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1 COLLEGE COLLEGE OF ENVIRONMENTAL DESIGN OF ENVIRONMENTAL DESIGN BUILDING MATERIALS AND SYSTEMS : EVALUTION AND SELECTION Presented by Dr. Abdul-Mohsen Al-Hammad,
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IGN BUILDING MATERIALS
AND SYSTEMS : EVALUTION AND SELECTION
Presented by
Dr. Abdul-Mohsen Al-Hammad,
BUILDING MATERIALS
AND SYSTEMS : EVALUTION AND SELECTION
Presented by
Dr. Abdul-Mohsen Al-Hammad,
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• Introduction
• The Need for a Rational Approach
• Proposed Evaluation and Selection method
• The Case Study(Exterior Wall Systems) • Application of the Method
• Conclusion
• Introduction
• The Need for a Rational Approach
• Proposed Evaluation and Selection method
• The Case Study(Exterior Wall Systems) • Application of the Method
• Conclusion
CONTENTS CONTENTS
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• People who are involved in construction industry and require a more rational approach to evaluate and select building products are :
• Architects and engineers
• Construction Managers
• Subcontractors
• Building Material manufacturers
• Today,there is no unified rational approach for evaluation and selection a building product.
• People who are involved in construction industry and require a more rational approach to evaluate and select building products are :
• Architects and engineers
• Construction Managers
• Subcontractors
• Building Material manufacturers
• Today,there is no unified rational approach for evaluation and selection a building product.
INTRODUCTION INTRODUCTION
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• Historic Account of Material Use
• Stone
• Marble – Used in Egyptian and Greek Temple
• Brick & Concrete – Romans times
• Skilled in these materials were perfected
• Historic Account of Material Use
• Stone
• Marble – Used in Egyptian and Greek Temple
• Brick & Concrete – Romans times
• Skilled in these materials were perfected
THE NEED FOR A RATIONAL APPROCHTHE NEED FOR A RATIONAL APPROCH
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• No. of Materials used in different time periods
• Development of steel
• Development of many synthetic products
• Development of products that resulted from
• Human performance• Natural resources• Technological capabilities
• No. of Materials used in different time periods
• Development of steel
• Development of many synthetic products
• Development of products that resulted from
• Human performance• Natural resources• Technological capabilities
THE NEED FOR A RATIONAL APPROCH ( Continued)THE NEED FOR A RATIONAL APPROCH ( Continued)
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• For Examples:
• In Concrete there is about 60 variables from
• Mixing ,curing temperature,w/c ratio,etc
• In synthetic products, many variables affect them
• Sweets Catalogs – in 1906 one volume – 150-200 manufactures are listed
• Nowadays, more than 45 vol. annually are issued• One vol. Adds more than 2,300 Catalogs file each year as brand
catalogs for new materials
• For Examples:
• In Concrete there is about 60 variables from
• Mixing ,curing temperature,w/c ratio,etc
• In synthetic products, many variables affect them
• Sweets Catalogs – in 1906 one volume – 150-200 manufactures are listed
• Nowadays, more than 45 vol. annually are issued• One vol. Adds more than 2,300 Catalogs file each year as brand
catalogs for new materials
THE NEED FOR A RATIONAL APPROCH ( Continued)THE NEED FOR A RATIONAL APPROCH ( Continued)
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• Testing and research for evaluation has not been able to keep pace with the no. of newly developed products
• This enables products to be used or marketed before the design professional can be assured that the products do indeed fulfill the desired requirements.
• Testing and research for evaluation has not been able to keep pace with the no. of newly developed products
• This enables products to be used or marketed before the design professional can be assured that the products do indeed fulfill the desired requirements.
THE NEED FOR A RATIONAL APPROCH ( Continued)THE NEED FOR A RATIONAL APPROCH ( Continued)
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• The question is how design professional evaluate & specify a new product
• Do they depend on the manufacture literature only
• What kind of the question the designers should ask the manufacturer?
• Thus,there is a need for the design professional to use a rational approach to evaluate and select the products
• The question is how design professional evaluate & specify a new product
• Do they depend on the manufacture literature only
• What kind of the question the designers should ask the manufacturer?
