The life cycle and integrated design process can be understood as a design process to deliver a building, in which its relationship to the surrounding context, technical components and technologies are parts of a whole system, for the whole building life cycle (Larsson, 2005). This objective can be obtained once interdisciplinary professional team members work collaboratively right from the inception and conceptual design to make strategic decisions and address all design issues. In this way, energy efficient technologies and strategies can be incorporated into the building design in a way that is integral to life cycle considerations.
Such results are often not achievable using a conventional linear design process, which usually begins with the architect and the client agreeing on a design scheme. The mechanical and electrical engineer and the civil and structural engineer are then asked to provide their inputs according to the agreed design scheme. The engineers, therefore, are tightly bound by the earlier agreed upon design parameters. As a result, their inputs for energy efficiency are usually not optimal, but rather add-on features or an attempt to rectify inefficient design decisions made earlier. For example, for a pre-agreed built form that exposes large building glazing to the west, engineering inputs are limited to the selection of an energy efficient glazing system and to provide additional air-conditioning load by choosing an energy efficient HVAC system. This result is far from optimal and it unnecessarily increases the overall building cost. Furthermore, from the life cycle perspective, the high embodied energy of the additional HVAC equipment and large area of double or triple glazing panels used to reduce heat gain on west façade can be considered as wastage. A better approach is to have these issues raised and solved at the conceptual design stage through the life cycle and integrated design process; and perhaps the issues caused by large glazing façade on the west façade can be avoided altogether.
The typical elements of life cycle and integrated design process can be clustered into three groups:
- Interdisciplinary and interactive approach: an interdisciplinary team should be formed right from the project’s inception. The involved parties, depending on the complexity of the project, are the client, architect, engineers, quantity surveyor, energy consultant, landscape architect, facility manager, contractor (builder) and design facilitator (in more complex projects) (Lohnert et al., 2003). The team members first establish a set of agreed performance objectives, and work collaboratively to achieve these objectives.
- Lifecycle based decision making: Decisions made during the design process, such as built form, orientation, design features, building materials, structural systems, mechanical and electrical equipments, should be based on a lifecycle assessment. The assessment should take into account the products’ or systems’ embodied energy, performance, lifecycle cost, lifespan and end-of-life.
- Computer assisted design tools: the design of sustainable buildings has recently been made easier with growing number of computer assisted design tools. These tools simulate building environmental performances, and calculate the energy required for cooling or heating, CO2 emissions, life cycle analyses and so on. Simulation tools predict building environmental performance, usually for aspects such as sun path and sun shadow, daylight, computational fluid dynamics for air movement, etc. The tools make design strategies visible through graphic-based user interfaces. They are particularly useful for:
- Providing feedback to inform the design process. For example, a sun path analysis provides outputs that allows the design team firstly to identify the areas requiring sun shading devices, secondly to design the form and dimensions of sun shading devices for them to be effective, and thirdly to simulate and verify the performance of sun shading devices on the building model.
- Comparing different design options, strategies, and technologies to facilitate the interdisciplinary team’s decision making process.
Computational simulation technologies have also been rapidly developed to facilitate decision making during the design process to enhance the environmental performance and cost effectiveness of buildings. The five main areas for which computational simulations are usually applied are listed below, with examples of software:
- Sun path and sun shadow simulation: ECOTECT
- Daylight and glare simulation: Radiance, Daylight, DAYSIM
- Thermal simulation: TAS, IES
- Computational fluid dynamics (CFD): CONTAM, FLOVENT, FLUENT, IES
- Energy demand and supply balance: Energy Plus, eQuest.
In recent years, individual computer assisted design tools have gradually been replaced by an integrated, one-stop computational platform, that can serve as a drafting tool, visualisation tool, simulation of various environmental performance, local code compliance checking tool, and even a facility management tool. An example is Bentley Tas Simulator software V8i. The software provides:
- A design tool (to simulate natural ventilation, room loads, energy use, plant sizing, CO2 emissions, and running costs)
- A compliance tool (i.e., simulation and calculation compliance with ISO and are approved for calculation methods to some British building regulations)
- A facility management tool (for computing detailed and accurate energy use predictions, energy and
cost savings for operational and investment options) (Bentley, 2009).
