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.obsidian/bookmarks.json
Vendored
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@@ -14,6 +14,11 @@
"type": "file",
"ctime": 1761313177282,
"path": "nfpa-70_national-electric-code.md"
},
{
"type": "file",
"ctime": 1766074735360,
"path": "consolidate-estimating-thoughts.md"
}
]
}
2025-12-18.md
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---
id:
aliases: []
title: "2025-12-18"
tags:
- authorship/original
- destiny/permanent
- status/draft
- type/daily
---
# 2025-12-18
## 2025-12-18 08:32
[[uncertainty-in-construction-estimating]]
## 2025-12-18 10:38
#topic/meta
I definitively think my new approach
of putting nascent ideas in daily notes
rather than separate fleeting notes
is superior.
The unfortunate reality is I'll never look at most of them again,
so better that they don't crowd out my main notes.
## 2025-12-18 14:18
What interests me most in [[construction-estimating]]
is an idea you might call "estimating golf":
the goal is to produce a satisfactory[^1] estimate,
the estimator can not view the project documents
and must ask questions about the job
(answerable in a sentence or less)
of a neutral party ("the reader").
The estimator fails if the estimate is unsatisfactory[^1],
but otherwise is scored by number of questions asked.
[^1]: satisfactory in terms of accuracy and precision,
according to the standards of the organization.
a control estimate must be prepared accordingly
by a neutral party ("the control").
You could further imagine different brackets
for required accuracy and precision,
whether organization historicals are freely available
or must be questioned like project details.
The most interesting part of this problem is choosing when to stop,
since it requires one to estimate their certainty of their estimate.
## 2025-12-18 15:22
PDI has moved up the schedule to transition to Accubid Anywhere
and will be signing a contract with Trimble in late January.
[Drawer AI | Automated Electrical Takeoff & Estimating](https://drawer.ai/)
## 2025-12-18 15:30
[Kip (unit) - Wikipedia](https://en.wikipedia.org/wiki/Kip_\(unit\))
[Construction Cost Estimating](https://www.quantity-takeoff.com/index.htm)
actuarial-science-for-construction-estimating.md
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@@ -22,3 +22,5 @@ In this way, projects are better compared to _insurance accounts_.
* cost of individual service is uncertain
* cost to customer must be minimized
![[decrease-in-sigma#^pdf]]
actuarial-science.md
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@@ -13,6 +13,10 @@ tags:
[actuarial science](https://en.wikipedia.org/wiki/Actuarial_science)
Divorced from its traditional context of insurance,
actuarial science is determining the optimal price of a service
given [[uncertainty|uncertain]] cost.
## Terms
* [discounted cash flow](https://en.wikipedia.org/wiki/Discounted_cash_flow)
bid-price-modeling.md
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@@ -55,7 +55,7 @@ $$
\Phi : \mathcal{P}([0,\infty)) \to [0,\infty),
$$
mapping a cost distribution $\mu_C$ to a scalar.
mapping a cost distribution $\mu_C$ to a **scalar** (a single value).
Examples of such functionals include:
carbon-monoxide-detection-takeoff.md
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@@ -4,7 +4,7 @@ aliases: []
tags:
- authorship/original
- destiny/permanent
- occupational/takeoff/standalone-systems
- occupational/takeoff
- status/draft
- type/guide
title: Carbon Monoxide Detection Takeoff
consolidate-estimating-thoughts.md
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@@ -30,11 +30,11 @@ Remove estimating-specific content from irrelevant notes.
