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An Environmental Impact of a Wooden and Brick House by the LCA Method

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The main objective of this paper thesis is to determine the environmental impact of two houses made of two alternative materials-a wooden and a brick house-using a Life Cycle Assessment (LCA). By comparing the material composition of their design to determine the environmental impacts of global warming, human health, consumption of resources and ecosystem quality. An overall comparison showed that the materials for the construction of a wooden house have less negative impact on the environment than materials for the construction of a brick house. Using the GWP method, results show that the materials for the construction of a brick house leave twice the carbon footprint in the environment than materials for a wooden house. This resultant state is mainly due to the use of natural materials in the wooden house (wood, fibre insulation), unlike the materials used in the brick house (ceramic masonry, insulation from stone wool) and so on.
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An Environmental Impact of a Wooden and Brick House by the LCA
Method
Jozef Mitterpach1, a *, Jozef Štefko2,b
1TU in Zvolen, KEI FEE, Department of Environmental engineering, T. G. Masaryka 24, 96053,
Zvolen, Slovakia
2TU in Zvolen, KDS FWST, Department of Wooden Constructions, T. G. Masaryka 24, 96053,
Zvolen, Slovakia
a*jozef.mitterpach@gmail.com, bstefko@tuzvo.sk
Keywords: LCA, building, wood, construction, environmental impact
Abstract. The main objective of this paper thesis is to determine the environmental impact of two
houses made of two alternative materials - a wooden and a brick house - using a Life Cycle
Assessment (LCA). By comparing the material composition of their design to determine the
environmental impacts of global warming, human health, consumption of resources and ecosystem
quality. An overall comparison showed that the materials for the construction of a wooden house
have less negative impact on the environment than materials for the construction of a brick house.
Using the GWP method, results show that the materials for the construction of a brick house leave
twice the carbon footprint in the environment than materials for a wooden house. This resultant state
is mainly due to the use of natural materials in the wooden house (wood, fibre insulation), unlike the
materials used in the brick house (ceramic masonry, insulation from stone wool) and so on.
Introduction
The method of settlement and way of life in mountain pastures formed the base of a special,
initially wooden, architecture with straw and, later, shingle roofs in the Podpoľanie area – Slovakia.
This type of rustic architecture in this area included the Central Slovakia wooden log house, see Fig.
1a. These are mainly around Poľana, Vepor, Zvolenská Panva, Slovenské Rudohorie, Javorie and
the northern slopes of Krupinská Vrchovina. This basic wooden construction is barely visible
almost throughout the area since the stone and log walls have been plastered with clay and whitened
with lime. Simple finishing of walls can only be found in mountain pastures where just the gaps
between the wooden logs were filled with clay and the wooden house was then whitened with lime.
The entire area was dominated by a truss construction, and a saddle construction was only rarely
used. Fire resistant material - stone - gradually started to be used when, by the 19th Century, stone
as a solid, non-combustible material, started to prevail in villages on the northern slopes of
Krupinská Vrchovina and in the south western part of Zvolenská Panva. However, wood as a basic
building material was used in the mountain pastures under Poľana until the 1930s. Settlements in
these areas were built in an L or U shape [1].
The theme of permanently sustainable construction, which is currently defined in the Agenda 21
basic document for sustainable construction, represents a complex issue with a large number of
parameters in various fields of the building industry [2]. Optimisation of building design in terms of
environmental parameters is a wide, multi-criteria issue [3].
Life Cycle Assessment (LCA) methods were used to evaluate the protection process of various
products for a fairly long time. The application of this method in the building sector has only been
seen for the last 10-13 years [4]. Since the LCA method has a complex and systematic approach to
environmental evaluation, interest lies in including the LCA method into the building decision-
making process for selecting and favouring ecological products, as well as for assessing and
optimising building processes [5].
Key Engineering Materials Submitted: 2015-07-20
ISSN: 1662-9795, Vol. 688, pp 204-209 Accepted: 2015-10-13
doi:10.4028/www.scientific.net/KEM.688.204 Online: 2016-04-26
© 2016 Trans Tech Publications, Switzerland
All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans
Tech Publications, www.ttp.net. (ID: 194.160.162.141-20/02/16,23:29:44)
Goal and scope
The main aim of this paper is to assess the environmental impact of building a house using two
alternative material bases - a brick house and a wooden house - using the life cycle assessment
(LCA) method. To determine the environmental impact for the final points of a life cycle
assessment in terms of global warming, human health, consumption of resources and ecosystem
quality.
