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Data Sharing for Sustainable Assessments: Using functional databases for interoperating multiple building information structures

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This paper presents the development and implementation of an automatic sustainable assessment prototype using functional databases. For the practical purpose, we use Leadership in energy and environmental Design (LEED) as the exemplar standard to demonstrate the integrative process from building information aggregation to final evaluation. We start with a Building Information model, and use Construction Operations Building Information exchange (COBie) as a bridge to integrate LeeD requirements. At present, the process of sustainable building assessment requires information exchange from various building professionals. However, there is no procedure to manage, or use, information pertaining to sustainability. In our research, we translate rules from LeeD into computable formulas and develop a prototype application to produce templates for LEED submission.
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T. Fischer, K. De Biswas, J.J. Ham, R. Naka, W.X. Huang, Beyond Codes and Pixels: Proceedings of
the 17th International Conference on Computer-Aided Architectural Design Research in Asia, 193–202.
©2012, Association for Computer-Aided Architectural Design Research in Asia (CAADRIA), Hong Kong
DATA SHARING FOR SUSTAINABLE ASSESSMENTS
Using functional databases for interoperating
multiple building information structures
TAJIN BISWAS, TSUNG-HSIEN WANG
Carnegie Mellon University, Pittsburgh, USA
tajin@cmu.edu
and
RAMESH KRISHNAMURTI
ramesh@cmu.edu
Abstract. This paper presents the development and implementation of
an automatic sustainable assessment prototype using functional data-
bases. For the practical purpose, we use Leadership in Energy and Envi-
ronmental Design (LEED) as the exemplar standard to demonstrate the
integrative process from building information aggregation to nal eval-
uation. We start with a Building Information model, and use Construc-
tion Operations Building Information Exchange (COBie) as a bridge
to integrate LEED requirements. At present, the process of sustainable
building assessment requires information exchange from various build-
ing professionals. However, there is no procedure to manage, or use,
information pertaining to sustainability. In our research, we translate
rules from LEED into computable formulas and develop a prototype
application to produce templates for LEED submission.
Keywords. Building information databases; sustainable assessment.
1. Introduction
In the building industry, assessment schemas are increasingly being used
to objectively measure sustainability achievements. These are also known
as ‘green/sustainability’ rating systems. A green/sustainable building rating
system is dened as a tool that examines the performance or expected per-
194 T. BISWAS, T.-H. WANG AND R. KRISHNAMURTI
formance of a ‘whole building’ and translates that into an overall assessment
that allows for comparison against other buildings (Fowler and Rauch 2006).
In the US, a commercial green building is generally considered to be one
certied by a sustainable building rating system; for example Leadership in
Energy and Environmental Design (LEED), which is developed by US Green
Building Council (USGBC) to establish a common standard of measurement
and evaluation (Yudelson 2008). Green building evaluation is a multi-person
and multi-phase process (Turkaslan-Bulbul 2006); therefore, sharing build-
ing design information among different building domains and professionals
is essential. The current process of sustainable building evaluation is highly
disparate. Even with the use of conventional Computer-Aided Design (CAD)
tools, this requires a great deal of human intervention and interpretation. This
makes the process of sustainability assessment costly and time consuming.
(Nguyen et al. 2010)
Keysar and Pearce (2007) have identied 275 tools in 14 categories, which
are required, at various times, in evaluating sustainable buildings. To enhance
cooperation and use of building information for assessment, we focus our
research on current building information interoperability tools and standards
in the Architecture Engineering, and Construction (AEC) domain coupled
with functional databases.
2. Sustainability assessment and tools
Green/Sustainable architecture is no longer a current phenomenon. It is
increasingly being addressed in the building industry by different sustainabil-
ity assessment standards (Solomon 2005). Krygiel and Bradley (2008) state
that “many tools used to measure the impact of sustainable design strategies
are not directly accessible within a Building Information Model (BIM) itself;
therefore, data needs to be exported to another application or imported from a
external data source.” A “Building Information Model is a digital representa-
tion of physical and functional characteristics of a facility; a shared knowledge
resource for information about a facility forming a reliable basis for decisions
during its life-cycle.” (Smith and Edgar 2008)
2.1. SUSTAINABILITY ASSESSMENT STANDARDS
There are many different assessment systems used around the world. Fowl-
er’s study (2006) shortens the list rst, by combining several rating systems
used in multiple countries, and second, by subsuming those that are derived
from other rating systems. A summary of two such representative assessments
standards are given below.
