LBL Scientists Develop Tools For Architects and Engineers

Fall/Winter 1992

Computer programs developed at LBL are helping architects and engineers to increase the energy efficiency of buildings.

By Diane LaMacchia

From the gigantic glass blocks of a huge international conference center at the base of the Eiffel Tower to the catwalks of a cozy theater near San Francisco's Candlestick Park, buildings around the world are being designed with the help of a powerful set of tools developed at LBL.

American buildings alone consume a hefty $200 billion worth of energy per year. For more than a decade, scientists in the Energy and Environment Division have been creating computer programs to help building designers keep that energy consumption down. Building Technologies Program leader Steve Selkowitz says these tools offer the potential to save 50 percent more energy than is now required by building codes.

Not only do the tools work well, but some of them--like WINDOW 4.0, a program that calculates the thermal properties of windows, and DOE-2, a program that simulates a year's worth of energy use on an hour-by-hour basis for any given design--serve as benchmarks for other design programs and are the basis for national and state standards. And public utilities are using LBL's design tools as part of their "demand-side" management programs.

"Utilities have historically worried about the supply side-- about building more power plants," says Fred Winkelmann, a physicist who has worked with DOE-2 since its inception. "Now they're worrying about the demand side--using energy more efficiently so they don't have to build more power plants."

Utilities such as Pacific Gas and Electric (PG&E) and Southern California Edison (SCE) use DOE-2 to determine what incentives to offer builders of energy-efficient buildings. By using the program to forecast future energy needs, they can calculate incentives that are cost-effective and likely to help avert the construction of a new power plant, which can cost into the billions of dollars. Currently, PG&E offers architects and engineers a design-assistance service that involves running a building analysis on DOE-2 or a similar program. This service can be worth as much as $10,000 for a large building.

A computer program that has been run on everything from mainframes to personal computers, DOE-2 is the basis for new national standards for federal buildings established in 1991 and for the national voluntary standards for commercial and residential buildings set by the American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE). DOE-2 calculates the hourly energy use and cost over a year's time for houses, office buildings, and other kinds of structures. It takes into account all sources of cold and heat--for example, heat from lights, sunlight, and occupants--and calculates how the heating and cooling equipment operates to meet the loads.

To use the program, the designer enters information about the proposed building, including dimensions, materials, location, orientation, and hourly weather data. The designer also specifies how the building is operated (when the lights are used, how efficient the lighting is, and when people are there) as well as the heating, cooling, and distribution systems and their corresponding efficiencies. The program, in turn, calculates the amount of electricity and fuel used each hour for a year to provide the thermal comfort required by the designer. If the designer tells the program the local rate schedules, DOE-2 can calculate the building's annual energy bill.

Once the program has calculated energy costs, the designer may run a "What if?" scenario. For example, what if I used different materials? What if I used different lights? DOE-2 can then resize the heating and cooling equipment to meet the redesigned building's needs. "It tells you how much energy you're going to save with double glazing, an energy-efficient furnace, or more insulation," says Winkelmann.

Architectural engineer and urban designer Vladimir Bazjanac says that in 1977 he was the "first user to apply the program to real life." Since then, he has used it to simulate design performance and improve designs on a number of notable buildings, including the Pacific Museum of Flight in Seattle, the Farm Credit Bank building in Spokane, and the California state office building in Sacramento. He is currently using DOE-2 to design the "high-security, high-visibility" glass International Conference Center in Paris at the base of the Eiffel Tower.

"When architects work on buildings like this," says Winkelmann, "enormous buildings, costing millions and millions of dollars, it's in their interest to make them not only architecturally sound but energy-efficient. In this kind of building, if you don't do an energy simulation, you end up with heating and cooling systems that are way oversized, expensive, and inefficient."

"DOE-2 has been tremendously useful and has been a fabulous design tool for me," says Bazjanac. "But the real benefits are not to me but to those who own the buildings, because they end up with better buildings."

About $30 billion worth of energy escapes through American windows each year. Another LBL-developed tool that has become a standard in the industry is WINDOW 4.0. Created 12 years ago, WINDOW originally ran on a mainframe computer but was modified in the mid-1980s to run on a personal computer.

"We gave copies to 50 people in the industry to help them in product development and to provide them with a standard tool for comparing and rating their products," says Dariush Arasteh of the Windows and Daylighting Group, who has worked with WINDOW for years and is a member of the National Fenestration Rating Council.

Now thousands of people--mostly window manufacturers but also architects like Vladimir Bazjanac--use WINDOW worldwide. In January 1993, all windows manufactured in California will be required to carry rating labels. WINDOW 4.0 is the program that calculates those ratings.