Material and method
Characteristics of a brick house and a wooden house
Fig. 1 Model house: a-historical architecture (present), b,c- brick house, d- wooden house
(unfinished), e- 3D design for a wooden house and a brick house by "a"
The brick house (Fig. 1b, c, e) is single storey without a basement. The construction lies on a
strip foundation. The house has two chimney stacks. The construction of the circumference is made
of ceramic masonry insulated with a thermal insulation composite system covered with a silicon
coating. Internal partitions on the ground floor are made of ceramic masonry coated with plaster.
The ceiling load-bearing construction consists of ceiling beams placed along the whole width of the
house and protruding to the exterior. The ceiling beams hold the ceiling decking made of tiles,
which holds the attic flooring. Internal partitions in the attic are made of a frame sandwich walls
coated with chipboard and plaster boards which are covered with a layer of plaster. The house has a
saddle roof with an incline of 42°. Joists and wall beams are placed on the ceiling beams into
which they are anchored. Double sided stud ties are fixed to the truss by studs. Stone wool thermal
insulation is placed between the trusses. There are three dormers on the roof, situated on the
southern side. The northern side contains three roof windows. The roof covering is made of concrete
tiles.
The wooden construction of a wooden house (Fig. 1d, e) is a constructional copy of the brick
house, apart from the used materials and their construction principles. For example, the brick house,
like the wooden house, is built on strip foundations with a higher strength class of the concrete. The
circumference walls are a double-walled wooden construction. The double-wall is formed of two
wooden profiles. There are cork chippings between the two, acting as thermal insulation. The
internal partitions are made of a frame sandwich construction with wood-fibre insulation. The walls
are covered with chipboard with mounted clay panels and coated with clay. The ceiling construction
is identical to the construction in the "brick house" apart from acoustic insulation which is wood-
fibre. The construction of the external walls below the gable is made of frame sandwich
construction. Fibre insulation is designed to act as thermal insulation. A wooden, ventilated façade
Key Engineering Materials Vol. 688 205
is created at the exterior. The interior coating is made of woodchip boards on which clay panels are
mounted. A layer of clay coating is added to the panels. Internal partitions in the attic are of the
same construction as the partitions on the ground floor. The shape and construction of the roof is
identical to the roof of the brick house. There are only two differences which are the use of different
thermal insulation (wood-fibre insulation) and roof covering, which in this case is wooden shingle.
Life Cycle Assessment methodology
The LCA methodological framework is described in STN EN ISO 14040. Environmental
management. Life cycle assessment. The principles and structure (ISO 14040:2006) [6] and STN
EN ISO 14044:2006. Environmental management. Life cycle assessment. Requirements and
instructions (ISO 14044: 2006) [7]. The SimaPro database tool was selected for a life cycle
assessment of houses [8]. The level of environmental impact upon selected categories of impact:
human health, consumption of resources and ecosystem quality, was determined using the ReCiPe
assessment method. The main aim of the ReCiPe is to transform all inputs and outputs into a limited
number of environmental output indicators. In this paper, we evaluated two constructions at the 2nd
level in 3 end points - Human Health, Ecosystem Quality and Resources. The impacts of the
material composition of the wooden house and brick house upon global warming are expressed and
assessed using the IPCC 2013 GWP 100a method [8].
The designed houses are assessed based on the input material composition which was divided
into the main construction units, into: Foundations (Table 1), Ground Floor (Table 2), Attic (Table
3, Roof (Table 4).
