Nathan Kegel
IES Ltd | Vice President
Speaker
Track C: Decarbonization and Electrification Strategies
Session C1: Building Decarbonization
March 11, 2026 | 2:30 pm - 3:00 pm
Loads & Codes: Why updating "Rules of Thumb" is Essential to Delivering Value
| Accurate HVAC load calculations and system sizing are critical to achieving high-performance, low-carbon buildings. ASHRAE Fundamentals provides the foundation for these calculations through the Heat Balance Method, which captures the dynamic interactions between envelope, internal gains, and systems. Proper application of these methods is essential for desired thermal comfort and increased equipment reliability while also reducing lifecycle carbon. As buildings transition toward electrification and renewable integration, load calculations inform critical metrics such as the Thermal Energy Demand Intensity (TEDI), Energy Use Intensity (EUI), and Carbon Use Intensity (CUI). Incorporating hourly load simulation, climate-specific design data, and realistic occupancy profiles enhances the precision of sizing and supports optimization across thermal comfort, energy efficiency, and cost. This session will explore the significance of advancing load calculations to not just include peak design day conditions, discuss potential policy changes to promote advanced load and sizing methods into more building designs, and share what building design teams are doing today to implement these advances into real building designs. Ultimately, HVAC load analysis is not only a procedural task but also a key decarbonization strategy. By integrating sound fundamentals in an integrated design process with lifecycle and carbon accounting frameworks, engineers and architects can align design intent with performance outcomes—delivering systems that lower lifecycle carbon without increasing first cost. |
Speaker Bio
Nathan has over 20 years of design and building performance simulation experience using a variety of design and modeling tools and platforms. He has largely focused on lifecycle analysis, energy and carbon savings, and cost/benefit of building technologies. He has performed design and post-occupancy analysis on hundreds of buildings and dozens of building types all over the world. In addition, Nathan has built and led High Performance Design Teams, trained over 1,000 industry professionals on using and applying building performance simulation to the design process, and was the coach and captain of the ASHRAE Lowdown Showdown 2022 winners. He is ASHRAE BEMP certified, a LEED AP, and a RESET AP and serves as the co-chair of the Data Analysis and Reporting Working Group for MEP 2040 and is a co-author of “The Beginner’s Guide to MEP Embodied Carbon”.