The Basics of BIM: Revit Analyzing


Analyzing

As with visualization, the authoring environment of a BIM platform isn’t necessarily the most
efficient one on which to perform analysis. Although you can create some rendering and
animations within Revit, a host of other applications are specifically designed to capitalize on
a computer’s RAM and processing power to minimize the time it takes to create such media.
Analysis is much the same way—although some basic analysis is possible using Revit, other
applications are much more robust and can create more accurate results. The real value in BIM
beyond design documentation is the interoperability of model geometry and metadata between
applications. Consider energy modeling as an example. In Figure 1.9, we’re comparing three
energy-modeling applications: A, B, and C. In the figure, the darkest blue bar reflects the time it
takes to either import model geometry into the analysis package or redraw the design with the
analysis package. The lighter blue bar reflects the amount of time needed to add data not within
Revit, such as loads, zoning, and so on. The lightest bar represents the time it takes to perform
the analysis once all the information is in place.

Figure 1.9

Introduction- The Basics of BIM 9

In A and B, we modeled the project in Revit but were unable to use the model geometry in
the analysis package. This caused the re-creation of the design within the analysis tool and also
required time to coordinate and maintain the design and its iterations between the two models.
In application C, you can see we were able to import Revit model geometry directly into the
analysis package, saving nearly 50 percent of the time needed to create and run the full analysis.
Using this workflow, you can bring analysis to more projects, perform more iterations, or do the
analysis in half the time.
The same workflow is true for daylighting (Figure 1.10) and other types of building
performance analysis. With the ability to repurpose the Revit model geometry, we are able to
move away from anecdotal or prescriptive design solutions and begin to rely on calculated
results. Using Revit also ensures consistency because the model is the sole source for design
geometry.
Building analysis can reach beyond just the design phase and into the whole building
life cycle. Once the building has been constructed, the use of BIM doesn’t need to end. More
advanced facilities management systems support tracking—and thereby trending—building
use over time. By trending building use, you can begin to predict usage patterns and help
anticipate future uses such as energy consumption or future expansion. This strategy can help
you become more proactive with maintenance and equipment replacement because you will be
able to “see” how equipment performance begins to degrade over time. Trending will also aid
you in providing a more comfortable environment for building occupants by understanding
historic use patterns and allowing you to keep the building tuned for optimized energy
performance.

Figure 1.10

Introduction- The Basics of BIM 10

Strategizing
To maximize your investment in a BIM-based workflow, it’s necessary to apply a bit of planning.
As in design, a well-planned and flexible implementation is paramount to a project’s success. By
identifying goals on a project early on in the process, it allows BIM to be implemented efficiently
to reach those objectives. An effective strategy answers three key questions about a project:
◆ What processes do we need to employ to achieve our project goals?
◆ Who are the key team members to implement those processes?
◆ How will we support the people and processes with technology or applications?
Ask these questions of your firm as a whole so you can collectively work toward expertise
in a given area, be that sustainable design or construction or something else. Ask the same
questions of an individual project as well so you can begin building the model in early stages
for potential downstream uses. In both cases (firm-wide or project-based), processes will need to
change to meet the goals you’ve established. Modeling techniques and workflows will need to be
established. Analysis-based BIM requires different constraints and requirements than a model
used for documentation or clash detection. If you’re taking the model into facilities management,
you’ll need to add a lot of metadata about equipment but at a lower level of detail than if you
were performing daylighting studies. Applying a new level of model integrity during a design
phase can be a frustrating and time-consuming endeavor. Regardless of the goal, setting and
understanding those goals early on in the project process is a prerequisite for success.

 

Focusing Your Investment in BIM

One of the common assumptions is that larger firms have a better opportunity than smaller
firms in their capacity to take on new technologies or innovate. Although larger firms might
have a broader pool of resources, much of the investment is proportionally the same. We have

been fortunate enough to help a number of firms implement Revit over the years, and each
has looked to focus on different capabilities of the software that best express their individual
direction. Although these firms have varied in size and individual desire to take on risk,
their investments have all been relatively equal. From big firms to small, the investment ratio
consistently equates to about 1 percent of the size of the firm. If you consider a 1,000-person
firm, that equals about 10 full-time people; however, scale that down to a 10-person firm, and
that becomes 1 person’s time for five weeks.
The key to optimizing this 1-percent investment is focusing your firm’s energy and resources
on the most appropriate implementation objectives.
Identifying the importance of visualization, analysis, and strategy to your process will help
guide you in selecting areas of implementation within your own practice. If your investment
(regardless of scale) is focused and well planned, it will yield strong results. When choosing
areas of implementation or how much focus to give to these areas, there are no wrong answers.
Just choose a path that reflects the comfort level of your firm while maintaining focus on
achieving success.
We elaborate on most of these topics throughout the remainder of this book. Using
real-world examples, we illustrate a variety of techniques to visualize, analyze, and strategize
using Revit.

