Upcoming Events:

Please join us at our Ozarks ASHRAE monthly meeting. Per usual, the event will start with networking followed by a speaker and lunch. We look forward to seeing you there!

Monthly Meeting Location:
1538 South Enterprise Avenue Springfield, MO 65804

Nathan Kegel, BEMP, LEED AP

Vice President of Business Development, North America – Integrated Environmental Solutions Limited

PRESENTATION: ASHRAE Heat Balance Method – Load Calculations and System Sizing

Load calculations and HVAC system sizing are fundamental tasks in designing HVAC systems for all buildings. Considering load calculations have a dramatic impact on HVAC equipment size and HVAC system first cost, energy consumption, refrigerant quantity, and carry a significant amount of liability for the Engineer of Record, determining accurate loads is essential to any building, building owner, and design team.Methods for calculating loads have changed significantly over time. “Traditional” methods assumed near instantaneous heat transfer or simplified the methods of estimating time-delay through weighting factors. These simplifications were made for a number of reasons including limited access to computing power and a lack of empirical tests for calculation methods.Over 20 years ago, ASHRAE published (in the Handbook of Fundamentals) the Heat Balance Method for calculating loads. This method is considered to be the most accurate and has some empirical testing to validate the calculation methodology. This session explores how the Heat Balance Method is different from other methods, how energy code has impacted HVAC sizing calculation assumptions, and the impact of oversized and undersized systems on energy, comfort, and environmental impact.The new ASHRAE HQ building is used as a case study in applying the Heat Balance Method for calculating loads for a building.


Mr. Kegel has over 20 years of design and building performance simulation experience using a variety of design and modeling tools and platforms. He has performed design and post-occupancy analysis on hundreds of buildings and dozens of building types all over the world. He 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. Currently, he trains building design professionals how to apply performance simulation and calculations of all types to the building design process. He is ASHRAE BEMP certified, a LEED AP, and a RESET AP.

Meeting Location

Not a Member?

We are looking for volunteers for roles inside the chapter. These roles include the following:

  • Committee Chairs and Co-Chairs
  • Social Media Presence
  • Photos

Very little time, can go a long ways. Please contact Zach Altis for details.



To advance the arts sciences of heating, ventilation, air conditioning and refrigeration to serve humanity and promote a sustainable world.


ASHRAE will be the global leader, the foremost source of technical and educational information, and the primary provider of opportunity for professional growth in the arts and sciences of heating, ventilating, air conditioning and refrigerating.



ASHRAE education, technical information and all other activities and products will always reflect the best practices that lead our industry. We strive for continuous improvement and innovation in all our practices and products.


ASHRAE and its members are passionate about serving the built environment, creating value, and recognizing the accomplishments of others.


ASHRAE is committed to the highest ethical standards. We work transparently, observing essential requirements for due process and peer reviews to assure our members and stakeholders that we do the right things the right way.


ASHRAE seeks and embraces collaborative efforts with organizations, agencies, and individuals sharing our commitment to sustainable built environments.


Members lead ASHRAE at every level, serving ASHRAE and helping ASHRAE serve society.

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