Commissioning-Style Assessment — Academic Building

• Site: Sample University (demo-site.bdxcloud.com)
• Building: Academic Building
• Window: Last 7 days, hourly aggregation
• Report date: 2026-05-19
• Source: BDX TrendView via BDXpy, cached site inventory CSV

1. Equipment Inventory

The plant for this building consists of two dedicated chilled-water pumps (CHWP1/CHWP2) and two dedicated heating hot-water pumps (HWP1/HWP2), feeding 4 ErwDrawThrough AHUs that serve 193 VAVs.

2. AHU Performance Snapshot (7-day rollup)

All 4 AHUs ran continuously (168/168 hours fan-on). Outdoor air averaged 72.9°F during the period (range: ~55–90°F).

Encouraging:

• No simultaneous heating + cooling on any AHU during the cooling-mode period.
• No freezestat trips, no filter alarms, no general alarms.
• Duct-static control is tracking setpoint within ~0.07″wc on all units.
• Heating valves are confirmed closed (0%) during cooling-season operation — heat output is parked, not leaking.

Concerning: flagged in operational findings below.

3. Operational Findings — ranked by impact

🔴 #1 — AHU_1 over-ventilating during warm weather

What's happening. AHU_1 averages 70.9% open on its outdoor-air damper — substantially higher than its three peers (AHU_2/3/4 hover around 50%). Its actual outdoor airflow averages 7,475 cfm, which is close to its total supply airflow (7,450 cfm) — meaning the unit is approaching 100% OA during a 73°F-average week.

During the 67 hours with OAT > 75°F, AHU_1's OA damper sat above 50% for 59 of those hours (88% of the time). The three peer AHUs sat at minimum OA position the entire time (0 hours > 50% OA when OAT > 75°F). Because OA is significantly warmer than return air during these periods, the unit is dragging in load instead of recirculating cooler return air.

Why this matters. AHU_1 is the highest-cooling unit on the building (coolOutput avg 39.9% vs 30–37% on peers). The abnormal OA tracking explains a meaningful share of that excess load — AHU_1 is cooling more outdoor air than peers structurally larger than it (e.g., AHU_3 at 8,341 cfm supply).

Investigate: - Verify economizer high-limit lockout and minimum-position controls on AHU_1 — the OA damper should sit at minimum (or outdoorAirMinDamperPos) when OAT > a high-limit cutoff (typically 60–65°F dry-bulb on the Gulf Coast climate). - Confirm the outdoorAirMinDamperPos programming — the minimum-OA airflow setpoint reads 0 cfm on all four AHUs, which suggests demand-controlled-ventilation logic is not engaged. - Inspect the damper actuator and end-switch calibration; a stuck-open economizer is a common failure mode.

TrendView (AHU_1 — economizer / ventilation criteria): - Excessive economizing scorecard - Outdoor air ventilation high limit scorecard - OA damper position range scorecard - AHU_1 device dashboard

🔴 #2 — Energy-recovery wheels offline on AHU_1 AND AHU_3

What's happening. Two of the four AHUs have their energy-recovery wheels effectively out of service for the entire 7-day window:

erwSpeed = 0% for all 168 hours, with both OA-bypass and EA-bypass dampers pinned at 100% — meaning the entire outdoor-air and exhaust-air streams are routing around the wheel rather than through it. AHU_2 and AHU_4 are operating normally as the peer reference: wheel speed in the 12–22% average range, bypass dampers modulating around 60%.

Why this matters. ERWs typically deliver 60–75% enthalpy-recovery effectiveness in cooling season — recovering cooling from leaving return air to precondition incoming OA. With both wheels down, AHU_1 and AHU_3 must condition their entire OA stream from outdoor conditions instead of the much cooler post-ERW supply air. This is a continuous energy penalty whenever the fan is running and OA differs from RA, which is every hour of this 7-day window.

Investigate (apply equally to BOTH units): - Confirm intent. Is there a seasonal lockout disabling ERW operation? Check the BAS schedule and any enable-temperature parameters; if intentional, the rationale should be documented. - Inspect ERW bypass dampers. Both erwOutdoorAirBypassDamperPos and erwExaustAirBypassDamperPos are stuck at 100%. Verify the actuators are functioning and the command from the BAS is correct. - Check erwStartStop / erwStatus. If the start command is not being asserted, look at the upstream enable logic (typically requires fan-status + enable-temp + occupancy). If the command is asserted but erwStatus = 0, the wheel motor or VFD may be tripped. - Belt / drive inspection. If the wheel mechanism has failed mechanically (broken belt, seized bearing, VFD fault), the BAS may have intentionally driven the bypass dampers to 100% to keep the unit functional while flagging the wheel as out-of-service.

