EXPLORING DESIGN SUPPORT POSSIBILITIES OF BUILDING
PERFORMANCE SIMULATION TOOLS IN BUILDING DESIGN
PROCESS
Gülsu Ulukavak Harputlugil1, Merve Bedir2
g.u.harputlugil@gmail.com1, m.bedir@tudelft.nl
Faculty of Safranbolu F. T. Fine Arts & Design- University of Karabük, Turkey1, OTB Research Institute for Housing, Urban & Mobility Studies-TU Delft, the
Netherlands2
ABSTRACT
Simulation is claimed to be an effective tool in building design to degrade the systems integration matter into comprehension of designers with either a tool or a process related approach. In this study, pre-design phase is considered with energy performance point of view. Aim of the study is exploring integration possibilities of building performance simulation tools in building design process by analyzing these tools from design support point of view. Number of building performance simulation programmes, selected according to development goals of them, are evaluated according to their early design phase data requirement and supply of design data in return. Future work will be a real time building project design process observation to find out how specific parameters are decided during concept development and also these parameters’ weighting factors by executing a survey among a group of architects. This will help designers in choosing the most appropriate tool according to their conceptual approach.
Keywords: Building design, building performance, design support, simulation tools
THEORETICAL BACKGROUND
Since the building design process began to get complicated with the new technological building elements’ introduction, experts of each field have supported designers by consultation through the process. Progressively, various simulation programmes have been introduced based on two approaches; tool box metaphor and computer supported design environment [Clarke, 2001]. The former proposes that the designer conducts the performance evaluation of a specific building component with the help of a simulation programme and translates this knowledge to the related
design parameter. Whereas, the latter is based on computer aid and design decisions are evaluated through the simulation program and the performance data is directly feeded to the design process. For energy performance evaluation, either tool box or computer supported design based, simulation programmes used to be the tools for engineers to make necessary calculations for the building, designed by the architect. Later it is revealed that simulation tools should be more architect oriented due to the fact that energy performance of a building is more related with the early design stages.
Figure 1. Tool box approach Computer supported design approach
It should be emphasized that the architect as the designer should still have a knowledge background of the technologies and their applications for better integration of building components to the building design and also for the management of the design process. Besides, there is still the need for the architect to have experience and specialty in using the simulation programme. Therefore performance simulation programmes have been improved towards the architects’ more efficient use of the programme. (User friendly design tools)
When the current professional design offices’ working structures are considered, it could obviously be pointed out that design offices are not only architectural project based anymore; but extending to a wider scale as design centres, where experts from many professions work together approaching the building as a whole system. This idea, defined as design decision support system, leaded to the change in simulation programme design as well. The tendency has shifted from being ‘user friendly’ towards a more specialized direction for design support, which proposes the involvement of required simulation programme and specialist to the building design ‘process’ at necessary stages.
Augenbroe [2002] defines these two approaches mentioned above as (1) tool related; targeting advancements of tool functionality and (2) process related, targeting functional integration of simulation tools in the design process. The Design Analysis Integration (DAI) workbench is developed depending on the second approach, assuming that “the workbench is process centric and should allow for explicit
definition; and expert knowledge and expertise are essential elements of performance assessment” [Augenbroe et al., 2003]. The crucial difference between user friendly tools and design integrated tools is the reduction and inaccessibility of domain knowledge in the former whereas the design context is much more enriched in the latter. Augenbroe adds that the challenge of the next decade is to better integrate simulation in the design process as a whole, increase quality control and exploit the explosion of opportunities that the internet offers.
Figure 2. The schematic relation through design process between the simulation programmes’ potential of developing design and obtainable data
Important aspects of using simulation programmes through design process would be assumptions in the early stages because of insufficient design data; selection of the suitable simulation programme for the related phase and simulation programmes’ assumptions especially about lighting, equipment and HVAC system parameters.
SCOPE AND AIM
Morbitzer et al. [2001] consider the decision support systems to help in evaluation of building performance in energy and environment contexts, within a framework from concept to application project level. In concept project level, simulation programmes could be used to search for understanding the effect of the main design decisions, such as building geometry, on building performance. In project level, using simulation programmes, designer can further obtain data about building performance in relation to energy and environmental considerations. At this stage, optimisation of building performance and architectural design components are important. In
application project level, efficiency of the passive and active systems are calculated and validated through simulation programmes. In Morbitzer’s approach, simulation programmes are proposed to be used according to their complexity levels which precede parallel to the detail level of design.
