Sustainability and BIM: The Role of Building Information Modeling to Enhance Energy Efficiency Analysis 1/7/2014

University of Salford – School of Built Environment Student name: Ahmad Naser Alsaadi Roll number: @00312494

Module name: BIM Theory and Practice

Program of study: MSc BIM and Integrated Design

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Abstract

The energy analysis was too complex and expensive process, usually delayed to the end of the design.

How can BIM as approach to facilitate and improve the energy efficiency of design building? The

purpose of this paper is to demonstrate the role of BIM to optimize building energy performance and

provide an understanding of how the BIM system operates the whole energy simulation process. It

starts with overall explanation about the relationship between BIM and energy analysis, then definition

of energy modelling. Later the process of energy simulation and case study will be presented.

It is found that achieving an efficient energy design of buildings is the way to enhance sustainability and

economic saving by BIM system and tools. The difficulties of complexity and cost have been exceeded

through the advance of energy applications which are many of them became free and easy to access

with quick results and immediate feedback. However, there are various energy applications with

different plug-ins which provide dissimilar result, this matter leads the user to not depend on analysis

program.

1- Introduction

During last two decades, the design in fields of movie and music production, airplanes and machinery

have been developed significantly by information technology. Architecture, Engineering and

Construction (AEC) industry are now adopting a similar tools and approach in building design (Autodesk,

2005). The most advanced feature of these tools is delivering persistent and immediate feedback with

great margin from the traditional tools. These tools and approach are utilized in design, structure,

durability, management, energy efficiency and other building systems at different levels driving the

building technology towards a digital epoch (Che, Gao, Chen & Nguyen, 2010). This approach, which is

different from the conventional process of using CAD software, is known as Building Information

Modelling (BIM). BIM is “an integrated process which is used to facilitate the exchange of design and

construction information to project participants” (Moakher & Pimplikar, 2012).

The built environment need of generating the sustainable buildings and enhancing the environmental

conscious is no longer a noble desire, but it is an urgent requirement. According to the American

Institute of Architects (AIA), the main source of greenhouse emission in USA is buildings. Within AEC

industrial and historical context, it has been unimportant to accurately understand the progressive

process of energy efficiency and sustainable design (Hodges, 2009). Hodges adds that globalization and

increasing the expectations of clients are forcing the industry professionals to design projects in more

sustainability and energy efficiency. Furthermore, (Dorta, Assef, Contero & Rufino, 2013), mentioned

different studies conclude that improving buildings energy performance leads to economic saving

between 30% (IDAE, 2008) and 75% (NAVARO, 2009), which means that energy efficiency is not only

sustainable, but also profitable.

This paper describes the relationship between BIM and energy analysis and its role as a regime to run

the process. Also its presents a progressive process of energy analysis to achieve the efficient

performance buildings through Building Information Modelling and evaluate the energy performance of

design alternatives in case study.

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2- Literature Review

2-1- BIM and Energy Analysis

There is a huge misconception of BIM in AEC (Architectural, Engineering, Construction) industry field

that BIM is no more than software, and that return to the confusion between the BIM process and BIM

model. (Dorta, Asset, Cantero & Rufino, 2013; NIBS, 2007) show that BIM acronym can be referred by

several aspects, as product (means a data set that structured to describe a building), as activity (is the

act of generating a building information model) or a system (the framework structured to manage and

coordinate the work and communication of the different stakeholders which maximize the efficiency

and quality). In addition, BIM is a system of planning, construction and operation of a facility during its

life-cycle (Stumpf, Kim & Jenicek, 2011). Generally, Building Information Modelling is a combination of

interacting processes, generating technologies, policies that creating a methodology to manage data

and design systems in digital format throughout the building life ( Succar, 2009). While, a BIM model is a

digital representation of the project’s functional and physical features (Stumpf, Kim & Jenicek, 2011).

