CBS Newsletter
Summer 1994
pg. 8

Computer-Based Design Tools

Reaching decisionmakers during the building design process

Concerns about energy production's environmental effects, which gained their first wide public exposure during the 1970s, and the high capital cost of new power plants continue to occupy the attention of scientists and policymakers. Twenty years of research efforts have produced a comprehensive understanding of the implications of building energy use as well as an increasing number of energy-efficient strategies and technologies with significant potential for energy savings.

Figure 1: Power DOE includes a user-controlled, three-dimensional perspective and axonometric display of the whole building configuration.

However, these strategies and technologies have not been transferred effectively to the building design community. The majority of new and retrofit buildings are still designed without any energy-related considerations beyond those enforced by energy codes. One reason this knowledge gap exists is because building designers do not have the means to assess the impact of new trategies and technologies efficiently and reliably during the building design process.

A reliable energy performance assessment requires the use of complicated algorithms that take into account specific attributes of the building and its context. The algorithms and the large computing power required to calculate year-round energy behavior has necessitated the development of building energy simulation computer programs such as DOE-2, produced by the Center's Building Technologies Program. Such programs were originally written for mainframe computers, but they are now under continuous development for today's powerful workstation and personal desktop computers. Thanks to the dramatic decrease in the cost of computing power, an increasing number of building design firms use such computers to create and maintain electronic versions of drawings and specifications through computer-aided drafting (CAD) software packages. The widespread availability of personal computers in most building design firms offers a unique opportunity to make powerful energy simulation tools like DOE-2 available to building designers.

PowerDOE

PowerDOE is a new version of the DOE-2 building energy simulation program. Its primary developers are the Building Technologies Program, Hirsch & Associates, and Regional Economic Research, Inc. PowerDOE has a graphical user interface running under Microsoft Windows, making it easier to use than DOE-2 while retaining DOE-2's calculating power and accuracy. Interface features include menu-driven input, on-line help, graphical results display, building component libraries, links to CAD packages, and the option to generate a building description automatically from type and vintage. PowerDOE has an open architecture to encourage third-party development of specialized performance analysis modules that can be attached to the core program. For example, a planned link to the object-oriented SPARK program will allow users to simulate new HVAC technologies of arbitrary complexity.

Figure 2: Through a Schematic Design Tool that incorporates shadow-casting visualization, EDA [BDA] will assist building designers with initial buildng massing and orientation decisions, providing feedback on multiple performance considerations.

PowerDOE, however, is still an analytical rather than a design tool, and its primary audience is engineers, energy consultants, and utility staff. It accepts as input the detailed physical description of a building, occupancy patterns, climate data, etc., and provides as output the building's energy performance. A design tool would go beyond calculating the energy performance to address other building design considerations like comfort, economics, and aesthetics. Also, a design tool would help its users formulate appropriate design criteria and improve building performance as the design evolves.

EDA

EDA is the code name for a building design tool that the Building Technologies Program is developing [the name has been changed since publication to BDA- Building Design Advisor]. EDA [BDA] will give building designers an integrated view of how well different solutions meet design criteria throughout the building design process, from the initial, schematic phase to the detailed specification of building components and systems. Based on a comprehensive design theory, EDA [BDA] will be linked to simulation algorithms for energy and other performance considerations, such as cost and environmental impacts, and to databases, such as electronic product catalogs, and utility programs. EDA [BDA] will also provide context-dependent advice on performance improvement.

Figure 3: The interactive user interface of Power DOE allows a designer to specify the various building components and systems easily while providing visual feedback on the placement of building envelope elements in plan and elevation views.

The first version of EDA [BDA] will be linked to PowerDOE and will incorporate a Schematic Design Tool and a multimedia-based Case Studies Database (CSD) to help building designers understand the energy and cost impacts of changing the values of building parameters (such as shape, orientation, and number of floors) using the PowerDOE simulation engine. This database will be the equivalent of an electronic magazine for existing buildings, providing a realistic set of benchmarks for evaluating the performance of proposed buildings. In addition to presenting conventional alphanumeric data for displaying descriptive and performance characteristics of buildings, CSD will allow the user to explore a building through the use of images, sound, and video.

The initial versions of PowerDOE and EDA [BDA] are scheduled for combined release in the spring of 1995.

—Konstantinos Papamichael

Info icon

EDA:
Konstantinos Papamichael
Windows and Daylighting Group
(510) 486-6854; (510) 486-4089 fax

PowerDOE:
Kathy Ellington
Simulation Research Group
(510) 486-5711; (510) 486-4089 fax


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