ASHRAE 135-2016

ASHRAE 135 (BACnet) — Clause 9, MS/TP MAC addressing

MS/TP reserves MAC 255 for broadcast and 128-254 for slave devices; 127 is the very top of the master range. Parking a field controller at 127 forces max_master to its ceiling, so every token rotation polls the entire 0-127 address space looking for masters that aren't there — network performance craters. Keep field controllers in a contiguous low range and set max_master just above the highest used address.

ASHRAE 135 (BACnet) — MS/TP Physical Layer

BACnet MS/TP requires a daisy-chain (bus) topology, not star topology. Star wiring creates signal reflections and communication failures. Each device must connect in series on the bus.

ASHRAE 135 (BACnet) — Object Types

Connecting a 0-10VDC analog output signal to a binary (digital) input terminal will not control the device properly. Binary inputs only read on/off states. Analog signals must connect to analog input terminals for proportional control.

ASHRAE 135-2016 / Crestline BAS Specification

Crestline specifications require all building automation systems to comply with ASHRAE Standard 135-2016 (BACnet). Proprietary, closed-protocol systems lock the owner into a single vendor and prevent competitive service and integration. Open-protocol BACnet is mandatory for all new installations.

ASHRAE 170 Table 7-1

This installation meets ASHRAE 170 Table 7-1 requirements for operating rooms. The standard requires a minimum of 20 total ACH with at least 4 ACH of outdoor air. The positive pressure relationship to corridors prevents unfiltered corridor air from entering the sterile environment. HEPA filtration and laminar flow delivery over the surgical table are best practices aligned with FGI Guidelines Section 2.1-3.2 for reducing surgical site infection risk. All specified parameters are at or above the minimum code requirements.

ASHRAE 170 Table 7-1 / FGI Guidelines

This passes all code requirements. ASHRAE 170 Table 7-1 specifies an OR temperature range of 68-75°F and a relative humidity range of 20-60%. The facility's 72°F and 45% RH are well within both ranges. The visible display allows the surgical team to verify conditions during procedures. The alarm capability ensures staff are notified if conditions drift out of range. The dedicated AHU with cooling, reheat, and humidification provides the three-stage control needed to simultaneously manage temperature and humidity — essential because cooling the air also removes moisture, requiring separate reheat and humidification stages.