Krygiel and Nies (2008) mentioned that BIM model is a grammatically incorrect term commonly refers to

the digital models generated by software under the BIM process.

During design and construction, all building data such as materials, geometric information, chosen

systems of design, spaces, facility are required to be accessible in order to evaluate the building various

performance for instance, the energy performance. The different stakeholders of the design and

construction team, for example, architecture, structure, MEP, schedules and cost estimators, energy

develop their own specific models in separate way, and then integrate these models into rich, intelligent

and comprehensive one model (Meridian, 2008). The fundamental premise of this generated model is

collaboration by multidiscipline at different stages of the facility life-cycle to extract, insert or develop

information during the process (Stumpf, Kim & Jenicek, 2011). This necessary collaboration cannot

found without the availability of open and neutral specification of digital data format represented by the

Industry Foundation Classes (IFC), because each BIM tool has a propriety data structures for delivering

the requested data.

Figure 1 Data exchange between stakeholders in BIM

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Generally, analysis and assessment of building performance have great opportunities offered by the

advent of BIM and through its software tools (Mokher & Pimplikar, 2012). In particular, advanced energy

analysis is crucial to design strategies to minimize the energy consumption and assist in design energy-

efficiency, such as, energy and day lighting analysis programs which have been developing for years, but

rarely adopted by the design firms (Autodesk, 2005). Furthermore, under traditional Cad approach,

design and evaluate and efficient energy performance is very limited and painful, mostly used at late

stage of the design process when the project’s characteristics cannot be changed (Mokher & Pimplikar,

2012). Typically considered time-consuming and costly process that needs an intensive work to

regenerate the building model in order to analysis it (Kumar, 2008). Kumar (2008), also added an

obvious benefit that Building Information Modelling through the interoperability between its tools

offers the opportunity of export the digital models of the building to energy analysis software without

the need of recreate it from scratch. Now, with BIM tools such as Revit and Green Building Studio (GBS)

the energy analysis process became simple. All the designer needs is visit the GBS web service to

register and download the Green Building Studio program into his driver to submit the project’s model,

that required analysis, via internet after export the model from the generator tool (Revit) as gbXML

format or upload it directly through Revit software. Then after a few minutes the results will obtain

containing statistics, consumption and other information related to energy with recommendation to

enhance the design (Mokher & Pimplikar, 2012). All these findings based on the data attached to the

submitted model, include local standards, material information, type of building, location climate, etc.

As a result, within this process the designer can modify his model and resubmit it again in order to,

make decisions during the design early stage, set the most suitable energy system and achieve the

energy efficiency for the project.

2-2- Energy modelling

One of the most essential factors to enhance the project sustainability is to understand a building’s

energy requirements. Buildings, such as houses, shops, offices and other functionalities, account for 40%

of world energy consumption and responsible for cause 36% of greenhouse emissions (European

commission, 2013; European commission, 2010). Improving the buildings energy performance is

inevitable, not only obtain the target of EU towards Nearly Zero-Energy Buildings (NZEB) by 2020, but

also to achieve the long term objectives of climate strategy by 2050 as set down in low carbon economy

roadmap (European commission, 2013; COM, 2011). A number of issues contribute to determine the

building energy needs and that simply does not related to people behaviour in energy consumption.

Furthermore, many of followed approaches and solutions within building different systems can affect

the energy use directly. For example, if the building’s south elevation has a lot of widows, it will provide

enough natural light and minimize the electric illumination need. However, in this case, the building will

need more air-condition if the sun shading devices was inefficient. As a result, the designer must take

into account all energy related items and exploring the energy use in the building during the design

stage and that is why it is urgent to use the BIM process and its technology of energy simulation tools

(Krygiel & Nies, 2008). These simulation environments work through coupling the climatological

information with building loads. Such as, the required calculation elements by (Energy Performance of

Building Directive) (International Energy Agency, 2008). This shows in the following table.

