AECbytes "Building the Future"
Article (December 2, 2010)
Greener Buildings Through Energy Analysis Tools
Vijay Kanal and Kelly Flores
In their quest to design energy-efficient buildings, architects and engineers are presented with many challenges when it comes to software tools. Not only are there several of varying capability and complexity to choose from, but there are several other issues related to how these tools are used in order to deliver on a “greener” building.
This article, which is the first of two on this topic, describes some of these challenges and offers some tips on how to overcome them. It is based on our research of available tools and interviews we conducted with several architects and engineers at leading firms.
The second article, to follow in a few weeks, will address in greater detail the capabilities of some of these tools.
Different Tools for Architects and Engineers
Architects and engineers have a wide assortment of tools to choose from to conduct building energy analysis. Some tools conduct whole-building analysis, while others are limited to a few areas like daylighting and massing. Tools such as EcoDesigner, Ecotect and Green Building Studio are relatively easy to use, while others such as eQuest, Energy Plus and IES are complex, requiring extensive training to be useful. But these complex tools are largely the domain of engineers and should remain so, according to several experts we spoke with, including Gerry Faubert, Vice President and Director of Integrated Design at HOK.
Although the firm has a full suite of tools available at its disposal, architects at HOK use Ecotect and Green Building Studio to inform them of the energy impact early in the design process, which the firm refers to as a “performance-based design approach.” They leave the detailed analysis to the MEP or energy-modeling firm, which would use the more complex tools. Faubert’s rationale is that architects and engineers have a common goal of energy efficiency but different expertise, so they should focus on the tool that’s appropriate for their background and needs. “The tools which inform architecture, like Ecotect, focus on building massing, siting and solar effects. The tools typically used by engineering firms focus on whole building energy use and systems. We need expertise from both architects and engineers using the appropriate tools at the appropriate time.”
Crawford Smith, BIM Specialist at SERA, a design firm in Portland, Oregon agrees. “Many of these tools require a pretty strong learning background and steep learning curve, so the complex tools are best left to the engineers,” he said. “One of the challenges with the tools today is finding a balance between simplicity and ease of use, and getting good and useful information out of them, so architects should stick to what they know best.”
While these experts agree that tools like Ecotect and Green Building Studio are not replacements for the more powerful tools, they are particularly helpful when time is a factor—for instance, in a competition where there are just 2-3 weeks to submit a design. “These tools are good enough if you just have to make choices between envelope and orientation options, but you still need tools like Energy Plus to properly conduct energy analysis,” said John Pulley, Vice President and Director of Engineering at HOK.
Even the folks at Autodesk, Graphisoft, and Bentley agree that detailed energy calculations are best left to the engineers using more sophisticated tools.
Autodesk’s John Kennedy, who is Senior Manager of their Building Performance Analysis tools, said, “Ecotect’s power is that it visualizes analysis results so the architect can make informed design choices. A more detailed analysis can be completed with Green Building Studio, which is a whole-building energy analysis tool. At this point, the architect can continue the detailed analysis workflow by exporting their designs to EnergyPlus, eQuest or DOE-2 for their engineers to use.”
Graphisoft’s EcoDesigner Product Manager Miklós Svéd said that their ArchiCAD clients typically use EcoDesigner before exporting to StruSoft’s VIP-Energy, which has the same analysis engine but with more advanced capabilities needed by engineers, such as multi-zone simulations.
Integrated Project Delivery
Another common theme in our discussion with experts was that decisions made during the concept and design phase will have the most significant impact on whether or not the final outcome will meet energy efficiency objectives. So communication and agreement between the architect, engineer, owner, and other stakeholders on an energy-efficient building is critically important early in the project. Achieving building energy efficiency becomes another reason to adopt Integrated Project Delivery.
“A building that’s 80% glass is not going to perform like a 30% glass building, no matter how efficient you make the HVAC system,” said Pulley of HOK. “So it’s really important to get everyone together to set objectives at the beginning of the project to balance efficiency and design objectives.”
Often the engineers are called in for the first time at the 50% DD stage, but several architects and engineers we spoke with argued that that’s too late in the process. Some input from the engineers is desired even during the schematic phase, they said, and the heavy lifting by the engineers can begin at a later stage.
