This course introduces the types of cost estimation from the conceptual design phase through the more detailed design phase of a construction project. In addition, the course highlights the importance of controlling costs and how to monitor project cash flow. Students will work on a break-even analysis of construction tasks in a project.
Lean Set Based Design
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En provenance du cours de Columbia University
Construction Cost Estimating and Cost Control
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À partir de la leçon
Lean in Cost Control
Sam Spata, Owner of Method Lean, presents this module on Lean In Cost Control.
Rencontrer les enseignants
Ibrahim Odeh, Ph.D., MBAInstructor, Department of Civil Engineering and Engineering Mechanics, Columbia University
Director of Research and Founder, Global Leaders in Construction Management
Now segmented and holistic,
here's where the parallel thinking, the batch thinking comes together.
In that example, this is the actual project as it was completed,
that mid-town tower.
We knew from the value proposition that on the economy side, maximizing FAR was key.
We needed to build every square foot to maximize the return on the investment.
Now when you look at floor are ratio, we're looking what architects we call
massing concepts, how does the building stack as it goes up?
That is an impact on elevatoring system because banks of elevators will drop
off at different levels, the current wall is affected, more corners.
You could have more high wind at areas, the Superstructures certainly
affected turns out do you have column setbacks or columns dropping out?
Are you picking up with a girder?
And the foundations,
how is that dead load and wind load getting transferred to the ground?
It could vary depending on that massing concept.
So if you took a section through the building
Well a good solution be a tall building, that had one floor plan,
went all the way up if you will, with a set back plaza.
But that wouldn't work, so well urbanistically.
Didn't work for what the clients wanted.
Floor place be getting a little too small,
it would not have been something easy to rent.
So another concept is to say,
well better what if we simply do a sloping mold that follows the zoning.
Envelope the sky exposure plane as defined in the New York City code,
Pottimy Zoning Resolution that was a better solution.
But the best solution turned out to be the traditional wedding cake solution for
New York City Towers.
Put in a series of set backs when we look at the cost for each of these, and
this is done parametrically at a very high conceptual level.
We're able to make a decision looking at this set of designs and
say we're going to go with the best one.
And that set,
once decided, started to inform all the other systems of the building.
Elevatoring, curtain wall, superstructure, foundations, etc.
We took the segment of the building, we looked at the base building.
We looked at it holistically, different elements affecting.
And we consider their impact on cost, their impact on function, impact on form
in terms of what does the market want, impact on schedule, and made a decision.
And the continuous parametric estimate is what helped us.
We looked in swim-lanes for major building system costs, we could use rules of thumb.
We know that if the best concept here,
if that allowed us to hit 17 and a half pounds per square foot on average,
of superstructure, we knew what that cost was going to come in at that market.
We used rules-of-thumb with people experienced in the marketplace.
So the swim lanes, the continuous estimating, looking at the systems
in a parametric basis, at a high level allowed good decision making.
This is a very successful project as you can see it has been completed fully
occupied and money, in this process as I like to say should be fundable.
We want to be able to look good better and best and
see what are the impacts on major systems.
So that for example in this one we have a total allowable cost which
does not change in each of those concepts.
But what does change is the line item transfer, where are we spending the money.
As we refine the structural system, we don't need pickups we can do something
better, we can reduce that budget for structure.
And refine our curtainwall and spend the money over there because we know that that
will have a bigger return, it will get us the kind of attendance we want.
Particular if we can spend more money down at the first few levels at grade and
create a store front and curtainwall experience that really has curb appeal.
So money has to be fungible in target value design.
We want to be able on a parametric basis to know what is system a cost,
reduce it and spend it where it has the most value for the owner.
Now as a designer a rule that I've used,
my rule number three, this is something I was using well before I learned about TVD.
And I would advise everyone, you can never expect design to budget
responsibility without the authority for line item transfer.
You can commit to hit a total cost, but market conditions,
escalation, trade, things change from project to project.
You need the ability to reduce cost in one area to spend elsewhere,
or reduce cost to simply stay within the allowable cost.
You have to have that authority if you're going to design to budget.
We want to look at those building costs at a high level on a systems basis.
Remember the nine typologies early?
These are just five of them and
that's a pretty big variation on a system by system basis.
But the importance is, in the early stages, you can effect changes
in a cost on a system basis in early design stages but
you can't do it very easily on a trade basis.
There are several trades involved in a foundation.
You've got excavators, you got concrete, you've got people tying rebar, form work,
laborers, hoisting, there's a lot involved to your ordering.
You don't need that detail.
What you need to know is what should my foundation cost
when normalized to my project time and place.
You want to think on a system's basis because that's where you can revise
a design concept and actually predict a cost.
You can either accurately nor precisely predict the impact on all the system's
components but you can know enough about the system to make good decisions.
Good, better, and best systems to keep your project on budget.
Traditional versus continuous estimating the traditional estimate is very detailed.
It's produced at the end of a milestone and we may find that that milestone tells
us we've over designed where blown the budget, and the generally few iterations.
Whereas continuous estimating sees the big picture,
it drives you to the milestone and has many iterations.