However, one-stop computational platforms are still at the market exploration stage and have yet been fully or widely implemented in building design practice.
Unlike a conventional linear design process, an integrated design process is characterised by a series of iterative activity loops throughout each design stage: from conceptual to schematic to detailed design and documentation for construction. Each activity loop involves all of the relevant team members to actively interact with one another to create optimal decisions. The assembling of a multidisciplinary team at the start of the project is crucial, and requires a belief in the process and full support from the building developers.
During the integrated design process, the time taken for the earlier design stages i.e., conceptual and schematic design, is inevitably longer than that of the conventional linear design process. However, this additional time is made up for by the shorter coordinating time at later design stages i.e., detailed design and documentation for construction. Furthermore, due to the involvement of the contractor (builder) in the early design stage, the construction period can be shortened with less coordination, fewer call-backs and variation orders and so on.
Multidisciplinary team members – often including an architect, structural and civil engineer, mechanical and electrical engineer, quantity surveyors and an energy specialist – are required to have a strong team spirit and willingness to listen and cooperate with one another. In this interactive working relationship, the architect’s roles are not limited to the generation of built form and spatial layout, but also include the reconciliation and incorporation of ideas/inputs of team members to the building design. The engineers’ roles go beyond the provision of systems and solutions to make a design work. Engineers are expected to take initiative to put forward conceptual ideas to contribute to the high performance objective from the early design stages. The quantity surveyor’s roles are also extended from the mere construction cost calculation to life cycle analyses and life cycle assessment of building materials and other technological systems to be incorporated into the design. The building developer also has to take a more active role than usual to engage in design workshop, especially those involving in performance goal settings. The high performance goals, life cycle consideration and other design targets should be the ultimate objectives to direct the interaction and working relationships of the team members.
Computational simulations should not just be used at the end of the design stage for verification and presentation purposes. They are particularly useful to simulate the performance of various design strategies and technological systems for comparison. Therefore, computational simulations should be deployed during the integrated design process as a design assisted tool to provide feedback to the team for design improvement and decision making. To be human resources- and time efficient, computational simulation can be applied at the macro level at conceptual design stage to show general/overall building volume for quick outcomes and overall direction. When moving to schematic and detailed design stages, more detailed computational simulations are required to support design improvements and fine tuning.
The integrated design process does not contain any radically new elements, but integrates a “well-proven approach into a systematic total process” (Larsson, 2005). For example, “the skills and experience of mechanical and electrical engineers, and those of more specialised consultants, can be integrated at the concept design level from the very beginning of the design process” (Larsson, 2005). Experiences from North America and European countries showed that with some initiatives and support from the government for demonstration projects, the integrated design process will subsequently adopted by the building-related professionals due to its proven beneficial outcomes.
The key success factor for the large-scale implementation of the integrated design approach lies in the main players in the building industry changing their mind sets in order to adopt the practice with open minds, initiative and the spirit of teamwork.
In the regions where a life cycle and integrated design process is not a common practice, capacity building is necessary to raise awareness among key players and professionals and to demonstrate how the process unfolds. There is also a need to train a workforce of energy specialists, experts on life cycle assessment and analysis, and experts on using computational simulations as design and decision making tools. In addition, it is also important to collect life cycle information on building materials, products, components, technological systems and establish a comprehensive data bank for life cycle assessment and analysis. These can be carried out in collaboration between local building regulators, research institutes, universities, building product suppliers and other building-related professionals.
In the context of sustainable buildings, life cycle and integrated design process have gradually progressed from experimental and ad-hoc applications to mainstream practice in the work of established consultancy practices and building developers. Integrated design process is also adopted as a criterion for pre-qualifying consultancy teams for publicly-funded projects in Canada (Public Works and Government Services Canada, 2011). Clear guidelines on implementing integrated design processes have been established by numerous international organisations and research bodies, such as the International Energy Agency Task 23 and the international initiative for a Sustainable Built Environment.