195DATA SHARING FOR SUSTAINABLE ASSESSMENTS
The British Research Establishment (BRE) was the rst to develop an
environmental impact assessment method, BREEAM, British Research Estab-
lishment’s Environmental Assessment Method. Subsequently, other countries
adopted the BRE approach in developing their own assessment method (Reed
2010). BREEAM has become the de facto measure of building environmental
performance in Europe “BREEAM” (2011). There are versions specic to
the UK; other versions are tailored to countries or regions to address specic
environmental issues and weightings; construction methods and materials and
reference to local standards. In assessing a building, points are awarded for
each criterion. The points are then summed for a total score. The overall build-
ing performance is awarded a “Pass”, “Good”, “Very Good” or “Excellent”
rating based on the score. BREEAM major categories of criteria for Design
and Procurement include the following: Management, Health and Wellbeing,
Energy, Transport, Water, Materials, Land use, Ecology and Pollution.
In the US, from the onset of the United Green Building Council in 1993,
there have been releases of different versions of its rating tool LEED for
various building types, the most current being LEED 2009 (this applies to ve
building types-new construction, core and shell, schools, existing building
and commercial interiors). This assessment system has six main categories;
Sustainable Sites, Water Efciency, Energy and Atmosphere, Materials and
Resources, Indoor Environmental Air Quality and Regional Priority and Inno-
vations in Design, each addressing specic environmental concerns “USGBC”
(2009). Within each category there are specic design goals that have to be
met for any particular LEED certication, namely, silver, gold or platinum.
Each goal is worth one point; the nal certication is based on evaluation of
the goals documented.
2.2. ASSESSMENT METHODS
Sustainability assessment criteria are evaluated by quantitative and/or qualita-
tive measures. Quantitative measures reect numerical values for instance,
annual energy use, water consumption, greenhouse gas emissions, volume of
reused material and so on.
On the other hand, qualitative measures use comparable measurements
such as the impact on ecological value, or rely on user testimony, for example,
that certain procedures have been followed. Qualitative criteria of assessments
are difcult to encode as they are subject to evaluation from unbiased third
parties (Nguyen et al. 2010). It takes time and effort to input data, and varies
in interpretation by the different professionals (AlWaer et al. 2009).
An assessment criterion can be evaluated whenever the relevant informa-
tion is available in the building model. Although this seems straightforward, in
196 T. BISWAS, T.-H. WANG AND R. KRISHNAMURTI
reality this involves transformations, which may entail subjective judgement.
A simple example is ‘oor area’. In different building information models
it can be named as as ‘NetFloorArea’, ‘NetArea’ and ‘GSA BIM Area’- all
referring to the same value of the ‘oor area’. There are other similar interpre-
tations for the numerous building elements that are involved in the exchange
throughout the AEC domain, Some of these confusions can be avoided if the
information is stored in a standard building information model.
2.3. BIM AND INTEROPERABILITY
According to buildingSMART (2010) “BIM standards will integrate standards
used in the AEC industry”. Current standards include the Industry Foundation
Classes (IFC), ISO standards, BIM templates and Construction Operations
Building Information Exchange (COBie) (East 2011, buildingSmart 2012).
According to the National BIM Standard Project Committee, “A Building
Information Model is a digital representation of physical and functional char-
acteristics of a facility. As such, it serves as a shared knowledge resource for
information about a facility forming a reliable basis for decisions during its
life cycle from inception onward.” (Smith and Edgar 2008)
There are commercial software, which provide BIM solutions, for instance,
Autodesk Revit Architecture, Bentley Microstation Triforma, and ArchiCAD
by Graphisoft, Inc. These BIM tools employ their own proprietary data struc-
tures for representing a building and other design information (containing
graphical and non-graphical information). Figure 1 depicts a typical data
exchange set up.