“I would see the architecture side doing higher level calculations early on with basic tools with input from engineers, then the engineers would be more involved with tools like IES or eQuest or Energy Plus. This is particularly important when you are submitting documentation for LEED, etc.” said Smith of SERA.
Project Schedule and Budgets are Tight
While most architects and engineers agree on the need to perform simulations and analysis early in the design phase, another challenge is lack of time and budget. So analysis is often overlooked, which leads to a less than optimum design, or greater cost, or both.
“The time required to do the analysis doesn’t match the speed of the design process, particularly in the early stages,” said Chien Si Harriman, Senior Building Performance Engineer at Guttman & Blaevoet, an energy consulting engineering firm. “And many firms have not worked out a business model for understanding when to draw a line around analysis. It’s partly a contract issue and partly an issue of proper application of engineering judgment and software use. I think this is a very delicate balance that can cause a lot of cost overruns for the engineering team.”
Engineering time for energy analysis typically adds about one-third to the cost of architectural design, according to Smith.
Interoperability is Still Difficult
Although software vendors have made efforts to ease the interoperability between BIM models and analytical tools, with the gbXML format for example, it’s still difficult for all but the simplest models, according to several practitioners we spoke with. The net result is that most of the time, the data entry into a simulation tool is still done manually from a BIM model, creating a “nightmare” situation.
“It’s due to geometry where it breaks down,” said Smith of SERA. “We’ve done a lot of work trying to figure out the best way to get information out of our Revit models into Ecotect. We’ve used gbXML, we’ve used DXF, but either way we end up having to do a lot of remodeling in Ecotect. It’s easier with gbXML, but it’s also very limited in what it exports. It’s either too much [with DXF] or not enough [with gbXML]. So it’s easier for us to start from scratch in Ecotect,”
“We need greater interoperability. Things like gbXML and the IFC file formats are the first steps in this direction, I think, but it’s still got a way to go before it can be really useful. We spend a lot of time going in circles. It’s easy to get these things to work nice when you’ve got a really simple model that’s just a 700 square foot house or something like that, but when we get really large, complex, and sophisticated sustainable buildings, that breaks down pretty quickly.”
Graphisoft and Autodesk have been working around this challenge by integrating more and more energy modeling functionality into their design software. One architect went so far as to say that Autodesk purchased the companies Ecotect and Green Building Studio “for parts” to put into Revit, because according to him, so little has changed with the individual packages since the deals were consummated about three years ago. But he was pleased with the greater analytical functionality being put into Revit. Graphisoft also makes it easy for architects to pull up EcoDesigner directly from ArchiCAD.
Although it’s too early to tell if this approach will work for architects in the long run, everyone we spoke with was pleased with the greater functionality being put into design tools to perform basic energy calculations.
Engineers Customize Tools and Interfaces
On the other hand, the Holy Grail in tools for engineers seems to be sophisticated, yet simple. They want the power of DOE-2, but complete flexibility with it. So while there are several energy analysis tools available “off-the shelf,” it’s quite common for engineering firms to complement or, in some cases, replace these tools with their own internally developed tools and interfaces. This gives them the flexibility to test every strategy on any project, which they claim an off-the-shelf tool often does not permit.
At the Weidt Group, for instance, which is a consulting firm that counts HOK as one of its many design clients, Vinay Ghatti, Energy Specialist said, “If you’re trying to quickly evaluate multiple options for daylighting, it takes some effort to analyze and compile the results together, so we built our own tool for that purpose. It’s a fairly simple interface—with a robust engine using the base algorithms also used in Radiance—which helps us inform our clients so they can make better decisions during the schematic design phase.”
In many cases, these tools are nothing more than sophisticated spreadsheets with data populated from various sources, but engineers are able to run some of the analyses in mere minutes with the spreadsheet, instead of the tens of hours that it might take with a more common tool.
Even design firms are known to build their own tools and interfaces. “The tools that are out there are not at our level of use,” said Smith of SERA, “so we have our in-house ones for things like rainwater catchment and PV array calculations, for example. It’s mostly spreadsheets and macros to do the calculations.”
