Energy, FDD and Re-Tuning

Learning objectives

• >Explain the building re-tuning process
• >Recognize common faults in AHU and plant trends
• >Explain low delta-T syndrome and its effect on pumping
• >Describe what fault detection and diagnostics (FDD) needs in order to work

Sessions

Three 2-hour weeknight sessions plus a weekend block. Check each one off as you finish it.

1. SESSION 1· 2 h Introduction to PNNL Building Re-Tuning
2. SESSION 2· 2 h PNNL online training: the AHU module
3. SESSION 3· 2 h PNNL online training: the central plant module
4. WEEKEND· 3 h Exercise: a "top 10 things to look for in AHU and central-plant trends" checklist. Skim the G36 AFDD addendum

Answer in your notebook first, then reveal the answer and grade yourself honestly.

1. Q1What is building re-tuning?

   [ reveal answer ]

   A low- or no-cost, systematic review of BAS trends and operations to find and fix operational problems.

   ✓ I got it ✗ Missed it

2. Q2What would simultaneous heating and cooling look like in AHU trends?

   [ reveal answer ]

   Heating and cooling valves open at the same time, or reheat running while supply air is colder than necessary.

   ✓ I got it ✗ Missed it

3. Q3Pumps sit at minimum speed while loop DP stays well above setpoint. What are two likely causes?

   [ reveal answer ]

   An oversized pump or a minimum speed set too high, an open bypass, or very low load.

   ✓ I got it ✗ Missed it

4. Q4What is low delta-T syndrome, and how does it affect pumps and chillers?

   [ reveal answer ]

   The return-minus-supply temperature difference runs below design. That forces more flow, raises pumping energy, and keeps chillers from fully loading.

   ✓ I got it ✗ Missed it

5. Q5According to the Guideline 36 AFDD addendum, what has to be in place for automated FDD to work?

   [ reveal answer ]

   Specific sensors and data have to be available.

   ✓ I got it ✗ Missed it