Figure 1. Current Data Exchange from software to another via IFC translation.
197DATA SHARING FOR SUSTAINABLE ASSESSMENTS
The ideal exchange, highlighted in blue in the gure, involves just IFC, which
is an extensible ‘framework model’ to cater to a large set of consistent data
representations in the AEC domains (Eastman et al. 2008). It is built using
the ISO-STEP EXPRESS language. In practice, IFC can have multiple imple-
mentations. Consequently, BIM tools with good IFC import/export translators
may still only be able to exchange very little useful data.
For this reason IFC translations from source applications have to be
enhanced, perhaps, in stages. Such enhancements need to be considered care-
fully when used by exchanging applications. For example, there are viewers
for IFC model geometry and property, which display attributes of selected
objects and provide means to view data in different sets of entities (Eastman et
al. 2008). Despite variations in object representation, efforts are being made to
dene IFC more uniformly and precisely. IFC models are non-proprietary, and
as such are increasingly being adopted by governments and agencies (Eastman
et al. 2008). However, generally, IFC models do not contain information suf-
cient for sustainability evaluations. In order to share design information from
a software tool, and sustainability related information, we found COBie to
serve as a suitable data structure to integrate the necessary building informa-
tion and evaluation requirements.
2.4. COBIE AS A DATA STRUCTURE
COBie is a format primarily intended for use of managed assets. In this data
structure, information is cumulatively provided during the design, construc-
tion, commissioning and handover phases of a building. The information
includes room lists and area measurements, material and product schedules,
construction submittal requirements, construction submittals, equipment lists,
warranty guarantors, and replacement part providers, which are normally
included in several different places within current contracts (East 2011). The
objective of COBie is not to alter the type of information that is required,
just to standardise the format of that information to save building owners
and occupants, having to rekey the information multiple times. We adopted
COBie data structure because the format offers a structure that could be used,
extended and augmented to drive sustainability assessments with a functional
database prototype.
3. From BIM to assessment
For sustainability assessment, we used a LEED NC 2.1 silver-certied build-
ing as the case study. The model was prepared in a commercial BIM tool. This
was exported rst as an IFC model, and then translated to a COBie model.
198 T. BISWAS, T.-H. WANG AND R. KRISHNAMURTI
During translation from BIM to COBie we had to address a number of issues.
First, dealing with loss of information during translation. Second, adding
information required for LEED assessments; these are external to the model,
such as occupant number, area of buildings surrounding the project for site
density, type of ground cover and their corresponding their runoff values etc.
Third, converting LEED rules into computable form. Lastly, creating a func-
tional database to aggregate, evaluate, and propagate information into LEED
submission ready templates. Figure 2 indicates where data is augmented in
COBie database. As shown, LEEDDensity is a new sheet that is added to the
database. Sheets such as Attributes, Facility, Type, Space, Zone, Systems, and
Job have added columns with new elds and rows of data. The sheets Floor,
Contacts, Component and Documents retain their original columns but have
rows with additional data.
Figure 2. Illustrating the augmentation of COBie for LEED
(COBie diagram source: http://www.wbdg.org/resources/cobie.php: Figure 5).
3.1. FUNCTIONAL DATABASE APPROACH
Current research using commercial BIM and LEED requirements have dem-
onstrated the feasibility for semi-automated evaluation (Barnes and Castro-
Lacouture 2009, Nguyen et al. 2010, Krishnamurti et al. 2010). In each study,
information for sustainability evaluation was added, either by providing exter-
199DATA SHARING FOR SUSTAINABLE ASSESSMENTS
nal databases or by augmenting the model using the capability of the software
to store additional information. Figure 3 shows the process of sharing infor-
mation from a BIM to ll LEED templates for evaluation.
Figure 3. Data sharing for sustainability assessment using prototype.
