Sustainable design analysis and BIM

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A screen shot from Autodesk Ecotect Analysis.

A screen shot from Autodesk Ecotect Analysis.

Rob Malkin of Autodesk explains how Autodesk Ecotect Analysis software helps architects and other users analyse the performance of their conceptual building designs.

According to the Australian Department of Climate Change and Energy Efficiency, buildings contribute approximately 20 percent of Australia’s greenhouse gas emissions, split fairly evenly between homes and commercial buildings. Australia’s building community has been guided by the Green Building Council of Australia and the National Australian Built Environment Rating System in reducing greenhouse gas emissions and slowing our impact on climate change. As programs such as the Green Star rating system become the basis for regulation, improving building energy performance presents an enormous opportunity for innovative architecture, engineering and construction practices.

Sustainable design in practice

Early design decisions can make a significant impact on the efficient use of vital resources. Sustainable analysis tools help architects and engineers to make better-informed decisions earlier in the design process, greatly affecting the efficiency and performance of a building design. In the past, analysis software has been complex and required special training, making it unsuitable for infrequent users such as architects and designers. Sustainable analysis tools, such as Autodesk Ecotect Analysis, help users to become proficient faster by providing access to immense stores of data and the ability to iterate more quickly for optimal sustainable designs.

New Zealand multidisciplinary design firm Jasmax has used Autodesk’s Ecotect software in the design of sustainable concepts. “The future of architectural design will rely heavily on sustainability and we are seeing it become a more significant part of our everyday workflow and procedures,” says Melanie Tristram, Revit Manager at Jasmax. “We have used Autodesk Ecotect Analysis to conduct sun and material analysis on various projects, which has enabled us to assess the effects our structures would have on surrounding environments and ensure that the most sustainable materials are used during construction.”

Designing and delivering more sustainable projects can be complex. It requires close coordination across different project stages, from design through construction and operation. Many firms are looking for the best way to integrate building information modelling (BIM) technology with sustainable design and analysis tools. BIM is core to Autodesk’s sustainable design approach for building performance analysis and simulation.

Analysing a building design

BIM enables architects and engineers to understand how their projects perform before they are built. Developing and evaluating multiple alternatives at the same time allows easy comparison and informs better sustainable design decisions.

“Almost at the click of a button, we are now able to alter designs, flipping back and forth through options to ensure that the final designs we produce are the best ones for each project,” says Tristram.

A computable Autodesk Revit Architecture design model is devised for sustainability analyses – even during early conceptual design. As soon as the layout of a building’s walls, windows, roofs, floors and interior partitions (elements that define a building’s thermal zones) are established, the information employed to create a Revit model can be used to perform analyses. Performing these analyses in a CAD workflow is fairly difficult, as the CAD model has to be exported and carefully massaged to work with analysis programs. Using Ecotect Analysis to analyze early building designs emerging from a Revit-based BIM process can simplify the analysis process.

Whole-building energy, water and carbon analysis

Subscribers to Ecotect Analysis can also get access to Autodesk’s Green Building Studio web-based service for the duration of their subscription. The web service enables faster, more accurate whole-building energy, water and carbon emission analyses and helps architects – the majority of whom are not specially trained in any of these analyses – to evaluate the carbon footprint of a Revit-based building design with greater ease.

The Green Building Studio web service was first introduced in 2004. Today, its analysis results meet American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Standard 140 and are qualified by the U.S. Department of Energy (DOE). The service received the Microsoft Ingenuity Point Award in 2008.

Built specifically for architects and using green building extensible markup language (gbXML) for easy data exchange across the internet, the web-based service was one of the first engineering analysis tools to deliver easy-to-use interoperability between building designs and sophisticated energy analysis software programs such as DOE-2.

The link between the Revit platform and the Green Building Studio web service is facilitated through a plug-in that enables registered users to access the service directly from their Revit Architecture design environment. This streamlines the entire analysis process and gives architects faster feedback on design alternatives, making green design more efficient and cost effective.

Based on the building’s size, type and location (which drives electricity and water usage costs), the web-based service determines the appropriate material, construction, system and equipment defaults by using regional building standards and codes to make intelligent assumptions. Architects can change any of these settings to define specific aspects of their design: a different building orientation, a lower U-value window glazing or a four-pipe fan coil HVAC system.

The service uses precise hourly weather data as well as historical rain data, accurate to within nine miles of the given building site. It also uses emission data for electric power plants across the United States and includes the broad range of variables needed to assess carbon neutrality.

Analysis results

Usually within minutes, the service calculates a building’s carbon emissions and the user can view the output in a web browser, including the estimated energy and cost summaries as well as the building’s carbon neutral potential. Users can then explore design alternatives by updating the settings used by the service and re-running the analysis, or by revising the building model itself in the Revit-based application and then re-running the analysis.

The output also summarizes water usage and costs and electricity and fuel costs, calculates an Energy Star score, estimates photovoltaic and wind energy potential, calculates points toward LEED daylighting credit, and estimates natural ventilation potential. The Green Building Studio report is easy to understand, giving architects information they need to help make greener design decisions.