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Table 1 the required calculation elements of EPBD

Through BIM, the energy model integrates all these elements to anticipate the demands of energy in

order to set the most appropriate HVAC system and other related parameters of the building

components based on an accurate energy needs and understanding the possible design impact on the

global environment.

2-3- Applying BIM for Energy Analysis

Using BIM approach, energy modelling and the process of integrated team is urgent to achieve the high-

performance energy and specified consumption goals (Cho, Chen & Woo). It must be realized that data

received from analysis of energy model is critical to recognize its effect on the design. The designer

should never consider the energy findings as a gospel, but the causes of these results should be

identified (Krygiel & Nies, 2008). The combination between energy analysis and BIM can maximize the

accuracy and efficiency, however, it can be tedious and time consuming if not done properly (Miller,

2010). So, it is essential to understand what results anticipated from energy analysis in different design

stages and how to implement it in design formation. Energy analysis findings can be linked with building

massing research to make a decision that determines the location of the building within the site at the

inception stages of the design (Autodesk, 2005). During the early design phase, the analysis data would

be used as comparative tool to enhance decisions making instead of focusing to measure the accuracy

of loads information, because many decisions are still undecided at the earlier stages of design or

probably will change in the future (Krygiel & Nies, 2008). For instance, based on the result gained from

analysis at the conceptual phase, the designer might find that tall building with small footprint

overcomes options with large built area and low elevations, or increasing the glass surfaces on the south

facade can optimize the day lighting, while it leads to an increase in energy demands to set a

appropriate air-condition system. According to Krygiel & Nies (2008), the analysis through BIM needs the

following tools to run energy modelling:

The project BIM model.

A proper application for energy simulation.

Apply the whole BIM approach, the full collaboration between the energy analyst, mechanical

engineer and other team members, through the integrated approach, enhances the analysis

process, if the team members are unfamiliar with interpreting the data of energy analysis.

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2-4- Run the energy modelling process

2-4-1- BIM model

The energy modelling needs a well-built solid model in order to be successful. In some cases, the process

does not require all details and information that related to energy determined, but some basic

conditions have to be established. (Stumpf, Kim & Jenicek, 2011), outlined three different steps in the

process of energy modelling, as shown in figure 2.

Figure 2 The steps of energy modelling process

step one determines the energy requirements of the project. Challenges may emerge here because

typically any project has resources, specific cost target and schedules. To pass this step, all project

parties have to contribute in identifying the project needs alternative energy solution under the BIM

approach and during the planning phase.

Step two divides the process of energy modelling in two stages, concept and detailed design. The first

stage is related to building envelope and orientation, while the later is related to building elements and

details such as, materials, shape, and size.

Step three is an improvement process by using independent software to ensure the validation of energy

analysis results and support the essential needs. An example activity of this process is the repeated

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export of building’s model until achieve the energy goals or using more than one analysis program for

comparison the findings.

There are a few basic conditions should be included within the model structure to ensure that energy

process run correctly and get the proper results. First of all, the designer must be certain about the

existence of the following points; floors and roofs must be included within the model, ensure that walls

touches the floors and roofs and building geometry must surround all areas required to analysis ( Krygiel

& Nies, 2008). After checking these three points, Stumpf, Kim & Jenicek (2011), noted that energy loads

can be estimated and calculated based on building’s envelope characteristics (windows, doors), building

orientation and thermal zone. Similar but expanded key elements stated by Krygiel & Nies (2008),

project location, building envelope, room volumes and any specific settings of the application, should be

captured and transferred from the BIM model generator tool to the energy analysis application through

the ability of export a digital model format such as gbXML as mentioned before.

Project location

Climate is the most important factor to determine the building exterior loads. The designer has to define

site properties within the modelling application.

Building’s envelope

Although some of these following sound clear in concept, energy analysis cannot run without

establishing an accurate envelope such as, each space needs to be bounded by walls, roofs and floors.