Although some of the capabilities of the more advanced analysis tools can now be found in design tools like Revit, it requires an experienced architect to make reasonable assumptions in order to get any meaningful data out of the model. Even then, such tools only provide a “30,000-ft high view of the energy model and should not alone be used to make informed decisions during the design phase,” said Ghatti. “As energy analysis involves a complex integration of building systems, it requires an experienced analyst to understand systems complexity, which often necessitates going beyond the conventional capabilities of the modeling tools. One of the key aspects of ‘going beyond’ includes doing sensitivity analysis on a lot of variables. Experience is this way gained and is critical in interpreting the result of energy analysis.”
Even with Green Building Studio, which is targeted at architects, some are less comfortable with it compared with Ecotect, according to Harriman of Guttman & Blaevoet. “While GBS provides important information such as how many kilowatt-hours the building will use, they’re not sure what those numbers mean. So they rely on the engineers to interpret the data or delegate the energy analysis work entirely to the engineers.”
It’s also important to build the model “technically correct at the outset in the design tool, otherwise exporting to the analysis tool creates a lot of discontinuities, and one has to rebuild the model,” said Smith. So again, experience and some basic expertise are essential among architects aiming for energy efficient buildings.
And if architects don’t have the experience, they should work with an energy analyst from the get-go, according to Faubert. He makes the case that “clients expect a level of expertise and that expertise has to be backed up by knowledge in making decisions.”
The Emergence of Open Source and Cloud Computing
One of the more common open source tools is ESP-r, which is a whole building analysis tool for simulation of the energy and environmental impact in buildings. It has been in development since 1974. It is highly technical, but customizable, and help is available from the online community. It is not for the faint of heart because there is no easy to use interface, but with its powerful and customization features (along with it being free), it does have its fans.
For some scientists and engineers, open source software coupled with cloud computing resources is the most cost-efficient, time-efficient and reliable means to solving complex climate and energy performance simulations, particularly related to climate and design integration. One proponent is Meiring Beyers, Director at Klimaat Consulting & Innovation, who argues that “open source tools are now much more mature and validated. At the same time, cloud-computing resources have become mainstream and competitive. The combination of the two means that you can have 24-hour access to an extensive array of high performance compute nodes that you don’t have to maintain, allowing timely delivery of computationally intensive solutions at a fraction of the cost of procuring and maintaining your own cluster systems. This allows the resources to instead be focused on building truly innovative, client-focused tools, processes and design solutions.”
However, there are others who maintain that the delays inherent with cloud computing and the complexity associated with open source software will limit their application to the scientific community. It is still too early to determine which view is valid and what impact these two emerging technologies will have on energy analysis capabilities going forward.
Given the high interest in energy efficient buildings, it may be tempting for the architect or engineer to grab the nearest tool available and get to work. But as we have seen, there is a tool and process appropriate to the task at hand and the training of the individual, so they should choose carefully. It is also important to start working together early in the design process so that aesthetic and efficiency objectives can be balanced and have a reasonable chance of being met. Beyond that, interoperability remains a challenge, with some vendors choosing to bring some of the analytical capability into the design tool to get around the problem. And finally, customization of tools and interfaces will likely remain strong in the engineering community, in order to provide them maximum flexibility to achieve optimum designs.
About the Authors
Vijay Kanal is Founder and Managing Principal at Kanal Consulting, a strategy, marketing, and sustainability consulting firm that helps some of the world’s biggest companies profitably and sustainably grow their business. With research as the foundation, his firm conducts assignments such as corporate strategy, identifying new market opportunities, programs, and product positioning & messaging, in many parts of the world. He has been advising senior management in the AEC industry since 2003 on issues such as BIM, data management, and sustainability. His current focus is on helping clients make sustainability initiatives a core part of the their entire value chain, from strategy to operations to communications. He is a frequent author and speaker on this topic. Vijay holds an MBA from the Wharton School and a Bachelor's in Electrical Engineering. He is also a Certified Management Consultant (CMC). He can be reached at firstname.lastname@example.org or 415-788-8500.
Kelly is a Senior Consultant at Kanal Consulting with an extensive background in strategy, marketing and technology. She has been conducting world-wide customer and industry research and making key recommendations to leading firms in the CAD industry since 2005. Her primary focus has been related to issues such as product positioning, branding, data management, and sustainability. Her expertise includes the design and analysis tools market in AEC and manufacturing. Kelly holds an MBA from the Wharton School, and a Bachelor's in Business, magna cum laude, from the University of Southern California. She can be reached at email@example.com.
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