• Thus,there is a need for the design professional to use a rational approach to evaluate and select the products
THE NEED FOR A RATIONAL APPROCH ( Continued)THE NEED FOR A RATIONAL APPROCH ( Continued)
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• The method of judging ideas as suggested by (Parker 1985) was used as a rational approach since it considers economic and non-economic criteria for selection.
• This method will consist of subjecting different materials or
systems to certain screening processes, namely
• feasibility ranking, • evaluation by comparison, • weighted evaluation which involves
• criteria evaluation, and• matrix evaluation.
• The method of judging ideas as suggested by (Parker 1985) was used as a rational approach since it considers economic and non-economic criteria for selection.
• This method will consist of subjecting different materials or
systems to certain screening processes, namely
• feasibility ranking, • evaluation by comparison, • weighted evaluation which involves
• criteria evaluation, and• matrix evaluation.
PROPOSED EVALUATION AND SELECTION METHOD PROPOSED EVALUATION AND SELECTION METHOD
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IGN • Exterior building wall systems evaluation & selection will be
used a case study
• Walls for buildings can be constructed in various ways using a variety of materials.
• Exterior walls serve as a protective shield against exterior
conditions for a building's interior spaces (Greeno 1986). • An architect faced with a variety of alternative exterior wall
systems.
• An evaluation and selection technique for exterior wall systems that are available in Saudi Arabia will be used.
• Exterior building wall systems evaluation & selection will be used a case study
• Walls for buildings can be constructed in various ways using a variety of materials.
• Exterior walls serve as a protective shield against exterior
conditions for a building's interior spaces (Greeno 1986). • An architect faced with a variety of alternative exterior wall
systems.
• An evaluation and selection technique for exterior wall systems that are available in Saudi Arabia will be used.
THE CASE STUDY (Exterior Building Wall Systems) THE CASE STUDY (Exterior Building Wall Systems)
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IGN • In Saudi Arabia, or elsewhere, the architect/designer has a
number of alternative exterior wall systems. • The first approach requires the list of all possible alternatives
for each particular building project. • In this case, based on a field survey of the Saudi market,
fourteen wall construction systems were identified as the most commonly used systems.
• An outline of these systems along with a brief description of
their assemblies is presented in Table 1. For further illustration, Fig. 1 shows cross sectional areas of samples of these systems.
• In Saudi Arabia, or elsewhere, the architect/designer has a number of alternative exterior wall systems.
• The first approach requires the list of all possible alternatives
for each particular building project. • In this case, based on a field survey of the Saudi market,
fourteen wall construction systems were identified as the most commonly used systems.
• An outline of these systems along with a brief description of
their assemblies is presented in Table 1. For further illustration, Fig. 1 shows cross sectional areas of samples of these systems.
THE CASE STUDY (Exterior Building Wall Systems) (continued) THE CASE STUDY (Exterior Building Wall Systems) (continued)
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• The method will consist of subjecting the different wall
systems to certain screening processes, namely • feasibility ranking, • evaluation by comparison, • weighted evaluation which involves
• criteria evaluation, and• matrix evaluation.
• The method will consist of subjecting the different wall
systems to certain screening processes, namely • feasibility ranking, • evaluation by comparison, • weighted evaluation which involves
• criteria evaluation, and• matrix evaluation.
APPLICATION OF THE METHODAPPLICATION OF THE METHOD
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IGN • As a rough screening process, five factors were used for the
first filtering process of judging alternatives. Field experience should be used to reach a decision at this filtering process.
• These five factors are state of the art of the idea, cost to
develop the idea, probability of implementation, time to implement and potential benefit.
• These factors are scored on a one to 10 basis, with 10 being the
score for least cost, least time, most benefit, highest probability of implementation, and most current state of the art.
• The feasibility ranking of the exterior wall system alternatives
is given in Table 2.
• As a rough screening process, five factors were used for the first filtering process of judging alternatives. Field experience should be used to reach a decision at this filtering process.
• These five factors are state of the art of the idea, cost to
develop the idea, probability of implementation, time to implement and potential benefit.
• These factors are scored on a one to 10 basis, with 10 being the
score for least cost, least time, most benefit, highest probability of implementation, and most current state of the art.