When energy performance of buildings is considered, two main steps define the design team’s work scope. The first step is the passive component design and the second is the building system design. Passive component design step mainly regulated and managed mainly by the architect’s choice and includes building component selection and their design with the aim of improving energy performance. This step’s goal is to design the building model with decided passive design features for further evaluation in energy performance. In the second step, building system design, the mechanical system of the building is determined and designed. This process is where energy consultants and simulation experts are involved to find the measures through simulation, for energy and fuel use reduction. These two steps should work in a feedback mechanism so that the findings of each stage could result in a change in the other step’s decision.
This study focuses particularly on the ‘development of the concept’, even before pre-design within first phase. The aim is to investigate the pre-design support affectivity of current simulation programmes to energy conscious design in the context of the first step aforementioned: ‘passive component design’.
Figure 3. Design team’s work scope (considering energy conservation)
This first step’s outputs are,
• Design decisions on the integration of renewables like BIPV, bio-fuels, wind turbines
• Heating and cooling loads of spaces.
If the passive component design is further analyzed, 3 main stages of could be pointed as pre-design, actual design and detailed design. The concept parameters in figure 5, which are listed by the authors depending on their experiences regarding general approach of architects, are the sources of the first sketch contributing to the pre-design stage. It should be noted that it is possible to extend the concept parameters list by various similar that are not included here.
Figure 4. Three basic phases of design (considering energy conservation)
DESIGN SUPPORT POSSIBILITIES OF SIMULATION PROGRAMMES: A COMPARISON
A great number of decisions need to be taken during the design process. It is self-explanatory, that decisions at earlier phases of the design have a bigger impact on the building performance than decisions/ measures taken at later design stages or during building operation [Hopfe et al., 2005]. Moreover, the appreciation of performance requirements during the development of concept parameters will potentially enhance the awareness towards performance targets.
Recently a number of studies were conducted to enhance the ways of supporting the decisions of early stages of design even concept development stage by the help of performance simulations [i.e. Harputlugil, et al. 2006]. Through this study, support possibilities on design decisions of the use of building performance simulations have been investigated. By exploring the benefits of building performance simulations at the concept development stage, the main gaps of tool abilities, that are intended to support concept development stage of design which is mainly under control of architects, will be identified.
There are four simulation programs selected for evaluation. All the tools are introduced as supportive instruments for conceptual phase of design. In order not to commercially advertise the tools, it is preferred to label the tools as A, B, C and D. Each tool has different input detail levels and has different aspects for outputs. The comparison has been done mainly considering the concept parameters listed below and it is aimed to reveal their ability to meet with the expectations of architects at the concept level [Table 1].
Considering the importance of each parameter taken into account during conceptual decisions, the tools are ranked from good to poor as pointing out their ability. The results can be seen as follows;
Program of Requirements: Defining building type is usually helpful for conceptual developments.
B - C A-D
GOOD POOR
Site & climate Data: Using a weather data package and local terrain information is always an advantage for design decisions even at concept development stage.
A - D B C
Occupancy Profile: It is necessary to have detailed information about occupancy profile from the beginning as all the decisions are depended on occupancy expectations.
A - B – C - D
GOOD POOR
Standards & regulations: Design decisions should be developed under the limitations of standards. Even during conceptual development the directions of standards must be considered.
A B - C - D
GOOD POOR
Geometry: The visualisation and representation of the building is in 3D. Thus, it is obvious that the tools providing 3D modelling are preferable for visualisation of concepts easily.
A - D B C
GOOD POOR
Mass Properties: Although building form and ratio are important parameters there is no need to go in depth of detail for conceptual development.
C B A-D
GOOD POOR
Building orientation: Similar with site data, providing orientation adjustment is essential.
A - B - D C
GOOD POOR
Material: Since many of the detail in design is not decided during concept development, less information input on building construction and material is much more acceptable.
