are running out makes us think of new

solutions and ways to lower the energy and raw material consumptions.

The most common thing that architects and engineers are trying to

improve is the energy consumption of the building after it is built. The

energy consumed in the process of building a house takes huge amounts

of recourses therefore through a Life Cycle Assessment we can find a

solution to our problem and the most suitable materials for a certain

building.

Preserving the environment could be done in many ways and in my

belief low embodied energy materials are a great solution to the global

problem. The amounts of energy used to produce new materials, to

transport them and put them on the site, could rapidly be reduced. A

reduction of CO2 ignitions could be reached as well.


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Through an online research and thorough investigation of the

problem I hope to give the reader a good overview of the usage of low

embodied energy materials and its future. The research would be a great

help for me in my future career as a constructing architect.

1.3 Problem statement and research questions:

What is the impact of the building industry on the environment?

How can low embodied energy help solving the building industrys issues

in concern of energy consumption and the extinction of raw and

nonrenewable building and energy resources?

Research questions:

1. What is embodied energy?2. What would help to lower the energy consumption in the building

industry?

3. How can we use a Life-cycle assessment as a tool to define lowembodied energy materials?

4. What can we define as low embodied energy materials?5. What makes low embodied energy materials better than regular

materials?

1.4 Delimitation

This dissertation provides information on low embodied energy and

methods of estimating and assessing low embodied energy materials in

the building industry. It doesnt provide exact formulas on the calculation

of embodied energy and it couldnt be used as a basis of such calculations.

1.5 Methodology

Both empirical quantitative and qualitative research methodologies

were used to analyze facts and data on low embodied energy. All the data

in the report is secondary, provided by books and articles, or information

found on the internet. Some of the information found in the dissertation is

based on my own personal logical explanation.


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2. The global problem of vanishing raw materials

Nowadays investigations show very pessimistic results. Scientists

state that the earths resources on certain building materials and raw

materials are running low. One of the most important and world-moving

energy resources is oil. It is well known that the resources of oil are

running low and we should be very careful in how we as responsible

human beings use the vanishing material.

Many people think that oil is not a big part of the building sector. On

the contrary ,scientists have proven that huge amounts of oil has been

used in the construction sphere for different purposes, for example

producing prefabricated elements or using heavy machinery,

transportation, erection on site and etc. Therefore, in order to preserve

the raw material resources not only of oil but other building materials as

well, we have to think of new and more durable solutions to the given

problem.

One way of decreasing the consumption of raw materials is by

thorough planning of the building process on site. A research in

Scandinavia proves that 10 percent of the total waste in the building

industry is actually produced on site. Therefore, by planning the process

of the building we can make sure that all the products come in the rightcut and will fit fast and easy to the building without the need to use extra

machinery or materials, which will prevent the waste of building materials

and oil.

Another way of decreasing the raw material consumption is by

prolonging the lifespan of the materials used. Of course a product that will

last 60 years will harm the environment twice as less if we compare it to a

product that will last only 30 years. Why? Simply because, the product

with a longer lifespan will need only maintenance in a period of 60 years,where on the other hand the less lasting product will have to be renewed

which leads to the usage of new raw materials and energy resources, or

energy used to recycle or renew the existing ones. However the life span

of a material can be defined from different factors:

1. The physical and chemical structure of the material itself2. Construction and execution3. The local environment and climatic conditions4. Maintenance and management of the building material


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The best way of finding the life span of a material is through a research of

the material in a real life situation with specific local climate properties,

which takes a lot of time meaning that we are investigating or looking for

a material with a long life span.

A third solution to the problem would be recycling the already

created materials. A great improvement in harming the environment can

be reached by recycling material rather than creating new once. The

pollution levels are drastically lowered by prolonging the life span of an

existing material. Therefore, such recyclable products have a big

advantage when we get to compare them to the green labeled products

that dont allow recycling. The recycling possibilities depend on the

company executing the demolition process of a building. A research shows

that the smaller complicity levels that the material has the easier it is to

recycle it. Recycling can however be separated in three different spheres:

1. Re-use2. Recycling3. Energy recovery

In order to make the materials suitable for re-use they have to be

simplified or standardized. For example Germany has a rich market on

variable materials reaching up to 300 000 products, both different in

design and composition, which would not be compatible if reused.

All the above stated factors would be vital in defining whether a

material has low embodied energy or not.

3.What is low embodied energy?

Embodied energy is hard to be defined by simply one sentence. The

formula of how to calculate it could vary as well. However The Universityof Bath and in particular Sustainable Energy Research Team (SERT) has

done a research where they calculate the Embodied Energy and Embodied

Carbon of specific construction materials. While doing a research on low

embodied energy, one should not consider only the energy used but also

the amounts of CO2 released. It is extremely important to consider the

Carbon emissions, because they are a great factor that harms the

environment.