• The feasibility ranking of the exterior wall system alternatives
is given in Table 2.
FEASIBILITY RANKING FEASIBILITY RANKING
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• A decision is now made by the evaluator to drop those ideas whose total points are below a certain number, namely 30 points.
• Therefore, five alternative ideas are dropped: double faced
rubble wall, metal framed wall, plastic wall panel , timber wall panel, and glass wall system.
• As can be seen, scoring in the first screening step is subjective. • This is mainly due to the fact that what might be new
technology to one person, might not be so to another. However, no alternative is discarded without being scored.
• A decision is now made by the evaluator to drop those ideas whose total points are below a certain number, namely 30 points.
• Therefore, five alternative ideas are dropped: double faced
rubble wall, metal framed wall, plastic wall panel , timber wall panel, and glass wall system.
• As can be seen, scoring in the first screening step is subjective. • This is mainly due to the fact that what might be new
technology to one person, might not be so to another. However, no alternative is discarded without being scored.
FEASIBILITY RANKING (Continued) FEASIBILITY RANKING (Continued)
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IGN • The remaining alternatives will be subjected to a second
screening process, called evaluating by comparison, in which the advantages and disadvantages of each alternative are listed.
• Then ranks are given based on a subjective assessment by the
evaluator of the relative advantages or disadvantages of each alternative.
• The advantages and disadvantages may be equal in number,
but they will not be equal in strength or importance. Evaluation by comparison is presented in Table 3.
• A decision is made to drop those ideas whose ranking is above
four. Therefore, four alternative ideas were dropped:
• The remaining alternatives will be subjected to a second screening process, called evaluating by comparison, in which the advantages and disadvantages of each alternative are listed.
• Then ranks are given based on a subjective assessment by the
evaluator of the relative advantages or disadvantages of each alternative.
• The advantages and disadvantages may be equal in number,
but they will not be equal in strength or importance. Evaluation by comparison is presented in Table 3.
• A decision is made to drop those ideas whose ranking is above
four. Therefore, four alternative ideas were dropped:
EVALUATION BY COMPARISON EVALUATION BY COMPARISON
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• The performance criteria that are considered to be important in the final selection of exterior wall system alternatives, were obtained from a survey of professional designers and consultants.
• These criteria were evaluated through a survey of 25 randomly
selected designers and consultants
• The purpose of conducting this survey was to test the soundness of these criteria and to see whether any more criteria
• In order to get a relative weight of each criterion, the
techniques of probability and expected value were used..
• The performance criteria that are considered to be important in the final selection of exterior wall system alternatives, were obtained from a survey of professional designers and consultants.
• These criteria were evaluated through a survey of 25 randomly
selected designers and consultants
• The purpose of conducting this survey was to test the soundness of these criteria and to see whether any more criteria
• In order to get a relative weight of each criterion, the
techniques of probability and expected value were used..
CRITERIA EVALUATION CRITERIA EVALUATION
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• Table 4 shows the evaluation terms with their weights. • Table 5 illustrates the criteria with the various responses • Expected value of responses (E(x)), mean response, severity
indices (S.I.), and ranking as obtained from the survey findings.
• No additional comments regarding additional criteria were
obtained from the survey.
• The result of the survey as shown in Table 5 indicates that all sixteen criteria are important for an evaluation and thus, they will be used to evaluate the wall systems.
• Table 4 shows the evaluation terms with their weights. • Table 5 illustrates the criteria with the various responses • Expected value of responses (E(x)), mean response, severity
indices (S.I.), and ranking as obtained from the survey findings.
• No additional comments regarding additional criteria were
obtained from the survey.
• The result of the survey as shown in Table 5 indicates that all sixteen criteria are important for an evaluation and thus, they will be used to evaluate the wall systems.
CRITERIA EVALUATION (Continued) CRITERIA EVALUATION (Continued)
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• The four alternatives which passed the two filtering processes are now subjected to a third screening process called weighted evaluation.
• This system of evaluation is divided into two processes:
• paired comparisons of criteria and
• matrix evaluation.
• The four alternatives which passed the two filtering processes are now subjected to a third screening process called weighted evaluation.
