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.
4640 South 59th Street | Omaha, NE 68117 402.502.2340 | bes-tech.net
HOW THE DIGI-RTU WORKS
4640 South 59th Street | Omaha, NE 68117 402.502.2340 | bes-tech.net
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
4640 South 59th Street | Omaha, NE 68117 402.502.2340 | bes-tech.net
- 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 & Diagnostics (FDD)
DIGI-RTU ROOFTOP ADVANCED CONTROLS
DIGI-RTU ENERGY PERFORMANCE: EER
Improve RTU seasonal performance over 30%
4640 South 59th Street | Omaha, NE 68117 402.502.2340 | bes-tech.net
With Digi-RTU
Without Digi-RTU
MAIN APPLICATIONS
4640 South 59th Street | Omaha, NE 68117 402.502.2340 | bes-tech.net
– Package rooftop units, water and air source heat-pumps, split units
– HVAC rooftop units between 3 to 30-ton
– Up to four cooling stages
– Up to two heating stages
– Scroll compressors & reciprocating compressors
– All original equipment rooftop units
– Thermostat and BAS interfaces
DIGI-RTU ADVANCED CONTROLS FUNCTION
4640 South 59th Street | Omaha, NE 68117 402.502.2340 | bes-tech.net
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 - VAF
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
4640 South 59th Street | Omaha, NE 68117 402.502.2340 | bes-tech.net
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.
DIGI-RTU ADVANCED CONTROLS FUNCTION
kW Reductions Are Not Achieved by Adjusting Up Space Set-Points
4640 South 59th Street | Omaha, NE 68117 402.502.2340 | bes-tech.net
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
continued communication, data collection,
and visibility with existing building strategies
existing BMS &
database server
existing IP T-stat
& database server
router/
modem
e.mail alert
TXT alert
FAULT DETECTION & DIAGNOSTICS (FDD)
DIGI-RTU ADVANCED CONTROLS FUNCTION
4640 South 59th Street | Omaha, NE 68117 402.502.2340 | bes-tech.net
DIGI-RTU ADVANCED CONTROLS FUNCTION
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 - VRF
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
BENEFITS OF USING A DIGI-RTU
4640 South 59th Street | Omaha, NE 68117 402.502.2340 | bes-tech.net
– 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; equipment loan/lease or
performance contract
OMAHA, NE
DIGI-RTU CASE STUDY –
PHARMACEUTICAL DISTRIBUTION CENTER
4640 South 59th Street | Omaha, NE 68117 402.502.2340 | bes-tech.net
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 –
PHARMACEUTICAL DISTRIBUTION CENTER
4640 South 59th Street | Omaha, NE 68117 402.502.2340 | bes-tech.net
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
4640 South 59th Street | Omaha, NE 68117 402.502.2340 | bes-tech.net
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
4640 South 59th Street | Omaha, NE 68117 402.502.2340 | bes-tech.net
February - March 2014
71% kWh
decrease
Pre blue line Post red line
Daily Electrical Energy Consumption; Pre (blue ) and Post (red ) vs. Ambient Temperature
SAN ANTONIO TX
4640 South 59th Street | Omaha, NE 68117 402.502.2340 | bes-tech.net
SEPTEMBER – OCTOBER 2012
BOX RETAIL
4640 South 59th Street | Omaha, NE 68117 402.502.2340 | bes-tech.net
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
4640 South 59th Street | Omaha, NE 68117 402.502.2340 | bes-tech.net
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
4640 South 59th Street | Omaha, NE 68117 402.502.2340 | bes-tech.net
- 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
4640 South 59th Street | Omaha, NE 68117 402.502.2340 | bes-tech.net
- 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
4640 South 59th Street | Omaha, NE 68117 402.502.2340 | bes-tech.net
Bes-Tech, Inc. 402.502.2340
www.BES-TECH.NET
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