They define the term Embodied Energy as:


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The total primary energy consumed during the life time of a product,

ideally the boundaries would be set from the extraction of raw materials

(inc fuels) to the end of the products lifetime (including energy from;

manufacturing, transport, energy to manufacture capital equipment,

heating & lighting of factory...etc), this boundary condition is known asCradle to Grave. It has become common practice to specify the

embodied energy as Cradle to Gate, which includes all energy (in

primary form) until the product leaves the factory gate. The final

boundary condition is Cradle to Site, which includes all energy consumed

until the product has reached the point of use (i.e. building site).

www.bath.ac.uk/mech-eng/sert/embodied/ October 2011

Embodied energy has been researched for decades and its main goal

is to define the connection between construction materials, the process ofbuilding and after coming impact on the environment. The embodied

energy itself can be separated in two different categories:

1. Initial embodied energy2. Recurring embodied energy

Where the Initial embodiedenergy represents the energy used in

extracting raw materials, their manufacturing and their processing. On the

other hand a big part of the initial embodied energy is consumed due to

transportation to site and constructing the building. Therefore, the Initial

embodied energy could be divided in two sub chapters, which would be

Direct and Indirect energy. The direct energy is used for transportation

and etc. and the indirect energy is used to acquire, process and

manufacture the building materials. Where the indirect energy includes

the one used for transportation related to the listed activities. The

Recurring embodied energy is actually the energy used during the life

cycle of the building, used to maintain repair and restore or replace

materials. A building becomes more energy-efficient, when the embodiedenergy of the building is decreasing due to the long lifespan. There are

buildings that claim to be zero energy but still havent considered the

energy used on the construction process itself and the maintenance after

words. That is a very common mistake in the building industry to define a

building with and energy class zero or passive when the amounts of

energy used for the production is of great significance. Architects have

thought for decades that since the building is designed so that the tenants

would use small or no amounts of energy to heat, light or ventilate the

building, it could be defined as a zero energy building.


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The main construction structures for housing and office buildings

would be designed from wood, steel or concrete. A research done by

Raymond J. Cole and Paul C. Kernan compares three different

constructions in one and the same building made exactly of the above

stated materials forming the envelope, structure and services of thebuilding. The results show that the biggest part of the buildings initial

(non-renewable) embodied energy is taken from the main structure of the

building and it takes up to 74% of the total initial embodied energy, which

has an average 4.82 GJ/m2. The finishes of the construction represent

only 13% percent of the Total Initial embodied energy and are considered

to have the highest increase in recovering embodied energy. An

interesting relationship is revealed by the research of recurring embodied

energy. Firstly the structures of the building does not recur embodied

energy, but after 25 years the building recurs 57 per cent of the initialembodied energy and by the 100thyear of the buildings existence the

recurred embodied energy reaches up to 325 per cent, which comes to

prove that the life span of a building plays a significant role in defining the

energy efficiency of a building. The longer the building lives, the more

valuable is the initial (non-renewable) embodied energy. This relationship

could also be defined as differential durability. Differential durability is a

term used to describe how the useful service life of building components,

such as structure, envelope, finishes and services, differs - both between

components, and within the materials, assemblies and systems comprisingthe components.

10th Canadian Conference on Building Science and Technology Ottawa,

May 2005

This chart shows only the results

from Cradle to site without including

the maintanence and renovation of

the building in the future, which is a

big part of the embodied energy of a

building knowing that nowadays

constructions have a very long life

span. The longer the building lives,

the lower the embodied energy of

the buidling is.

Figure1 Initial embodied energy into an officebuilding


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4.How do we calculate the embodied energy of a certainmaterial?

The university of Bath in the United Kingdom has done a research

on the most common and vital materials for a building. The only problem

is that they have done the calcucalations only from cradle to gate, which

means that if we want to have a complete embodied energy analysis of a

material we have to finish the rest on our own. Of course the calculation is

not done further, because in different cases different methods of

constructing will be used and the amounts of embodied energy will be

different. If we want to finish the calculation we have to have in mind the

total amount of embodied energy used from the Gate to the Site and

afterwords from the Site to the Grave.

The method that has been used to deffine the embodied energy of

the materials is as follows; the energy used for producing a kilogram of a

certain material is calculated in MJ/kg ,the CO2 emisions are calculated

and measured in tCO2(tones of carbon dioxide per kg of product),

afterwards the tCO2 has to be converted to MJ (1 kgCO2 = 10.204 MJ). It

is not very usefull if we convert the MJ to CO2 simply because different

types of energy sources produce different amouts of emisions.

For example the calculation of the embodied energy of concrete as amaterial can be a very complex process with a lot of variables and no

certain value of Embodied Energy per kilo can be defined. There are too

many various types of concrete and some of them are being analyzed in

the following chart.

Figure 2. Embodied energy statistics of Concrete; Inventory of carbon andenergy version 2.0 2011

In this table (Table. 1) the authors have described the average of

124 records of concrete analysis which gives us a total number of 2.92

MJ/kg., however the difference between the minimum and the maximum

values is devastating - going from 0.07 MJ/kg up to 92.50 MJ/kg. This isonly to prove that there are forms of the certain material that are a great


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harm of the environment and in my personal opinion would not be

considered sustainable. As the table shows there is a significant diference

between pre-casted and in situ-casted concrete. The maximum

EE(Embodied Energy) of precasted concred reaches 3.80 MJ/kg when the

concrete in general can reach up to 92.5 MJ/kg. That comes only to provethat the usage of prefabricated concrete elements for the construction of a

building would be a much more sustainable solution in terms of embodied

energy and carbon emissions than in situ-casted concrete. But when it

comes to a more detailed investigation or a comparison between a Precast

RC 40/50 MPa with general concrete with strength of 40/50Mpa. The

results show that the EE of the pre-casted concrete is bigger than the

regular concrete and that would be normal knowing that it consumes more

energy to be produced. However if the precast and general concrete are

delivered to the one and the same site and from one and the samefactory, than it would be most logical to use prefabricated concrete

elements in order to lower the EE of the building. The embodied energy

analysis allows us to compare different materials not only the derivatives

of a certain raw material.

