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Abstract

The following article is a case study of the “Austrian house”, a sustainable building. The case study will present how such a building can entirely be designed in Revit Architecture, software by Autodesk based on BIM. Furthermore, one of the options Walter is offering to our clients is the energy analysis of the building by using Autodesk software called Green Building Studio (GBS). This case study presents the results obtained by applying the sustainable principles and using GBS and how they can be used to optimize the future building early in the design process.

Keywords:

Revit, BIM, Green Building Studio, energy analysis, design process

 

 

1. INTRODUCTION

The usual practice in building design is for the architects to first develop a set of drawings and documents. This documentation is then taken over by structural, mechanical, and electrical engineers who design their part of the project. And lastly, all of this material is then used to develop the energy analysis of the building. This process is time-consuming and oftentimes there is a lack of direct communication between different participants in the design process. Designing becomes an iterative/repetitive process and can take a lot of time, making the entire process costly. In addition to this, valuable information is being lost since it is stored in different locations and the investor or facility manager at the end never receives full information about the building. Additionally, this usual practice may force an aesthetic feature without considering performance impacts and it may not provide performance measurement/evaluation of a certain design solution [1].

Building Information Modelling (BIM) is a systematic process of the management and dissemination of holistic information generated throughout building design development and operation [2]. The advantages of BIM design are many. BIM is a set of interrelating strategies, procedures and skills that creates a framework to monitor the vital building design and display data in digital layout throughout the building’s life-cycle [3]. Since one file is being used throughout the entire lifecycle of the building, no information is being lost and the building model becomes one large encyclopedia of information that can be easily accessed. There are no collisions in works, which is often the case in traditional design processes. Now, all the engineers work on one file and there is clear digital communication between different participants in the project, which avoids mistakes. This saves time and money. In addition to this, by using BIM one can foresee and envisage the likely errors in design and subsequently adjust the designs early in order to reduce the possibility of project failure [4].

 

BIM throughout the life-cycle of the building In order to evaluate and optimize the building performance, different analysis cycles by simulations should be part of an integrated design process, which is referred to as the performance-based design method [1]. This enables the designers to conduct the simulations in order to validate the performance, improve and select the optimal design. In particular, the performance-based design method uses software to predict the energy use of the building. It analyses different energy and mass flows inside the building in order to predict its future performance. One such software is an Autodesk Green Building Studio (GBS). GBS is a flexible cloud-based service that allows the engineer to run building performance simulations to optimize energy efficiency and to work toward carbon neutrality earlier in the design process [5]. It is compatible with Autodesk Revit Architecture, a tool that allows the intelligent model-based process to plan, design, construct, and manage buildings and infrastructure [5]. Furthermore, GBS provides the ease of iterations between the conceptualization and calculation stage [6]. BIM tools, such as GBS, have the ability to provide users with an opportunity to explore different energy-saving alternatives at the early design stage by avoiding the time-consuming process of reentering all the building geometry and supporting information necessary for a complete energy analysis [7].

 

Walter is a company located in Sarajevo, Bosnia and Herzegovina, that offers solutions to the building industry based on BIM technology. Founded in 2011, Walter employs over 70 highly-skilled individuals. Walter’s team is comprised of developers, architects, structural, mechanical and electrical engineers, and designers.

This paper presents a case study of the “Austrian house”, designed in Walter in order to participate in the competition. The entire building is designed in Revit. Throughout the design process, GBS was continuously used in order to conduct the energy analysis of the building and optimize the future building early in the design process. Solar passive design techniques were implemented in order to minimize load on conventional systems. The proposal is made to use a solar photovoltaic system on the roof as a renewable energy resource and to meet part of the load, but since this project is in its preliminary stage, no further calculations are made for the active systems.

BIM is a new topic in this region of the world and no such analysis has been made for buildings in Sarajevo. One of the goals of this paper is to convince the local participants in the construction process to start using tools like this in order to achieve energy-efficient buildings.

 

2. DESIGN TOOLS AND ANALYSIS METHODS

2.1. The building design

Municipality Center in Sarajevo organized a public competition for the design of „Austrian house“ [8]. „Austrian house“, as proposed in this paper, is a functional, innovative, original, practical, economical, healthy, and pleasant urban space and is integral of park in which it is located. „Austrian house“ is almost zero building mostly built of natural, local materials. This contributes to the protection of planet Earth and encourages the development of the local economy while respecting the principles of the circular economy.

