The development of integrated building simulation environment is now firmly rooted in the current available computer technology. Over the past decade developments in the field of building simulation have given rise to the prospect of a new generation of design tools that has the potential to allow rigorous hypothesis testing at design stages. The move towards providing simulation support to the building industry has also been driven by the on going revision and introduction of new building regulations. This paper describes the DASS approach in bringing the simulation technology to the design profession. In delivering this service DASS has developed a business model of Participation, Integration, Open source resource Knowledge sharing (PIOK) together with a simulation framework, whereby all simulation tasks are operating upon a common data model, as technical support. The major elements of the simulation framework is described and the use of which is demonstrated by design examples.