• This system of evaluation is divided into two processes:
• paired comparisons of criteria and
• matrix evaluation.
WEIGHTED EVALUATION WEIGHTED EVALUATION
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IGN • Fig. 2 illustrates the methodology used to compare the
performance criteria in order to determine the weight of each criterion.
• Each of the sixteen criteria is assigned a letter of the alphabet and then compared with each of the other criteria based on the preference of the owner and/or the designer for each particular project.
• The importance of one criterion over another can be major,
“4”, medium, “3”, minor, “2”, and slight, “1”. • After all comparative evaluations are made, the raw score of
each criterion is totaled by summing the assigned letters in the matrix.
• Now, the raw scores are adjusted to a scale of 1-10 with 10 being assigned to the criterion with the highest raw score, and the other criteria adjusted accordingly as shown in Table 6
• Fig. 2 illustrates the methodology used to compare the performance criteria in order to determine the weight of each criterion.
• Each of the sixteen criteria is assigned a letter of the alphabet and then compared with each of the other criteria based on the preference of the owner and/or the designer for each particular project.
• The importance of one criterion over another can be major,
“4”, medium, “3”, minor, “2”, and slight, “1”. • After all comparative evaluations are made, the raw score of
each criterion is totaled by summing the assigned letters in the matrix.
• Now, the raw scores are adjusted to a scale of 1-10 with 10 being assigned to the criterion with the highest raw score, and the other criteria adjusted accordingly as shown in Table 6
PAIRED COMPARISONS OF CRITERIA PAIRED COMPARISONS OF CRITERIA
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IGN • In this process, all remaining alternatives from the previous
screening stages will be evaluated against the above-mentioned criteria.
• It is assumed that all the alternatives that have survived meet
the minimal needs or basic functions of the owner or the user. • The scoring system used in this analysis matrix involves
assigning 1 to 5 points on a scale of poor to excellent. The ranks of each alternative were multiplied by the corresponding weights of the criteria, and the resulting scores entered into the matrix.
• The total scores were then determined for each alternative.
• In this process, all remaining alternatives from the previous screening stages will be evaluated against the above-mentioned criteria.
• It is assumed that all the alternatives that have survived meet
the minimal needs or basic functions of the owner or the user. • The scoring system used in this analysis matrix involves
assigning 1 to 5 points on a scale of poor to excellent. The ranks of each alternative were multiplied by the corresponding weights of the criteria, and the resulting scores entered into the matrix.
• The total scores were then determined for each alternative.
THE EVALUATION MATRIX THE EVALUATION MATRIX
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• Based upon the previous analysis, the insulated reinforced block cavity wall system is considered the best choice.
• Based upon the previous analysis, the insulated reinforced block cavity wall system is considered the best choice.
CONCLUSION CONCLUSION
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• Al-Hammad.A. and Hassanain A.”Value Engineering in the Assessment of Exterior Building Wall Systems” Journal of Architectural Engineering,1996,Vol.2 No.3.
• Green,R.”Principles of Construction”,1986, 1st Ed. Longman Scientific & Technical ,Singapore.
• Parker,D.E.”Value Engineering Theory”,1985,The Lawrence D. Miles,Washington.D.C.
• Rosen,P.E. and Bennett,R. A.”Construction Materials Evaluation And Selection A Systematic Approach”,1979,John Wilely & Sons Inc. New York,N.Y.
• Al-Hammad.A. and Hassanain A.”Value Engineering in the Assessment of Exterior Building Wall Systems” Journal of Architectural Engineering,1996,Vol.2 No.3.
• Green,R.”Principles of Construction”,1986, 1st Ed. Longman Scientific & Technical ,Singapore.
• Parker,D.E.”Value Engineering Theory”,1985,The Lawrence D. Miles,Washington.D.C.
• Rosen,P.E. and Bennett,R. A.”Construction Materials Evaluation And Selection A Systematic Approach”,1979,John Wilely & Sons Inc. New York,N.Y.
REFERENCES REFERENCES
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TABLE 1: Exterior Wall Systems TABLE 1: Exterior Wall Systems No SYSTEM SYSTEM ASSEMBLIES
1 Rough stone over reinforced concrete back up wall Consist of two wythes of rough stone and reinforced concrete without air space between.
