Computer-Aided EcoDesign

3D model–based technologies are helping assess — and reduce — a design's impact on the environment.

Editor's note: This article was originally published in the Winter 2010 edition of Cadalyst magazine.

Until recently, building information modeling (BIM) software such as Autodesk Revit, Bentley Architecture, Graphisoft ArchiCAD, and Vectorworks Architect focused primarily on modeling and refining building geometry. To analyze the energy consumption of a building, users relied on third-party software such as Green Building Studio, Ecotect, Hevacomp, and IES . A series of acquisitions in the past few years changed that, however.  

In January 2008, Bentley Systems acquired energy-analysis software maker Hevacomp Ltd. In June 2008, the company struck an agreement with Environmental Design Solutions Ltd. (EDSL), securing exclusive worldwide rights to distribute EDSL's Tas, a full-featured analysis software suite intended for complex building systems and large projects. In July 2008, Autodesk followed suit. It snatched up Green Building Studio and Ecotect, signaling its intent to integrate Green Building Studio's web-based analysis tools and Ecotect's energy analysis tools with Revit.

Nemetschek, which develops and markets the Vectorworks BIM software and also owns Graphisoft, has made a considerable effort to ensure its modeling platforms are interoperable with IES (IES stands for Integrated Environmental Solutions and VE stands for virtual environment) and Autodesk Ecotect Analysis (which, even under Autodesk's ownership, remains available for use with competitors' BIM software). In May 2009, at the American Institute of Architects Convention and Design Expo, Graphisoft unveiled its own analysis module, called EcoDesigner. Built into the ArchiCAD user interface and accessible through a single button, it quite literally is a single-click analysis program. Although not as comprehensive as Ecotect or IES , EcoDesigner provides ArchiCAD users with basic energy- and carbon-checking functions.

At the moment, IES remains an independent analysis software provider, operating under the guidance of its founder, Don McLean. His desire to make analysis software that is easier to learn and use led to the distribution of IES VE-Ware, a free analysis module compatible with Google SketchUp, also free, and Autodesk Revit. Using Google SketchUp and IES VE-Ware, users can conduct basic building energy analyses — carbon emissions, energy consumption, and regulatory compliance — at no cost.

The integration of analysis functions in BIM software such as ArchiCAD and Revit and the availability of free analysis tools such as IES VE-Ware foretell a future where most, if not all, BIM software will include entry-level sustainability tools, much in the same way basic stress-analysis and finite-element analysis (FEA) tools have become standard features of most mid-range and high-end mechanical CAD programs.

Follow the Sun

Providing guidance for what it describes as "integrated whole building techniques and technologies," the Whole Building Design Guide (WBDG) portal urges architects to consider the "energy implications in site selection and building orientation." WBDG's suggestions include: "Orient buildings to be able to integrate passive and active solar strategies ... take advantage of natural ventilation and prevailing wind patterns ... and investigate the potential impact of future adjacent developments to the site (e.g., solar and wind exposure, daylighting, ventilation, etc.)."

Solar study — or identifying heat gain, heat loss, and comfort levels at the target site based on annual sun path — has become an integral component of most leading building energy-analysis software packages. Most products mentioned previously — including Ecotect, Hevacomp, and IES — offer this capability.

These tools allow a user to calculate the anticipated solar radiation on a virtual buildings' windows, surfaces, rooms, and spaces; compare summer and winter heat patterns; and identify heating and cooling requirements to keep residents comfortable throughout the year. Depending on the outcome of this simulation exercise, you might add shading devices, install photovoltaic panels, or reorient the building to take advantage of prevailing wind patterns.

The software needs localized climate data for its calculations, and energy-analysis software developers tend to use publicly available data. Ecotect Analysis, for example, comes preloaded with weather data, but it also offers the ability to edit that database or import other data. You can use Ecotect's weather tool to import typical meteorological year (TMY) data, U.S. Department of Energy EnergyPlus weather data, and data from other sources.

The weather data from the Green Building Studio web service, according to Autodesk, "is generated by consuming more recently documented data from a variety of government and other public sources and includes more than 1.5 million virtual weather stations. Users can download the Green Building Studio weather data set and import [it] for use in Ecotect Analysis."

IES provides a variety of preloaded default weather data from sources such as TMY, TMY2, and International Weather for Energy Calculations (IWEC). Users also can change and import any additional weather files that they choose. The software supports native EnergyPlus files (see the EnergyPlus weather data list link in the "Resources and References" sidebar). IES also uses data from ASHRAE (American Society of Heating, Refrigerating, and Air-Conditioning Engineers) and CIBSE (Chartered Institute of Building Services Engineers) for its energy load calculations.

Bentley's Hevacomp uses ASHRAE, CIBSE, and Carrier data. It also enables users to edit weather data, including Meteonorm weather data, gathered from more than 7,900 sites around the world.