The desktop tools in Ecotect Analysis provide a wide range of functions and simulations, demonstrating how environmental factors will affect building operation and performance in the early design phase.

Working with the environment

To mitigate a building’s impact on the environment, it is important to understand first the impact of the environment on the building. Autodesk Ecotect Analysis combines a wide array of analysis functions – including shadows, shading, solar, lighting, thermal, ventilation and acoustics – with a highly visual and interactive display that presents analytical results directly within the context of the building model. This visual feedback enables the software to communicate complex concepts and extensive datasets more effectively and helps designers quickly engage with multifaceted performance issues at a time when the design is sufficiently “plastic” and can easily be changed.

Analysing a design in the context of BIM

Revit-based models can be exported to gbXML format and imported directly into Ecotect Analysis for simulation and analysis throughout the design process. At the onset, very early stage Revit massing models can be combined with site analysis in Autodesk Ecotect Analysis to determine optimal location, shape and orientation, based on environmental factors such as daylight, overshadowing, solar access and visual impact.

As the design evolves, whole-building energy, water and carbon analysis can be conducted using the integrated access to Autodesk Green Building Studio in order to benchmark its energy use and recommend areas of potential savings. Once these fundamental design parameters have been established, Ecotect Analysis can be used again to rearrange rooms and zones, to size and shape individual apertures, to design custom shading devices or to choose materials, based on factors such as available daylight, glare protection, outside views and acoustic comfort.

Brisbane engineering consulting firm Bornhorst + Ward has benefited from using Autodesk BIM. “BIM helped everyone make better decisions early in the design process,” said Brett Taylor, a director at Bornhorst + Ward. “Using Revit Structure, our engineers could spin the model and more quickly visualize the appearance of the completed project and all its components. In a recent project with Industry Superannuation Property Trust and Brookfield Multiplex, we developed a thirty-eight-storey Regent office tower. To meet sustainability goals, we had to maintain an overall concrete-fly-ash content of 20 percent. We used Autodesk’s Revit Structure software to insert a fly-ash parameter in every model element, which facilitated the creation of more accurate fly-ash schedules, as well as high-quality, multicoloured 3D views illustrating fly-ash content throughout the project.”

Visual feedback

Perhaps the most unique aspect of the software is its visual and interactive display of the analysis results. The inability of the designer to easily interpret the results of analyses is often the biggest failing of building performance analysis software. Autodesk Ecotect Analysis provides feedback in the form of text-based reports and visual displays. These visual displays are more than just charts and graphs. The analysis results are presented directly within the context of the model display: shadow animations resulting from shadow casting analysis, surface-mapped information such as incident solar radiation, and spatial volumetric renderings such as daylight or thermal comfort distribution in a room. This type of visual feedback makes it easier for designers to interact with analysis data, often in real time. For instance, a designer can rotate a view of surface-mapped solar radiation looking for variations over each facade, or watch an animated sequence of solar rays to see how sunlight interacts with a specially designed light shelf at different times of the year.

Ongoing building performance analysis

During conceptual design, Ecotect Analysis and the Revit Architecture model can be used to perform overshadowing, solar access and wind-flow analyses and to explore orientation that maximizes building performance without impinging on the rights of neighbouring structures to light.

As the design develops and the elements that define a building’s thermal zones are established, the Revit model can be used for room-based calculations such as average daylight factors, reverberation times and portions of the floor area with direct views outside.

Eventually the Revit model can be used for more detailed analysis, such as shading, lighting and acoustic analysis. For example, the architect or designer can use Ecotect Analysis in conjunction with a shading louvre design modelled in Revit Architecture to simulate how the design will work under different conditions throughout the year. They can use Ecotect Analysis to assess the acoustic comfort of a Revit-based design and then adjust the location of a sound source, the internal wall layout or the geometry of sound reflectors for optimal comfort.

Summary

The consistent, computable data from Autodesk Revit Architecture and the breadth of performance analysis of Autodesk Ecotect Analysis work in combination to reduce the cost and time of energy modelling and analysis. Feedback from these analyses helps architects and other users to optimize the energy efficiency of their designs and work toward carbon neutrality earlier in the design process – a key ingredient not only for incorporating energy efficiency into standard building design practices, but also for mitigating the carbon footprint of our built environment.

Rob Malkin is sales director, architecture, engineering and construction, at Autodesk Australia New Zealand.

Further information

Autodesk Level 5, Building C
11 Talavera Road
North Ryde NSW 2113
+61 2 9844 8000,
www.autodesk.com.au

Construction Users Roundtable (CURT)
CURT provides an international forum for the exchange of information, views, practices and policies on construction to create a competitive advantage for construction users.
www.curt.org

BIM in Australia 2010 report
BIM in Australia 2010 provides an overview of the discussions at the BIM forums held in Brisbane, Melbourne, Perth and Sydney in 2010, hosted by the Australian Institute of Architects in partnership with Consult Australia and Autodesk.
www.architecture.com.au/bimreport2010


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