Table 1 Materials for the foundations of the wooden house and brick house
Material
mm
m3
kg
Material
mm
kg
Const. unit
wooden house
brick house
Foundations
Concrete C16/20
-
47.85
110055
Concrete C20/25
-
110055
Table 2 Materials for the ground floor of the wooden house and brick house
Material
mm
m3
kg
Material
mm
m3
kg
Const. unit
wooden house
brick house
Ground floor
oak parquet floors
-
4.66
3168.00
oak parquet floors
-
4.66
-
ceramic tiles
7
0.39
784.00
ceramic tiles
7
0.39
784.00
PE sheet
0.2
-
70.79
PE sheet
0.2
0.00
70.79
concrete screed
50
9.31
-
concrete screed
50
9.31
-
fibreboard
80
14.90
3427.69
exp. polystyrene
80
14.90
447.00
waterproofing
4
-
1279.00
waterproofing
4
0.00
1279.00
reinforced concrete C16/20
-
33.66
-
reinforced concrete C20/25
-
33.66
-
prism. softwood
92
17.52
8234.40
silikone plaster
-
17.52
513.00
cork insulation
-
37.71
1897.09
reinforcing mesh. *m2
190*
-
-
prism. softwood
44
8.09
3802.30
construkcion adhesive
-
-
1501.00
clay plaster
5
1.99
3781.00
rock mineral wool
60
11.40
1368.00
clay layer
30
1.49
3427.00
brick
440
83.60
62700.00
oriented strand board
15
1.49
1847.60
masonry mortar
-
0.59
-
fibre insulation
80
6.63
995.10
gypsum plaster
20
3610.00
oriented strand board
15
1.49
1847.20
gypsum plaster
20
0.27
253.65
clay layer
30
1.49
3427.50
brick
250
3.34
2503.13
clay plaster
5
1.99
3781.15
gypsum plaster
20
0.27
253.65
sawn. timber. softwood
-
2.83
1107.40
masonry mortar
-
0.02
-
206 Selected Processes of Wood Processing
Table 3 Materials for the attic of the wooden house and brick house
Material
mm
m3
kg
Material
mm
m3
kg
Const. unit
wooden house
brick house
Attic
wooden siding
25
1.38
828.00
silikone plaster
-
0.28
149.85
protection foil
0.15
-
-
reinforcing mesh. *[m2]
-
-
56.00*
fibre insulation
100
5.22
768.00
construkcion adhesive
-
-
437.80
fibre insulation
100
4.60
704.25
rock mineral wool
60
3.33
399.60
oriented strand board
18
0.93
576.60
brick
440
24.42
18315.00
fibre insulation
50
2.33
349.20
gypsum plaster
20
1.11
1050.70
clay layer
30
0.76
874.00
masonry mortar
-
0.17
-
clay plaster
5
1.01
959.50
gypsum plaster
20
0.19
180.50
clay plaster
5
3.12
2965.00
gypsum plaster
20
2.94
2793.00
clay layer
30
2.34
2692.00
gypsun fibre board
15
2.20
2530.00
oriented strand board
15
2.34
1451.60
oriented strand board
15
2.20
1364.00
fibre insulation
80
10.50
1575.15
rock mineral wool
80
10.00
800.00
oriented strand board
15
2.34
1450.00
oriented strand board
15
2.20
1364.00
clay layer
30
2.34
2690.00
gypsun fibre board
15
2.20
2530.00
clay plaster
5
3.12
2963.00
gypsum plaster
20
2.94
2793.00
clay layer
30
0.74
1081.00
gypsun fibre board
15
0.74
851.00
oriented strand board
15
0.79
489.80
oriented strand board
15
0.79
489.80
fibre insulation
80
4.00
599.40
rock mineral wool
80
4.00
599.40
oriented strand board
15
0.89
551.80
oriented strand board
15
0.89
551.80
clay layer
30
0.94
851.00
gypsun fibre board
15
0.94
1081.00
clay plaster
15
1.28
1216.00
gypsum plaster
20
1.28
1216.00
sawn. timber. softwood
-
3.96
1367.00
sawn. timber. softwood
3.96
1367.00
oak floors
-
2.46
1670.00
oak floors
DB
2.46
1670.00
fibreboard washer
20
0.33
81.75
fibreboard washer
20
0.33
81.75
ceramic tiles
0.7
0.06
116.00
ceramic tiles
0.7
0.06
116.00
PE sheet
0.2
-
1.60
PE sheet
0.2
-
1.60
oriented strand board
15
2.46
1523.34
oriented strand board
15
2.46
1523.34
fibre insulation
50
8.19
1884.16
fibre insulation
50
8.19
1884.16
wooden decking. softwood
-
4.10
1925.15
wooden decking. softwood
-
4.10
8279.43
sawn timber. softwood
-
8.61
4045.70
sawn timber. softwood
-
8.61
4045.70
wooden siding. softwood
-
4.64
2179.80
wooden siding. softwood
-
4.64
2179.80
sawn timber. softwood
-
0.27
128.78
sawn timber. softwood
-
0.27
128.78
Table 4 Materials for the roof of the wooden house and brick house
Material
m2
m3
kg
Material
mm
m3
kg
Const. unit
wooden house
brick house
Roof
sawn timber. boards
-
3.64
1277.00
sawn timber. boards
SM/JD
3.64
1277.00
sawn timber. skeleton
-
15.90
5566.00
sawn timber. skeleton
SM/JD
15.90
5566.00
wood shingle. softwood
444.119
-
concrete roofing tiles