In recent years, computational simulations have also gained popularity. The main reasons are:
- The industry has recognised that they contribute to enhancing the environmental performances of buildings and to cost savings (by preventing poor performance leading to costly operational or remedy costs after the buildings are constructed).
- The development of the technologies has been made more accurate.
- The development of the technologies has become more user-friendly, compatible and seamlessly transferable among various programs for modelling, drafting, visualisation and simulation. This shortens modelling and simulation time, which enables timely feedback of simulation outcomes into the design process.
This upward momentum of the global progress for life cycle and integrated design will be further propelled by the upward trend of global operations of many multinational corporations. These established companies (both consultants and building developers) are bringing their established practices in the integrated design and advanced computational assisted design tools beyond their home countries to new building projects in developing and least developed countries.
The life cycle and integrated design process contributes indirectly to social and environmental sustainability, through providing methodologies and computational tools to deliver high performance buildings. The life cycle assessment and life cycle based decision making also address the scarcity of natural resources, the use of building materials and components efficiently, and end-of-life considerations.
The life cycle approach also contributes to economic development through differentiating true-cost savings from up front construction cost savings that may eventually lead to negative building environmental performances and more spending during a building’s operation. The end result is the reduced overall lifecycle costs and social and environmental costs from building construction and operation.
The life cycle and integrated design process contributes indirectly to social development at large, through providing methodologies for stakeholders to deliver high quality buildings. The process strengthens the relationships between building-related professionals by promoting teamwork and positive interaction, leading to better sense of environmental and social responsibility. The process also provides a platform for cross learning, knowledge sharing and innovation/creativity in building a sustainable built environment.
The life cycle approach and assessment in the integrated design process makes way for cost optimisation based on the entire building lifespan rather than just on the upfront construction cost. Through life cycle analyses, building owners and property developers can better understand the long-term benefits of, and savings from, the integration of energy efficiency design strategies and technologies. These benefits come with a marginal increase in construction cost. Therefore, effective energy efficiency technologies have already been accounted for and are not subject to be removed during cost-cutting exercises, which is usually carried out just before the start of construction.
The life cycle and integrated design process has been proven to help deliver high-performance buildings within or just slightly above the budget estimated at the start of the project (Larsson, 2005). The overall financial requirements for the life cycle and integrated design process are minimal. In fact, the process can be considered as more about re-allocation of budgets among different stages of the entire building lifespan than additional investment requirements. From the building lifespan perspective, the budget shift occurs from using a portion of building operational saving to pay back for the slightly higher consultancy fees incurred during the design stage. The additional consultancy fees are for Engaging the engineers, quantity surveyors and energy specialist from the inception of the project, instead of after conceptual and/or schematic design stage.
The life cycle assessment and the use of computational assisted design tools to generate simulations to feedback to the design. This cost component varies according to the availability of such services locally. For example, the costs for life cycle assessment and computational simulation are relatively low in developed countries where the practices are established and there is price-competitiveness between service providers. In this context, many large consultancy practices have the in-house capability to provide the services, and often absorb the extra cost in their overall fee proposal for the project. However, in a local context where specialists on life cycle assessment and computational simulation are rare, the cost for such services can be higher and are often quoted separately in a consultancy contract to the client.
Bentley (2009). Product Data Sheet: Bentley® Simulator V8iIndustry – Leading Building Energy Modeling and Simulation. Bentley. [Online]: ftp://ftp2.bentley.com/dist/collateral/Web/Building/BentleyTas/BentleyTA...
Larsson N. (2005). Integrated Design Process. [Online]: www.iisbe.org/down/gbc2005/Other_presentations/IDP_overview.pdf
Larsson N. (2009). The Integrated Design Process; History and Analysis. iiSBE. [Online]: http://www.iisbe.org/system/files/private/IDP%20development%20-%20Larsso...
Public Works and Government Services Canada (06, Jan. 2011). Integrated Design Process (IDP). [Online]: http://www.tpsgc-pwgsc.gc.ca/biens-property/sngp-npms/conn-know/enviro/p...