Understanding and Minimizing Unmet Load Hours – A User Guide - Part 4: Identifying problematic HVAC zoning and control issues using manual UMLH tests

Part 4: Identifying problematic HVAC zoning and control issues using manual UMLH tests

This article describes the use and application of manual unmet load hour (UMLH) checks and related tools within VistaPro for tracking down sources of UMLHs, such as spaces with problematic HVAC zoning or inappropriate control of  space conditioning. This includes explanation and examples of the following:

• Manual UMLH testing fundamentals and applications.
• Identifying problematic HVAC zoning.
• Short simulations in support of manual UMLH testing for initial performance assessment.
• Selective focus on problem zones and peak load date ranges.
• Uncovering and resolving HVAC control issues that result in UMLHs.

Part 5 will then describe strategies for appropriate HVAC zoning to reduce UMLHs in simulation, thus also informing and improving the consistency and controllability of thermal comfort in the HVAC system design for the actual building. Parts 6–10 will cover other aspects of the model set up, application, configuration, sizing of HVAC systems, and so forth that may also affect UMLHs.

Look for an update of UMLH Guidance – Part 4 (this article) following the VE2022 Feature Pack 1 release, which will include an improved user interface for manual UMLH tests within VistaPro.

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You can view our other Understanding and Minimizing Unmet Load Hours articles by clicking HERE.