Recently, IES added a new Climate Energy Index tool that lets users "analyze the climate data for a location, bringing relevant characteristics to the surface for evaluation and to inform design strategy." Understanding the climate conditions of a target site may lead toward one type of sustainability initiative and away from others. For example, if local climate data shows a low level of rainfall, adding a rainwater collection system or a green roof might not be worthwhile.

Importing new weather data or customizing preloaded data to match a target site's microclimate isn't always straightforward. Future releases of analysis software packages could gain a competitive advantage if they offered easier access to the most frequently updated local climate data and the ability to customize it

On-Demand Carbon Neutralization 

Green Building Studio, the web-based building analysis tool acquired by Autodesk, is available today under its original model. The software is licensed annually for $745 per user. It's also a benefit for Autodesk Ecotect Analysis 2010 subscription customers.

Using Green Building Studio, users can specify a building's site, upload its window and wall properties, then obtain a report about the design's water use, carbon footprint, ENERGY STAR rating, photovoltaic prospect, and daylighting. Courtesy of Autodesk, Revit users can employ an available plug-in to establish a direct link to Green Building Studio from the modeling environment. You can use Green Building Studio even if you happen to be using BIM software from one of Autodesk's competitors, provided your BIM software has the ability to export models in the gbXML format. 

Emerging Products

Aside from established brands such as Ecotect, Hevacomp, and IES , the analysis software market also has seen the growth of specialized packages, often developed by consultants, that are targeted at specific disciplines or industries. Virtualwind, part of the Canadian firm Rowan Williams Davies and Irwin, broke ground with its Virtualwind software, an advanced 3D wind-flow modeling and visualization system based on a computational fluid dynamics (CFD) solver.

Virtualwind users can import models from other 3D design packages as STL files. The company also offers a SketchUp plug-in that can be used to create and edit 3D models for export to Virtualwind. The results can be recorded as graphics images or as AVI movie files.

The ability to adjust the visualization plane lets users isolate and study variables such as the effects of wind on specific floors located at a certain height in a high-rise building. Its creators hope to capture the commercial market, in which developers must assure city planners that the designs of new buildings won't adversely affect residents in surrounding areas.

DesignBuilder Software, a private company in Stroud, United Kingdom, promotes its software DesignBuilder, now in version 2, to those seeking to model a building's energy use, fluid flow, structural integrity, and acoustic performance. It also sells the more specialized EFEN software, which it describes as an analysis program for evaluating fenestration [window placement] options in commercial buildings.

For more information about available applications, see the table below.

Regional and Regulatory Differences 

Although many software packages perform similar solarthermal analyses — often using the same underlying technologies and climate data (many of them use the EnergyPlus simulation engine — the outcome they produce might not be treated the same way by regulatory bodies in different regions. 

Bentley's Hevacomp Simulator V8i and IES are certified by the United Kingdom (UK) Communities and Local Governments (CLG) for dynamic simulation modeling. As a result, carbon dioxide (CO2) emission calculations reported using these software products are considered acceptable for Part L2 and Energy Performance Certificate (EPC) certification of the UK Building Regulations.

Green Building Studio is on the list of approved software for calculating commercial building tax deductions, which means that users can submit the energy and power savings calculated using the software to receive federal tax incentives.

IES VE-Toolkits, VE-Gaia, and VE-Pro include tools for calculating Leadership in Energy and Environmental Design (LEED) credits, which reflect daylighting, occupant comfort, water use, and renewable energy benefits of a building design. Recognizing the differences in regional crediting systems, IES recently launched the LEED-INDIA Green Building Rating System for assessing building performance in that country.

LEED the Way 

In September, the United States Green Building Council (USGBC) approved a change in the minimum program requirements in the 2008 and 2009 versions of LEED for Existing Buildings: Operations and Maintenance. The organization announced, "The occupancy rate required for certification has been lowered from 75% to 50%. This change is in response to current market realities that have disqualified an unprecedented number of properties from pursuing LEED certification because they are unable to meet the 75% occupancy rate requirement."

Responding to this news, IES resident blogger Suzanne Robinson remarked, "This means that if a building is only half full, it can still pursue certification under LEED for Existing Buildings: Operation and Maintenance" ("Recession and LEED," October 7, 2009). 

Although the LEED accreditation process has gone digital with the launch of LEED-Online, it remains, for the most part, a checklist that must be maintained manually by registered users for each project. 

The IES press office stated, "VE-Gaia for LEED currently offers report outputs that closely fit LEED submission templates; however, this is not yet automated." Similarly, the Autodesk press office noted, "The sustainability information required is available as a by-productof the BIM process, but no direct submission to LEED online exists." 

Most current analysis programs allow users to publish the outcome of energy performance predictions in HTML or PDF report packets, but currently no easy way exists to submit a project directly to LEED-Online. Future releases of analysis software may simplify the process by incorporating direct uploads of the required checklist in XML format.

