Digi-RTU® Digi-RTU is a Heating, Ventilation, and Air Conditioning ... from 50-100%, thereby...

Digi-RTU®

WHAT IS THE DIGI-RTU®

4640 South 59th Street | Omaha, NE 68117 402.502.2340 | bes-tech.net

The Digi-RTU is a Heating, Ventilation, and Air

Conditioning (HVAC) rooftop unit control kit that

is both a demand management and energy usage

device. It is designed to improve the energy

efficiency and demand requirements of a rooftop

unit as well as solve the humidity, common

noise, and frequent on/off issues of a rooftop

unit through modulating the capacity of a rooftop

unit to match the cooling or heating space

requirements.

DIGI-RTU

PERFORMANCE RECOGNITION

American Public Power Association’s

2011 DEED Energy Innovator Award.


HOW THE DIGI-RTU WORKS


By intercepting heating

and cooling calls, the

Digi-RTU’s patented

technology manages the

compressor and fan

speeds to match the

space requirements.

As a result space

temperature and humidity

are best managed. Digi-RTU Kit 4-5 hour install time

DIGI-RTU ENERGY PERFORMANCE: EER

Improve RTU seasonal performance over 30%


With Digi-RTU

Without Digi-RTU


- Integrates air-side economizers

- Controls supply fan speed (VAF)

- Controls Compressor capacity (VRF)

- Manages Demand-Controlled Ventilation, CO2

- Demand Response signal enabled (DR)

- Fault Detection & Diagnostic (FDD)

- Remote Monitoring & Control

DIGI-RTU ROOFTOP ADVANCED CONTROLS

MAIN APPLICATIONS


– Package rooftop units, water and air source heat-pumps, split units

– HVAC rooftop units between 3 to 50-ton

– Up to four cooling stages

– Up to two heating stages

– Scroll compressors & reciprocating compressors

– All original equipment rooftop units

– Thermostat and BMS interfaces

DIGI-RTU ADVANCED CONTROLS FUNCTION


Modulating mechanical HVAC equipment matches space operating

requirements and is an accepted industry standard

Modulating fan and compressor is the energy efficiency strategy for rooftop

units in all climate zones

Economizer Integration

Integration and management of the existing economizer

Extends existing economizer range by 30%

Fan Speed Control - VAV

ON mode - average fan savings are greater than 85%

AUTO mode - average fan savings are 70 – 80%

Demand Controlled Ventilation, CO2

CO2 sensor in the return-air duct integrated with the economizer meets

ASHRAE 62.1 and CA Title 24 IAQ


Demand Response

Digi-RTU responds to all space heating /cooling calls according to establish

set-points

Prior notice of a Demand Event, the Digi-RTU can “pre-cool” the space and

then maintain established space temperature per set-points of the BMS

A Load-Limit factor for the rooftop unit is sent

through the BAS to the Digi-RTU, and can range

from 50-100%, thereby limiting the speed of the

rooftop unit.


kW Reductions Are Not Achieved by Adjusting Up Space Set-Points


FAULT DETECTION & DIAGNOSTICS (FDD) continued communication, data collection,

and visibility with existing building strategies

existing BMS &

database server

IP T-stat

Building Gateway

3rd Party

Monitoring

Monitoring & Alerts

• Insufficient evaporator air-flow

• Condenser coil fouling

• Low/high refrigerant charge

• Compressor valve leakage

• Liquid line restrictions

• Economizer damper failure

• Sensor failure/degradation

cloud

storage & retrieval


continued communication, data collection,

and visibility with existing building strategies

Building Gateway

REMOTE MONITORING & CONTROL

existing BMS &

database server

Building Gateway

3rd Party

Monitoring

Remote Monitoring & Control

• kWh consumption

• kW

• Temperature and Set-point

• VFD speed

• Damper position

• Space CO2 level

• Any time measurement periods

• HVAC unit OFF



Existing Building EE Strategies, Platform & Equipment

Communicates with existing BAS platforms and existing installed

thermostats; programmable, IP etc.