-
-
19097.12
fibre insulation
-
74.50
11175.00
rock mineral wool
200mm
74.50
5960.00
Results
The data necessary for the life cycle assessment using the ReCiPe method for a wooden house
and brick house (Fig. 2), required by the SimaPro program, was taken from Tables 1-4. The life
cycle assessment for selected groups of environment impact of the wooden house shows that the
greatest negative impact of the wooden house is upon ecosystem quality, 7.4 kPt, then upon
consumption of resources, 1.97 kPt and finally upon human health, 1.55 kPt. The life cycle
assessment of the brick house upon selected groups of environmental impact shows that the greatest
negative impact was upon ecosystem quality, 5.35 kPt, then upon consumption of resources, 4.15
kPt and finally upon human health, 3.05 kPt. kPt (Kilo point) is a standard eco-indicator normalized
unit [8].
Key Engineering Materials Vol. 688 207
Fig. 2 Comparison of the life cycle assessment of the wooden house and brick house, ReCiPe
From a comparison of the negative impacts in the groups of impact (Fig. 2), it follows on that the
brick house negatively influences (4.155 kPt) the assessed final impact, Resources, by than twice
the negative impact of the wooden house (1.978 kPt). This is a result of the materials used in the
wooden house, from renewable resources (wood, wood-fibre insulation, clay coating). A
comparison of the negative impact upon human health shows that the overall negative impact of the
brick house (3.060 kPt) upon human health is approximately double the negative impact of the
wooden house (1.559 kPt). This result is mainly caused by the use of ceramic bricks in the
circumference walls, concrete roofing and the selected insulation. A comparison of the negative
impact upon ecosystem quality shows that the wooden house influences ecosystem quality (7.403
kPt) more than the brick house (5.355 kPt). This result is mainly due to the use of wooden raw
materials in the construction of the wooden house and the negative impact mainly due to the mining
of wood raw materials as the main material. A comparison of total negative impact using the
ReCiPe method shows that the total negative impact upon the environment by the wooden house
(10.937 kPt) is less than the negative impact of the brick house (12.569kPt).
Fig. 3 Life cycle assessment of a wooden and brick house, IPCC 2013 GWP 100a
Comparison IPCC 2013 GWP 100a (Fig. 3) shows that the wooden house leaves a carbon
footprint in the environment with a value of 47454.11 kg CO2eq, which is less than half that of the
brick house construction which leaves a carbon footprint of 102981.49 kg CO2eq.
208 Selected Processes of Wood Processing
Conclusion
The main aim of this paper was to evaluate the environmental impact of building a house using
two alternative materials: a brick house and a wooden house. An overall comparison using ReCiPe
showed that the materials for building a wooden house have a less negative environment impact
than materials for building a brick house. Using the GWP method, the results showed that the
materials used for building a brick house leave double the carbon footprint in the environment than
the materials used for building a wooden house. Assessment using the ReCiPe method showed that
the use of wood has the greatest negative impact upon the selected final impact, Ecosystem Quality.
This is caused by the unsuitable method of management and mining wood as a renewable material
resource, which was included in the assessment. The results of the work further show that building
wooden houses when using suitable materials is friendlier in terms of the consumption of resources
and has less impact upon human health. The results of the analysis [9] point to the fact that it is
possible to reduce the environmental impacts by up to 61.0 % in particular structures. A more
significant decrease in the creation of greenhouse gases can be achieved by using suitable materials
[10], as well as improving ecosystem quality, e.g. by planting suitable plants in the countryside.