Create and use cross-topic notes for complex thoughts:
* [[uncertainty-in-construction-estimating]]
* [[actuarial-science-for-construction-estimating]]
* [[risk-oriented-estimating]]
* [[risk-management-for-construction-estimating]]
* [[risk-oriented-estimating]]: resource allocation
* [[auction-theory-for-construction-estimating]]
* [[bid-process-strategy]]
@@ -58,7 +58,6 @@ Create and use cross-topic notes for complex thoughts:
* [[statistical-modeling-for-construction-estimating]]
* [[transparency-in-construction-estimating]]
* [[estimating-ethics]]
### Orphaned Notes
decrease-in-sigma.md
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# Decrease in Sigma
```tikz
\usepackage{pgfplots}
\pgfplotsset{compat=1.16}
\begin{document}
\begin{tikzpicture}
\begin{axis}[
width=13cm,
height=7cm,
axis lines=middle,
xlabel={$x$},
ylabel={$\varphi(x;\mu,\sigma)$},
xmin=-6, xmax=6,
ymin=0, ymax=0.85,
samples=400,
domain=-6:6,
legend style={draw=none, fill=none, at={(0.98,0.98)}, anchor=north east},
legend cell align=left,
ytick=\empty,
]
% Normal PDF: (1/(sigma*sqrt(2*pi))) * exp(-(x-mu)^2/(2*sigma^2))
\addplot[thick]
{ (1/(1.8*sqrt(2*pi))) * exp(-((x-0.8)^2)/(2*1.8^2)) };
\addlegendentry{$\mu=0,\ \sigma=1.8$}
\addplot[thick, dashed]
{ (1/(0.8*sqrt(2*pi))) * exp(-((x-0.8)^2)/(2*0.8^2)) };
\addlegendentry{$\mu=0,\ \sigma=0.8$}
\end{axis}
\end{tikzpicture}
\end{document}
```
^pdf
```tikz
\usepackage{pgfplots}
\pgfplotsset{compat=1.16}
\pgfmathdeclarefunction{erfapprox}{1}{%
\pgfmathparse{%
% save sign and work with |x|
( (#1<0) ? -1 : 1 )
* ( 1 - (1 + 0.278393*abs(#1) + 0.230389*abs(#1)^2 + 0.000972*abs(#1)^3 + 0.078108*abs(#1)^4)^(-4) )
}%
}
% Normal CDF using erf approximation:
% F(x;mu,sigma) = 0.5*(1 + erf((x-mu)/(sigma*sqrt(2))))
\pgfmathdeclarefunction{normcdf}{3}{%
\pgfmathparse{ 0.5*(1 + erfapprox((#1-#2)/(#3*sqrt(2)))) }%
}
\begin{document}
\begin{tikzpicture}
\begin{axis}[
width=13cm,
height=7cm,
axis lines=middle,
xlabel={$x$},
ylabel={$F(x;\mu,\sigma)$},
xmin=-6, xmax=6,
ymin=0, ymax=1.05,
samples=400,
domain=-6:6,
legend style={draw=none, fill=none, at={(0.02,0.98)}, anchor=north west},
legend cell align=left,
ytick={0,0.5,1},
]
% Normal CDF: 0.5*(1 + erf((x-mu)/(sigma*sqrt(2))))
\addplot[thick]
{ normcdf(x,0,1.8) };
\addlegendentry{$\mu=0,\ \sigma=1.8$}
\addplot[thick, dashed]
{ normcdf(x,0.8) };
\addlegendentry{$\mu=0,\ \sigma=0.8$}
\end{axis}
\end{tikzpicture}
\end{document}
```
distributed-antenna-systems-takeoff.md
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tags:
- authorship/original
- destiny/permanent
- occupational/takeoff/standalone-systems
- occupational/takeoff
- status/draft
- type/guide
title: Distributed Antenna Systems (DAS) Takeoff
@@ -22,17 +22,19 @@ title: Distributed Antenna Systems (DAS) Takeoff
> [!info] Cellular Systems
> Less common than ERRCS are "cellular DAS" systems
`COMMON ASSEMBLIES`/`FIRE ALARM & DAS SYSTEMS`/`DAS ASSEMBLIES`/...