Room volumes

It can be said that all major BIM programs (Revit, Bently, ArchiCAD) work in similar approach to export

gbXML file. The minor difference between them is related to room volume ( Revit bound the spaces by

using Room Tag, while ArchiCAD using Zoon tool) (Stumpf, Kim & Jenicek, 2011). However what is

important to the process is to create and export a three dimensional bounded spaces.

Specific setting of the application

Each program has its specific requirements to run the analysis process. For instance, before export the

gbXML file in Revit, many data needs to be addressed such as, building zip code and location, building

type and calculate the room volumes.

2-4-2- Energy modelling applications

Now, the BIM model has all needed energy information and ready to import as a gbXML into energy

application. Choosing the proper analysis tool depends on many factors for example, the project phase,

skills of user or time availability. The following data are taken from ( Krygiel & Nies, 2008), (Mokher &

Pimplikar, 2012), (Kumar, 2008) and (Pallapalli, 2010), for five tools presented as a comparision.

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Application type Advantages Disadvantages

IES<VE> Integrated Environment Solution

Present a high level of accuracy and interoperability with BIM

Operate the whole environmental series (analysis, day lighting, CFDs).

Complex for the user.

Expensive comparing with relative tools.

The inability to import a large number of gbXML.

Saving the IES files in many of separate files such as, light, cfd,..etc.

Ecotect It has a friendly graphical interface.

Easy to run and use.

The application is supported with other tools (day lighting, weather, ventilation, airflow analysis).

Produce annual and peak loads.

It has challenges with importing, exporting BIM model directly depends on program used for example Revit, but Autodesk about to build API-level integration between them.

eQUEST Free tool.

Has the ability for energy simulation including (heat loads, HVAC, climate data).

The ability to import from CAD programs.

Cannot export geometry to programs.

Cannot estimate the thermal comfort and analysis the natural ventilation.

Design Builder Has the ability to export and import models.

Has a great ability for analysis (heat loads, HVAC, climate data).

Relatively expensive.

Does not have the ability to simulate the heat and cold storage that gained seasonally.

Green Building Studio Free service.

Produce quick graphical simulation for building energy performance.

The survey details are not high.

It has limited choices, if the building does not suitable for these options, the result will be inaccurate.

Table 2 comparison between most common analysis applications

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2-4-3- Optimizing the energy use

This process occurs during the operation of energy analysis to compare between design options.

Optimizing the energy use relies on realizing the relative energy that affect the building performance.

Krygiel & Nies (2008), mentioned the following example which provides a good illustration in terms of

comparing and choosing the most appropriate option. The example project has two alternatives for an

energy comparison, design 1: does not include sunshades, design 2: includes sunshades. The design aims

to supply a saving in cost throughout the building life-cycle which justifies the extra cost of installing the

shades to the project. Green Building Studio service was used in this analysis after export the project

BIM model as gbXML from Revit. After a few minutes the result, shown in figure 3, came back to prove

that shaded option will reduce the life-cycle energy cost.

Figure 3 a result of comparison between two BIM models was run in GBS

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2-5- Case study of CESS Building (Stumpf, Kim & Jenicek, 2011)

2-5-1- general information

Project name and location: Community Emergency Service Station (CESS) at Fort Bragg, North Carolina.

Project facilities: police services, ambulance and fire fighting.

Project size: 8,300 square feet.

Project objective: achieve LEED-NC 2.2 Platinum rating.

Project standards: ASHRAE 90.1-2004.

Comparison factor: Annual energy cost.

Project requirements: A charrette process, held at the earliest stage and for four days, used to

understand the participants’ interests, generate solutions and specify the project target.

Project challenges: firstly, it was important to supply the stakeholders with result of energy analysis at

the beginning and during the charrette. Secondly, energy analysis considered as a time consuming

because the process of re-input all data of the project to generate the energy result.

BIM tools: Revit, Revit MEP, Green Building Studio GBS and eQUEST.