2 Double faced rubble wall Consist of large roughly square stones (uncoursed) bonded with mortar.
3 Solid reinforced brick wall Solid brick masonry units with steel reinforced to support loads. All joints are filled with mortar.
4 Reinforced brick cavity wall with insulation Consist of two wythes of reinforced brick masonry with air space and insulation in between.
5 Solid reinforced block wall Solid block masonry units with steel reinforcement to support loads. All joints are filled with mortar.
6 Reinforced block cavity wall with insulation Consist of two wythes of reinforced block masonry with air space and insulation in between.
7 Metal framed wall Un-insulated Steel or Aluminum cladding panels
8 Metal framed sandwich panel with insulation Steel or Aluminum infill panels with slight air space and insulation in between.
9 Precast concrete wall panel Precast concrete wall panels, cured off site.
10 Precast concrete wall panel with insulation Insulated precast concrete wall panels, cured off site
11 Plastic wall panel Prefabricated large panels of glass.
12 Timber wall panel Wall sheathing applied directly to wooden studs.
13 Plain monolithic concrete wall Cast-in-situ concrete containing no reinforcement other than that which may be provided to reduce shrinkage cracking.
14 Glass wall Large panels of glass cladding.
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TABLE 2: Feasibility Ranking TABLE 2: Feasibility Ranking No List of Alternatives State of
the artCost to develop
Prob. Of implement
Time to implement
Potential benefit
Total
1 Rough stone over rein. conc. back up wall
8 4 7 4 8 31
2 Double faced rubble wall 6 7 1 4 5 23
3 Solid rein. brick wall 3 5 9 10 8 35
4 Rein. brick cavity wall with insulation 7 6 6 9 9 47
5 Solid rein. block wall 5 7 10 7 9 38
6 Rein. block cavity wall with insulation 7 7 9 7 8 38
7 Metal framed wall 6 5 3 4 5 23
8 Metal framed sandwich panel with insulation
6 5 4 4 7 26
9 Precast conc. wall panel 10 9 7 7 3 36
10 Precast conc. wall panel with insulation
10 8 8 6 6 38
11 Plastic wall panel 7 6 2 2 1 18
12 Timber wall panel 4 3 3 5 2 17
13 Plain monolithic conc. wall 6 7 8 6 3 30
14 Glass wall 9 5 7 7 2 30
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TABLE 3: Evaluating by Comparison TABLE 3: Evaluating by Comparison No Idea Advantages Disadvantages Rank
1 Rough stone over reinforced concrete back up wall system
1. Better aesthetics2. Less maintenance3. Durable material and finish4. Efficient energy performance
1. Require skilled labor2. High initial cost of material3. Long construction time
8
2 Solid reinforced brick wall system
1. Less maintenance2. Low initial cost3. Materials are available
1. Thermal heat gain2. Large material wastage3. Long construction time
6
3 Reinforced brick cavity wall system with insulation
1. Efficient energy performance2. Low initial cost3. Materials are available
1. Large material wastage2. Large construction time
4
4 Solid reinforced block wall system
1. Durable wall system2. Low initial cost3. Materials are available
1. Thermal heat gain2. Frequent maintenance3. Long construction time
7
5 Reinforced block cavity wall system with insulation
1. Efficient energy performance2. Low initial cost3. Materials are available4. Durable wall system5. Less maintenance
1. Long construction time 2
6 Precast concrete wall panel system
1. Better aesthetics2. No required maintenance3. Durable material4. Fast construction time5. Better quality control 6. Included wall texture7. Reduction in weight