## Backbone
### FACR to Every Elevator Shaft
1. `COMMON ASSEMBLIES`/`FIRE ALARM & DAS SYSTEMS`/`DAS ASSEMBLIES`/`FACR TO ELEV PIT = ...`
1. .../`FACR TO ELEV PIT = ...`
* **Length** = _Match Fire Alarm takeoff Length_
* **Count** = _Match Fire Alarm takeoff Count_
### FACR to Every Staircase
1. `COMMON ASSEMBLIES`/`FIRE ALARM & DAS SYSTEMS`/`DAS ASSEMBLIES`/`FACR TO STAIRWELL = ...`
1. .../`FACR TO STAIRWELL = ...`
* **Length** = _Match Fire Alarm takeoff Length_
* **Count** = _Match Fire Alarm takeoff Count_
@@ -40,22 +42,22 @@ title: Distributed Antenna Systems (DAS) Takeoff
1. * `Area` = "Typical - Stairwells Building Even Levels"
`COMMON ASSEMBLIES`/`FIRE ALARM & DAS SYSTEMS`/`DAS ASSEMBLIES`/`STAIRWELL RISER EVERY 2 FLRS = ...`
.../`STAIRWELL RISER EVERY 2 FLRS = ...`
* **Count** = Each stairwell
### FACR to Electric Room
1. `COMMON ASSEMBLIES`/`FIRE ALARM & DAS SYSTEMS`/`DAS ASSEMBLIES`/`FACR TO 2HR-RATED RM = ...`
* **Length** = _Match Fire Alarm takeoff Length_
1. .../`FACR TO 2HR-RATED RM = ...`
* **Length** = _Match Fire Alarm Terminal Cabinet takeoff Length_
### Electric Room Riser to Every Floor
1. `COMMON ASSEMBLIES`/`FIRE ALARM & DAS SYSTEMS`/`DAS ASSEMBLIES`/`2HR-RATED RM RISER TO EVERY FLR = ...`
1. .../`2HR-RATED RM RISER TO EVERY FLR = ...`
* **Count** = Each Electric Room
### Top 2H Rated Room To Roof
1. `COMMON ASSEMBLIES`/`FIRE ALARM & DAS SYSTEMS`/`DAS ASSEMBLIES`/`TOP 2HR RATED RM TO ROOF = ...`
1. .../`TOP 2HR RATED RM TO ROOF = ...`
* **Length** = Top level ceiling height to structure (minimum 15ft)
## Horizontal
@@ -64,5 +66,5 @@ title: Distributed Antenna Systems (DAS) Takeoff
> Usually only for cellular DAS.
> Confirm takeoff requirement with [[pdi-estimating#Bid Estimating|Bid]].
1. `COMMON ASSEMBLIES`/`FIRE ALARM & DAS SYSTEMS`/`DAS ASSEMBLIES`/`CORRIDORS ...`
1. .../`CORRIDORS ...`
* **Length** = Length measured for every corridor/garage
electrical-takeoff.md
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@@ -5,7 +5,7 @@ title: Electrical Takeoff
tags:
- authorship/original
- destiny/permanent
- occupational/takeoff/electrical
- occupational/takeoff
- status/draft
- type/guide
---
emergency-systems-research.md
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@@ -16,6 +16,8 @@ title: Emergency Systems Research
> * [[two-way-takeoff]]
> * [[distributed-antenna-systems-takeoff]]
[[wiring-method-selection]]
1. Find Fire Alarm plans (if present)
2. Locate the following rooms:
* Fire Command Center (FCC)
feeders-takeoff.md
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@@ -4,7 +4,7 @@ aliases: []
tags:
- authorship/original
- destiny/permanent
- occupational/takeoff/feeders
- occupational/takeoff
- status/draft
- type/guide
title: Feeders Takeoff
fire-alarm-takeoff.md
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@@ -1,13 +1,13 @@
---
id:
aliases: []
title: Fire Alarm Takeoff
tags:
- authorship/original
- destiny/permanent
- occupational/takeoff/fire-alarm
- occupational/takeoff
- status/draft
- type/guide
title: Fire Alarm Takeoff
---
# Fire Alarm Takeoff
@@ -28,46 +28,58 @@ _Mid Rise, High Density (Wood frame):_ Free air, conduit only where required.
## Backbone
Put all backbone takeoff in the `Area` of the Fire Command Center.
Include [[sleeving-takeoff]] as necessary.
`COMMON ASSEMBLIES`/`FIRE ALARM & DAS SYSTEMS`/...
### Fire Command Center
1. `COMMON ASSEMBLIES`/`FIRE ALARM & DAS SYSTEMS`/`HEAD END EQUIP`/`... HEAD END`
1. * `Area` = As shown.
* `Phase` = As shown.
.../`HEAD END EQUIP`/`... HEAD END`
### Generator Room
1. `Area` = Same as FACR
1. * `Area` = Same as FACR.
* `Phase` = Same as FACR.
