Web Based BACnet Compatible Controls Applied to Emerging HVAC Technologies Stanley A. Mumma, Ph.D., P.E. Prof. Architectural Engineering Penn State Univ. Park ASHRAE Orlando Seminar 8, February 6, 2005

Presentation Outline Emerging Technologies: EW, DOAS, CRCP, Continual Performance monitoring Practical Application EW Control: 3 regions, w/ frost control CRCP: condensate control Control Logic, (Symp. paper OR ) Some benefits of employing Web Based Ctr’l Some benefits of using BACnet Conclusions and recommendations

DOE Report

The Technologies Integrated 20-70% less OA, DOAS Unit W/ Energy Recovery Cool/Dry Supply Parallel Sen. Radiant Cooling System High Induction Diffuser Building With Sensible and Latent cooling decoupled

Practical Application V3

Practical Application Cont’d

Practical Application Graphic

EW Control Region 1 Region 2 Region 3

CRCP Condensate Control First Stage: keep panel inlet fluid temperature above the space DPT. Second Stage: Use a passive fail safe condensate sensor, with a spring return temperature control valve to isolate CRCP from source of cooling, if condensate sensed. Alt Second Stage, for buildings with movable sash: Monitor the sash position and act as appropriate.

Sash Position Condensation Control

The System Control Logic: Single Zone, or Multi-Zone

Now the Web Based Control Discussion

Web Based Facilitates system monitoring and control from anywhere. We could do it here if we had an internet connection. Access to system and trend logs lead to discoveries and refinements, previously hard to realize. (an example will follow) Can facilitate occupant participation (an example will follow).

An Example Refinement: Winter Supply Air Temperature

Observations EW is operating in the on-off mode Supply air temperature to the space varies from about 35F to 65F. Good that high induction diffusers are used. It only takes about 20 minutes for the space temperature to drop 1F (control set to hold space temperature between 73 and 74F) In some cases the SAT remains at OA temperature for over 3 hours.

What are the Alternatives? Modulate the EW speed to prevent on-off cycling rpm 5  Capacity control in first ~5 rpm

Operating the panel pump in the winter with EW On-off V3

EW on-off w/ & w/o panel pump

Panel Inlet Water Temperature As The EW Cycles On-off.

An Example of Occupant Participation aided by web access

Now the BACnet Compatible Control Discussion

BACnet Advantages, even in this very small project. Enables web access from anyplace with an internet connection. Performance and control available from the campus central computer system. Enables expansion of a full control module to accommodate more inputs/outputs. Impacts the ease and cost of installation. May reduce mislabeled points.

Web Browser Server Router Control Module 24V Power Supply Cond Window t 5 : t 14 t 1, h 1 : t 4, h 4 CO 2 -1 CO 2 -2 FM 1 : FM 5 SF RF EW Ch 1 Ch 2 Panel P D 1 V 1 V 2 V 3 Digital, I Analog, I Chiller FAV Digital, O Analog, O

What If the FAV Had a BACnet Control? Could connect the FAV control to the BACnet MS/TP network. Free 5 input connections and associated wire and installation Free 4 output connections and associated wire and installation. 15% of the input and 40% of the output connections now eliminated.

Web Browser Server Router Control Module 24V Power Supply Cond Window t 5 : t 14 t 1, h 1 : t 4, h 4 CO 2 -1 CO 2 -2 FM 1 : FM 5 SF RF EW Ch 1 Ch 2 Panel P D 1 V 1 V 2 V 3 Digital, I Analog, I Chiller FAV Digital, O Analog, O FAV

What If the Chiller Had a BACnet Control? Could connect the Chiller control to the BACnet MS/TP network. Free 3 input connections and associated wire and installation Free 3 output connections and associated wire and installation. Another 12% of the input and 30% of the output connections eliminated

Web Browser Server Router Control Module 24V Power Supply Cond Window t 5 : t 14 t 1, h 1 : t 4, h 4 CO 2 -1 CO 2 -2 FM 1 : FM 5 SF RF EW Ch 1 Ch 2 Panel P D 1 V 1 V 2 V 3 Digital, I Analog, I Chiller FAV Digital, O Analog, O FAV Ch

What If the Air Flow Measuring Devices were BACnet Enabled? Could connect the 3 Air Flow Measuring Stations to the BACnet MS/TP network. Free 5 input connections and associated wire and installation. Another 19% of the input connections now eliminated. If all 3 changes were implemented, 46% of the input and 70% of the output connections eliminated. And associated wire and installation.

Web Browser Server Router Control Module 24V Power Supply Cond Window t 5 : t 14 t 1, h 1 : t 4, h 4 CO 2 -1 CO 2 -2 FM 1 : FM 5 SF RF EW Ch 1 Ch 2 Panel P D 1 V 1 V 2 V 3 Digital, I Analog, I Chiller FAV Digital, O Analog, O FAV Ch Air FM

Impact On Wire Pulling, Terminating & Expansion Modules!

Conclusions Control of this system employing EW, CRCP, DOAS, and Chiller was successfully achieved. Web accessibility made a complete under- standing of the system performance possible. Web accessibility made control logic revisions easy. BACnet capability has the potential to reduce the installation costs if properly considered at the beginning, or Free up input and output terminals on existing control modules, allowing expansion.