Energy Saving DDC Control Strategies

BACnet

BCU

AH541CH530 ZN521

MP581

VV550

BCU

Operator Interface Level

Unit ControlLevel

Building ControlLevel

LonTalk

SQL Server

Ethernet LAN

DDC Controls Architecture

Energy Saving Control Strategies for VAV Systems

Optimum Start/Stop

Fan Pressure Optimization

Supply Air Temperature Reset

Demand Controlled Ventilation

Optimum Start/Stop

Lowers system run time Increases occupancy comfort

Tracer Summit Optimal Start

Optimum Start/Stop

Fan Pressure Optimization Fan Outlet Static Control (Good) Supply Duct Static Control

(Better) Critical Zone Reset (Best)

ASHRAE 90.1 Prescriptive Path

Fan Outlet Static Control

VAVVAVterminal unitsterminal units

supplysupplyfanfan

static static pressure pressure sensorsensor

sensor locatedat fan outlet

Fan Outlet Static Control

Sample Case

Supply Duct Static Control

VAVVAVterminal unitsterminal units

supplysupplyfanfan

static static pressure pressure

sensorsensor

sensor located2/3 down supply duct

Supply Duct Static Control

Sample Case

Critical Zone Reset

damper damper positionspositions

communicating communicating BASBAS

fan speed fan speed

VAVVAVterminalterminalunitsunits

supplysupplyfanfan

static static pressure pressure sensorsensor

sensor locatedat fan outlet

Critical Zone Reset

Sample Case

Fan Pressure Optimization

controlcontrolmethodmethod airflowairflow

fan staticfan staticpressurepressure

fan inputfan inputpowerpower

% full-load% full-loadpowerpower

full load

fan outlet

supply duct

optimized

part load

24,000 cfm24,000 cfm[11.3 m[11.3 m33/s]/s]

18,000 cfm18,000 cfm[8.5 m[8.5 m33/s]/s]

18,000 cfm18,000 cfm[8.5 m[8.5 m33/s]/s]

18,000 cfm18,000 cfm[8.5 m[8.5 m33/s]/s]

2.7 in. H2.7 in. H22OO[672.5 Pa][672.5 Pa]

2.1 in. H2.1 in. H22OO[523.1 Pa][523.1 Pa]

1.9 in. H1.9 in. H22OO[473.3 Pa][473.3 Pa]

1.5 in. H1.5 in. H22OO[373.6 Pa][373.6 Pa]

22 hp22 hp[16.4 kW][16.4 kW]

13 hp13 hp[9.7 kW][9.7 kW]

12 hp12 hp[8.9 kW][8.9 kW]

9.5 hp9.5 hp[7.1 kW][7.1 kW]

100%100%

60%60%

55%55%

43%43%

Fan Pressure Optimization

airflow

sta

tic p

ressu

re

1000 rpm800 rpm

900 rpm

duct static pressure control

fan-pressure optimization

surge

potential savings

Fan Pressure Optimization Advantages

Reduced supply fan energy Lower sound levels Reduced risk of fan surge

Supply Air Temperature Reset Advantages

Lower compressor and reheat energy

Increased economizing time Disadvantages

May increase fan energy Increased humidity level

Key to success: Combine as a balanced approach

with fan pressure optimization

Basic Control Model ExampleSAT Reset, Pressure Optimization, Opt

Start

Demand-Controlled Ventilation Methods of Ventilation:

Fixed Damper position OA method (min at design) ASHRAE method (min at worst case)

Flow Control Ventilation Reset

Demand-Controlled Ventilation What kind of energy saving should

you expect?

30

40

50

60

70

80

90

100

% HVAC Energy Consumption

Miami Minneapolis Seattle Toronto

Ventilation Control Method Comparison

Fixed Damper

Flow Control

Ventilation Reset

Demand-Controlled Ventilation How do I save more energy?

The right tools CO2 sensors Occupancy sensors TOD schedule

Advantages Ensures compliance with ASHRAE 62.1 Reduce outside air during low

occupancy Decreases reheat energy LEED EQ Credit 1: Outdoor Air delivery

monitoring

LEED Credit Possibilities EA Prereq 1 – Commissioning EA Prereq 2 – Minimum Energy

performance EQ Prereq 1 – Minimum IAQ performance EA Credit 1 – Optimize Energy Performance

through energy simulation EQ Credit 1 – Outdoor air delivery

monitoring EQ Credit 2 – Increased Ventilation EQ Credit 6.2 – Controllability of systems:

Thermal Comfort EQ Credit 7.1 – Thermal Comfort: Design

Chiller Plant Optimization

Chilled Water Reset Increasing chilled water temp to

reduce compressor energy Increases pumping energy

Plant optimization Weighing the energy use of CT vs.

Chiller vs. Pumps COP Weight

Chiller Plant Optimization

Modeled Example

Energy Management

“Intelligent Building”

Building Dashboards

Demand Control

Energy Management

Energy Management

Retro-Commissioning

The Easiest Energy Saver

Building Operators Changes

How To Stay On Top Of This

Constant Reporting

Thank You!References:Trane Engineering Newsletters

http://www.trane.com/Commercial/DNA/View.aspx?i=5

Intelligent Buildings Roadmap (CABA)

http://www.caba.org/trm

BuildingLogiX Images

http://www.buildinglogix.net/ecorate

http://energy.buildinglogix.net/blxenergy/index.html