Acknowledgements
This research was supported by VEGA 1/0213/15.
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Key Engineering Materials Vol. 688 209
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At the time of writing this report there is no LCA-based tool that is sophisticated enough to be used at the whole building level to assist in decision-making processes for materials to minimise environmental impacts. This can only be determined on a case-by-case basis. However, LCA can be used to inform policy decisions regarding the use of materials to minimise the climate change impacts of the built environment in Norway, if the GWP (global warming potential) impact category is used in combination with the embodied energy data. But the methodology does have inherent uncertainties. The original terms of reference for the report, were as follows:  General considerations on the different methods of environmental impact analysis and evaluations (LCA, EPD, HWP, BREEAM….) and what the differences are between these systems;  Conduct an analysis on wood LCAs that have been done in Norway and comparable countries, anda compilation of these data. Which factors influence the analysis and how much do single factors affect the result?  Conduct a similar analysis on competing materials like concrete and steel;  Conduct an analysis comparing the environmental impacts of wood and other materials. What is actually being compared and what does it imply for the real climate footprint?  Summarise the results, evaluation of their importance and the use such findings can have for political decisions in the future. The report begins with a description of the Norwegian built environment and forest products’ sectors and then gives an overview of the methodologies used in LCA and the strengths and weaknesses of the technique. LCA is a complex subject and there is still debate about the methodologies and impact categories. LCA does not have the level of accuracy needed in many impact categories in order to make comparative assessments and only the impact categories global warming potential and ozone layer depletion potential are considered to be sufficiently robust to give accurate and reliable data. A review of building assessment schemes has also been undertaken. LCA comprises only a minor part of building assessment schemes, such as the Building Research Establishment Environmental Assessment Method (BREEAM) and Leadership in Energy and Environmental Design (LEED) and these have little to say about the choice of materials for construction. These schemes have some value in promoting more environmentally-conscious designs, but they are not sufficiently robust to be used as tools to inform policy-making, or building material choices. The report focuses on issues surrounding carbon sequestration in forests and how atmospheric carbon can be stored in long-life products in the built environment. One of the advantages of using timber in construction is the potential for the storage of biogenic carbon (derived from atmospheric carbon dioxide) in long-life structures. Although this does have a role to play in climate change mitigation, this literature review has revealed that most studies show that the effects of substitution for high embodied energy materials and for fossil fuels for energy production are much more significant. The overwhelming majority of LCAs of timber products have shown that the amount of atmospheric carbon stored in the wood (measured as CO2 equivalents) is always larger than the GHG (greenhouse gas) emissions associated with the processing of the material. Additional benefits arise when the wood is incinerated at the end of the life cycle, with substitution of fossil fuels. The highest fossil fuel substitution benefits arise when coal is replaced with timber wastes/by-products. In a Norwegian context, the highest benefits will arise if wood is used as a fuel for cement kilns, or as a carbon-source for aluminium anodes, followed by a replacement of oil for heating then natural gas for heating or electricity production. This report also reviews the scientific literature of published LCA studies of commonly-used building materials (timber, cement/concrete, aluminium, steel, poly(vinyl chloride)). It is shown that the outcomes of the LCAs are very heavily dependent upon the assumptions made and the system boundaries used. It is not possible to arrive at definitive a value of (for example, global warming potential, GWP) that is characteristic for a material, but there is a range of values. The methodology used to determine the environmental impacts is complex and many studies are not readily amenable to comparative studies. This is because of differences in functional unit, supporting databases, assumptions regarding material life, maintenance, end-of-life scenarios, etc. In addition, most studies lack sufficient transparency to allow for proper verification of the results obtained. LCAs also inevitably contain simplifications, which may affect the accuracy of the data. Most studies do not employ a sensitivity analysis to show how the assumptions and variabilities affect the results. It is necessary to consider the whole life cycle when making materials choices and the only way to do this is at the whole building level. However, this increases the degree of uncertainty in the calculations and involves assumptions and the introduction of scenarios which may not be realistic or reasonable. A variety of factors can affect the LCA of building materials over their lifetime, which can be divided into uncertainties