 

 

Urban space is a platform for all human activity, creativity, and occupation. People spend about 80% of their time inside. Oftentimes, the common construction technologies don’t place a human and his/her senses into focus, but rather economy and practicality. Synthetic materials are often used; they can be toxic and cold and lead to many diseases, such as allergies, depression, insomnia, anxiety, etc. Architecture is a science and art that has to have a holistic approach and give answers to many questions, not only practical, functional and economical, but environmental, social, and health.

One of the goals of the competition was to create a space for healthy growing-up and education of the youth. The beginning of this is in the construction of a healthy and educational building. The main lessons this house has to transfer to its future users are the following:

Urban space should be healthy and part of nature

The goal was to create a space that is a logical continuation of the park in which it is located. Park combines nature and playground, this is why „Austrian house“ exudes greenery and playfulness. Building communicates and is connected with the park on several levels.

 

 

Most of the building is constructed of natural materials. This creates an even stronger feeling of belonging to nature. The structure is made out of wood, exterior walls of straw-bales covered with earthen plasters. The ground floor is made of earth in repute to Martin Rauh and his floor in Berlin chapel, while the first floor is wooden. The roof is green. Friedensreich Hundertwasser considered trees and plants in his buildings as the most economical inhabitants. They pay the rent by improving the air quality in the building and in the city (greenery directly decreases the heat island effects) [9].

Biomimicry is reflected in a circular layout surrounded by wooden structural elements and straw walls with a central wooden staircase and gallery designed in the golden mean. All of this reminds of a wood trunk. An additional, central column that carries the perforated metal ceiling reminds of a tree making the visitor feel like he/she is protected from the sun by a thick treetop.

 

Urban space should be functional, practical, sensible, and pleasant. Its originality and innovation should inspire.

The main entrance leads the visitor into the central exhibit space. Inside, the visitor is permeated with the warmth of natural materials and silence they make, sun rays and shadows made by perforated suspended ceiling below the glass portion of the roof and carefully positioned plants. The visitor explores the ground floor exhibit space, wooden staircase (perfect for sitting) and gallery exhibit space. For visitors with special needs, the glass elevator is designed which enables sightseeing from the height of the total exhibit space as well as park on the outside. The entire exhibit space can also serve as an amphitheater.

 

Behind the exhibit space, the rooms are positioned respecting the need for appropriate light, silence and communication with the exterior.

Structurally, the building is simple and logical both geometry-wise as well as with the material selection. Wooden columns radially placed in combination with laminated beams carry the entire space. They transfer the load to the reinforced concrete strip foundation.

One of the biggest threats to the straw buildings is moisture, so they need to be protected from rainfall and capillary action. This is why the entire building is raised above the ground. Additionally, the upper part of the building, above the peripheral ramp is a wooden facade, while the final layer of the lower part faced below the ramp is earth/lime plaster. The plinth is made of stone.

Originality and innovation is revealed through many aspects: material selection, central staircase, peripheral ramp that leads to the green roof with the perforated fence which is „drilled“ with dancing children.

Architecture is sustainable and it encourages the local economy

Sustainable architecture exploits site conditions, local construction materials, renewable energy resources, it spends water, air, earth, and energy rationally and creates minimum maintenance, renovation, recycling and reuse of the building and location in the future.

The building is positioned to the south for solar heating during the winter. Earth’s ground floor is a thermal mass, which acts as a natural stove. It is ideal for children’s play and perfectly healthy (children should be in contact with the earth as much as possible). Straw walls are the perfect insulators. Additional insulation is placed on the floor and on the roof in order to create conditions for minimum energy spending and nearly zero house. The peripheral ramp saves the building from overheating during the summer.

63% of the territory of Bosnia and Herzegovina is covered with forest [10]. The energy necessary for the construction, maintenance, and recycling of wooden houses is the lowest when compared to all other construction materials [9]. Every cubic meter of used wood contributes to CO2 decrease in the atmosphere by 2 tons [11]. It is the most beautiful and warm construction material. These are just a few reasons why wood is used in this building.

Bosnia and Herzegovina produces 200,000 tons of straw annually which can be used in the construction industry [9].

Today, most of this straw is waste. This means that 10,000 passive houses could be constructed annually in Bosnia and Herzegovina [9]. Straw buildings are referred to as „factor 10“, which means that they spend 10 times less energy than conventional houses.