So let's recap set-based design, you get a design space and
that design space in the example we looked at was the zoning envelope.
And that's within the conditions of satisfaction directly flowing from
the owner's value proposition.
We did set narrowing, we had a set of three ways to achieve the maximized
zoning envelope and we made our decision at the latest possible moment.
We looked at the concurrent building system,
subsegments of that base building massing.
We made the decision, so
in the validation is where are set our baseline for selection.
The validation publish process told us where we needed to be in terms our
reliable cost, the impact on other systems and
that's how we can choose which set at the less responsible moment.
Which point in that design set is the one to go forward with and
the one we went forward with in design is the one that was built.
Choosing by advantage as we've looked at earlier in our Introduction to lean,
I'll just go to very quickly here.
The five bits of it are the alternative an option subject to choice, an attribute,
a quality of only one alternative, the factor,
that's an elemental part of a decision.
And you can think of those problem statements like function, form,
economy, time has major factors which would have sub-factors within them.
The criteria is something measurable, the standard on which to base your decisions,
something to measure.
And the advantage is the beneficial difference between different attributes.
It all is based on this idea that decisions must be made
on the importance of advantages.
In our example of the midtown tower, we looked at the different advantages for
different ways of meeting the zoning regulations and
staying within the sky exposure plain.
We look at the advantages, this traditional wedding cake
set back is the one that really met the advantages best.
You could use buying advantages in lots of different ways.
In this case, this was for a university happen to be in Saudi Arabia and we're
looking at important tenant within that space department, where do we put them?
And in that case there we were choosing by advantages.
We have alternative, we had factor each factors had a criteria and
that we measured and
as we do in choosing by advantages we look at what the paramount advantage.
And in this case was productivity getting space that allow those people in
that department to do their job best.
But we also overlayed colors, we use a traditional red,
yellow and green approach.
Colors may not quite look like that but that's okay, because for
that organizations culture they were used to seeing alternatives presented that way.
And the point to that story is it's okay to take a lean process and
adapt it to the culture in which you're trying to communicate and
that's what we did for choosing by advantages.
A3 thinking is a way of looking at a single problem and
figuring out how do I solve it.
This is a problem for Lean strategy for owners, consultants, designers, and
constructors.
And it is the standard A3 thinking of a theme at the top, you define
the background, what's the current condition, do a root cause analysis.
Which then leads you to okay, whats my plan, what do I want to implement,
what are the targets I want to hit?
And finally, your metrics, you can use the A3 thinking to look at for
example, how do I hit a envelope?
We actually did some A3 thinking there earlier when we talked about
the background, the value proposition.
What are the conditions?
Well, we've got a site, we've got the zoning regulations, what does it mean?
What's the route that we're trying to get at?
Well, we want to get systems that work within an envelope.
Look at different ways to implement it with set-based design,
we looked at the different points.
And we picked one, we followed up and
we knew we were right in terms of we hit our budget, we hit our schedule.
And we got to the market with a product, rentable commercial space,
that the market wanted, so let's recap.
The information index is a process that begins with broad aspirations, goals.
It develops the detailed requirements and
concludes with problem statements that summarize the owner's value expectations.
Value waste flow, most fundamental parts of Lean.
The system-driven estimating
the milestones enable our next steps.
We don't want to get to a milestone and look at the next bit and say,
we have to go back, we've blown the budget.
We want to get to each milestone so that it enables the next step in the process,
we use the big four processes of Lean.
Pull-planning, target value design, set based design, choosing by advantages.
And the foundational elements of our lean theory and vision or
what in form are used of those processes, the tools and habits of lean.
Target Value Design is what lean estimating
is all about the market value which we derive from benchmarks or
on the standing of the market and we normalize variables.
We set the market cost and set our allowable cost below the market,
we intentionally aim low as a forcing function.
Because what we're finding is that when good collaborative teams,
designers, constructors, owners, work together to hit a target,
they over shoot and we start delivering the same value for less money.
We use parametric estimating because we dont need the waste of all the processing
and delivering a detail, that's I mean too soon.
We're estimators, we have ambiguous, complicated, incomplete data.
We want to look at the parameters for
numbers because that's what drives our decision making.
We use set based design to meet those numbers.
We segment the building and we segment cost and use a holistic process.
We didn't just think about a zoning envelope, we thought about it's impact on
curtain wall, elevator systems, structure, the core, the lobby.
We conceptualize and we decide at the last responsible moment and
that's what pole planning was all about.
Where we in a live audience I would now, at this point, ask for your feedback.
I'm still going to ask for it, I can be reached and
the two types of feedback we look at are first, the takeaway intent.
What did you, the audience, take away from this course?
And then I compare that to what did I, the speaker, intend.
And where there's a gap,
that means I need to do a better job as a speaker to get that intention across.
And the second tool we use for feedback is a continuous improvement tool,
a lean tool, the plus delta.
What was helpful so
far in this course on lean estimating that should continue to be included?
And what would you add or subtract to make this more helpful.
Thank you, and I hope you found this helpful.
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