1. Transportation arrangement2. Thermal heat gain
3
7 Precast concrete wall panel system with insulation.
1. Better aesthetics2. No required maintenance3. Durable material4. Fast construction time5. Better quality control 6. Included wall texture7. Efficient energy performance8. Reduction in weight
1. Transportation arrangement
1
8 Plain monolithic concrete wall system
1. Low initial cost3. Materials are available4. Durable wall system
1. Thermal heat gain2. Frequent maintenance3. Long construction time
5
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TABLE 4: Evaluation Terms and their Weights TABLE 4: Evaluation Terms and their Weights
Evaluation Term Assigned Weight
Extremely Important 5
Major Importance 4
Important 3
Minor Importance 2
Slightly Important 1
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FIG. 2. Criteria Scoring Matrix FIG. 2. Criteria Scoring Matrix
B C D E F G H I J K L M N O P
A A-3 A-3 A-2 A-2 F-3 A-3 A-4 A-2 A-K A-3 A-2 A-2 A-3 A-2 P-4
B B-3 B-3 B-E F-4 B-3 B-3 B-2 B-2 K-4 B-2 B-3 B-2 B-3 P-3
C D-3 D-2 F-4 C-3 H-4 I-3 J-3 C-2 C-3 C-3 N-2 O-3 P-4
D E-3 F-3 D-3 H-3 D-2 D-4 K-4 D-3 D-3 D-2 D-2 P-4
E F-4 E-3 E-H E-3 E-3 K-4 E-2 E-2 E-3 E-2 P-3
F F-4 F-3 F-4 F-3 F-3 F-4 F-4 F-2 F-3 F-P
G H-2 I-3 J-3 K-3 L-3 G-2 N-2 O-2 P-4
H H-3 H-4 K-3 H-2 H-3 H-2 H-3 P-4
I I-3 K-3 I-L I-M I-2 I-2 P-3
J K-3 L-3 M-2 N-3 O-4 P-3
K K-3 K-4 K-2 K-3 P-K
L L-M L-O L-3 P-4
M M-3 M-2 P-3
N N-2 P-2
O P-2
1. Slight, No Performance
How Important:
4. Major Performance
3. Medium Performance
2. Minor Performance
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TABLE 6: Evaluation Terms and their Weights TABLE 6: Evaluation Terms and their Weights No. Criteria Raw Score Assigned Weight
A Structural satiability 32 6.5
B Strength 27 5.5
C Exclusion of rain and water 11 2.2
D Durability 22 4.5
E Fire safety 25 5.1
F Initial cost 49 10.0
G Flexibility 2 1.0
H Maintainability 27 5.5
I Thermal properties 15 3.1
J Acoustical properties 6 1.2
K Construction time 37 7.6
L Availability 12 2.5
M Compatibility 9 1.8
N Security 9 1.8
O Aesthetics 9 1.8
P Maintenance cost 45 9.2
29C
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TABLE 7: The Analysis Matrix TABLE 7: The Analysis Matrix
Rank Score Rank Score Rank Score Rank Score
Structural satiability 6.5 3 19.5 5 32.5 4 26 5 32.5
Strength 5.5 2 11 3 16.5 4 22 4 22Exclusion of rain and water
2.2 3 6.6 4 8.8 4 8.8 4 8.8
Durability 4.5 3 13.5 4 18 3 13.5 3 13.5
Fire safety 5.1 2 10.2 3 15.3 2 10.2 2 10.2
Initial cost 10 3 30 5 50 3 30 4 40
Flexibility 1 2 2 3 3 3 3 3 3
Maintainability 5.5 1 5.5 5 27.5 3 16.5 3 16.5
Thermal properties 3.1 3 9.3 4 12.4 1 3.1 4 12.4
Acoustical properties 1.2 1 1.2 3 3.6 2 2.4 3 3.6
Construction time 7.6 2 15.2 5 38 3 22.8 3 22.8
Availability 2.5 3 7.5 4 10 3 7.5 3 7.5
Compatibility 1.8 2 3.6 4 7.2 2 3.6 2 3.6
Security 1.8 3 5.4 3 5.4 4 7.2 4 7.2
Aesthetics 1.8 2 3.6 4 7.2 5 9 5 9
Maintenance cost 9.2 2 18.4 5 46 3 27.6 3 27.6
Total scores --- --- 162.5 --- 301.5 --- 213.2 --- 240.2
Precast concrete wall panel
Insulated precast concrete wall panel
ALTERNATIVES
Insulated reinforced brick cavity wall
Evaluation criteriaAssigned
weightInsulated reinforced
block cavity wall
30C
OLLEGE
COLLEGE
OF
EN
VIR
ON
ME
NT
AL
DE
SIG
N O
F E
NV
IRO
NM
EN
TA
L D
ES
IGN
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