5.How would it help to lower the energy consumption in thebuilding industry?

As the world is moving really fast into developing new technologies

Figure 3. The global usage of energy resources (www.wikipedia.org) Oct. 2011


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and building up the surface of the earth so rapidly the resources are

running low. The most common problem of the world and the most

recently discussed topic is how to save energy. There are many

researches done on providing new sources of energy such as wind, water

or solar power. The temperature of the earth is used as a source ofheating up buildings and etc., but there are different methods that could

be used in the search of lowering the energy consumption. If we lower the

energy consumption for domestic purposes it would be only a small part of

the worlds in total. Therefore, we have to think globally. We have to think

of new solutions to lower the energy consumption in the industry zone.

Most of the electricity is produced from non-renewable resources such as

oil, coal and nuclear power and they have a low efficiency degree from

0.25 to 0.30 (25% to 30%) the rest of the energy is lost. On the other

hand electricity produced due to the power of water has an efficiencycoefficient of 0.6 which is not very impressive but still is better than the

stated above. It is best to avoid the usage of raw materials to produce

energy a better solution would be to produce energy is rotary power (wind

and water).

Low embodied energy analysis would be a great solution to the

world known problem and the construction sector. A big part of the energy

consumption can be reduced by planning and predicting the process of

constructing a building and all the activities in connection with that. Forexample a research on where would it be

most appropriate to get the materials for

the construction can lead us to lowering the

embodied energy of the building in means

of transportation. It would be even better if

we manage to establish factories for

manufacturing of raw materials close to the

resource location and still not too far from

the city or the area where the specificconstruction or building is build. In the

United Kingdom scientist state that most of

the prefabricated concrete elements have to

travel an average of 150 km to reach their

destination.

Another efficient way to drastically

lower the energy consumption is by using

raw materials located on the site instead of

using manufactured materials from a Figure 4.Illustrating positioning of recyclingactories


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factory located away from the area of building. For example a great choice

of material will be using stones found on the site while digging the

foundation of a building and manufacture them on site by hand or by the

usage of very low-consuming energy equipment. Canadian scientists

calculated that the embodied energy of stones is 0.79 MJ/kg, which isalmost three times less the embodied energy of bricks (2.5MJ/kg), which

leads to the conclusion that stones could be a great material to be used

instead of bricks for example. But if we get to compare oven burned bricks

to sun burned bricks the once that are made into a factory may contain a

higher embodied energy but still have a smaller embodied energy in a life

span of 150 years (as it is stated that nowadays bricks can last for that

long).Furthermore a raw material as stones could be used as

reinforcement while laying the foundation of a building.

The great amounts of construction waste in the world are reaching a

disturbing level and many manufacturers are starting to use the waste

into producing new materials that could be as efficient as the once

manufactured from raw materials. This process could be defined as

recycling materials and it allows us to lower the energy consumption in

the construction industry drastically. In China, more specifically Beijing 40

million tones of construction waste are thrown away every year. Most of

the waste is piled up or covered under domestic waste. The construction

waste is not that toxic and harmful to the environment, but if all thosetones of waste are instead recycled or reused this would be a great help of

the environment and planet earth. Most of the constructions in China are

made out of concrete or bricks and they could be

A big part of the waste is also reinforcement used in concrete and is

extremely easy to recycle or reuse into new buildings. In this way we

could save energy and lower the embodied energy of a lot of buildings and

also prolong the life span of raw material resources. A great example of

recycling materials is the recycling of bricks. Scientists say that seven

recycled bricks are equal to 1 liter of oil. Metals such as steel have a

rather high embodied energy, but if recycled we can save from 40 up to

90 per cent of the energy used for extracting ore. Recycling also has its

disadvantages, it has to be done in a local facility or in other words a

factory close to the demolished building, if the construction waste has to

be transported to distanced location the consumption of energy for oil

changes everything (see Picture 1.).

The more we ignore the problem the harder it becomes to save the

environment. The more we use non-renewable resources and increase theenergy consumption the harder the future will be. If we lower the energy


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consumption by using materials with lower embodied energy we could

save the non-renewable resources or at least use them as less as possible

and then use them on more important occasions or in more drastic needs.

The primary consumption of energy in producing materials is

actually the energy needed to manufacture the building product. When

calculating the primary energy consumption the most important factor is

the combustion value, which is the amount of energy produced by the

certain material if burned as fuel and it is mainly included in the primary

consumption energy calculation if the product is highly valuable as an

energy source. If we dont include the combustion value this can lead to

wrong results. The primary energy consumption is around 80% of the

total energy input in a material and is separated as it follows:

The energy used in the extraction of raw materials and theproduction process are defined as the direct energy consumption.

Of course this depends on the type of machinery used during the

process of extraction and the machinerys energy consumption.

During the process of manufacturing the energy consumed is calledsecondary energy consumption, which refers to the energy used

for heating, ventilating or maintenance of the given factory.

Last but not least is the energy consumed for transportationThe following table shows how much and what type of energy is used inNorway for the transportation of one tone of raw materials per year.