The building is smartly open with glass portals in order to maximize the use of natural lighting. To make the space playful and additionally illuminate, central portion of the green roof is glazed and then covered with perforated metal from the inside. These perforations create the light and shadow game on the ground earth floor and wooden gallery floor. Additionally, they protect from overheating during the summer.

The central glazed roof can partially be open in order to ensure natural ventilation (stack ventilation). Additionally, ventilation with recuperation is proposed in order to meet the guidelines for passive houses and ensure a clean, warm or cold air supply into the building. Green roof additionally saves energy.

The building is almost zero. The necessary energy is produced by diffuse solar panels placed on the roof.

 

Architecture can only be sustainable if the construction takes over the circular process of planning instead of the linear process that is often used today [12]. This means that the building configuration needs to be designed to ensure disassembling. In respect to this, the „Austrian house“ is designed to be somewhat flexible. Most of the interior partitions can be moved and space shaped in accordance to new trends. Since most of the construction materials are natural, they can be recycled down to compost.

Construction costs of the houses built of natural materials are even cheaper than of the traditional building techniques and materials [13]. The biggest savings of this building are in its maintenance.

2.2.  ANALYSIS METHOD

To develop building energy simulation in GBS, the following procedures are adopted:

• Developing a 3D BIM solid model using Autodesk Revit Architecture while respecting solar sustainable passive design techniques,
• Set the design parameters for different options analyzed in Autodesk GBS (refer to the table below),
• Run the simulation in Autodesk GBS and evaluate the results.

In short, once when the building was initially designed in Revit Architecture, GBS was used in order to conduct the energy analysis. The building is virtually placed in Sarajevo. In addition to this and in order to present how this software can be used in the analysis, this building is first analyzed with walls made of straw, like it was in the design. Later on, it was analyzed for the walls made of brick with Styrofoam insulation with only double windows. And lastly, since it was discovered by the GBS analysis that most of the energy gets wasted through the windows, one building was made with half of the windows as the original one, while the other one with half of the windows plus no window roof simply to demonstrate the savings. All these results are then evaluated in order to reach valuable conclusions about the building and to come up with the final design which is the most effective when it comes to energy saving.

3.   ENERGY ANALYSIS AND RESULTS

After the analysis, GBS produces the report, which contains lots of information, such as energy use intensity, renewable energy potential, annual carbon emissions, monthly heating and cooling loads, the annual wind rose, humidity, etc.

 

For presentation purposes, only monthly heating and cooling loads are compared.

The following are the monthly heating and cooling loads for the Building type 1:

 

As it can be seen, the highest heating load is around 10000 MJ for the month of January, while the maximum cooling load is 42000MJ for the month of July.

When compared to Building type 2 (refer to figure 11 and 12), it is visible that Building type 1 is much more energy efficient: maximum heating load for the month of January is 15400 MJ and maximum cooling load for the month of July is 50000 MJ for Building type 2.

As it can be seen, the heating loads are above 10000 MJ. This is far from nearly zero or low energy building requirements. One reason is that GBS has predefined HVAC systems that can be analyzed and there are not that many options [14]. Based on these systems, GBS generates energy data that is far from the realistic one. This is one of the weaknesses that GBS has. It would be much better if there was an option that no HVAC systems are to be used in the analysis or even better if the engineer can create his/her own HVAC system for the building. This is why the best use of GBS is for comparison purposes and for decision-making in the early process of design.

Building type 1 has lots of windows and it is visible in figures 8 and 9 that the windows lose the most energy.  This is why two more modifications have been made in order to see if additional savings can be reached. Building type 3 has half of the windows when compared to Building type 1 while Building type 4 has half of the windows and no roof window and the following are the summary of all the results:

 

As it can be seen, considerable savings could be made if the roof window would be removed and the number of windows in general decreased. The reason why the original building had the roof window is to provide extra light in the central portion and to assist with the heating of the building. However, there is plenty of natural daylight that comes through the windows (even if the number is decreased), so it would be quite reasonable to implement this change in the original project.

4. CONCLUSION

Energy analysis is typically performed after the architectural/engineering design and related documents have been produced. This process does not consider the integration between the design and energy analysis processes during the early stages and leads to an inefficient way of backtracking to modify the design in order to achieve a set of performance criteria [15].

BIM system can contribute to collaboration and communication between different participants of the project in the early design phase to effectively provide the economic future building in every aspect. This paper concretely deals with collaboration between sustainability and passive design in architecture and energy analysis. It demonstrated the ease and the advantages of designing and analyzing when in particular Autodesk Revit Architecture and GBS are used. It showed how early in the design stage, the designer can make a selection of appropriate building elements in order to achieve greater energy savings during the facility management of the building.

