Written by Heather Johnson
It’s a dilemma faced by architects and engineers when considering early-stage design analysis: which is more important– accuracy or precision? Accuracy refers to the closeness of a measurement to an actual or known value, while precision is related to variation between multiple measurements of the same element.
Accuracy vs precision
According to engineer M. Dennis Knight, P.E., founder and CEO of Whole Building Systems and ASHRAE board member, in early-stage design processes accuracy trumps precision. Knight notes that practitioners often confuse accuracy with precision when performing Building Performance Analysis (BPA). However, in early-phase modeling, when comparing alternatives, accuracy of results takes priority.
Accuracy lets the building owner and design team make more informed decisions than using a precise forecasted performance. According to Knight, if early-phase comparisons use consistent workflows and methods, and our simulation tools provide results that are “close enough” to known values in building performance, then results should be accurate enough to inform better decisions. Precision, he argues, involves detailed, expensive modeling not needed early in the design process.
Advanced tools within the Autodesk AEC Collection, including Revit and Insight, deliver the accurate feedback needed in early-phase energy analysis. Knight says BPA software such as Revit’s Insight plug-in allows design teams to quickly analyze multiple design alternatives. “Basic project information provides reliable, accurate results that can be compared to various benchmarks such as ASHRAE 90.1, the IECC ICC or the Architecture 2030 Challenge,” he says.
Achieving accurate EUI
For example, Dekker/Perich/Sabatini (D/P/S), a multidisciplinary architecture and design firm based in Albuquerque, New Mexico, uses Revit and Insight for its projects. The tools allow D/P/S to provide clients with fast, accurate energy analysis that help it meet its sustainability goals.
Revit and Insight help D/P/S educate stakeholders about the benefits of various sustainable design approaches early in the process. The solutions also provide accurate, real-time feedback that helps the company iterate to design more energy-efficient buildings. One D/P/S project, for example, had a predicted energy use intensity (EUI) of 130. Insight’s analysis showed 41.4 EUI—a big difference.
“This discrepancy prompted the engineers to rerun their analysis, and after identifying a few model errors, they produced a revised EUI that was just 0.1 off from Insight’s number,” explained D/P/S intern architect and energy specialist Aaron Ketner. “This process verified that Insight results are highly accurate—and that we can trust the guidance of Insight’s analysis.”
Energy analysis early and often
HOK, a global multidisciplinary firm headquartered in Washington, DC, has prioritized sustainable design for nearly 20 years. HOK runs energy analysis on every project. Before Insight, architects had trouble accessing quality data. Because they couldn’t read models clearly, they left analysis to the engineers.
With Insight, architects can model design change effects on lighting, cooling and other sustainability measures directly inside Revit and FormIt Pro. Design teams can leverage energy analysis themselves, beginning with early conceptual models, receiving constant feedback along the way.
Accurate feedback in the cloud
Before the 1970s, when the building sector considered energy abundant and inexpensive, architects rarely considered energy use. Thanks to the energy crisis, energy conservation became more of a priority. However, initial tools were slow, tedious and time-consuming to use.
Today’s early-phase BPA tools provide highly accurate feedback within minutes. The cloud allows design teams to collaborate easily, work efficiently, and save time. With early energy analysis, design teams can meet owners’ demands, hit sustainability goals and make overall smarter design decisions. “We make sure our architects are empowered to seek feedback in terms of performance earlier and more often in the design process,” said HOK director of sustainable design Anica Landreneau. “Nobody should have to work in the dark.”
In early-stage design processes, accurate feedback can give you the information you need to keep clients happy and meet your sustainability goals.