`COMMON ASSEMBLIES`/`FIRE ALARM & DAS SYSTEMS`/`GEN, ELEV, FIRE PUMP & FA ROOM ASSEMBLIES`/`GENERATOR ROOM ...`
.../`GEN, ELEV, FIRE PUMP & FA ROOM ASSEMBLIES`/`GENERATOR ROOM ...`
### Fire Pump Room
1. `Area` = Same as FACR
1. * `Area` = Same as FACR.
* `Phase` = Same as FACR.
`COMMON ASSEMBLIES`/`FIRE ALARM & DAS SYSTEMS`/`GEN, ELEV, FIRE PUMP & FA ROOM ASSEMBLIES`/`FIRE PUMP ROOM ...`
.../`GEN, ELEV, FIRE PUMP & FA ROOM ASSEMBLIES`/`FIRE PUMP ROOM ...`
### Elevator Control Rooms
> Also "Elevator Machine Room"
* `Area` = Same as FACR.
* `Phase` = Same as FACR.
For each Elevator Control Room (ECR):
1. `COMMON ASSEMBLIES`/`FIRE ALARM & DAS SYSTEMS`/`GEN, ELEV, FIRE PUMP & FA ROOM ASSEMBLIES`/`ELEV CONTROL ROOM ...`
1. .../`GEN, ELEV, FIRE PUMP & FA ROOM ASSEMBLIES`/`ELEV CONTROL ROOM ...`
* **Count** = 1
2. `COMMON ASSEMBLIES`/`FIRE ALARM & DAS SYSTEMS`/`GEN, ELEV, FIRE PUMP & FA ROOM ASSEMBLIES`/`FACR TO ELEV CONTROL RM ...`
2. .../`GEN, ELEV, FIRE PUMP & FA ROOM ASSEMBLIES`/`FACR TO ELEV CONTROL RM ...`
* **Length** = Length measured from the most distant points of the FACR and ECR.
* Input adder length to reach the level of the ECR (Minimum 15ft).
* Input adder length to reach the level of the ECR (Minimum 15ft).
### Elevator Shafts
* `Area` = Same as FACR.
* `Phase` = Same as FACR.
For each elevator shaft:
1. `COMMON ASSEMBLIES`/`FIRE ALARM & DAS SYSTEMS`/`GEN, ELEV, FIRE PUMP & FA ROOM ASSEMBLIES`/`ELEV SHAFT ...`
1. .../`GEN, ELEV, FIRE PUMP & FA ROOM ASSEMBLIES`/`ELEV SHAFT ...`
* **Count** = 1
2. `COMMON ASSEMBLIES`/`FIRE ALARM & DAS SYSTEMS`/`GEN, ELEV, FIRE PUMP & FA ROOM ASSEMBLIES`/`FACR TO ELEV SHAFT ...`
2. .../`GEN, ELEV, FIRE PUMP & FA ROOM ASSEMBLIES`/`FACR TO ELEV SHAFT ...`
* **Length** = Length measured from the most distant points of the FACR and elevator shaft.
* Input adder length to reach the level of the shaft (Minimum 15ft).
@@ -91,7 +103,10 @@ For each elevator shaft:
For each stairwell:
1. `COMMON ASSEMBLIES`/`FIRE ALARM & DAS SYSTEMS`/`GEN, ELEV, FIRE PUMP & FA ROOM ASSEMBLIES`/`FACR TO STAIRWELLS 1" CONDUIT ...`
1. * `Area` = Same as FACR.
* `Phase` = Same as FACR.
.../`GEN, ELEV, FIRE PUMP & FA ROOM ASSEMBLIES`/`FACR TO STAIRWELLS 1" CONDUIT ...`
* **Length** = Length measured from the most distant points of the FACR and stairwell.
* Input adder length to reach the level of the stairwell (Minimum 15ft).
@@ -104,8 +119,8 @@ For each stairwell:
1. Horizontal:
* `Area` = Same as FACR
* `Area` = Same as FACR.
`... HORIZONTAL RUN`
* **Length** = Length measured from FACR to all electrical rooms
@@ -128,10 +143,10 @@ For each stairwell:
## Central Monitoring Loop
> [!important]
> Garden Style only.
> Garden Style only.
> Fire Alarm Control Panels from each building will send a signal to a central location.