Type of transport MJ/ton/km

Diesel: road transport 1,6

Diesel: sea transport 0,6

Diesel: rail transport 0,6

Electric: rail transport 0,2

Figure 5. Illustrating the usage of non-renewable energy resources fortransportation of raw materials in Norway

The energy consumption during building, use and demolition is also a big

part of the total energy consumption of the construction process.

The transportation of manufactured products to the buildingsite is about 20 per cent of the total amount of energy used for the

building process. Transportation of heavy materials should be done

on local basis. A bad example of energy consumption is the

transportation of lightweight concrete elements from Norway to


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Korea which uses almost three times more energy/m3 than the

production of the product itself.

The energy consumption used for the building process on site hasincreased in comparison with the past. In search of a faster way tobuild and due to mechanization of some process the energy

consumption has increased drastically. For example in the past

construction processes were about to start during spring so the main

structure of the building would dry out and the construction process

can continue. Nowadays most of the in-situ casted concrete is dried

thanks to machines such as industrial fans or heaters. An important

factor is also the choice of material for the main construction if we

have to compare a concrete wall (in-situ) and a wooden wall (in-

situ), then of course the wooden wall will need less time and energyto dry.

The energy consumption during maintenance strictly depends onthe materials used into the construction, they should either be

renovated or replaced. Renovation would be found in processes such

as repainting or impregnating finishes of the faade or simply just

removing the old covering and replacing it with a new one (which is

more time and energy consuming but still an acceptable solution).

Last but not least the demolition process and the energy consumedin it. Statistics show that this is almost 10 per cent of the

construction total energy consumption, but it depends on the

materials used.

So now that we know the major energy consuming processes in the

life span of a material we know the areas where we should focus to lower

the energy consumption. If that analysis is done for every major materialused into a construction and we estimate the embodied energy of not only

the materials but the whole building, we would be able to save the

environment and hopefully prevent the extinction of certain raw energy

material resources such as oil for instance, knowing that the source of

power in the transportation and construction of buildings is petrol. If we

take transportation for example an average truck loaded with materials

will be consuming an average of 30 to 35 liters of diesel fuel per 100 km

(0.35l/km, 1l=38.6 MJ => 110.4MJ/km).


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6.How can we use a Life-cycle assessment as a tool todefine low embodied energy materials?

6.1What is a Life-cycle assessment (LCA).

A life-cycle assessment is defined as (LCA, also known as life-

cycle analysis, ecobalance, and cradle-to-grave analysis) a

technique to assess environmental impacts associated with all the stages

of a product's life from-cradle-to-grave (i.e., from raw material extraction

through materials processing, manufacture, distribution, use, repair and

maintenance, and disposal or recycling).

/www.wikipedia.org October 2011/

The main idea of a LCA will be to compare the environmental effects

of products and services in order to improve different processes and in the

same time provide a solid basis for sustainable decisions. The term life

cycle refers to the process of extracting, manufacturing, transporting and

establishing steps needed for the product to exist. LCA is a complex

assessment and it can be used in various occasions, for example the

production of a simple product and its environmental impact and the

construction of a new power plant. In the early years of its existence LCA

has been used only to define the environmental impact of small products,

but since we could use it to define the sub-products of a major product

with a much higher importance, we could use it for bigger projects. The

small products are defined as conventional and the major once as

unconventional.

Therefore we have two different types of LCAs: Attributional and

Consequential. The Attributional LCA is to describe the environmental

affect on or from a product or process, while the Consequential LCA is to

determine future changes in the environment if we make certaindecisions. Basically the ALCA is based on facts and already absorbed

knowledge and on the other side the CLCA is to predict future changes

based on guesses and experiments. Usually the difference between the

two LCAs can be found or stated in the Goal and scope part of the given

process. All Life-Cycle assessments are under the supervision of ISO and a

part of the ISO 14000 environmental management standards. Every LCA

is structured in four different phases:


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Goal and scope Life Cycle inventory Life cycle impact

assessment

Interpretation

The Goal and scope phase of the study is basically the beginning

of the LCA, where one should state in what method and to whom the

results should be given. According to the ISO standards the goal and

scope of the assessment have to be distinctly described and consistent

with the intended application. The Goal and scope document is used as a

guide to give us the readers further information on the following:

The function unit, giving us a definition of the studied subject in aprecise manner and provides us with information about the

quantities the system produces, providing a reference to which theinputs and outputs can be related. For example the usage of energy

in the manufacturing of a concrete element.

The boundaries of the system. For example finishing the process ofa life cycle assessment of a concrete element will be done from

cradle to gate, knowing that the destination of the element is

unknown.

Assumptions and limitations. The allocation methods used to separate the environmental load of a

process when different products and functions are used in the same

process.

The impact categories chosen. For example the energy consumptionor the CO2 emissions.

The second part of the life cycle assessment is the Life Cycle

Inventory (LCI) and its main function is creating an inventory flow of

products from and to nature for a certain product system. The flows

usually include inputs of water, energy, raw materials and outputs to air,

land and water. For further development of the inventory we couldconstruct a model of the flow of the system and incorporate the inputs

Figure 6. showing the main flow of the LCA


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the Goal and scope section of the LCA. The LCI provides information

about all the inputs and outputs in the form of elementary flow and the

effect of those flows to the environment. The number of those flows

depends on the product systems complicity and its boundaries. In case of

lack of data, questionnaires can be sent to competent organs, such asother producers of the same product or producers of the sub-materials

needed to manufacture a certain product.

