Building energy modeling can offer a host of benefits for savvy building operations.
For property managers and building owners, building energy modeling allows them to understand a facility’s operating characteristics before they take over a building, according to Skelton.
For new construction or major renovations, Franconi sees benefits in reduced first costs as well as operating costs, along with improved occupant satisfaction. For existing buildings, building energy modeling provides a “holistic assessment of systems and their interaction in order to optimize operations, which can result in reduced costs, improved maintenance, and increased equipment life,” points out Franconi.
“Energy modeling allows designers to push the envelope with less risk,” explains Muehleisen. Building energy modeling also helps engineers “avoid over-designing systems, adding to wasted resources, energy and costs,” he adds.
The approach is valuable for buildings planning extensive retrofits to make dramatic cuts in energy use. “Whole-building energy modeling can benefit existing buildings undergoing deep retrofits by allowing outside financing entities to verify savings against actual weather and observed occupancy, analyzing variances from expected performance and including the interactive effects,” observes Eldridge.
Building energy modeling can be very helpful in new construction and for extensive HVAC and lighting retrofits of large facilities.
“Energy savings calculations for more complex retrofits with multiple interacting measures benefit from whole-building modeling,” says David Eldridge, associate with Grumman/Butkus Associates, “as do measures that change with occupancy and weather. New construction, where there is no existing baseline for comparing savings, also benefits.”
Even when whole-building energy modeling may be too costly or time consuming, elements of the approach can be tailored to fit many projects.
“Projects that would benefit from a high-level analysis, and that don’t support the cost of a more detailed analysis, can still use tools that provide a streamlined modeling approach to yield a high-level analysis,” explains Eldridge.
Skelton believes modeling can result in building a better building “to save energy and operating costs down the road.”
However, when building energy modeling is not required for code or certification compliance, experts note that other less costly and time-consuming options may be better options for some facilities.
“Some energy efficiency projects have operating characteristics that make them suitable for spreadsheet models, instead of whole-building modeling. These facilities have consistent operating hours, limited possibility for operator overrides, simple weather dependence (or are not related to weather) and don’t include mutual interactive effects with other efficiency measures being considered,” says Eldridge.
Franconi agrees: “For smaller, simpler buildings, engineering calculations or prototype building studies might be more cost effective.”
Dennis Knight, CEO of Whole Building Systems, points out “Few engineers do energy modeling for day-to-day HVAC designs. They use load calculations modeling software to predict peak and non-peak loads for sizing equipment and systems.”
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