>
>
> In case of an emergency,
> the fire department will go to the central fire alarm station
> and find out what the issue is.
@@ -141,32 +156,23 @@ For each stairwell:
### Smoke Detectors
1. `COMMON ASSEMBLIES`/`FIRE ALARM & DAS SYSTEMS`/`INITIATING DEVICES WITH WIRE - ...`/`SMOKE DETECTOR W/ BASE - ...`
_Design Build:_
Count every stairwell at every level.
* **Count:** As shown, otherwise (1) every stairwell at every level.
### Pull Stations
1. `COMMON ASSEMBLIES`/`FIRE ALARM & DAS SYSTEMS`/`INITIATING DEVICES WITH WIRE - ...`/`PULL STATION - ...`
_Design Build:_
Count every stairwell at every level
and every exterior exit.
* **Count:** As shown, otherwise (1) every stairwell at every level and every exterior exit.
### Flow/Tamper Switches
No free-air. If wood frame, take off as EMT.
_Design Build:_
Count every stairwell at every level.
1. `COMMON ASSEMBLIES`/`FIRE ALARM & DAS SYSTEMS`/`INITIATING DEVICES ...`/`ADDRESSABLE DUAL MONITOR MODULE - FLOW/TAMPER - ...` (No free-air)
* **Count:** As shown, otherwise (1) every stairwell at every level.
### Magnetic Door Holders
1. `COMMON ASSEMBLIES`/`FIRE ALARM & DAS SYSTEMS`/`INDICATING DEVICES WITH WIRE - ...`/`MAGNETIC DOOR HOLDER - ...`
_Design Build:_
Count 2 for every set of double doors.
(Typical of elevator lobbies and corridors)
* **Count:** As shown, otherwise (2) every set of double doors.
(Typical of elevator lobbies and corridors)
### Horns, Speakers, and Strobes
@@ -177,8 +183,8 @@ _Design Build (method 1):_
* measure with circles on Bluebeam
* or divide relevant SF area by 4415
* $\pi(\frac{75}{2})^2 \approx 4415$
* every elevator lobby,
* and every BOH room on the first floor and garage levels.
* every elevator lobby, and
* every BOH room on the first floor and garage levels.
_Design Build (alternative method):_
* 15ft from end of corridor,
fire-resistive-wiring-methods-takeoff.md
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@@ -4,7 +4,7 @@ aliases: []
tags:
- authorship/original
- destiny/permanent
- occupational/takeoff/electrical
- occupational/takeoff
- status/draft
- type/guide
title: Fire Resistive Wiring Methods Takeoff
fixture-designations.md
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@@ -4,7 +4,7 @@ aliases: []
tags:
- authorship/original
- destiny/permanent
- occupational/takeoff/fixtures
- occupational/takeoff
- status/draft
- type/guide
title: Fixture Designations
fixtures-takeoff.md
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@@ -4,7 +4,7 @@ aliases: []
tags:
- authorship/original
- destiny/permanent
- occupational/takeoff/fixtures
- occupational/takeoff
- status/draft
- type/guide
title: Fixtures Takeoff
grounding-takeoff.md
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@@ -5,7 +5,7 @@ title: Grounding Takeoff
tags:
- authorship/original
- destiny/permanent
- occupational/takeoff/feeders
- occupational/takeoff
- status/draft
- type/guide
---
lighting-controls-takeoff.md
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@@ -4,7 +4,7 @@ aliases: []
tags:
- authorship/original
- destiny/permanent
- occupational/takeoff/electrical
- occupational/takeoff
- status/draft
- type/guide
title: Lighting Controls Takeoff
lightning-protection-takeoff.md
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@@ -3,7 +3,7 @@ id:
aliases: []
tags:
- destiny/permanent
- occupational/takeoff/lightning-protection
- occupational/takeoff
- status/draft
- type/guide
- authorship/original
low-voltage-takeoff.md
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@@ -4,7 +4,7 @@ aliases: []
tags:
- authorship/original
- destiny/permanent
- occupational/takeoff/low-voltage
- occupational/takeoff
- status/draft
- type/guide
title: Low Voltage Takeoff
me-isms.md
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# Me-isms
* (when misunderstood) "No, no, no."
