MCDM

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MCDM23
A Multi-Criteria Decision Support Method
for Whole Building Solar Design
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MCDM-23 was developed within International Energy
Agency Solar Heating and Cooling Task 23
Optimization of Solar Energy Use in Large
Buildings
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Requirements forSuccessful Solar Building Design

• Start with a client and design team committed to
  high per-formance, and willing to alter the
  normal design process

• Select a design team with a wide range of
  technical skills

Integrated Design

• Add an energy engineer and other relevant
  specialists to the team

• Commence with teamwork from the very start of the
  Pre-design Stage

• Define performance goals at the outset and
  referring to them throughout

• Use new methods and tools throughout the process

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MCDM23 seeks to facilitate some ofthe
challenges of integrated design

• Application and integration of knowledge and
  judgements from a range of experts from different
  disciplines
• Balanced specification and integration of
  design criteria that are incommensurate and may
  be conflicting (e.g. economics vs. environment,
  aesthetics, etc.)
• Balanced integration of both quantitative and
  qualitative performance criteria (qualitative
  criteria tend to be under-valued or poorly
  documented)

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• Problems in doing tradeoffs
• Criteria have different units (kWh, , kg of
  SO2, percent satisfied, score on a scale of ten,
  etc.)
• Some are quantitative, some are qualitative
• For some, smaller is better (resource use), for
  others, bigger is better (quality issues)

How to picture diverse criteria together so we
can decide between alternatives?
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MCDM-23 isa structured approach to

• Make judgements and values explicit to promote
  learning and cooperation across disciplines and
  to reach a common understanding of the overall
  design problem
• Handle values and judgements alongside
  quantitative assessments in order to clearly see
  the overall goodness of the design
• Help organize and select relevant information and
  to focus on the most important issues

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WHO should use MCDM23?

• In the building design process All members of
  the design team, including the client
• In a design competition The competition
  organizers and the judging committee
• A person needs to be appointed to organize the
  work with the method and to take care of the
  mechanics of aggregating the information

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WHEN should MCDM23 be used?

• For selecting and specifying design criteria in
  the pre-design phase, and for prioritizing among
  design criteria
• For evaluating alternative design strategies and
  solutions at various stages in the design process

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WHAT is MCDM23?
A method and tool based on CRITERIA, WEIGHTS AND
SCORES that is a means to encourage the members
of the design team to make their knowledge,
values and judgements EXPLICIT - so that the
other members (and the outside world) can better
understand, learn and interact!
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STEPS in MCDM23
Step 1 Select and describe main criteria and
sub-criteria Step 2 Develop measurement scales
for sub-criteria Step 3 Weight the main criteria
and sub-criteria Generate alternative
solutions Step 4 Predict performance Step 5
Aggregate scores Step 6 Analyze results and make
decisions
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STEP 1
DESCRIBE, SELECT, AND STRUCTURE CRITERIA

• Top-down approach Start with overall objectives,
  then go into details
• Bottom-up approach Test the criteria on relevant
  alternatives (cases)
• Start out wide (use check lists), then narrow in
• Document the reason why a criterion is important
• Irreversible consequences?
• Wide ranging consequences?
• Far from fulfilling national goals?

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STEP 1
DESCRIBE, SELECT, AND STRUCTURE CRITERIA
Advantages of a hierarchical structure
main goal (optimal housing area)

• Lower-level criteria explain the concrete meaning
  of upper-level criteria
• Helps sorting out redundancies and double
  counting
• Allows keeping the overview as well as going into
  the details

Main criteria (e.g resource use, functionality,
comfort)
Sub-criteria (e.g. energy use)
Indicators (e.g. kWh/m2)
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Example of criteria set for main criterion
Resource Use
Sub-criteria Sub-sub-criteria Indicators Energy
Net use of energy MJ/m²/person Land Net
area of land used m²/occupant Change in
ecological value judgement Water Net
consumption of water m³/year/person Materials Re
tention of existing building of floor
area Use of recycled materials of
cost Re-useable materials of
cost Re-cyclable materials of cost
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STEP 2
DEVELOP MEASUREMENT SCALES FOR SUB-CRITERIA
Score Judgement 10 excellent 9
8 good 7 6 fair 5 4 marginally
acceptable
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Example of measurement scalefor quantitative
criteria
Annual Electric Use
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Example of measurement scalefor qualitative
criteria
Adaptability
Score
Judgement
10
excellent
Different clients without change
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Different clients by moving
a
d
justable partitions
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good
Different clients by rebuilding non-
load bearing part
i
tions
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Different clients by rebuilding some
non-load bearing partitions
6
fair
Different clients by rebuilding
mostly non-load bearing part
i
tions
5
Different clients by rebuilding all
load bearing partitions
4
marginally accep
t
able
Not adaptable to different cl
i
ents
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The value of creating scales

• Generates a concrete discussion about how the
  building should perform
• The process of setting end-points leads to an
  active search for alternative options Can we
  not do better than that?
• Facilitates interpretation of criteria the same
  words may have different meanings for different
  individuals
• Helps define the general nature and context of
  the problem - may lead to restructuring of the
  model
• Allows each member of the team to express his or
  her own expertise to the group as a whole

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STEP 3
WEIGHT THE MAIN CRITERIA AND SUB-CRITERIA
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Example of weighing using the tool
Pie chart button displays graphic
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The value of weighting

• Make values and hidden judgementsexplicit to the
  group as a whole
• Generates discussion and visualizesdifferent
  viewpoints
• May lead to a redefinition of the scales
• Helps focusing on the mostimportant issues

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GENERATE ALTERNATIVE SOLUTIONS

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STEP 4
PREDICT PERFORMANCE using

• computer simulations
• databases
• rules of thumb
• experience
• expert judgement

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Enter the number in the program
Click the button to plot the value on the value
graph
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STEP 5
AGGREGATE SCORES
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STEP 6
ANALYZE RESULTS AND MAKE DECISIONS
After entering all the values for all the
schemes, there are four results options 1)
Worksheet for each scheme 2) Star diagram for
each scheme 3) Summary bar graph showing all
schemes 4) Summary table showing all
schemes Tables can be exported as comma-delimited
files. Diagrams can be copied to the clipboard.
Both can be printed.
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Worksheet
Provides documentation of the process
Scheme B is not so good ( 5.6 out of 10 )
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Star Charts
Functionality
Functionality
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Bar Graphs
Functionality
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Summary Table
This table was generated automatically in
MCDM-23, copied directly from the screen, and
pasted into this presentation. It can also be
exported as a csv file.
Scheme A is the best ( 8.98 out of 10 )
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CONCLUSION
MCDM23 is a means to organize the multi-criteria
design work and to
understand and learn about whats important NOT
to produce the right answer!