BEM project lifecycle

BEM project lifecycle illustration. (Source: IBPSA-USA BEM Workshop)

For many projects, energy modeling tends to happen later in design, for code compliance or LEED certification. However, there are many design questions that could be informed by earlier energy modeling.

In the early stages, BEM can be used to make fundamental decisions such as:

• Building form for natural ventilation and daylighting
• Construction type, thermal mass
• HVAC type: radiant, displacement, ceiling fans, VRF… have building form implications

Primary roles for BEM analysis during a design project. (Source: CalBEM)

As the design progresses into design development, design concepts can be refined and optimized with BEM including:

• Envelope details
• Equipment selections
• Analyzing specific measures such as whether to use heat recovery, whether chillers should be water cooled or air cooled
• Detailed life cycle cost analysis of design options and efficiency measures

Towards the end of the design process, the models are updated to reflect the final design and to document the final design's performance estimates. During this stage, energy modeling for code compliance and beyond-code programs may occur. These compliance models follow a somewhat different process than analyzing the design because the compliance models must follow a set of rules prescribed by the code or beyond-code program.

This page is a simple overview, but for much more detail on specific modeling exercises that are used during each phase of the design, refer to the Learn by Design Task section of this site which describes these concepts in detail.