TrendView — AHU_1 (ERW criteria): - ERW heat-transfer effectiveness (cooling) scorecard - ERW heat-transfer effectiveness (heating) scorecard - AHU_1 device dashboard

TrendView — AHU_3 (ERW criteria): - ERW heat-transfer effectiveness (cooling) scorecard - ERW heat-transfer effectiveness (heating) scorecard - AHU_3 device dashboard

🟠 #3 — AHU_2 chronic SAT undershoot (1.9°F average below setpoint)

Context first — SAT reset IS working on all four AHUs. All four units run their SAT setpoint between 55°F and 60°F, cycling down toward 55–58°F during occupied/cooling-demand hours and lifting back to 60°F overnight when zone cooling demand drops. AHU_1, AHU_3 and AHU_4 all track their setpoint within 0.5°F (good control). AHU_2 is the lone outlier, undershooting its setpoint by 1.9°F average and by more than 3°F for 46.4% of fan-on hours. Worst case: 55.9°F SAT vs 60.0°F SP at 6 PM Tuesday.

Cool output averages only 36.7% during the AHU_2 undershoots — so the chilled-water valve is not at full stroke. The undershoot occurs across the day, not just at startup. There is no concurrent heating output, which rules out hunting between coils.

Likely causes (multi-variable): - Oversized cooling-coil valve or stuck-partially-open: with the valve barely modulating (~37% avg), low cooling demand still over-cools the air. Look at coolOutput vs coolingCoilLeavingTemperature for valve characterization. The other three AHU cooling valves apparently have correct authority for the load — AHU_2's is likely mis-sized or has hysteresis/stiction. - Mixed-air temperature dipping due to OA damper modulation. AHU_2's OA averages 50% but actual OA airflow is 4,192 cfm against 5,325 cfm supply — that's a 79% OA fraction, which is much higher than the damper position suggests. Worth checking damper calibration. - Cooling-coil valve actuator stroke calibration — confirm the 0–100% command actually swings the valve through its full design range.

Energy cost. Subcooling 1.9°F average × ~5,325 cfm × ~120 fan-on hours/week ≈ ~140 kWh/wk of redundant cooling, plus reheat load at downstream VAVs that have to re-warm the over-cold supply air to maintain space setpoint.

TrendView — AHU_2 (SAT criteria): - Supply air temperature low limit scorecard - Supply air temperature control (comfort) scorecard - AHU_2 device dashboard

🟠 #4 — Hydronic pump status feedback faults (CHWP2 & HWP2)

What's happening. The pump pumpOnOff (command) and pumpStatus (feedback) channels disagree on two of four pumps:

Both #2 pumps are likely on lead-lag rotation with the #1 pumps, and during their commanded runs the differential-pressure (or current) status switch is not reporting closure.

Why this matters. A pump-status feedback fault can: - mask a tripped pump (the BAS thinks it's running, BTU delivery is zero); - prevent BAS-driven lead-lag rollover when the lead pump fails; - defeat any safeties wired to status (low-flow lockouts, alarming).

Investigate: - Check the status switch differential set point on CHWP2 and HWP2 — it may be set above the actual run-condition pressure or current. Lead-pump #1s pass on the same logic, so the wiring layout is presumably the same. The discrepancy suggests instrument drift on the #2 units. - Confirm pump VFD min-speed and ramp logic — CHWP2's pumpVfdPercent averages 8.5% across only 8 of its 41 commanded hours, suggesting it spins at a low speed (or never spools up) and never trips the flow switch.

TrendView: - CHWP2 device dashboard - CHWP1 device dashboard (reference / healthy lead) - HWP2 device dashboard - HWP1 device dashboard (reference / healthy lead)

🟡 #5 — Chronic cool zones (5 VAVs averaging < 68°F)

What's happening. Of the 193 VAV boxes analyzed, 5 spaces had 7-day-average space temperatures below 68°F:

Two distinct failure modes (confirmed via DAT data):

1. VAV_1_2_1221T and VAV_2_1_2108 have 0% reheat output — confirmed: DAT for VAV_1_2_1221T averages 59°F (only ~1.5°F above SAT), so there is no thermal injection happening at these boxes. They either have no reheat coil installed or the reheat is mechanically locked out. With 56–58°F supply air entering and no terminal reheat, occupied space temperature falls below comfort range.
2. VAV_1_1_1127, VAV_1_4_1157_1, VAV_2_4_2157_1 are running 34–39% reheat continuously, hitting 100% reheat at peak. DAT data confirms the coils ARE working — VAV_1_4_1157_1 averages 75.5°F DAT (+18°F lift over the 57.5°F primary) and peaks at 104°F. The reheat coils are doing their job; the boxes simply cannot put enough warm air into the space to overcome the building load. Possible root causes: undersized reheat coil for the actual load, primary airflow setpoint too high (over-cooling the space faster than reheat can offset), or building-envelope issue.