* certainly
risk-management-for-construction-estimating.md
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@@ -15,84 +15,15 @@ tags:
Cross-topic of [[risk-management]] and [[construction-estimating]].
## Prioritizing Tasks
ROE prioritizes estimating tasks by their contribution to _cost certainty_.
### Estimating as Risk Mitigation
## Estimating as Risk Mitigation
* reduce risk of wasted estimation effort due to bid loss
(prefer lower bid)
* reduce risk of project overrun
(prefer higher bid)
Estimating resources are allocated by Return on Mitigation (RoM)
Estimating resources should be allocated
according to Return on Mitigation (RoM),
that is, their contribution to _cost certainty_.
### Determining Necessary Detail
ROE determines the appropriate level of [[estimating-detail]]
given an organization's [[risk#Risk Tolerance]].
#### EVI Takeoff
Expected value of information (EVI)
#### Takeoff Optimization
For systems where EVI analysis determines manual takeoff is still necessary,
optimizations can be made to decrease the required effort of takeoff,
and thus the opportunity cost of takeoff.
See [[optimal-estimating-patterns]] for more.
# Estimating Detail
The acceptable level of detail of an estimate
in [[construction-estimating]] is a contentious subject.
What's worse, estimators often disagree
on what makes an estimate more detailed than another.
The commonly repeated answer is this:
> As detailed as possible,
> given required turnaround and available estimating resources.
This analysis is flawed
because it implies more time always ought to be preferred,
when the reality is that when considering larger organizational factors,
ideal estimate certainty is likely far lower than most expect.
The correct answer involves optimizing for these factors:
* value of increased bid certainty
* value of increased estimate volume
An estimate's detail is irrelevant to its quality.
A less detailed estimate is a more [[risk|risky]] bid,
but it is not the role of the estimator to determine acceptable risk.
## Experiment
Perform a system takeoff (lighting for example) in exacting detail,
the maximum amount you would ever consider using,
and measure the time required to do so,
as well as the cost of the scope.
Have another estimator takeoff the same scope
using the proposed time saving strategy.
Repeat the test on additional projects.
Treat the detailed takeoff as the true value
and find the error of the time saving strategy.
$\frac{d\sigma}{dt}$
### Expectation
Time-saving strategies will overestimate or underestimate detailed takeoff
depending on the assumptions used in their creation.
## Human Error
It is commonly understood that a "detailed takeoff"
is more "accurate" than a square foot estimate.
$\text{Efficiency} = -1 \times \frac{d\sigma}{dt}$
risk-oriented-estimating.md
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@@ -1,120 +0,0 @@
---
id: risk-oriented-estimating
aliases: []
tags:
- destiny/fleeting
- status/incomplete
- topic/estimating
- topic/risk
- type/supertopic
- authorship/original
title: Risk Oriented Estimating
---
# Risk Oriented Estimating
## Abstract
Risk-Oriented Estimating (ROE),
is a [[estimating-methodologies|methodology]]
for [[construction-estimating]] which:
* prioritizes estimating tasks,
* determines necessary [[estimating-detail]]
ROE leans heavily on [[uncertainty#Value of Information]],
which challenges the natural tendency to fear even the smallest risk
with the reality of the **cost of certainty**.
ROE does not endorse common shortcuts that round up to "cover" uncertainty,
as these ultimately _increase_ risk by inflating the apparent project cost,
increasing the probability of loss to a competitor.
%%
## TALK
This note currently gets too far into the weeds
of critiquing common practice.
%%
## Potential Objections
Objections to the use of historical data in new estimates are not unfounded.
A framework to do so competently and consistently
does not currently exist.
Nor does the software necessary to utilize such a framework efficiently.
The goal in and of itself ought not be controversial, however.
Businesses regularly make far riskier decisions based on projections
informed by the same data.
By definition, if one could adjust historical pricing accurately for all dependent factors,
the adjusted price would be accurate to the new job.
The issue is that there are hundreds to thousands of potential dependent factors.
A nonstarter for uncreative minds,
but a worthwhile challenge for estimators truly passionate about their field.
It is unique of construction estimating among similar fields
that analysis and discussion of risk is largely absent from pre-approval review.
The tools common of our trade almost always lack the means
to quantify the dollar amount implications of our assumptions.
