BIM and Analysis for Sustainable Design, Part 2 (1-2-3 Revit Tutorial)1 May, 2007 By: AIA ,Rick Rundell
New heating and cooling analysis tools, plus two case studies.
Last month I began a two-part series exploring how BIM supports analysis for sustainable design -- discussing how the Revit building information model can be used directly by building analyses modules from IES (Integrated Environmental Solutions).
I ended the article with a description of IES's new Sustainability Toolkit, an analysis package unique to the Revit platform that lets architects conduct a variety of analyses using a Revit BIM.
This month, I begin by highlighting new functionality contained in Revit MEP for heating and cooling load analysis, also based on the IES analysis modules. We'll wrap up the series by describing how two prominent North American design firms are currently using the integration between Revit and IES to enhance their ability to conduct multiple types of building performance analyses and design greener buildings.
Heating and Cooling Load Calculations for MEP
As I explained last month, the integration between Revit and IES manifests itself in both the <VE> (the <Virtual Environment>, IES's software) and Revit. The Sustainability Toolkit described last month for thermal assessments and daylighting calculations is part of the <VE>.
Revit MEP has new native functionality for heating and cooling load analysis that uses the IES analysis modules. Like the Sustainability Toolkit, the direct link between Revit and the IES software eliminates the need to recreate geometry for analysis within the <VE>. Simply by selecting the Heating & Cooling Loads icon from the Revit MEP mechanical menu, the Revit BIM is loaded into the <VE> completely transparently to the user.
The IES <VE> software works directly on the Revit BIM, eliminating the need to recreate geometry for analysis.
With the native heating and cooling load-analysis capability in Revit MEP, you simply define analysis parameters for rooms in the building model and click on the Heating & Cooling loads tool. A visual representation of the analysis model is presented, along with additional analysis inputs that can be used to refine the data that's automatically assigned to the building and rooms for the analysis. Data such as occupancy, internal loads, room type and construction and even building location that are defined in the Revit model can be adjusted and overridden for the analysis if desired.
You then click on Calculate. An ASHRAE steady-state analysis is performed and the results are displayed in an HTML report, showing room-by-room air-flow requirements as well as heating and cooling loads -- and totalling these values for overall building energy consumption. In addition, the air-flow and load calculations for each room are posted back to the Revit model as room attributes and can be used to begin equipment and ductwork sizing.
If you have access to all of the <VE> tools (i.e. you purchased them separately from IES), you then can click on the <Virtual Environment> icon in the dialog box and <VE> automatically reads all the necessary geometry and parameters from the Revit BIM and prepares it for further analysis. You are then transferred to the <VE> platform for further types of analyses.
The air-flow and load calculations for each room are posted back to the Revit model as room attributes and can be used to begin equipment and ductwork sizing.
It's important to note that this heating and cooling analysis is the same analysis included in the Sustainability Toolkit described in last month's article. Workflow alone differentiates the two: one is done to gain insight into a building's overall energy performance, particularly in the early stages of design; the other is to support the MEP design process.
In the MEP workflow, the analysis could also be used to iterate a more sustainable design. For example, a client may be wondering about combining a few smaller rooms into one larger one. An MEP engineer reruns the analysis to see what effect the proposed change would have on the MEP systems: a more efficient air handler or just a rerouting of the duct system. Or, perhaps the engineer is wondering how alternate glazing properties of the windows might reduce the cooling loads for the building, so without having to update the architectural building model, he or she quickly overrides those building properties in the Heating & Cooling Loads dialog box and reruns the analysis. In this way, the engineer can provide more meaningful feedback to the architect throughout the design process, especially in the early design stages when the feedback can make the biggest difference.
Within the Heating & Cooling Loads dialog box, you can override the room and construction data to quickly evaluate multiple sustainable design options.
To get a more detailed perspective of the role BIM can play in analyzing a building design for sustainability, let's look at two firms that currently using this software integration: Canadian firm Stantec and U.S.-based Burt Hill.
Edmonton, Alberta-based Stantec is recognized as a world-class leader in the delivery of sustainable solutions. The firm recently received a coveted international ASHRAE award that recognizes successful applications of innovative design, effective energy management, indoor air quality and mechanical design management technology.
With 80 locations in North America and the Caribbean, Stantec offers planning, engineering, architecture, surveying and project management services to public and private clients. The company also practices what it preaches: its headquarters building was one of the first in Edmonton to earn a LEED-New Construction (NC) silver certification.
Stantec is also known for using an integrated design team approach on its projects and therefore has a heightened appreciation of the multidisciplinary value of BIM. The firm uses the entire Revit platform for all key disciplines -- MEP engineering, structural engineering and architecture -- and was recently awarded Autodesk's Revit BIM Experience Award Winner for effective integration of the entire Revit BIM platform. The company first began using Revit Structure at end of 2005, then Revit Architecture in spring of 2006, quickly followed by Revit MEP in mid-2006.
