Building life cycle and integrated design process

The typical elements of life cycle and integrated design process can be clustered into three groups:

1. 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.
2. 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.
3. 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.

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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:

1. Sun path and sun shadow simulation: ECOTECT
2. Daylight and glare simulation: Radiance, Daylight, DAYSIM
3. Thermal simulation: TAS, IES
4. Computational fluid dynamics (CFD): CONTAM, FLOVENT, FLUENT, IES
5. 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:

1. A design tool (to simulate natural ventilation, room loads, energy use, plant sizing, CO2 emissions, and running costs)
2. A compliance tool (i.e., simulation and calculation compliance with ISO and are approved for calculation methods to some British building regulations)
3. 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.