Load Calculation Data and Procedures
ASHRAE Technical Committee 4.1

Meetings Information

Houston Summer Conference.  June 2018

SUNDAY, June 24, 2018, 1:30 PM - 3:00 PM
WORKSHOP 5 - Load Calculations Missing Link: Taking Load Calculations Through to Equipment Sizing 
Track: Fundamentals and Applications
Room: 372AD
Sponsor: 4.1 - Load Calculation Data and Procedures
Chair: Glenn Friedman, P.E., Taylor Engineering, Alameda, CA

TC4.1 Load Calculations limits its scope to room loads. Practitioners take these room loads and use them as the basis for equipment selection. There are many loads external to the room that affect the equipment selection such as weather conditions, ventilation loads, infiltration and sensible heat ratio. This workshop takes groups of attendees through load to equipment selection group exercises.

1. The Design Tool Vendor's Perspective
James Pegues, Member, Carrier Corporation, Syracuse, NY.
2. The Design Engineer's Perspective
Steven Bruning, Fellow ASHRAE, Newcomb & Boyd, Atlanta, GA.

WEDNESDAY, June 27, 2018, 8:00 AM - 9:30 AM
Convective Vs. Radiant Load Calculations: Are They Different?
Track: Research Summit
Room: 372CF
Sponsor: 4.1 - Load Calculation Data and Procedures
Chair: Som Shrestha, Ph.D., Oak Ridge National Laboratory, Oak Ridge, TN

Radiant cooling uses cooler surfaces to remove heat from a space. Traditional load calculations are based on assumptions of a well-mixed space with surface temperature symmetry and a time lag between radiant heat gains and when the all-air-based system removes the heat. How accurate are traditional load calculations for a radiantly cooled space? To answer this question, ASHRAE is funding research project RP 1729 - Experimental Verification of Cooling Load Calculations for Spaces with NonUniform Temperature Radiant Surfaces. This session provides the history of this research projects development through ASHRAE's research process and presents the research methodology and results.

1. Why ASHRAE Needed the Research on Cooling Load Calculations for the Radiant Cooling System?
Christopher K. Wilkins, Member, CBR USA, Cambridge, MA.
The calculation of the cooling load for space is an essential first step in the design process for air conditioning system. The load has long been defined as the amount of heat extracted by the air. Radiant systems fundamentally change the way that heat is extracted from space and led to questions regarding the appropriateness of traditional cooling load calculation methods when applied to these systems. This presentation looks at how these questions led to the identification of a need for an ASHRAE research project to explore the differences in the dynamics of the cooling load in a space. 

2. Navigating ASHRAE Research: Research Project RP 1729 Journey from Concept Through Research
Glenn Friedman, Fellow ASHRAE, Taylor Engineering, Alameda, CA.
Research is an important part of our industry’s growth and improvement. Glenn Friedman unravels the mystery of ASHRAE’s research process and how RP 1729 started from a concept and navigated its way from the research subcommittee through TC 4.1 Load Calculations Technical Committee to a Research Topic Acceptance Request (RTAR) for formal approval by ASHRAE’s Research Administration Committee (RAC), then on to a Work Statement for ASHRAE to use for bidding the research project. After the bids, the journey continued through a Project Evaluation Subcommittee (PES) and a contract and a Project Monitoring Subcommittee (PES). 

3. Can We use Heat Balance Method and Radiant Time Series Method for Load Calculation with Radiant Cooling Systems?
Atila Novoselac, Member, University of Texas at Austin, Austin, TX .
Load calculation methods, such as the Heat Balance Method (HBM) and Radiant Time Series (RTS) Method, are developed for all-air systems. They assume that all heat energy is extracted via air through convection from internal surfaces. However, this is not correct for systems that include radiant cooling components; the dynamics of heat transfer in a room with radiant panels is very different. This presentation shows the fundamental differences in convective, conductive and radiative heat transfer in rooms with all-air and radiant cooling systems. It points out the deficiencies of HBM and RTS when applied to designs utilizing radiant systems. 

4. Comparison of Radiant Cooling and All-Air systems, Methodology for Experimental and Numerical Load Analysis
Stephen Bourne, Member, University of Texas at Austin, Austin, TX.
The presentation describes the methodology for a side-by-side performance comparison of radiant cooling and all-air systems applied in a typical office space. It will show how two identical test rooms, with interchangeable HVAC and façade systems, are used for the development of experimental benchmark data when considering cooling load calculations. A set of comparison experiments are developed for different types of heat gains, operation conditions, and control strategies. The experimental results are also used to develop computational models that are further utilized to compare these two systems. The presentation also outlines the accuracy of experimental and computational methods. 

5. Difference in Cooling Loads for Radiant and All-Air Systems for Different Types of Heat Gains and Control (Operative vs. Air) Temperature
Ardeshir Moftakhari, Student Member, University of Texas (UT) at Austin, Austin, TX.
This presentation highlights major differences in the cooling load dynamics and load intensity of radiant and all-air systems based on experimental and modeled data. The study shows how the type of heat sources in the space (transmitted solar, internal radiative, internal convective, or combination) impacts the cooling load. The experimentally measured loads are compared to those obtained by Heat Balance and Radiant Time Series methods and the differences are explained. Also, the presentation shows the importance of controlled variable (air vs. operative temperature) when considering nominal cooling loads as well as the energy consumption and air/surface temperature distribution.

Attend a Committee Meeting

ALL ASHRAE committee meetings, including this TC’s meetings at the Winter and Annual Society conferences, are open to the public at no cost nor is conference registration required. Interested visitors, local chapter members, and potential new TC members are always welcome. However to attend technical program sessions sponsored by the TC will require registration and payment of any applicable fee.

Participation in an ASHRAE TC provides the opportunity to grow professionally and to contribute to the advancement of HVAC&R within an international organization recognized for shaping the future of the built environment through research, standards writing, publishing, and education.