Given its focus on sustainable solutions, Stantec was one of the first users of the integration between Revit and the IES analysis applications. "We started using IES's <VE> modules in the beginning of 2005, making building performance analysis an essential part of the integrated design approach," explains Dejan Radoicic, P. Eng., LEED AP, Mechanical Discipline Leader for Building Engineering at Stantec. "The new integration between IES and Revit lets us use the building information model directly for a broad range of building performance analyses during all stages of design."
In the past (before their adoption of IES or Revit), their analysis workflow began by importing CAD files or measuring directly from hardcopy drawings and then building 3D models and separate analysis models for each different design option or analysis. Each analysis model may have taken several days to create, which significantly prolonged the building analysis time. As Radoicic puts it, "The less time we need to create analysis models means the more time we have for analyzing design options for better performing buildings."
They can now use BIM directly for a broad range of analyses to assess various what-if design scenarios, to optimize and integrate different systems (such as lighting and HVAC) and explore synergies between them. In addition to using the capabilities included in the Sustainability Toolkit and Revit MEP, Stantec also uses many of the other types of building analyses available from IES within the <VE> such as natural ventilation simulation and advanced airflow analysis.
Stantec uses the Revit BIM for a variety of building analysis such as the air-flow analysis shown here.
Stantec has already used the integration between IES and Revit to analyze a number of projects, including an 82,300 sq. ft. renovation/expansion of the Art Gallery of Alberta in Edmonton and a 250,000 sq. ft. new hotel, the Westin Kelowna Hotel in Kelowna, British Columbia. Analysis specialists like Radoicic were Stantec's early adopters, but the capabilities are spreading to the project teams -- engineers and architects alike -- to support Stantec's integrated design team approach.
Operating from seven locations in the U.S. and one abroad, Burt Hill offers architecture, engineering, interior design, landscape architecture and master planning services -- bringing a particular focus on sustainable design, technology integration and energy management to its projects. With more than 600 professionals working for the company, Burt Hill is recognized as an innovative leader in designing integrated solutions.
The firm was an early adopter of IES's <VE> since its introduction in North America and is using its analysis tools at every stage of project development from early marketing to postconstruction. Prior to implementing the <VE>, Burt Hill outsourced much of its building analyses, which was expensive and time consuming. In-house analysis was either experience-based, relying on an architect's intuition of the energy penalties associated with various design scenarios or based on approximate hand calculations. The end result was a limited ability to affect the performance of a design.
To further increase its energy-analysis capabilities, Burt Hill recently formed an in-house consulting group dedicated to building simulation. The group is charged with incorporating energy analysis into all new projects -- influencing design decisions early on in the project and giving it an "energy tag" that reflects what percentage above baseline standards (such as ASHRAE or LEED standards that provide minimum requirements for energy-efficient design of buildings) the building will perform. The capabilities of this new group also positions Burt Hill to take on the 2030 Challenge, an industry initiative that calls on the global building sector to immediately reduce energy use by 50% in new buildings and major renovations and be carbon-neutral by the year 2030.
Burt Hill, having implemented Revit in 2003, was a perfect fit for using computable BIM for building performance analysis. With the integration of Revit and IES, it doesn't have to create separate analysis models anymore -- it can use its Revit models directly in their analyses, and the Revit users can get instant energy feedback when comparing design options. "Using the Revit building information model for analysis is propelling our architects towards holistic BIM," explains Dustin Eplee, leader of Burt Hill's Energy Analysis Team. "When the architectural design model is also the energy model, energy modeling and responsiveness become core components of the design process." For example, rooms are designed explicitly as 3D energy-consuming volumes instead of just floor space bounded by walls.
By using the Revit architectural design model for analysis (as shown here), energy modeling and responsiveness have become core components of the design process for Burt Hill.
Burt Hill has already begun using the IES/Revit link on two early design stage projects: a LEED platinum project in Boston (a 275,000 sq. ft. luxury condominium building) and an eco-friendly literacy center in Pennsylvania that incorporates green features such as natural daylighting and ventilation. Work sessions and training seminars are being used to roll out the Sustainability Toolkit to the project teams to help them understand its underlying analyses and output.
"One key advantage of the Revit/IES integration is that it accommodates a fully integrated design approach and facilitates interdisciplinary decision making," remarked Eplee. "Architects and MEP engineers can use the analysis tools for their own baseline energy calculations and MEP design; then our team tackles the more in-depth building simulation, analysis and certification tools available in the IES <VE> -- resulting in a comprehensive, integrated analysis of building performance."
Seamless Building Performance Assessment
One of the many advantages of BIM is the level of detail and reliability intrinsic to a computable building information model -- critical components for rigorous building analysis. The integration of the Revit BIM and IES analysis tools represent a new chapter for integrated building analysis. Without the encumbrance of specialized skills, separate analysis packages or the need to recreate the building geometry, this pairing provides an easy way for architects and engineers to assess a building's performance and make better decisions to support sustainable design and a greener built environment.