Chart 3 illustrates the flow of the production of concrete elements

and provides us information of the main components (steel, lumber,

cement and aggregate suppliers) used in the process. It also shows us the

steps taken in the process. So by having this data we can start the life

cycle assessment of the process and get the total amount of embodied

energy needed to produce one element. The producers of raw materials

could provide us with the information on the embodied energy of their

products and the energy used to transport them to the factory where the

elements are produced. The next steps would be the calculation of the

amount of energy used for every single activity in the process. This way

the process of calculating the embodied energy of a concrete element

could be done from cradle to gate

Life cycle impact assessment follows the inventory analysis. This

past of the LCA is where we evaluate the potential environmental impact

of the process and products based on the flow model. The main elements

in the life cycle impact assessment are:

The categories of impact have to be selected, as well as thecategory indicators and the characterization models.

The classification stage, where the inventory parameters are sortedand assigned to specific impact categories.

The impact measurement, where we characterize the categorizedlife cycle impact flows, using one of many different possibilities of

life cycle impact assessment. All the assessments have to be donein equivalent units so that they can be added together in the end to

get the total overall impact.

The life cycle interpretation is where we systematically identify,

quantify, check and evaluate the information from the results of the life

cycle inventory and/or impact assessment. Here we also summarize the

results of the previous phases. The basic idea of the interpretation is to

provide conclusions and recommendations for the given study. The

interpretation should include:


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Identification of significant issues based on the results of theprevious phases of the life cycle assessment.

The completeness, sensitivity and consistency checks are beingcontrolled and evaluated.

Conclusions, limitations and recommendations are givenThe interpretation determines the level of confidence in the final results

and connects them in a fair and accurate manner. The results of the life

cycle assessment are not very simple so the choices of solutions to the

problem can be more than one. The final choice is made according to the

Goal and scope of the life cycle assessment, as we make sure the results

of the LCA meet the goals set in the beginning.

In a world where we are looking for sustainable solutions to prevent

harming the environment the LCA could be used as a great tool to definethe best choices of materials, constructions and even ways of building.

The process Cradle to cradle or Open loop Production is going to help

improve buildings and if followed will allow us to reach a smaller human

impact on the environment. If we use a life cycle assessment to assume

the energy consumed for the process of building and finding the best ways

of constructing, give the building a lower embodied energy and follow the

regulations in sizing materials (so that they are easily recyclable) we

would significantly help the environment. The life cycle assessment can

give us great results on the embodied energy of different materials and

even better it can provides with information on how those materials

actually harm the environment. Due to some life cycle energy analysis

new ways of energy recovery has been established. The disposal of

materials can be used as an energy resource, where the waste is being

burned and used for electricity production. That is of course done in

special facilities that are equipped with filtering systems so that they lower

the emissions and prevent harming the environment. That is great form of

recovering energy and on the other hand we can stop waste land-filling

(collecting garbage in open garbage depots) and greatly reduce the

energy consumption and green house gas emissions.

Critics disagree with the fact that LCA is replacing cost analysis with

energy efficiency analysis. But in such an advanced world, knowing all the

problems we have with the environment such as the global warming, we

should focus mainly on the impact of humanity on the environment and

less on the money we spend. LCA can also lead us to preserving the low

amounts of raw nonrenewable energy resources left.


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The life cycle assessment is a tool that can help us determine the

difference between, for example certain wall constructions in a certain

area, and lead us to the best choice of materials in long life span.

7.What can we define as low embodied energy materials?

7.1 Low embodied energy materials

There are many factors that need to be considered when we are

defining low embodied energy materials. Mainly in consideration is taken

the energy used to produce the certain material, the energy used to

deliver it and build with it on site and the energy used to maintain it after

words.

In the past many of the products used into a construction were

found and manufactured on site. Such materials as stone, timber and mud

have been the most common to be used in building structure. Nowadays

these materials are to be replaced by concrete, steel and bricks. The

newly developed techniques of building, consume greater amounts of

energy due to the usage of heavy machinery. In the past most of the

construction materials were manufactured by hand or used in a raw form,

which means no energy was used to build a house.

A material with low embodied energy can be defined by the

following factors:

How far the materials have to travel (local materials are better) The amount of raw materials used. How difficult it is to actually manufacture the product (the more

complex the process is the more energy is being used)

The size of the building should be connected with the needs it hasto fulfill the waste of space leads to higher usage of energy due to

extra materials needed. How much waste do you have during production and if the waste

could be reused

Recycling possibilities of the given material The usage of renewable resources is desirable (if possible) Efficiently design the building so the use of energy and materials is

lowered

The most common types of low embodied energy building materials

are:


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Mud bricks Stabilized earth Air dried timber Concrete blocks Precast concrete Recycled materials that dont require the usage of raw materials as

they are already manufactured once

7.2Stones in comparison with other low embodied energy materialsTo the above stated materials we could include stones. Stones have

been compared in a metaphorical way with the bone structure of our

planet and scientists give them three different categories:

Igneous stones. These are rocks that we can find on the surface ornot deep below the surface of the earth. They are considered to be

the hardest stones such as granites, syenites and dolerites.

Sedimentary stones. They are composed of grains and are combinedwith organic materials such as corals for instance. In this group we

can find sandstone, slate and limestone. Limestone is one of the

most popular in the ancient times and has been used construct

many historical buildings such as the pyramids and the GreekPantheon.