2-5-2- Energy modelling process

The process divided into two sub-processes based on project phases:

The macro-level: focusing on selecting the most appropriate shape, size, orientation.

The micro-level: This related to building details such as, material of the envelope and energy

systems of the building.

Figure 4 CESS Building BIM model.

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2-5-2-1- Concept phase (macro-level), See figure 5

Step1- The architect developed three alternatives: A) Two separate buildings. B) Single building with

two storeys. C) Single building with one storey.

Step2- Estimating the three options annual cost of energy in order to choose the most efficient

envelope. An important point to mention that the summer cooling is the most dominant load for the

building which depends on the project location. So, according to analysis had been done the mechanical

engineer, the C option was the chosen alternative.

Step3- Considering the best orientation to decrease energy needs. Based on a functional requirement,

the architect wanted a 15 degree rotation for the part of apparatus room to facilitate the vehicles

movement. The analysis found the highest energy cost will be generated when the orientation becomes

120 degree, while the energy cost will be very low if the building long axis face the south. In order to

meet the architect request the annual energy cost increased only 75$, which considered a small amount

to meet such important functional requirement.

Figure 5 concept phase process (macro-level)

2-5-2-2- Detailed design phase (micro-level), see figure 6

Six groups of building elements were considered in analysis using GBS after export the BIM model as

gbXML from Revit MEP, HVAC (10 options), glazing (17), roof (20), walls (15), lighting (4) and lighting

control (3). The result showed that the greatest effect on annual energy cost was the HVAC options.

However, the lowest impact was the lighting control.

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Figure 6 detailed design phase (micro-level)

2-5-3- Optimizing process

A comparison between the baseline model and proposed design model, that created by energy analysis

experts using GBS and eQUEST to validate the CESS building model. The findings were validated

according to ASHRAE 90.1-2004 annual energy cost standards. As a result the difference between

baseline model and proposed model was about 35-40% at the confidence level of 80-85%, which shows

that baseline model was successful to achieve ASHRAE 90.1-2004 with 6% difference while the proposed

was 15.5%.

2-5-4- lesson learned

Achieving an optimal energy design needs a collaborative and innovative strategies for design and

analysis can be run by BIM. Even the most expert mechanical engineers cannot analyse the energy

performance perfectly without the efforts of other team members. BIM supplies the analysis phases

with intelligent data for direct use.

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3- Conclusion and recommendations

Considering building energy aspects and efficient performance are become the trend to achieve

sustainable design which is now most required because of the growing emphasis on environmental

conscious. This paper has presented the role of BIM as approach to run and manage the energy analysis

process. Also, it provided an overall demonstration about the progressive process of the energy

simulation. Furthermore, a case study has been examined to explore how energy design alternatives can

be optimized and compared by BIM tools to obtain efficiency.

The integration between BIM concept and environmental parameters such as, location climate and

orientation can maximize the building energy performance. Using the energy analysis applications under

the BIM approach during the early stage of design would generate efficient energy buildings. The ability

of BIM tools to produce a basic model, that has all required energy data, is the key success of building

performance analysis through energy tools. The most important role of energy tools during any level of

design phase is comparing between design alternatives, according to the project identified goals and the

chosen energy standards, to determine the most appropriate options. That can be happened by the

capabilities of energy software such as, GBS and Ecotect which facilitate the professionals’ access and

quick feedback.

So, it is recommended to use the energy programs, for example, Green Building Studio, in the beginning

to configure the building shape and orientation, while during the detailed level, to specify the most

efficient energy systems of the buildings. However, the analysis process requires from project

participants to do not completely rely on the result gained from one application, but it should be

compared with other applications results. The energy tools capabilities needs to be combined into

sustainable design and BIM regime to achieve the specified energy goals.

Finally, due to importance of this topic for the AEC industry and environment needs, it is valuable to

standardise the energy simulation process under BIM system as a workflow routine in future studies in

order to optimize the building energy performance.

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