Join us for our monthly meeting!

Please arrive at 5:45pm for registration and networking. Dinner will be served at 6:15pm followed by chapter announcements and the technical presentation. We look forward to seeing you!

Topic

HVAC Load Calculations and System sizing - heat balance method

Overview

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.

Presenter

Nathan Kegel

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”.

Meeting Notes