HVAC System Selection

For many projects the first step should be a focus on the architectural design. Evaluating HVAC system options is covered in the two rounds of design phase energy modeling required to earn points under Optimize Energy Performance. That said for certain projects it may very well be appropriate to evaluate HVAC options during predesign. Just because they are not on the list does not make them potential areas for evaluation at this phase for the right project. I think you could make the case for some projects that evaluating HVAC predesign would be appropriate. What we are trying very hard to avoid is the natural tendency of project teams to defer energy efficiency solely to the mechanical designer. Concentrating on HVAC at this stage for many projects can be counterproductive to producing an energy efficient project in my experience. Of course a project team that routinely produces energy efficient buildings does this all at once but those folks are the rare exception again in my experience.

At the same time I think it is incumbent upon the mechanical engineer to push back on the architects regarding the impact of their design on the building loads instead of just passively accepting them and designing a bigger chiller. The lack of overall understanding regarding how to produce an energy efficient building in the design community still astounds me. Hopefully the design phase modeling required in LEED will enlighten some. Unfortunately too many will probably still treat this as a sort of check the box thing without really engaging in the true value of the analysis to the development of the design.