The Growing Advantage of Energy Modeling

Feb 7, 2022DMA Engineering, Steven Forrester - Principal

As the International Energy Conservation Code becomes more stringent the overriding question becomes: How do we make buildings meet the code intent and still be a functional building with unique architectural features?

The code makes provisions for code compliance verification using energy modeling, and is a performance path described in the code.  The advantage to this section when designing a building is that it allows trade-offs between all the components of the building: For example, reductions in the wall insulation could be offset by combining a higher roof R-value with a higher performing heating system.  To simulate these trade-offs, we use an energy modeling software package that models the predicted energy consumption of the building.  To perform such an analysis two models are developed, a baseline model (that is the code minimum) and the proposed building model.  If the resulting energy consumption of the proposed building (as measured in dollars) is less than the baseline building, the proposed building is in compliance.

DMA Engineering has performed energy modeling of several buildings in recent years to show code compliance.  The advantages of energy modeling are best demonstrated for an existing building we recently worked on.  The building was changing from a marijuana grow facility to children’s theater.  The building had sit vacant for several years, with the building sitting in Denver the code change to the 2015 IECC presented some challenges.  Using the perspective path the envelope was going to need significant upgrades, the code official recommended thy use the performance path and engaged DMA to perform the energy modeling.  Using this method we developed a baseline building in its current state for the envelope and the baseline mechanical system is code as described in the code.  Minor upgrades to the building’s envelope or higher performing mechanical systems show compliance, which in this instance was the use of roof insulation, reduction in glazing and a higher performing HVAC system.

The City of Boulder has adopted its own conservation code, which requires that energy modeling be performed on buildings based upon the anticipated construction costs. This requirement applies to existing buildings undergoing renovations that are greater than 26% of the assessed valve.

Many certifications such as LEED, or Enterprise Green Communities require that energy modeling be performed for points or to show compliance. Such modeling is beneficial in the design phase to reduce the energy consumption of the building and meet the statements set out in the owner’s project requirements.  When the building is complete and measurement and verification is taking place, the energy model is used as a baseline to compare the actual consumption versus the predicted consumption.  Such insights shown that the energy model didn’t, for example, have a schedule for the evening cleaning crew—which led to greater-than-predicted energy consumption once the building was in use.  That understanding brought a substantial drop in building energy consumption by simply changing the schedule of the cleaning crew and educating them to turn on the lights in only the areas they were actively working.