Integrates with the original equipment HVAC controller

Mounts inside the HVAC rooftop unit

Compressor Optimization - VRV

Conforms to original equipment manufacturer recommendations for

speed reduction down to 45Hz

Programmed logic provides soft start & stop of the compressor

Compressor modulation savings are double fan power savings for a

significant portions of the climate zones

Peak Demand savings of 4 – 5kW for an average 10-ton rooftop


• Equipment loan/lease

• Performance contract – shared savings

• “HVAC as a Service” equipment and service financing

• On-bill financing

DIGI-RTU – 3RD PARTY FINANCING

BENEFITS OF USING A DIGI-RTU


– Sustainable reduction in electricity and therm consumption

– Reduces peak demand and associated peak demand charges

– Integrates with existing space temperature management devices

– Better maintains space humidity and temperature decreasing

comfort complaints

– Reduces compressor cycling up to 75%, reducing maintenance

costs

– Reduces HVAC equipment noise in occupied space

– Applicable kW, kWh, Demand Response, Fault Detection and

VFD utility incentive programs

– Available financing options

OMAHA, NE

DIGI-RTU CASE STUDY –

DISTRIBUTION CENTER


71% kW

decrease

-20

0

20

40

60

80

100

0

10

20

30

40

50

60

70

80

90

100

9/18 10/18 11/17 12/17 1/16 2/15 3/17 4/16 5/16

OA

T (

F)

Po

we

r (k

W)

Date

Without Digi-RTU With Digi-RTU OAT

Measured Power Consumption and Ambient Temperature

Measured RTU Power

Pre - blue

Post - red

Ambient temperature

5-minute intervals

DIGI-RTU CASE STUDY –

DISTRIBUTION CENTER


85% kWh

decrease

Measured RTU Power

Pre blue

Post red

5-minute intervals 0

10

20

30

40

50

60

70

80

90

100

30 40 50 60 70 80 90

Po

wer

(kW

)

OAT

Without Digi-RTU With Digi-RTU

Comparison of Measured Power Consumption with and without Digi-RTU

SAN DIEGO

DIGI-RTU CASE STUDY – OFFICE SPACE


February - March 2014

43% kW decrease

Measured RTU Power for One Minute Interval

Pre blue line Post green line Ambient temperature red line

DIGI-RTU CASE STUDY – OFFICE SPACE


February - March 2014

71% kWh

decrease

Pre blue line Post green line

Daily Electrical Energy Consumption; Pre (blue ) and Post (red ) vs. Ambient Temperature

SAN ANTONIO TX


SEPTEMBER – OCTOBER 2012

BOX RETAIL


Two weeks with and

two weeks without

29.5% kW

decrease

0

10

20

30

40

50

60

70

80

90

100

0

1

2

3

4

5

6

7

8

8/2

78

/28

8/2

98

/30

8/3

19

/19

/29

/39

/49

/59

/69

/79

/89

/99

/10

9/1

19

/12

9/1

39

/14

9/1

59

/16

9/1

79

/18

9/1

99

/20

9/2

19

/22

9/2

39

/24

9/2

59

/26

9/2

79

/28

9/2

99

/30

10

/11

0/2

10

/31

0/4

10

/51

0/6

10

/7

OA

T, D

eg

F

kW

Before

After

AVG-OAT

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

kWh

9/23/12 (OAT = 78 F; weekend; after install)

9/26/12 (OAT = 80 F; weekday; after install)

9/9/12 (OAT =79 F; weenkend; before install)

9/11/12 (OAT = 79 F; weekday; before install)

DIGI-RTU INSTALL ASHRAE #2

BIG BOX RETAIL


Two days with and

two days without

74% kWh

reduction

VERMONT

BURLINGTON ELECTRIC – STUDY Office Building

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

9,000

kWh

Metered Savings = 65%

W/O Digi-RTU

With Digi-RTU

65% kWh reduction


- Equipment sub-metered

- Two weeks pre

- Two weeks post

- IPMVP

0

20

40

60

80

100

4-Aug 9-Aug 14-Aug 19-Aug 24-Aug 29-Aug 3-Sep 8-Sep

Avg

. O

AT

Date

Without Optimizer With Optimizer

*Efficiency Vermont press release

EFFICIENCY VERMONT - STUDY Distribution Center

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

kWh

Metered Savings = 68%

W/O Digi-RTU

With Digi-RTU

68% kWh reduction


- Equipment sub-metered

- Two weeks pre

- Two weeks post

- IPMVP

0

10

20

30

40

50

60

70

80

20

-Se

p

22

-Se

p

24

-Se

p

26

-Se

p

28

-Se

p

30

-Se

p

2-O

ct

4-O

ct

6-O

ct

8-O

ct

10

-Oct

12

-Oct

14

-Oct

16

-Oct

18

-Oct

Avg

. O

AT

Without Optimizer With Optimizer

*Efficiency Vermont press release

Date post:	06-Apr-2018
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