ASHRAE 90.1-2019, Table 6.5.1.1.3

ASHRAE 90.1-2019, Section 6.5.3.2.2

ASHRAE 90.1 requires static pressure reset for VAV systems with DDC. A fixed setpoint wastes fan energy during part-load conditions. The setpoint should reset down based on zone damper positions — when all dampers are less than 90% open, the static pressure setpoint should decrease. ASHRAE Guideline 36 specifies Trim and Respond reset logic for static pressure.

ASHRAE 90.1-2019, Section 6.5.4.4 (temperature reset) / Section 6.5.4.2 (variable-flow DP reset) / Guideline 36

This chiller plant sequence fails ASHRAE 90.1-2019 Section 6.5.4.4 (Chilled- and Hot-Water Temperature Reset Controls), which requires chilled water supply temperature reset for systems with DDC controls. A fixed 44 degrees F supply temperature forces the chillers to work harder than necessary during mild weather and part-load conditions — wasting significant energy (roughly 1-2% per degree F of potential reset). Additionally, the fixed differential pressure setpoint on the variable-flow pumps violates Section 6.5.4.2 (Hydronic Variable Flow Systems), which requires the DP setpoint on DDC variable-flow pumps to be reset downward based on valve positions. Best practice per ASHRAE Guideline 36 likewise resets DP based on the most-open control valve position, reducing pump speed when full design pressure is not needed. Both reset strategies — supply water temperature and differential pressure — are essential for energy code compliance and efficient chiller plant operation.

ASHRAE 90.1-2019, Section 6.5.4.4 / Guideline 36

This is a proper implementation of chilled water supply temperature reset per ASHRAE 90.1-2019 Section 6.5.4.4 (Chilled- and Hot-Water Temperature Reset Controls) and Guideline 36 Trim and Respond logic. Raising chilled water temperature when loads are low improves chiller efficiency significantly — roughly 1-2% per degree F of reset. The valve position-based reset ensures cooling capacity is available when needed.

ASHRAE 90.4 / TIA-942

Branch circuit monitoring is required for capacity planning and to detect load imbalances. ASHRAE 90.4 mandates metering of electrical distribution in data centers, and most Tier III+ designs require per-circuit monitoring.

ASHRAE Fundamentals Handbook — Hydronic System Design

The decoupler (common) pipe connections must be spaced at least 4 to 6 pipe diameters apart so primary and secondary loops are genuinely hydraulically decoupled; at 2 diameters the two loops interact and flow in the common pipe no longer reflects the true surplus or deficit. Note what is NOT the defect here: the absence of isolation valves on the decoupler is CORRECT as installed — valving the common pipe would defeat decoupling entirely.

ASHRAE Guideline 13 — Alarm Management

Alarms must be prioritized based on severity. A freeze stat alarm (life-safety) should be higher priority than a dirty filter alarm (maintenance). Without prioritization, critical alarms get lost in nuisance alarms, a condition called 'alarm flooding'.