To operate WINDOW, the user feeds information about window characteristics into the program. This includes descriptions of the glass to be used, the number of layers and their solar and infrared properties, the type of low-conductivity gas between the layers, and frame size, dimensions, and materials. In turn, WINDOW comes up with rating numbers, the most important of which is the "U" value, a measure of heat transmission. It also specifies the solar heat gain coefficient, which influences cooling loads, and the visible transmittance--how much visible light comes through the window. All of these numbers relate to energy efficiency and tell manufacturers or designers if their windows comply with energy codes.

WINDOW and the new version of DOE-2, called DOE-2.1E, have a link between them so that proposed windows can be analyzed and a data file created and fed from WINDOW into DOE-2 as one of many factors it needs to analyze total energy use in a building.

The Simulation Research Group, headed by Winkelmann, plans to create a similar link with RADIANCE, a lighting simulation program developed at LBL. Developed originally to operate on an engineering workstation but now running on PCs, RADIANCE provides colorful, photo-realistic images that help the designer to arrive at the desired quality of light.

"The simulation gives you the qualitative aspects of what lighting can do," says Greg Ward, a member of the Lighting Systems Research Group and the creator of RADIANCE. "RADIANCE can render scenes with millions or even billions of surfaces."

RADIANCE was used recently by Mark Mack, the architect who designed the Candlestick Theater. By using RADIANCE, he found out that his planned catwalks would cast a distracting shadow because of the way the lights were positioned. Instead of making a costly mistake, he was able to correct it in the design stage by moving the lights before they were actually installed.

The images created by RADIANCE allow the user to judge how a space is lit, but there are also numbers--retrievable by clicking the mouse on any pixel--to verify the quantity of light.

More than 100 people use the program to design buildings, and hundreds of software packages have been sent to university researchers, large architectural firms, and individual consultants.

"The tool tells them if their design will meet the visibility requirements, visual comfort constraints, and light levels desired, while optimizing efficiency with advanced fixtures and placement," says Ward. "Without a tool like this, the only option they have is overdesign. This tool verifies that the necessary illuminance can be achieved at a lower energy level."

Ove Arup and Partners of London, the world's largest engineering firm, used RADIANCE to design the Kansai international airport, scheduled to open in 1994 on an artificial island in Osaka Bay. Ward says the engineers used RADIANCE to analyze the lighting for the large curved roof structure which dominates the building. The light fixtures in the airport are to be mounted above head level; the lights will shine on the ceiling and reflect back.

The designers created a model of the building with a computer aided design program (CAD), which provided a three- dimensional geometric description that had particular building materials associated with particular areas. For each material they specified the reflectance, color, specularity (shininess), and output distribution for light sources. The building model was then imported into RADIANCE, and the simulation showed what the light on the ceiling would look like and determined the light level on the floor. The illuminance level on the floor was obtained at one-meter intervals.

"RADIANCE gives numerically accurate results," says Ward. "They wanted to know the illuminance within one percent. This kind of accuracy in a prediction obviates the need for overdesign in a lighting system."

Charles Ehrlich, the owner of the San Francisco-based business, Space and Light, uses RADIANCE to provide a rendering and lighting analysis service to architects, engineers, and lighting designers. In one recent project, which involved 50,000 square feet of hallway, he rendered a three-dimensional model of carpet patterns and textures, wall textures, and the candlepower distribution of the light fixtures to give an accurate portrayal of the apartment hallway's interior space. By showing the owner what the light would actually look like, he was able to convince him to use energy-efficient fluorescent lighting rather than the traditional incandescent lights he favored--"at a significant energy savings," says Ehrlich.

In spite of the recognition these energy-saving tools have received, researchers in the Building Technologies Program are not satisfied that they are accessible early enough in the design stage to be maximally effective. The tools are often used today by engineers and energy consultants who become involved later in the building design process. The researchers are working on ways to get their tools to architects at the earliest stages of building design when they are just beginning to visualize the buildings and make critical design decisions.

Selkowitz is convinced that architects would benefit from DOE-2, for example, if it were more user-friendly. "We have to add features and repackage this tool in a way they'll instinctively use it," he says.

Currently, says Selkowitz, there are two ways to meet the energy efficiency requirements of modern building codes. The first is the "prescriptive path," in which architects adhere to design guidelines prescribed by the building codes--for example, how much insulation is required, and how many windows are allowed.

The second way is the "performance path," in which an architect can build whatever she or he wants as long as a program like DOE-2 shows that it meets a specified energy budget. This is more complex and time consuming but allows for greater creativity on the part of the architect and can far outstrip the energy- efficiency requirements of the building code.

