1. 2010 CRC PhD Student Conference
An Investigation into Interoperability of Data Between
Software Packages used to Support the Design, Analysis and
Visualisation of Low Carbon Buildings
Robina Hetherington
R.E.Hetherington@open.ac.uk
Supervisors Robin Laney
Stephen Peake
Department/Institute Computing
Status Fulltime
Probation viva Before
Starting date January 2010
This paper outlines a preliminary study into the interoperability of building design and
energy analysis software packages. It will form part of a larger study into how
software can support the design of interesting and adventurous low carbon buildings.
The work is interdisciplinary and is concerned with design, climate change and
software engineering.
Research Methodology
The study will involve a blend of research methods. Firstly the key literature
surrounding the study will be critically reviewed. A case study will look at the
modelling of built form, with reflection upon the software and processes used. The
model used in the case study will then be used to enable the analysis of data
movement between software packages. Finally conclusions regarding the structures,
hierarchies and relationships between interoperable languages used in the process will
be drawn. This will inform the larger study into how software can support the design
of interesting and adventurous low carbon buildings.
Research questions:
1. What are the types of software used to generate building models and conduct
the analysis of energy performance?
2. What is the process involved in the movement of data from design software to
energy analysis software to enable the prediction of the energy demands of
new buildings?
3. What are the potential limitations of current interoperable languages used to
exchange data and visualise the built form?
Context
Software has an important role in tackling climate change, it is “a critical enabling
technology” [1]. Software tools can be used to support decision making surrounding
climate change in three ways; prediction of the medium to long term effects,
formation and analysis of adaptation strategies and support of mitigation methods.
This work falls into the later category, to reduce the sources of greenhouse gases
through energy efficiency and the use of renewable energy sources [2].
Climate change is believed to be caused by increased anthropogenic emissions of
green house gases. One of the major greenhouse gases is carbon dioxide. In the UK
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the Climate Change Act of 2008 has set legally binding targets to reduce the emission
of carbon dioxide by 80% from 1990 levels by 2050 [3]. As buildings account for
almost 50% of UK carbon dioxide emissions the necessary alteration of practices
related to the construction and use of buildings will have a significant role in
achieving these targets [4]. In 2007 the UK Government announced the intention that
all new houses would be carbon neutral by 2016 in the “Building a Greener Future:
policy statement”. This is to be achieved by progressive tightening of Building
Regulations legislation over a number of years [4]. Consultations are currently taking
place on the practicalities of legislating for public sector buildings and all new non-
domestic buildings to be carbon neutral by 2018 and 2019 respectively [5]. The
changes in praxis in the next 20-30 years facing the construction industry caused by
this legislation are profound [6].
Software used in building modelling
Architecture has gone through significant changes since the 1980s when CAD
[Computer Aided Draughting/Design] was introduced. The use of software has
significantly altered working practices and enabled imaginative and inspiring designs,
sometimes using complex geometries only achievable through the use of advanced
modelling and engineering computational techniques. However, the advances in
digital design media have created a complex web of multiple types of software,
interfaces, scripting languages and complex data models [7].
The types of software used by architects can be grouped into three main categories:
CAD software that can be used to generate 2D or 3D visualizations of buildings. This
type of software evolved from engineering and draughting practices, using command
line techniques to input geometries. This software is mainly aimed at imitating paper
based practices, with designs printed to either paper or pdf.
Visualization software, generally used in the early design stages for generating high
quality renderings of the project.
BIM [Building Information Modelling] software has been a significant development
in the last few years. BIM software contains the building geometry and spatial
relationship of building elements in 3D. It can also hold geographic information,
quantities and properties of building components, with each component as an ‘object’
recorded in a backend database. Building models of this type are key to the
calculations now required to support zero carbon designs [8]. Examples of BIM
software are Revit by Autodesk[9], and ArchiCAD by Graphisoft[10] and Bentley
Systems [11]
Energy analysis software
Analysis software is used to perform calculations such as heat loss, solar gains,
lighting, acoustics, etc. This type of analysis is usually carried out by a specialist
engineer, often subsequent to the architectural design. The available tools are thus
aimed at the expert engineer who have explicit knowledge to run and interpret the
results of the simulation. This means that, until recent legislative changes, there was
no need for holistic performance assessment to be integrated into design software
[12].
Calculation of energy consumption requires a model of the proposed building to make
the detailed estimates possible. Examples of expert tools that use models for the
calculation are TRNSYS [13], IES Virtual Environment [14], EnergyPlus [15]. One
tool that supports the architectural design process is Ecotect [16], which has a more
intuitive graphical interface and support to conduct a performance analysis [12].
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Energy analysis is one-way iterative process, with geometric meshes and data
transferred from the design package to the various analysis tools. Every design
iteration will (or should) involve a re-run of the environmental analysis tool [17]. The
mesh geometry requires manipulation for this movement into the analysis software
from the modelling environment and data such as material properties needs to be re-
entried, with a significant penalty in time and possible loss or corruption of data
[18][19].
Key research into interoperable languages used in the AEC [Architectural
Engineering and Construction] industry
A number of interoperable languages, relating to building designs, have been
developed since the release of version 1.0 of the XML [eXtensible Markup
Languages] standard in February 1998. They include visualisation schemas mainly
used for as the source for the display of models: X3D[eXtensible 3D], based on
VRML [Virtual Reality Modeling Language], CityGML for the representation of 3D
urban objects and COLLADA [COLLAborative Design Activity]. The ifcXML
[Industry Foundation Classes eXtensible Markup Language] specification, developed
by the IAI [Industrial Alliance for Interoperability], was designed to facilitate the
movement of information from and between BIM software. It was designed in a
“relational” manner, as a result of the BIM database concept. Accordingly there is
concern about the potential file size and complexity of the standard arising from the
XML format and the amount of data it can contain [20] [21]. Also, the seamless
interoperability it is intended to support has proved to be elusive. Take up has been
slow and incomplete with software companies not always supportive [22]. A
language designed specifically for interchange of data between design modelling
environments and energy analysis packages is gbXML [Green Building eXtensible
Markup Language]. In comparison with ifcXML it is considerably simpler and easier
to understand [23]. However, it limitations are evident in the geometric detail
contained in the file which inhibits the transfer back to the design package [17].
Next stage – a case study
This paper has set the case study in context and given the key research in the area of
interoperability in AEC projects. In the next stage a small house will be designed in
Revit and the environmental design analysed in Ecotect to gain experience in using the
tools and enable reflection on the software and procedures involved. ifcXML and
gbXML files will be exported and analysed.
Future work
The software used in this study are all developed by commercial organizations,
typically with an incremental, yearly update. New software, such as Ecotect, is often
brought in from an independent developer. However, open platforms are generally
considered to “promote innovation and diversity more effectively than proprietary
ones” [24]. In the field of climate change, given the profound threat to humanity, a
community approach is seen as potentially a better way forward [25]. Future work
will look at how building design software may evolve to meet the challenge of
designing interesting and beautiful low carbon buildings.
References
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Proceeding of the 24th ACM SIGPLAN conference companion on Object oriented programming
systems languages and applications - OOPSLA '09, Orlando, Florida, USA: 2009, p. 1057.
[2] S. Peake and J. Smith, Climate change : from science to sustainability, Milton Keynes
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[England]; Oxford: Open University; Oxford University Press, 2009.
[3] Great Britain, Climate Change Act of 2008, 2008.
[4] Department for Communities and Local Government, “Building a Greener Future: policy
statement,” Jul. 2007.
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