Staffing for BIM

As you rethink the process of design and documentation, one of the fundamental changes
you will need to address is staffing. A common misconception of project management when
teams are first moving from CAD to BIM is that staffing the project will be the same in both
workflows. This couldn’t be further from the truth because when the workflow changes, staffing
allocations, the time to complete tasks, and the percentage of work by phase are all affected as a
result of the changes.
Several years ago, Patrick MacLeamy, FAIA, set out to illustrate the fundamental benefit to
more informed design that happened to be a by-product of building information modeling.
The graph, which has come to be known as the MacLeamy Curve (Figure 1.11), is not intended
to imply a simple shift in labor earlier in the design process; rather, it stresses the importance
of being able to make higher-value decisions before it becomes too difficult to make changes
to a design. The x-axis of the chart represents project phases from conceptual design through
occupancy, whereas the y-axis represents the amount of effort in each phase.
Another way to think about this shift is as a diagram of leverage, as shown in Figure 1.12.
Implementing BIM in earlier phases of a project gives you the greatest opportunity to add
value to the overall compilation of building information delivered for a facility. When you
begin BIM earlier, you may need to increase staff to build a better model or to perform energy
analysis or preliminary quantity takeoffs; however, using a better tool like Revit software will
not necessarily translate to the same labor used in a CAD-based project. You will find how this
affects your team effort after a few BIM projects.

Understanding Project Roles

With such a significant change in the effort behind a BIM-based project workflow, it’s also
important to understand how this change affects the various roles and responsibilities for the
project team. Project managers need to be able to predict staffing and time to complete tasks
throughout the project phases and have relied on past precedent of staff and project types

to do this. Because a BIM-based project can significantly alter the project workflow, many of
the historic timetables for task completion are no longer valid. However, a BIM-based project
can be broken down into a few primary roles that will allow you some level of predictability
throughout the various project phases. Although the specific effort and staffing will vary
between offices (and even projects), there are some general roles that will need to be accounted
for on every project.

Figure 1.11

 

Introduction- The Basics of BIM 11

Figure 1.12

Introduction- The Basics of BIM 12

 

Here are three primary roles that should be considered on every BIM project:
Architect Generates design intent and coordinates issues such as material, code
compliance, wall type, spatial program, and so on.
Modeler Creates 2D or 3D content that directly represents the design intent.
Drafter Works with annotations, sheet layout, view creation, and detail creation.
These roles represent efforts and general tasks that you need to take into account on any
Revit project. On a large project, these roles could also represent individual people, whereas on
a smaller project they might be all the same person fulfilling multiple roles. We’ll now explore
each of these in more detail and discuss how these roles affect the project workflow.

Describing the Role of the Architect
The role of the architect is to generate the design intent and manage the technical issues
of the project. As the model is being created, you will naturally have to solve issues like
constructability and wall types and managing the program of spatial and equipment
requirements, as well as other issues involving code compliance and client relationships. This
role will be the one applying standards to the project (as in wall types, keynotes, and so on) and
organizing the document set. This role will need to be present on the project from the beginning
to ensure consistency of the virtual building creation and isn’t necessarily limited to only one
person. This role also might or might not be a “designer.” Although it is possible to do early
design in Revit software, many project teams prefer to use other tools such as SketchUp or even
a pencil and tracing paper. The job of the architect is steering the creation of the building within
the Revit environment. This role includes the following tasks:
◆ Leading the creation of architectural elements and building from within the model
◆ Designing around code requirements and other building logistics
◆ Constructability and detailing aspects of the design

Describing the Role of the Modeler
The role of the modeler—in some firms referred to as the BIM coordinator—is to create and
manage the 3D families and detail components needed in the project, which include all the
parametric families for things such as windows, doors, casework, wall types, stairs, railings,
furnishings, and so on. Typically, this role is the responsibility of less-experienced staff who
might not be able to fulfill the role of architect. This role tends to have longer periods of
undisturbed time, making it better suited to deal with some of the longer, more involved tasks
in modeling content. Finally, it also tends to have some familiarity with modeling applications
from academia or prior work experience. The modeler might not have worked with Revit
software directly but possibly with 3ds Max software or Rhino. This role includes the following
tasks:
◆ Creating model content and families
◆ Creating drafting components
◆ Managing system families within the project

