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Task 23

Integrated Design Process

Increased performance requirements

The global drive towards sustainable development has resulted in an increasing level of pressure on building developers and designers to produce buildings with a markedly higher level of environmental performance. Chief amongst these is energy performance, and current expectations of energy performance pose a definite challenge to designers, in terms of reducing purchased energy consumption and the application of solar technologies, all within the constraints of minimal fees and the time pressure of the modern development process.

Traditional design process

Nowadays the increased performance requirements cannot be addressed without the efforts of an interdisciplinary design team. The team should be a skilled partner for the client to create a well-balanced, i.e. integrated, design in the concerted action of quality, cost and environment. Particularly in the first stages of the design process important decisions are made, whereas the input of expertise within a traditional design process is limited. Therefor it is recommended to structure the design process in a different way with the goal to apply more knowledge and creativity in the early stages of the process: the integrated design process.

Integrated design process

Based on experiences in Europe and North America, the overall characteristic of an integrated design process (IDP) is the fact that it consists of a series of design loops per stage of the design process, separated by transitions with decisions about milestones. In each of the design loops the design team members relevant for that stage are participating in the process. The benefits of the IDP process are not limited to the improvement of environmental performance. The experience of Task 23 members is that the open inter-disciplinary discussion and synergistic approach will often lead to improvements in the functional program, in the selection of structural systems and in architectural expression.


The IDP has impacts on the design team that differs from a conventional design process in several respects. The client takes a more active role than usual; the architect becomes a team leader rather than the sole form-giver, and the mechanical and electrical engineers take on active roles at early design stages. The team always includes an energy specialist, and in some cases, an independent Design Facilitator.

The guide 'Integrated Design Process - a Guideline for sustainable and solar-optimised building design' elaborately describes the theory and practice of integrated design. The guide is a key document and also refers to other instruments and publications developed by the Task 23 experts.

The methods and tools developed in Task 23 represent the first international attempt to develop a formalised integrated design process that will enable a large number of clients and designers to take advantage of them.


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International Energy Agency Solar Heating and Cooling Programme