However, there are some problems in using BIM for sustainable design that need to be overcome. Using BIM for energy analysis currently relies on estimated values for loads, air flows, and heat transfer simulations which may result in unreliable estimates [16]. This can be resolved by using real data gathered from buildings. And this is why GBS is good for comparison purposes; just to see which building elements to use in the design, but not for final energy calculations. In addition to this, there is a slow uptake in the adoption of new technologies throughout the AEC sector. Using BIM requires significant training and there are huge costs associated with purchasing, licensing, and training. This can be resolved by hiring companies such as Walter that specialize in this type of work and can provide clients with fast and effective design solutions.

5. FUTURE WORK

This paper presents the work at the initial design of the building (architectural phase). Future work could involve the work of structural/mechanical/electrical engineers and the analysis of active design systems and how this can be altered in order to achieve greater energy savings.

6. ACKNOWLEDGMENTS 

We extend our sincere thanks to Assist. Prof. Dr. Sanela Klaric who took part in the design of this building and gave her advice on the use of natural materials.

7. REFERENCES

[1]     Aksamija, A., 2013, Architecture and Engineering of Sustainable Buildings, Special Issue: National Science Foundation Workshop, Research Journal, Vol. 05.01.

[2]     Gerrish, T., Ruikar, K., Cook, M., Johnson, M., Phillip, M., Lowry, C., 2017, BIM application to building energy performance visualisation and management: Challenges and potential, Energy and Buildings, 144: 2018-228.

[3]     Penttila, H., 2015, Describing the changes in architectural information technology to understand design complexity and free-form architectural expression, The effects of CAD on Building Form and Design Quality, 11, ITCON, 395-408.

[4]     Oduyemi, O., Okoroh, M., 2016, Building performance modelling of sustainable building design, Gulf Organisation for Research and Development, International Journal for Research and Development, 5: 461-469.

[5]     Autodesk official webpage: https://autodesk.com/. Accessed on 06 Sep 2017.

[6]     Ceranic, B., Latham, D., Dean, A., 2015, Sustainable Design and Building Information Modelling: Case Study of Energy Plus House, Hieron’s Wood, Derbysire UK, Science Direct, Energy Procedia 83, 434-443.

[7]     Jalaei, F, Jrade, A., 2014, An Automated BIM Model to Conceptually Design, Analyze, Simulate, and Assess Sustainable Building Projects, Journal of Construction Engineering, Vol. 2014, Article ID 672896.

[8]     Municipality Centre Sarajevo, 2017, Competition for preliminary architectural-urban solution of “Austrian home”, official web page: http://www.centar.ba/stranica/konkursi-i-oglasi. Accessed on 01 May 2017.

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[9]     Klaric, S., 2015, Sustainable living. Wood, sheep’s wool and straw. Challenges and Potentials of Traditional Natural Materials. IBU Publications, ISBN: 978-9958-834-46-2.

[10]   UNDP, 2014, Possibilities of Use of Biomass in Forest and Wood Industry in Bosnia and Herzegovina. UNDP official webpage: http://www.ba.undp.org. Accessed on 01 Feb 2016.

[11]   Guy-Quint, C., 2006. Tackle Climate Change Use Wood. European Parliament Brussels.

[12]   Durmisevic, E., 2006, Transformable Building Structure. ISBN-10: 90-9020341-9 ISBN-13: 978-90-9020341-6.

[13]   Krasny, E., Klaric, S., Korjenic, A., 2017, Analysis and comparison of environmental impacts and cost of bio-based house versus concrete house, Journal of Cleaner Production, 161: 968-976.

[14]   Official Autodesk webpage, HVAC Systems, https://knowledge.autodesk.com/support/revit-products/learn-explore/caas/CloudHelp/cloudhelp/2016/ENU/Revit-Analyze/files/GUID-38A9EB5B-8631-43B4-9AD6-6F532BC860D8-htm.html. Accessed on 20 Sep 2017.

[15]   Jalei, F, Jrade, A., 2013, Integrating building information modeling (BIM), energy analysis and simulation tools to conceptually design sustainable buildings, 11th CSCE Conference, Montreal, Canada.

[16]   Crosbie, T., Dawood, N., Dean, J., 2010, Energy profiling in the life-cycle assessment of buildings, Management of Environmental Quality: An International Journal, 21(1), 20-31.