C B A-D
Table 1. Comparison of the selected simulation programmes in terms of their support to the first phase of design
Design phase-parameters P rogr a m A B C D CO NCE P T Program of Requirements Nothing specified
Building type Building type Nothing specified Site &
climate data
• Weather data
• Local terrain • Weather data • No specific site data • Climate selection • No specific site data • Weather data • Local terrain Occupancy profile • Occupant number • Occupancy schedule • Comfort band • Occupant number • Occupancy schedule • Thermostat set points • Occupancy schedule • Person density (pers/m2) • Thermostat set points • Occupancy schedule • Thermostat set points Standards & regulations • UK Part-L compliance No standard or regulation data No standard or regulation data No standard or regulation data S K ETC H
Geometry • 3D modelling • Floor area • Number of floors • Room dimensions • 3D modelling Mass properties Based on 3D model • Aspect ratio • Gross dimensions • Number of windows • Number of windows / facade • Window area • Window type (glazing &blinds) • Overhangs Based on 3D model Building orientation
North offset Building rotation clockwise Window orientation Building rotation clockwise Material • Material choice • Construction development • Construction type • Material choice • Insulation type and thickness • Material choice • Construction development CONCLUSIONS
As building design evolves towards a more holistic approach and simulation programmes towards a more specific, expert oriented direction, first it should be emphasized that design process should work in a more efficient feedback mechanism. Experts of each field, involved in either passive component or building system design, should be able to collaborate. Another important outcome regarding to simulation programmes would be to have simulation experts in design team, as well as the need of a simulation guide for design process support. Secondly, it should be pointed out that simulation programmes do not have to keep a parallel complexity level with the design development, i.e. detailed simulation could be needed in the
early phases as well. For example, through deciding on the geometry of the building, an analysis of the relation of the designed building with the surrounding buildings and their total effect on wind pattern and microclimate would require a detailed CFD analysis although form decision is an early stage architectural design issue.
Through the comparison of the selected simulation programmes, the programmes that are supportive in following aspects would be more efficient through early design phase; defining building type, using a weather data package and local terrain information and orientation adjustment possibility, translating detailed information about occupancy profile for design support (as all the decisions are depended on occupancy expectations), providing 3D modelling. On the other hand, mass properties and material properties are not needed to be analysed in depth for early phases. Nevertheless it should be emphasized that each is design is unique, so experience and knowledge obtained from similar projects are tended to be integrated to other new projects’ articulation but, design could start from scratch.
Setting out from this point, as future work, a real building project should be observed to find out how specific parameters decided during concept development and by executing a survey among a group of architects, weighting factors of each parameter would be revealed. This will help designers in choosing the most appropriate tool according to their conceptual approach.
REFERENCES
Augenbroe, G. de Wilde, P. Moon, H.J. Malkawi, A. Brahme, R. Choudhary, R.
(2003) “The Design Analysis Integration (DAI) Initiative”, 8th International IBPSA
Conference, Eindhoven, Netherlands, pp. 79-86
Augenbroe, G. (2002) “Trends in Building Simulation”, Building and Environment, Isuue 37, pp. 891-902
Clarke, J. A., (2001), “Energy Simulation in Building Design”, Adam Hilger Ltd., Second Edition, Bristol, UK.
Crawley, D.B. Hand, J.W. Kummert, M. Griffith, B.T. (2005) “Contrasting Capabilities of Building Energy Performance Simulation Programs”, A Joint Report, Version 1.0, EERE, USA, pp. 2-15
Morbitzer, C. Strachan, P. Webster, J. Spires, B. Cafferty, D. (2001) “Integration of
International IBPSA Conference, Rio de Janeiro, Brazil, pp. 697-704
Hopfe, C.J., Struck, C., Ulukavak Harputlugil G., Hensen, J.L.M., De Wilde, P., 2005, “Exploration of the Use of Performance Simulation for Conceptual Design”, IBPSA-NVL Symposium, TU Delft, Netherlands (CD).
Harputlugil G. U., Hopfe, C.J., Struck, C., Hensen, J.L.M., 2006, “Relation Between Design Requirements and Building Performance Simulation”, CIB Student Chapters Postgraduate Conference Proceedings, METU Faculty of Architecture, Turkiye (CD).