There is an enormous gap in complexity between pure square foot pricing and
[[traditional-estimating-methods]] that tools do not exist to bridge.
At all points in the estimating process,
It should be possible to give a confident budget.
## In Comparison
For most contractors, there is not usually a minimum amount of project detail
required to provide a budget for a project
Estimators know what the most likely and most expensive options are for a given scope
and can fill in the detail required for item-oriented takeoff.
This is called an **assumption** and is the basis of cost estimation.
Assumptions are fundamentally incompatible with item-oriented estimating
as it is commonly implemented.
It is not possible to compare price possibilities
except by creating separate takeoffs and breakdowns for each one.
Rather than building the job one `WOOD NAIL - GALV STEEL - #10 - 5-INCH` at a time,
risk-oriented estimating focuses on reducing risk of a decent budget.
Risk-oriented estimating understands a `NAIL` like an estimator:
an abstract item in a certain price range requiring labor in a certain hour range.
A practitioner of this style would find
that the impact of such details on the final price of a job
are so low as to be trivial.
Not to say that they shouldn't be addressed,
only that they ought not be addressed before more significant factors.
Risk is a measure of the effect of uncertainty on outcome.
Uncertainty being a necessity of estimating,
the language and tools that we use
must facilitate discussions of risk management.
In estimation in fields other than construction
it is common to give an estimate as a _confidence interval_,
a range in which a result has a certain percentage chance to fall.
This interval can be determined from a population of possible prices.
The _accuracy_ of a risk-oriented estimate remains roughly the same
(approaching 100% with continuous input)
through the takeoff process, and---assuming no incorrect input---
is entirely out of the hands of the estimator doing the "takeoff".
Other notes describe how a centralized system
separates the concerns of adjustment factors
and data input for individual projects.
The "takeoff" workflow then is not about progressively approaching the target
price as with item-oriented methods,
but reducing the range of possible target prices,
reducing the risk of the estimate.
Abandoning an item-oriented estimate
at any point before 100% completion
results in effectively 100% wasted effort.
In contrast, an abandoned risk-oriented estimate
becomes a budget with no additional effort.
standalone-systems-takeoff.md
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aliases: []
tags:
- destiny/permanent
- occupational/takeoff/standalone-systems
- occupational/takeoff
- status/draft
- type/guide
- authorship/original
statistical-modeling-for-construction-estimating.md
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@@ -15,6 +15,22 @@ tags:
Cross-topic of [[statistical-modeling]] and [[construction-estimating]].
%%
## TALK
This note should discuss the application of modeling in estimating,
including what is already common practice (e.g. average run lengths),
as well as the potential for more robust models.
Models are useful where information is limited,
and where more precise methods would be suboptimal[^1].
[^1]: see [[risk-management-for-construction-estimating]].
Specific examples should generally be relegated to linked notes.
%%
## Bayesian Takeoff
#### User Story
subfeeds-takeoff.md
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aliases: []
tags:
- destiny/permanent
- occupational/takeoff/subfeeds
- occupational/takeoff
- status/draft
- type/guide
- authorship/original
switchgear-takeoff.md
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tags:
- authorship/original
- destiny/permanent
- occupational/takeoff/switchgear
- occupational/takeoff
- status/draft
- type/guide
title: Switchgear
telecom-takeoff.md
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tags:
- authorship/original
- destiny/permanent
- occupational/takeoff/telecom
- occupational/takeoff
- status/draft
- type/guide
title: Telecom
estimating-ethics.md → transparency-in-construction-estimating.md
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@@ -1,16 +1,23 @@
---
id:
aliases: []
title: Transparency in Construction Estimating
tags:
- authorship/original
- destiny/permanent
- status/incomplete
- status/not-started
- topic/construction
- topic/estimating
- type/philosophy
title: Estimating Ethics
- topic/transparency
- type/cross-topic
---
# Estimating Ethics
# Transparency in Construction Estimating
Cross-topic of [[transparency]] and [[construction-estimating]].
## Estimating Ethics
### Ethics for the Solicitor
Contractors engaging in unethical bidding practices
can quickly gain a reputation for doing so,
@@ -24,15 +31,7 @@ To ensure a transparent bidding process, one must
* maintain confidentiality of bid submissions, and
* provide equal access to bidding information.
