Using BEM to support a charrette

BEM can be a valuable tool to provide information in a collaborative design exercise such as a design charrette. An analysis performed in advance and presented at a charrette directs focus on important decisions. During the charrette, BEM can be used to evaluate additional concepts or explore questions that arise. Following a charrette, BEM can be used to compare performance of alternative design strategies.

Perform pre-charrette analysis

A model developed in advance of the charrette might be based on limited information, but results can be useful even if based only on information such as building type and location. Read more about Preparing Model Inputs for guidance. Potential analysis approaches include simple box modeling and use of prototype models.

For suggestions on alternatives to evaluate prior to a charrette, see:

• Assess likely energy use patterns
• Common use cases for simple box models
• Building form and mass
• Design features

Pay attention to developing a clear, visual presentation of results.

Consider also developing a list of potential energy conservation measures (ECMs) to bring to the charrette for discussion.

Perform analysis during the charrette

Due to time constraints, it can be challenging to evaluate additional alternatives during a design charrette. However, planning ahead can help make it work.

• Develop a base case simple box model and other alternatives as appropriate.
• Become familiar with steps to modifying the model.
• Consider creating a checklist for modeling steps to use as a reference during the charrette.
• Spend time in advance on a model quality review. Read more about Analyzing Model Outputs for guidance.  
• Develop in advance a format for presenting results and comparisons of alternatives.
• Discuss the agenda in advance with the charrette leader to allow for adequate time.
• Practice the process of altering the model and presenting results

During the charrette, consider working with a partner to help reduce chances of input errors and to help interpret and present results.

Perform post-charrette analysis

There are likely questions that cannot be answered during the charrette; often the group develops a long list of possible design concepts. The energy modeler can help the team to evaluate and prioritize the concepts with follow-up analysis. Here are some considerations to maximize the benefit of a post-charrette BEM analysis.

• Identify the analysis objectives, focusing on design questions
• Based on the questions, choose an appropriate analysis approach, which might be developing or updating a simple box model or developing or updating a more detailed conceptual design model.
• Prioritize efforts so you can respond quickly; design can move very fast and rapid feedback from BEM maximizes impact.
• Make appropriate inputs, considering the questions being evaluated.
• Identify integrated design impacts such as the effect of envelope changes on heating and cooling loads.
• Provide additional insights, such as additional savings opportunities.
• Document the primary BEM input assumptions and review with the team.