This is the second in a series of columns in which I am demonstrating examples of systems performance information that can be gleaned from trend log analysis. In these columns, I introduce a system or sub-system, show a trend graph, and then leave it up to the reader to discover the operational “issue” illustrated in the graph. The answer will be given at the start of the subsequent month’s column.
This is the first in a series of columns in which I plan to demonstrate examples of systems performance information that can be gleaned from trend log analysis. Whether the trended data comes from a BAS or from portable dataloggers, the analysis is the same.
Using data trend logs to supplement in-field functional performance testing (FPT) has always been an option in the commissioning process, particularly for HVAC systems controlled by DDC systems. As DDC system trending capabilities and computer hardware storage capacities have improved substantially over the past few years, I propose that trend logs be given a more prominent place in the commissioning toolbox.
As noted in last month’s column, accessibility
to mechanical, electrical, and control system components is critical for
sustainable systems operation. However, the design and construction industry is
sorely lacking when it comes to agreeing on what appropriate accessibility
means. In order to make a meaningful difference in how systems are delivered to
owners/operators, it is critical to define measurable accessibility acceptance
criteria early in the design phase and allow the commissioning professional to
shepherd that criteria through the design, construction, and acceptance phases.
Leaning on experience and data from various K-12 cities and projects, the author pursues some less conventional design approaches. They may revolve around radiant heating and/or cooling, but depending on school size and other factors, the smart use of heat recovery, DOAS, and improved central plants could also put a project on the HVAC honor roll.