Since LEED requirements are periodically revised, we can bypass hardwiring
the requirements by developing a computable set of LEED rules stored in a
database format. Taking the evaluation rules as input, these are then interpreted
for real-time evaluation. By providing this additional functionality to an oth-
erwise static database, it allows the application to easily accommodate future
rating requirement updates. It enables the multi-disciplinary cooperation from
sustainable assessment rule mapping to corresponding building data (and vice
versa). The output generates LEED submittals in XML format, which contain
aggregated results ready for evaluation. This demonstrates a process where
design information can be embedded and retrieved by different software and
professionals—from design to sustainable assessment.
3.2. ASSUMPTIONS AND CHALLENGES
We made certain assumptions when preparing COBie sheets for evaluation.
These are: (i) building data comes from the translated BIM; (ii) data required
for LEED evaluation is augmented, either by adding new data sets to the origi-
nal COBie format or by augmenting the structure; and (iii) preprocessed data,
typically requiring simulation, such as energy usage, or lighting qualities of a
space, e.g., whether 75% of spaces are naturally lit, require the COBie struc-
ture to be augmented.
The challenges we faced were in identifying the kinds of information that
would readily translate to COBie, and determining how and where to store
200 T. BISWAS, T.-H. WANG AND R. KRISHNAMURTI
the requisite information for LEED evaluation. From a data storage perspec-
tive the original data structure requires extension, without altering its basic
premise and purpose. From a LEED perspective, both qualitative and quan-
titative measures need to be assessed through the LEED queries. Qualitative
measures are veried by the presence or absence of certain documents as
required by LEED—these are stored in the spreadsheet named ‘Documents’.
Quantitative measures are processed by queries to mapped entities in COBie,
for example, building area, volume of recycled material used, etc.
Data is extracted and collected from the given database by invoking the
assessment rules codied in the mapping database. The mapping database
maintains the underlying interoperation mechanisms for various data struc-
tures. Figure 4 illustrates the integrative process of our prototype application,
which takes a COBie database as input, automates data exchange by execut-
ing mapping rules in the functional database, and populates the XML LEED
templates.
Figure 4. Data sharing for sustainability assessment using prototype.
4. Conclusion
This study shows an approach to sharing BIM information through a series
of inter-operation between various standard data structures, namely, IFC
and COBie. We use a database approach to manage the data exchange rules
required for sustainability assessments. The prototype application demon-
201DATA SHARING FOR SUSTAINABLE ASSESSMENTS
strates automation of LEED NC 2.1 template generation within an integrative
process. The expected contribution is the acceleration of the integration and
cooperation between various building professions to pursue improved sustain-
able environments.
We analysed the nature of the data required to ll LEED NC 2.1 templates.
Our analysis show that approximately, on average, 45% of the data is retrieved
from the COBie model without augmentation, the remaining 55% is retrieved
from data that is added to COBie. Of the added data (55%), 35% of the data
can be identied as attributes of the building elements. This includes the data
that has to be post processed from simulation results, for example, for energy
and lighting. The remaining 20% mainly pertain to queries for support docu-
ments that are required for submission.
We are currently exploring this approach to automatically create LEED
2009 templates. This exible approach will allow for easy update of assess-
ment standard rules as they evolve and change. It also has the potential to be
scaled to consider multiple buildings (Krishnamurti et al. 2012). Other assess-
ment standards such as Green Star of Australia or BREEAM could potentially
be mapped and assessed. Any limitations observed are due to information loss
from the translation from BIM to COBie and its unidirectional ow. The aug-
mented COBie data structure and data cannot be fed back to the initial BIM
due to the internal COBie to IFC mapping structure. Identifying, formalising
and mapping of LEED required data to possible IFC entities and/or ‘psets’ is
ongoing work.
Acknowledgements
The work done for this project, Automated LEED datasheets from lightweight IFC models was
funded by Construction Engineering Research Laboratory (CERL), which aims at integrating
building information with sustainability assessments using COBie as an intermediary platform.
However, any opinions, ndings, conclusions or recommendations presented in this paper are
those of the authors and do not necessarily reect the views of CERL.
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