Metamorphic stones. Formed by exertion of pressure and the actionof high temperatures former igneous or sedimentary rock types are

being transformed into another structure. Examples of these rock-

types are crystalline, slate and quartzite.

According to Asher Shadmon of the HABITAD center in Naibori:

Stone is the building material of the future. We are on our way into a

new stone age. The resources are limitless and evenly spread over the

whole globe. Extraction does not require a lot of energy and does not

pollute. And most important of a ll is that the material is durable (1983)

The ecology of building materials

Stone has been used into buildings since the Stone Age and,

through the Middle Ages until nowadays. In the past stones were used to

construct all of the building structure: foundation, walls and roof as well.

But stones physical properties dont allow it to span in long distances


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because of its low tensile capacity. On the other hand stones can be used

in high buildings, knowing that it has great compressive capacity therefore

is a perfect material for load bearing walls. In the Middle Ages stones has

been used in the foundation and ground floor walls of the house and the

rest was made of bricks. Stone walls have a special characteristic ofpreserving and protecting from heat. A thick stone wall, thanks to the

density of the material, can keep the building cool during the summer and

worm during the winter, as the wall construction slowly heats up and

slowly cools down.

Figure 8. Illustrating examples of the usage of stone in buildings in thepast and an example of the life span of limestone constructions.

Nowadays crushed stones are used in the reinforcement of concrete,

for the production of tiles and slabs, but no longer for the construction of

walls and etc. The U-value of Limestone is 1.70 W/m2K which is only 0.11

over the U-value of high density concrete. That means that it could be

used into modern-time constructions as a substitute of concrete and since

it takes less energy to produce stone blocks and it could be put by hand

on the building site, that directly means that stone could be considered as

a material with a lower embodied energy than concrete. The density of

stone gives it

Stone blocks could also be compared to bricks according to theirfunction. Clay bricks go through a long process of manufacturing from raw

clay until we get to the product or the result that we are looking for. The

clay has to be extracted from the ground and that process is using great

amounts of energy, after words it has to be formed in the shape of the

brick also due to the help of machinery that uses energy and later on it

has to be burned and that means additional energy. Last but not least

comes the energy used to transporting the bricks to the site knowing that

they cant be produced on the site. On the other hand we have stone


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blocks that are extracted and shaped. If being lucky we could find suitable

stone resources on the building site while digging the foundation or etc.

Another low embodied energy material is the mud brick. The soft

mud method is the most common, as it is the most economical. It starts

with the raw clay, preferably in a mix with 25-30% sand to reduce

shrinkage. The clay is first ground and mixed with water to the desired

consistency. The clay is then pressed into steel moulds with

a hydraulic press. The shaped clay is then fired ("burned") at 900-1000 C

to achieve strength

www.wikipedia.org November 2011

However a common method of producing mud bricks is to naturally

burn them using only the sun, that method is of course only suitable forcountries where the climate allows that process to succeed. Mud bricks

have a lower embodied energy than the fabricated bricks simply because

they are not being burned, but they have a much shorter life span,

therefore mud brick constructions need to be renewed more often and

that leads to additional usage of energy. Stone blocks on the other side

have e very long life span if we consider structures made of stone in the

ancient times that are still standing. While bricks and concrete

significantly pollute the environment in the process of manufacturing,

stone blocks dont need to be exposed to high temperature therefore inthe process no gasses are released that can harm the environment. Stone

blocks are mainly produced due to a mechanical process that can be

supplied by energy from water-, wind-, and hand-power resources.

The weight of stone however requires the transportation of the

material to be done in short distances, but that could be applied also to

the transportation of bricks and concrete.

If stones are being extracted in large quantities the landscape of the

region changes and that leads to altered groundwater conditions and it

can harm local ecosystems. However there is a method of extracting

granite called the gloryhole which involves drilling a rock in vertical axes

from the top. By drilling that vertical tunnel there is a cone formed in the

inside of the rock, meaning that the whole gets wider the deeper it goes.

Due to this method the external appearance of the landscape is not/or

less disturbed and in lowers the harm on the local ecosystem.

By extracting stones there is a small possibility of radon being

released in the air and that could harm a local neighborhood, but with theextraction of limestone, marble and sandstone the risk of causing


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radiation is significantly low or minimal. A great advantage of stone is that

most of its products such as pressed blocks are easily recyclable. Crushed

stone has a potential for recycle when concrete is re-used. These recycled

products are usually valuable and suitable to be reused.

It is known that stone blocks are best to be used in foundations but

they can also be used in wall structures. Limestone and sandstone decay

in the same way as concrete when exposed to aggressive air pollution.

They have a great load carrying capability.

Using stone constructions does take us back in time, but with new

technologies the stone structure can be improved, insulation from water

and frost could make the construction last as long as concrete. Thermal

insulation can help stone structures to reach the modern time

requirements for thermal loss in connection with energy consumption.Knowing that the embodied energy of the product is low and all the above

stated factors make it a sustainable material.

There are examples of pure lime mortar keeping its functional properties

for 2000 or 3000 years, on the other hand there are examples of Portland

cement mortars that have crumbled within 10 years. Some concrete

buildings can stay undamaged for over 100 years. That is only to prove

that the life span of a construction depends on the materials used and the

way that we use them. Of great importance is the environment of thebuildings location.