and variabilities. Uncertainties arise from lack of precise knowledge regarding processes or the use of assumptions. Variabilities can arise due to different choices regarding the use of materials, such as frequency and type of maintenance, different disposal methods, transport distances, etc. Combinations of uncertainty and variability can be difficult to separate. There is considerable scope for uncertainty to affect the data, especially when the in-service and end-of-life stages of the life cycle are included. Consequently, there is considerable variability in the methodology applied for LCAs, which has a significant influence on the output and hence the task of making comparative assertions is extremely difficult. However, there has been some degree of consensus reached with the introduction of environmental product declarations (EPDs) and standardisation of procedures; known as product category rules (PCRs). Nonetheless, there is still concern that inter-product comparisons are not reliable, due to uncertainties and variations in the assumptions made, the use of different databases, etc. The main advantage with EPDs which are produced in conformity with the European standard EN 15804, is that the impacts have to be reported separately for different life cycle stages. Of these, the cradle to factory gate life cycle stage (modules A1-A3) is likely to be the most reliable, since this part of the life cycle involves the least assumptions and the most accurate data. This study has largely focussed on data concerned with the embodied energy associated with materials and the global warming potential (GWP) environmental impact category, because these have the lowest uncertainties. GWP data is strongly influenced by the time-frames of the study and by a range of different factors that have to be taken into account when making comparative studies:  Greenhouse gas (GHG) emissions associated with the manufacture of construction materials, maintenance, replacement and disposal;  GHG emissions associated with operational energy requirements, if these are relevant and realistic and have not been introduced to favour one material over another;  Carbon emissions and storage from forestry operations and sequestration by growing biomass;  Substitution effects associated with the use of timber in comparison to other building materials;  End-of-life scenarios, such as recycling, or incineration with energy recovery. The embodied energy used to produce construction materials is an important consideration when analysing the environmental impacts. This initial embodied energy is to be distinguished from the recurring embodied energy which arises due to maintenance of the materials and the operating energy, which is energy consumed due to the operational requirements (e.g., heating) of the building. As the operating efficiency of buildings improves, the embodied energy will be a larger proportion of the overall energy requirements. The embodied energy also represents a greater proportion of the overall energy consumption of the sector in a growing market. Sawn timber products are lower embodied energy materials when compared, on a functional unit basis, with non-renewable construction products. The increased use of timber in construction will result in more carbon storage in the harvested wood products carbon pool at a critical time. This can form part of a wider strategy to move to a low fossil carbon economy. Although timber is the dominant material used in single-family dwellings, it is little used in multipleoccupancy buildings. The Norwegian forests are currently absorbing levels of carbon dioxide which are equivalent to about 40% of the annual emissions, but this will fall as the age structure of the forests matures. In order to maintain these high levels of sequestration it is necessary to increase the harvesting intensity of Norwegian forests. The carbon in the HWPs produced should be stored in long life products in the built environment for the maximum climate change mitigation effect. The use of timber in high-rise non-residential and multiple-occupancy residential construction would give benefits from a climate change mitigation perspective. The Norwegian forest products sector should use the opportunity provided by the increased use of timber in multi-occupancy and multi-storey buildings to develop an export industry in pre-fabricated structures. Adding value to the forest products sector is essential. By encouraging a cross laminated timber industry in Norway, there will be potential for export of multi-occupancy buildings using modular construction methods to exterior markets, such as the UK.
... Wood wool panels, bonded with cement, were developed around the beginning of the 20th century [32]. These composites are made of wood particles, fibers and excelsior wood and bonded with Portland cement, and they were developed as panels, bricks and other products for construction [33][34][35][36]. Nowadays, wood wool cement boards are reinforced with smart materials (e.g., nano-minerals) [37]. ...
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Analysis of the environmental impact of concrete-framed family house using LCA method
  • M Ondová
  • A Eštoková
M. Ondová, A. Eštoková, Analysis of the environmental impact of concrete-framed family house using LCA method, Ciencia E Tecnica Vitivinicola, 29, 7 (2014), pp. 267-376. Key Engineering Materials Vol. 688 209
Agenda 21 on Sustainable Construction
Agenda 21, Agenda 21, Agenda 21 on Sustainable Construction, CIB Report Publication 237, Rotterdam, 1999.