Describing the Role of the Drafter
The role of the drafter is to create sheets and embellish associated views with annotations or
other 2D content. The drafter is responsible for the bulk of the work needed to document the
project. In earlier stages of the project, this role is typically assumed by either the architect or the
modeler, but as documentation progresses into later phases of design, this can quickly become
the role of multiple people on a larger project. This role includes the following tasks:
◆ Keynoting
◆ Dimensioning
◆ Creating sheets and configuring views
◆ Creating schedules

Establishing a BIM Execution Plan

To optimize your results with BIM, it’s important to start with the end in mind. Although a lot
of tasks are possible with a BIM model before you draw your first wall, you will want to create
a BIM execution plan. We go into more detail about creating these plans and some resources
for them in Chapter 6, “Working with Consultants,” but essentially a BIM plan helps to drive
the direction of the modeling effort and modeling outcomes. Will your project need to add
parameters for energy modeling? Daylighting? Does the owner have expectations for a model
deliverable? How much does everyone model without being too much? All of those possibilities
and more are explored and documented in a BIM execution plan. It gives the project team a
definitive outcome to model toward.
The BIM plan will also help address which team members you’ll need at which phases of
the design. For instance, at the inception of a project design, a modeling role will be of the best
use. This person can help create building form, add conceptual content, and get the massing for
the building established. If you’re using the conceptual modeling tools (covered in Chapter 8,
“Advanced Modeling and Massing”), the modeler can even do some early sustainable design
calculations (covered in Chapter 9, “Conceptual Design and Design Analysis”).
Once the project begins to take a more established form and you complete conceptual design,
you’ll need an architect role to step into the project. As in a typical project, you’ll have to mold
the form into a building by applying materials, applying wall types, and validating spatial
requirements and the owner’s program.
During schematic design, you’ll need to include the role of the drafter to begin laying out
sheets and creating views. These sheets and views don’t have to be for a construction document
set as of yet, but you’ll need to establish views for any schematic design submittals. If these
views are set up properly, they can be reused later for design development and construction
document submittals as the model continues to gain a greater level of detail.
You should avoid adding staff to your project during the construction documentation phase.
In a BIM/Revit workflow, this can sometimes cause more problems than it solves and slow
down the team rather than get work done faster.
Another proven technique of managing larger Revit projects is to assign work according to
elements of the building rather than by drawing a series. For example, one person would be
responsible for building enclosures and another for structure, interior partitions, furniture,
vertical circulation, and so on. This strategy encourages each team member to develop their

portion of the design more collaboratively because the modeling for each component must be
coordinated with the surrounding systems.
Even though your team won’t be assigned work through a series of sheets, each person
should be tasked with overseeing each sheet series. The annotation related to each building
system is the responsibility of the respectively assigned team member, but someone else will be
responsible for reviewing each series of sheets to ensure that they are appropriately maintained
for presentation or distribution. On smaller projects, the project architect would likely be the
person supervising the entire sheet set.
This dual responsibility is an important aspect of team management that will keep your BIM
projects on track. Spending the majority of time working in the model and thus neglecting the
preparation of properly annotated sheet views becomes very alluring.

Adding Team Members to Fight Fires

In many projects, there might come a time when the schedule gets tight and project
management wants to add more staff to meet a specific deadline. When in a 2D CAD
environment, new team members would be added to help meet a deadline and would have the
burden of trying to learn the architecture of the building, the thoughts behind its design, and
how its various systems interact. In a Revit project, they have that same obligation, but they
have the additional task of learning how the model has been configured. The model will have
constraints set against various elements (such as locking a corridor width) and various digital
construction issues (such as how floors and walls might be tied together, what the various
family names are, or workset organization). New team members require additional time to
“ramp up.”
Regardless of planning, deadlines still escape the best of architects and project managers.
It’s a good idea to know when and how you can “staff up” to be sure to meet those deadlines.
Keeping in mind that your team members new to the project have to learn about both the design
and the model, here are some task ideas to both help production and make sure they don’t
accidentally break anything:
Content Creation You will find that you will be making model families or detail
components until the end of the project. This will help get the new team members engaged
in a specific part of the project and also isolate them enough until they learn a bit more about
how the model has been configured.
The Drafting Role Even if this isn’t their ultimate role, having new team members help
create views and lay out sheets will get them familiar with the architecture while still
allowing the team to keep progressing on the document set.
Working on Detailing Every project can always use someone who knows how to put a
building together. If you have someone new to the project and possibly even new to Revit
software, let that individual embellish some of the views already created and laid out on
sheets with 2D components, linework, and annotations.