"To get complete architectural freedom and achieve the largest possible energy savings, you need to use a program like DOE-2," says Selkowitz.

Winkelmann also is committed to getting building design programs into the hands of architects early in the design process, before they make the many decisions that affect energy use, such as the size and numbers of windows, the type of glass, the orientation of the building, and the materials used. As it stands, the approximately 1000 DOE-2 users, mostly in the US but also in 40 other countries, are almost all engineers.

"Architects don't like numbers and rarely use computer programs," says Winkelmann. "Few architects now do any energy analysis because it's time-consuming and difficult to do."

Because DOE-2 can be such a great energy-saver, Winkelmann and his colleagues are working on modifications that will encourage more architects to use it. The goal of a new project with the Electric Power Research Institute (EPRI), the research arm of the electric utility industry, is to use DOE-2 as the computational engine and develop a user-friendly shell to allow more people to access the power of DOE-2 more easily. For example, as it stands, the DOE-2 user has to describe the geometry of the building numerically; but linking DOE-2 with a CAD program would allow an architect to draw the building instead and, from the drawing, input the description needed by DOE-2.

The LBL-EPRI project would ultimately link DOE-2 to other special purpose Department of Energy-supported programs, such as RADIANCE and programs that calculate air flow and indoor air quality, as well as to other EPRI-supported software and private- sector software modules.

Architects are visually oriented and need to create and juggle vast amounts of visual and graphic information simultaneously. The LBL researchers asked themselves: What kind of design tool would fit in with the way they already do business? Instead of columns of numbers, why not deal directly with images?

The group has begun to explore the world of multimedia, linking computers with optical disks to use video, animation, sound, and interactivity to spark the interest of architects. They are experimenting with "virtual reality," in which an architect can design a space and then "walk" through it and evaluate it without having to physically build it.

"Rather than constructing a $100 million building and then finding out people don't like it, they can explore the building via a computer model," says Selkowitz.

The design workstation of the future may include an Energy Design Advisor, a program that uses energy calculators such as DOE-2 and WINDOW but also provides other information, such as a multimedia library of successful energy-efficient building-- complete with pictures, floorplans, and video walk-throughs. To be developed as a central element in the EPRI-LBL collaboration, the Energy Design Advisor will warn the designer if a proposed building would be wasteful and will give suggestions on how to reduce energy use.

"The program will show architects and engineers the energy impact of various products and then provide a selection of those that are appropriate," says Winkelmann. "We expect that by making DOE-2 more responsive to the design process and easier to use with the Energy Design Advisor, the number of users will increase ten-fold. We have to make it easy enough to do an energy analysis in a day rather than in weeks, as it is now for a large, complex building."

Two members of the Windows and Daylighting Group, Bob Sullivan and Michael Wilde, acquired expertise in multimedia by putting together the Energy Efficient Building Design Information Kiosk for Southern California Edison. The entertaining, user- friendly kiosk consists of a computer with a touch screen that provides information through video, text, images, graphics, animation, and sound. The idea is to give SCE's customers information about energy services and to provide technical guidance to design professionals. SCE has provided the LBL group with funding to continue its research into multimedia design and implementation.

Another visually appealing, easy-to-use tool that was recently completed will soon be found in several building materials stores in the San Francisco Bay Area and at PG&E's Pacific Energy Center in San Francisco. For its computational engine, the kiosk uses a program called RESFEN, which was originally developed for the National Fenestration Rating Council's rating and labelling project. Using multimedia to provide consumers with energy comparisons for residential windows, the kiosk concept was developed after the 1991 Oakland hills fire to help people who had to rebuild their houses make energy-efficient window choices. It employs a large color monitor with a touch screen and leads the user through a set of interactive steps to evaluate the energy performance and cost of alternate window selections. The kiosk provides background information and expert advice to assist the user.

"We tried to make this very simple, because it's intended to be used by homeowners who walk in off the street," says Sullivan, one of the program's creators.

Simplicity and relevance to the design process are two ways to realize the enormous energy-saving potential of LBL's design tools.

"It's been our challenge for a long time--to get people to pay attention to saving energy," says Wilde. "The thrust of our projects has been to put the tool into the appropriate medium so it's used by the building industry."

The trick is to make the tools simple enough so that people will use them, but not to sacrifice their analytical and computational power and flexibility. "We want to make them more versatile, more powerful, more cost-effective and easier to use all at the same time," says Selkowitz.

"To get them into broader use, we want to tie in the new tools that allow designers to make decisions about energy with the traditional tools that they use for other aspects of design, so that thinking about the energy impact becomes part of their normal routine."