Investigate: Walk these 5 zones, verify reheat coil presence/function, check VAV box flow vs occupied min-flow, and survey occupants for cold complaints. These five appear to be in the 1st and 2nd floor exterior west zones (room numbers 1100/1200/2100 series).

Note on minimums. VAV_1_2_1221T at 100 cfm average is essentially at minimum flow — suggesting the box is closed nearly all the time but the space still drifts cold, which points to envelope/exfiltration rather than HVAC.

Hot zones: Only 3 spaces hit > 78°F at any point in the week and no VAVs were chronically warm (avg > 76°F) — comfort risk is skewed entirely to overcooling.

TrendView — per-VAV space temp control (VAV_COMFORT_SPACE_TEMP_CTL): - VAV_1_2_1221T - VAV_1_1_1127 - VAV_1_4_1157_1 - VAV_2_4_2157_1 - VAV_2_1_2108

TrendView — reheat effectiveness (VAV_EFF_HEATING_DA_TEMP) for the saturated-reheat trio: - VAV_1_1_1127 reheat - VAV_1_4_1157_1 reheat - VAV_2_4_2157_1 reheat

🟡 #6 — AHU_3 SAT excursion at 4 AM Sunday (–6.2°F)

What's happening. AHU_3's worst SAT undershoot in the period was 53.8°F vs 60.0°F setpoint (–6.2°F) at 04:00 on Sunday morning. At that moment cool output was only 31%, OAT was 72.3°F. With no fan-status anomaly and no heating output, this looks like either:

• a brief setpoint reset transient (overnight setback rolling back),
• a flow-station/valve hunting episode, or
• a setpoint-reset configuration where the unoccupied/standby SAT setpoint was incorrectly elevated to 60°F while the unit kept producing 54°F air.

Investigate: Pull the same window at point-level resolution in TrendView and look at the cool-valve command, SAT, and activeCoolSetpoint together. If this is a single recurring event, suspect a schedule transition; if it occurs daily, suspect control hunting.

TrendView — AHU_3 (SAT criteria): - SAT low limit scorecard - SAT comfort control scorecard - AHU_3 device dashboard

4. Energy Snapshot (7-day)

Average power on the three submetered circuits:

Implied weekly fan electrical: ~4,840 kWh (28.8 kW avg × 168 hr).

The supply-fan average (~25 kW) is consistent with the 168/168 hours of fan-on operation across all four units. There is no evidence of overnight setback on the fans — they ran continuously through the period, which is a candidate for further investigation if the building schedule allows night setback.

5. Recommended Next Steps (priority order)

1. Restore ERW operation on AHU_1 AND AHU_3. Both wheels are completely offline with bypass dampers pinned at 100%. This is the single largest energy waste in the building because both units must condition raw OA continuously. Treat as one work order covering both units. (See finding #2.)
2. AHU_1 economizer recommissioning. Verify high-limit cutoff, restore minimum-OA airflow setpoint, and check damper actuator/end-switch calibration. (See finding #1.)
3. AHU_2 cooling-coil-valve characterization. This is the only AHU not tracking its SAT setpoint (1.9°F average undershoot, 46% of hours below by 3°F+). All three peer AHUs track within 0.5°F, so the SAT reset strategy is fine — the AHU_2 cooling-valve authority/calibration is the localized issue. (See finding #3.)
4. CHWP2 / HWP2 status switch calibration or replacement. Restores reliable lead-lag rollover. (See finding #4.)
5. Site survey of 5 chronic-cool VAVs. Mechanical inspection — particularly the two zones (VAV_1_2_1221T, VAV_2_1_2108) confirmed via DAT data to have no reheat injection. (See finding #5.)
6. AHU_3 4 AM SAT excursion follow-up. Pull point-level data and confirm whether it's a schedule transient or controls hunting. (See finding #6.)

What is working correctly (worth noting): - SAT setpoint reset is active and cycling 55–60°F on all four AHUs in response to zone demand. Three of four AHUs track their setpoint within 0.5°F. The reheat usage observed at perimeter VAVs during occupied hours (56–68% on the top-20 reheat-saturated zones) is the expected design response, not a controls fault.