### Terms
> [!info] Bid Shopping
> the practice of sharing a bidder's quote with other prospective vendors
> in order to solicit lower bids.
> The competing quote may be legitimate, fabricated,
> or a non-serious proposal from a colluding vendor.
## Bad Bid Practice
### Ethics for the Bidder
Deceptive proposal language is a quick way to get blacklisted.
@@ -43,3 +42,11 @@ is particularly reprehensible.
> * Not including consideration for voltage drop
> * Including standard, line-voltage switching as "lighting control"
> * Excluding all mechanical disconnects
### Terms
> [!info] Bid Shopping
> the practice of sharing a bidder's quote with other prospective vendors
> in order to solicit lower bids.
> The competing quote may be legitimate, fabricated,
> or a non-serious proposal from a colluding vendor.
two-way-takeoff.md
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@@ -7,7 +7,7 @@ aliases:
tags:
- authorship/original
- destiny/permanent
- occupational/takeoff/standalone-systems
- occupational/takeoff
- status/draft
- type/guide
title: Two-Way Takeoff
@@ -33,9 +33,7 @@ title: Two-Way Takeoff
* FCR to elevator lobbies
* FCR to stairwells
**Count** = Number of boxes run to. Per drawings if shown, otherwise use the greater of:
* Count of elevators
* Count of stairwells
**Count** = Count of elevator lobbies or stairwells (match length)
## Vertical
@@ -44,7 +42,7 @@ title: Two-Way Takeoff
`FIRE ALARM & DAS SYSTEMS`/`TWO WAY COMMUNICATION ASSEMBLIES`/`2-WAY COMMUNICATION = 1" CONDUIT ...`
* **Length** = 15ft * Count
* **Count** = _match Horizontal_
* **Count** = match Horizontal
## Firefighter Phone System
uncertainty-in-construction-estimating.md
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@@ -0,0 +1,62 @@
---
id:
aliases: []
title: Uncertainty in Construction Estimating
tags: []
---
# Uncertainty in Construction Estimating
Cross-topic of [[uncertainty]] and [[construction-estimating]].
This note is intended to be purely descriptive.
See [[actuarial-science-for-construction-estimating]]
and [[risk-management-for-construction-estimating]]
for strategy based on such uncertainty.
%%
## TALK
What do I mean that project cost is uncertain until the last invoice?
What distributions exist
which are known,
which can never be known and must be estimated?
[[bid-price-modeling]]
***
With perfect information all outcomes are certain.
There exists some distribution representing the range of possible costs for a project.
The remaining uncertainty represents ignorance of information an estimator can not feasibly obtain.
***
Suppose the estimator has spent years on the bid,
running simulations, consulting experts, etc.
Suppose the estimator has received a message from a time traveler
which details significant news events and commodity markets
for the duration of the project.
Suppose the estimator is prescient and has observed the final cost of the project
as reported in the winning contractor's historicals.
%%
## Expected Value of Perfect Information
[[uncertainty#Expected Value of Perfect Information]]
%%
an organization pays in estimator hours.
These hours have a direct cost in salary and benefits,
however the greater cost is the opportunity cost
of tying up an estimator who could otherwise be starting a new project.
In many cases, the utility of doubled throughput
far outweighs the increased risk of individual bids.
%%
uncertainty.md
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@@ -75,19 +75,6 @@ in order to gain access to perfect information.
The perceived _value_ of decreased uncertainty
must be weighed against its _cost_.
#### In Construction Estimating
This concept provides the basis for the solution
of one or more [[open-problems-in-estimating]].
To reduce [[risk]] in [[construction-estimating]],
an organization pays in estimator hours.
These hours have a direct cost in salary and benefits,
however the greater cost is the opportunity cost
of tying up an estimator who could otherwise be starting a new project.
In many cases, the utility of doubled throughput
far outweighs the increased risk of individual bids.
## Types of Uncertainty
### Aleatory Uncertainty
units-takeoff.md
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@@ -4,7 +4,7 @@ aliases: []
tags:
- authorship/original
- destiny/permanent
- occupational/takeoff/units
- occupational/takeoff
- status/draft
- type/guide
title: Unit Takeoff