(continued)

To be truly useful to the vast majority of building designers, the next generation of performance analysis tools must find their proper place within the gestalt of the design process. To realize this goal, the software engineers who build these tools need to develop a greater appreciation for the practice of architecture. They need to understand how CAD is currently being used in the real world and prepare for the digital transformations that are just around the corner.

To this end, Geopraxis, Inc. has conducted a survey to show how practitioners use current computer tools. An analysis of some of the survey data is given here. In general, the survey revealed that the most commonly used tools for 2D drafting and 3D modeling are not the same tools as those considered "most effective" by practitioners who do 3D modeling in schematic design. This lesson is important for energy tool developers because sustainability-related issues must be addressed by designers at the earliest phases. "Greening" cannot be applied during the construction documents phase, where most mainstream CAD is performed.

The Conceptual Design Energy Analysis Tool Project is developing a software module designed for XML-based energy analysis integration with existing 3D CAD architectural software tools. This project is conducted by Geopraxis and supported by the California Energy Commission.

How Do Designers Really Use 3D CAD?

To find out how designers use 3D CAD in practice, the project team engaged in substantial market research. Beginning in 1999, the first nine months were aimed at better understanding the design practices and software preferences of registered architects, architectural designers, building developers, and other users of 3D CAD. Detailed interviews, focus groups, a literature review, and a web-based survey were organized to look beyond conventional wisdom and probe more deeply than previous research.

The use of CAD software has become virtually a given on projects of any significant scale. A recent survey in California found that nine out of ten design professionals active in the commercial sector reported using some kind of CAD tool, presumably at least a 2D drafting program. Thirty-six percent said they use 3D tools.

How do designers use 3D? Common knowledge tells us that at present the most sophisticated 3D drafting tools are used more for marketing presentation—to create a snazzy rendering or animated walkthrough—rather than for building design. However, the market for 3D conceptual design is clearly growing.

A recent GeoPraxis focus group with architects in San Francisco confirmed that while all of the largest projects use 3D CAD during conceptual design, the vast majority of mid-size and smaller projects do not. As a result, larger firms tend to report higher percentages of CAD use. However, the exceptions can be notable. One mid-sized practice working primarily in Silicon Valley claimed all their projects are modeled in 3D from start to finish.

Another small San Francisco design firm described their process in detail: "In the schematic phase, we usually mass out our project in terms of sites. Then it's a big tool during schematic design for all our clients to get a feel for where the project is going. Through design development, it's used as a design tool pretty heavily to explore spaces and light and acoustics. And then in construction documents we don't really use it that much except for final presentation."

What will the future of CAD look like? We decided we needed a quantitative survey to understand present-day 3D CAD practices.

The Design Methods Survey

Hosted at DesignCommunity.Com, the survey was available online from October through December of 1999. With promotional assistance from the American Institute of Architects, the survey attracted over 700 interested visitors with over 400 eligible respondents representing 3D CAD users in 32 countries. Nine of every ten responses came from North America. The survey sampled 3D CAD users with a prior interest in "green building design" and "the energy performance of buildings." This group is most likely to include early adopters of the tool currently under development by GeoPraxis.

How often are 3D tools used? Most of the designers we surveyed are relatively active 3D users. Well over half use their 3D software at least three days per week. Fewer than one in five use it less than once per month.

How does amount of detail in a model differ at various phases of the design process? We found that early in design, "simple" 3D models are preferred over "detailed" models, by a factor of 2 to 1. Over 68% of the respondents report they always (27%) or frequently (41%) use a simple 3D CAD model early in their new construction design process. Some 30% "occasionally" use a simple model in the early phase of design while 2% "never" do.

The use of detailed 3D modeling is less common. Only 29% say they make regular use of a detailed 3D CAD model early in design (21% "frequently" and 8% "always"). Half only "occasionally" use a detailed model in the early phase of design while almost one in four (22%) never do. However detailed modeling is more popular late in design, when just over 42% always (14%) or frequently (29%) use a "detailed" 3D CAD model.

How often are 3D CAD assisted presentations produced? Table 1 shows that basic computer-rendered stills are used on about 44% of all projects. This group does not use 3D CAD at all on 31% of its projects. This indicates that over two-thirds of the represented projects receive some form of CAD-assisted presentation.