Green Manufacturing Express

Compared with the enthusiasm for green design witnessed in the building industry, the sustainable design movement in manufacturing seems to have a slow start. Most mechanical CAD programs — Autodesk Inventor, SolidWorks, PTC Pro/ENGINEER Wildfire, and Siemens PLM Software NX and Solid Edge — offer integrated stress and FEA analysis tools to help designers examine and test product concepts. These tools have contributed significantly to the reduction of physical prototyping, thus leading to a more sustainable product development workflow. For example, an automaker may use a digital replica of its new model to study and test structural integrity and ergonomics, thus reducing the number of clay or foam models required to perform the same tests. Consequently, the environment is spared the amount of carbon, energy, and material waste associated with the production of those physical models.

A more direct approach to sustainable design — one that lets users calculate the environmental impact of designs based on a 3D CAD model — made its debut in SolidWorks 2010, under the name SolidWorks Sustainability Xpress.

Developed in partnership with the sustainability consulting firm PE International, SolidWorks Sustainability Xpress appears as a module available under SolidWorks' Evaluate tab (where FEA tools also reside). With this module, users can specify the manufacturing site, deployment site (where the product will be sold or used), production method (injection molding, machine, etc.), and choice of material, and the software will calculate the anticipated water and air pollution, carbon emissions, and energy consumption resulting from the process. Because the software is tightly integrated with SolidWorks, it uses the CAD model itself to estimate and calculate the volume of materials, which in turn serves as the foundation for calculating environmental impact. The module first appeared as a work in progress on the SolidWorks Labs web site, as a free plug-in for SolidWorks 2009. It is now commercially available in SolidWorks 2010. It currently works only on parts, not assemblies. 

Mind over Matter

With its software already in beta testing with an extensive user community since April 2009, Sustainable Minds, a sustainability software as a service (SaaS) provider, recently unveiled Sustainable Minds release 1. The web-hosted software comprises lifecycle assessment tools, a learning center, and a community portal, all of which are designed to estimate, evaluate, and track the environmental performance of products throughout their lifecycle.

Terry Swack, cofounder and CEO, noted, "[Sustainable Minds] can be used in all stages of concept design, from screening possible directions through comparing final concepts, and is intended for use before using CAD or with CAD tools. You can assess any portion of the product, the whole product system, assemblies, subassemblies, and parts."

Uploading bill of materials (BOM) data involves populating Sustainable Mind's Excel BOM template with data such as materials and part numbers, names, and weights, which then populate the appropriate fields in the system BOM, to account for the effects of product manufacture, transportation, and end-of-life disposal. For Autodesk Inventor users, the job of importing BOM data is a bit easier, because Sustainable Minds has tweaked the software and its own database to let Inventor users upload a BOM without having to reformat the cells. Inventor materials have been mapped to Sustainable Minds' database for more accurate identification after upload.

Sustainable Minds is based on Okala, a comprehensive and transparent single-figure lifecycle assessment calculation. Originally published in 2003, Okala currently includes more than 550 impact factors with CO2-equivalent values. The data and science come from sources including the U.S. Environmental Protection Agency (EPA) and the National Institute of Standards and Technology (NIST).

The manufacturing industry currently has no advocacy group or institution that functions as the equivalent of the building industry's Green Building Council. The EPA encourages the use of good lifecycle assessment practices "to make more informed decisions through a better understanding of the human health and environmental impacts of products, processes, and activities." But it currently has no rating system that serves as an incentive, as the LEED rating system does for the building design community.

Software-based product lifecycle assessment tools are still in their infancy, but if they become an integral part of the product design process, a rating system could emerge from industry consensus.

Comparison Is Key

"There is no such thing as a green product. All products use materials, use energy, and create waste," observed Swack. "There are only greener products."

On its own, a manufacturing project — say, the production of a toaster that's expected to deplete 50 units of fossil fuel and 24 units of ozone — has little or no intrinsic green value, unless it's compared with another project — say, the production of the same toaster in a different material, which is expected to deplete only 40 units of fossil fuel and 10 units of ozone.

This comparison is the principle behind Sustainable Minds and SolidWorks Sustainability Xpress: The user registers and creates several product production scenarios and compares the environmental impact of each. After examining all options, that user would, in theory, select one that's less detrimental to the environment. 

Sustainable Software Delivery

Ever wondered about the environmental impact of the sustainability and energy analysis software tools themselves? Like everything else, software products have an environmental cost. For many, that cost is related to packaging and shipping the product.

Sustainable Minds CEO Swack believes web-hosted software or SaaS, compared with traditional software, is a more sustainable deployment approach. Because the software lives on a server and is accessed via a web browser, the delivery model lets its makers avoid the material wastes inherent in packaging and shipping. 

But more to the point, the SaaS model allows the developer to offer Sustainable Minds at a reasonable cost: $700 per user per year for professional use. This price, Swack pointed out, creates "a very low barrier to entry for companies of all sizes interested in designing greener products."