All the above stated materials (bricks, concrete and stone) are

qualified as materials with low embodied energy but still the resources

needed for them to be produced are non renewable. The most popular

renewable construction material is timber. Even though a lot of forests

have to be cut down for the production of timber, new trees are planted in

the same place and in time natures balance will be stabilized. Timber is a

material suitable for recycling.

Green building minimizes the impact or "environmental footprint" of

a building. Wood is the only major building material that is renewable and

uses the suns energy to renew itself in a continuous sustainable cycle.

Studies show manufacturing wood uses less energy and results in less air

and water pollution than steel and concrete

www.wikipedia.org November 2011

Of course not all kinds of timber could be used in the construction

field. Therefore, timber is divided into two categories softwood and


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hardwood. Softwood is mainly used into constructions while hardwood on

the other side is used for the manufacturing of furniture.

Softwood can be divided in terms of production method: air dried

and kiln dried wood. Air drying depends a lot on the climate of the timber

factory location. In areas with high humidity the process will be difficult to

dry and the other way around. The wooden plates are put onto stacks in a

cool, dry and shady place. An important factor in air drying is the

appearance of a constant air flow. Air drying wood is a process that

consumes zero energy.

Kiln drying on the other side is a process where manufacturers

expose wood to heat so that the water in its structure will evaporate faster

that if air dried. That process provides a better quality control of the

material and if controlled properly the occurrence of defects could beminimized. If the temperature used in the drying process is above 60

degrees Celsius the wood is being protected from insects (such as

termites).

According to the University of Bath sawn softwood has an average of

5.5MJ/kg embodied energy (a result of 33 research cases). These results

also include 4.2 MJ of bio energy used in the production.

The following table shows a comparison between different materials and

their embodied energy (all values are from theInventory of Carbon &

Energy (ICE) Version 2.0).

The comparison between the embodied energy of the above stated

materials is done only from cradle to gate. Surprisingly the softwood

average embodied energy has the highest value. But on the other side it

Figure 9. Embodied energy comparison

Material Embodied energy MJ/kg

Mminimum Maximum Average

Lime stone 0,03 2,45 1,24

Softwood 0,3 13 6,65

Prefabricated concrete 1,2 3,8 2,5

Clay bricks 0,63 6 3,2


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is from a renewable resource and it also has a lower weight, which means

less energy will be used for transportation.

If we get to compare a wall structure made from the above stated

materials the weight of a timber construction is significantly lower than a

stone, concrete or brick construction. The embodied energy of a 5m2

timber construction will be much smaller than the embodied energy of a

5m2 concrete construction, because of the different density of the

materials (a cubic meter of wood has a smaller weight than a cubic meter

of concrete).

Material Weight kg/m

Lime stone 2611

Softwood (pine,dry) 750

Prefabricated concrete 2370

Clay bricks 2402

Figure 10. Weight of materials per cubic meter

According to table 4, softwood has the smallest weight per cubic

meter. If we combine the information of both tables 3 and 4 a cubic meter

of softwood will have an embodied energy of 4988 MJ/m3, when a cubic

meter of prefabricated concrete will have an embodied energy of 5925

MJ/m

3

.

Comparison ofconcrete, stone, bricks and wood in a construction example

can give us some more information on which of the materials is with the

lowest embodied energy. If we have a building of 20m2 with a height of

Figure 11. Plan of a small building used as an examplefor wall construction comparison.


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2.5m and the load-bearing wall layer is 150mm the material used for that

layer will have a volume of 6.98 7 if it is made out of bricks, stone or

concrete. If the construction is wooden and the cutting list is as it follows:

1. 32 vertical studs (0.2m x 0.06m x 2.5m) = 0.96m32. 4 horizontal boards (5m x 0.2m x 0.06m) = 0.24m33. 4 horizontal boards (4m x 0.2m x 0.06m) = 0.192m3

The total amount of wooden material used will be 1.392m3 1.4m3. Then

the embodied energy of the wooden construction from cradle to gate

would be 6943.3 MJ. For concrete it would be 16590MJ, for lime stone

blocks it would be 18277MJ and for clay bricks it would be 16814MJ.

Therefore the best solution of a construction in that case would be wooden

construction. Anyway that is only a rough calculation from cradle to gate.

If we assume all the factories producing stone, concrete, bricks and

timber are located in the same place and the distance to the building site

is 50 km. we can calculate the energy used by the transporting company

and compare. If a truck can take only 2 concrete elements of a size

0.15mX2.5mX5m that means it has to make two roundtrips, which means

that the distance will be doubled up to 200km and if as we previously

estimated that a loaded truck will use 110.4MJ/km, that means that for

200km the truck will spend 22080MJ. Bricks, stones and timber can be

delivered in only one round trip because of them being more compactthan the concrete elements. Since this is a rough estimation we will

assume that the energy used by the trucks transporting bricks and stones

will be twice as less as 11040MJ. We cant say the same thing about the

truck transporting the timber material, knowing that the weight of the

shipment is almost three times less than the other three. Respectively we

assume that the timber transporting truck will use only half of the energy

=> 5520MJ.

So from cradle to site the concrete elements have used 28670MJ,the stone blocks have used 29347MJ, the bricks have used 27881MJ,

while the timber material has been delivered using only 12463MJ.

When delivered on the site the concrete elements have to be

erected with a crane. 4 concrete elements could be erected in 2 hours. If

the crane is operating for 2 hours it will use an average of 20 liters of

diesel fuel, which will be approximately 772MJ. The wooden brick and

stone construction is laid by hand and will not consume any important

amounts of energy. So the final results of the rough embodied energy


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calculation are as it follows concrete 29442MJ, stone blocks 29347MJ,

bricks 27881MJ and wood 12463MJ.