Levels of 3D CAD Assisted Presentation	Mean %
Basic Computer-Rendered Stills	44%
Photorealistic Computer-Rendered Stills	25%
Recorded Walkthrough Animation	8%
Live Walkthroughs	6%
3D CAD not used for Presentation	31%

Table 1

Which 2D and 3D tools are being used? As seen in a comparison of Tables 2 and 3, many frequent 3D users, like those we surveyed, prefer to use different programs for 2D drawing/drafting and 3D modeling. The most frequently mentioned tools for 2D tasks are shown in Table 2. Together, AutoCAD R-14 and its successor outpace the rest. Bentley's MicroStation comes in third.

Programs Used for 2D Drawing/Drafting
Rank	Program	%
1	AutoCAD R14	48
2	AutoCAD 2000	21
3	MicroStation	9
4	AutoCAD LT	9
5	VectorWorks	7
6	PowerCADD	5
7	DataCAD	5
8	MiniCAD	5
9	All Other (those under 3%)	20

Table 2

Notably absent are ArchiCAD and Architectural Desktop, which can be used for both 2D and 3D but are evidently not being used much by this group for 2D drawing/drafting.

The top-ranked CAD tools used most often for 3D modeling tasks are shown in Table 3. Again, AutoCAD R-14 remains far ahead of its closest competitor, form-Z. After AutoCAD 2000, DesignWorkshop is used by 9% of those surveyed.

CAD Tools Used Currently for 3D Modeling Tasks
Rank	Program	%
1	AutoCAD R14	32
2	Form Z	12
3	AutoCAD 2000	10
4	DesignWorkshop	9
5	VectorWorks	6
6	MicroStation	5
7	TriForma	4
8	DataCAD	4
9	All Other (those under 3%)	20

Table 3

How effective are 3D modeling products? Users were asked to choose which single CAD tool they use most extensively for 3D modeling at their firm. In a separate question, they were asked to rate on a 7-point scale the "effectiveness" of 3D CAD use at their firm. Table 4 shows, for each group of users, the percentage of firms that consider their CAD use to be highly effective. For example, 30.3% of firms where ArchiCAD is used primarily report effective CAD use.

Percent of Each Program's Users Reporting that Their Firm's Use of 3D Modeling is "Most Effective."
Rank	Program	%
1	ArchiCAD	30.3
2	3D Studio Max	22.9
3	Architectural Desktop	20.0
4	MicroStation	15.4
5	DesignWorkshop	14.8
6	Form Z	13.9
7	AutoCAD R14	13.0
8	TriForma	10.0
9	Accurender	10.0
10	DataCAD	6.7
11	3D Studio Viz	5.4
12	VectorWorks	5.3
13	AutoCAD 2000	0.0

Table 4

What tools are most often used for simple modeling "early in the design process"? To affect energy use, CAD tools need to be applied early in design. Users who said they "always" use simple 3D CAD models early in design were asked which 3D CAD tool their firm uses most extensively. Again, ArchiCAD turns up on top with the majority of its users reporting they "always" build simple models during conceptual design.

Percent of Each Products Users Who "Always" Use Simple 3D Models Early in the Design Process
Rank	Program	%
1	ArchiCAD	60.6
2	DesignWorkshop	44.4
3	VectorWorks	36.8
4	Form Z	33.3
5	DataCAD	33.3
6	TriForma	30.0
7	3D Studio Max	25.7
8	MicroStation	23.1
9	AutoCAD 2000	20.0
10	Architectural Desktop	14.3
11	3D Studio Viz	13.5
12	AutoCAD R14	11.6
13	Accurender	2.0

Table 5

These tables demonstrate a mismatch between 2D and 3D use and between frequency and perceived effectiveness of common tools. For energy-related software tools to be most effective in schematic design, they should aim at integration with 3D modelers that architects already find to be effective at that phase. Software now under development at GeoPraxis will use these results to ensure integration of energy analysis with effective 3D modelers for schematic design.

Thomas Conlon is an applied social anthropologist, and principal at GeoPraxis, Inc. in Sonoma, California.

Copyright 2000 GeoPraxis, Inc.

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