In conclusion of the rough estimation many factors lead the result

that wood would be the winner in the competition, knowing that it has the

lowest embodied energy, the least amount of energy used to transport

and no energy to be mounted on site. Wood is also the only material

which is made of a renewable recourse. From those four materials in that

case the best choice will be wood. Of course every case is different from

the others.

Wood is a renewable recourse but we still have to consider that the

abuse of the world forests is also harming the environment. Cutting down

great amounts of trees harms the local ecosystems and even though the

ecosystem can be stabilized it needs time for that. It is a well known factthat the forests are the lounges of the Earth and by preserving the forests

we are helping mankind and lowering the CO2 emissions, knowing that

plants are CO2filters. A great problem is the deforestation of the world,

therefore every single time a forest is cut down by human usage the same

people have to be responsible for the restoration of the forest. Wood

production fields have been established in the world where forests are

literally manufactured in order to be cut down and then planted again.

Figure 12 Showing the results of mindless cutting of forests


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8. ConclusionAs the world is rapidly developing new technologies and in the same

time there is a great negative human impact on the environment we need

to find new ways of preserving the planet Earth and its resources. The

main problem in concern of energy is the constant abuse and the

extinction of energy resources. Of course there are new method and

systems invented to create energy such as wind and water power. In the

search of new methods scientists have also find it important not only to

find innovative solutions but also to lower the amounts of energy used.

Here comes the term low embodied energy. In the construction sphere

low embodied energy can refer to many parts, but one of the most

important once is the embodied energy of the materials used in nowadaysconstructions. As new standards are established all over the world

concerning the energy consumption of a building, constructing companies

have to start thinking about the energy consumption of the building during

the construction phase. Life cycle assessments are used to predict how

much energy, financial and human resources would be used for the

construction of a particular project. Thanks to the Life cycle assessment

we could also estimate the embodied energy of a building and the process

of that is also called Cradle to grave. Cradle to grave is a process where

constructing companies calculate the energy used to extract, manufactureand build certain constructions made out of certain materials. It is a fact

that life cycle assessment depends on many factors such as planning of

the building process, transportation, the execution phase, future

maintenance and possible recycling of the used materials. Cradle to grave

is a great process that through a complex and time consuming process

can estimate the embodied energy of a building from the extraction of raw

materials until their recycling. Nowadays modern technologies of building

allow us to use various materials. The most common to be defined as low

embodied energy materials are: pre-casted concrete elements, bricks,timber, mud bricks and stone. Some of those materials have been used in

the past in great amounts but nowadays have been defined as unsuitable.

Maybe going back in time would be helpful for the future. In my personal

opinion materials such as stone can be easily used in constructions as a

substitute of concrete or bricks. Anyway as my research shows me the

material with the lowest embodied energy is timber. Not only that it

doesnt need great amounts of energy to be extracted, manufactured and

used on site, but it is also a renewable resource. A drastic problem

worldwide is the pollution of the air, thanks to gas and CO2 emissions. Theworld building industry is one of the greatest polluters and therefore


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solutions to that problem must be found. One part of defining a low

embodied energy material is also to estimate the environmental impact of

the material or in other words to see how much CO2 is produced, while

manufacturing a certain material.

There are many factors that need to be considered in the search of a

low embodied energy material and for each case there could be a different

solution. No certain values can be given due to the extreme amount of

variable and unknown figures in the Low Embodied Energy calculation. In

conclusion the usage of low embodied energy researches and estimations

in the building industry can slow down or prevent the extinction of raw

nonrenewable energy resources and prevent harming the environment. In

my personal opinion low embodied energy materials have a great future in

sustainable design.


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List of references:

Bjrn Berge, The Ecologyof Building Materials, First published asBygnings materialenes kologi Universitetsforlaget AS 1992First published in Great Britain 2000, Paperback edition 2001

English edition Reed Educational and Professional Publishing Ltd 2000,2001

Brander, M., Tipper, R., Hutchison, C., Davis, G Technical Paper |

Consequential and Attributional Approaches to LCA: a Guide to Policy

Makers with Specific Reference to Greenhouse Gas LCA of Biofuels

April 2008

Cole, R.J. and Kernan, P.C. (1996), Life-Cycle Energy Use in Office

Buildings, Building and Environment, Vol. 31, No. 4

Prof. Geoff Hammond & Craig Jones, Inventory of Carbon & Energy (ICE)

Version 2.0Sustainable Energy Research Team (SERT) Department ofMechanical Engineering University of Bath, UK

University of Bath 2011Websites:

http://en.wikipedia.org/wiki/Timber Accessed on the 11th of November

2011

http://en.wikipedia.org/wiki/LimestoneAccessed on the 9th of November

2011

http://www.canadianarchitect.com/asf/perspectives_sustainibility/measures_of_sustainablity/measures_of_sustainablity_embodied.htmAccessed

on the 30th of October 2011

http://www.iso.org/iso/iso_catalogue/management_and_leadership_stand

ards/environmental_management/iso_14000_essentials.htmAccessed on

the 4th of November 2011

http://www.stonecourses.net/environment/goallca.htmlAccessed on the

4th of November 2011
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low embodied energy materials in sustainable design by lazar petrov

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