Use of Operational Data for
diagnosing symptoms and
optimizing HVAC operation at
Zero cost
Presented by: Hemant Mehta, P.E.
March 30, 2010
HVAC SYSTEM
HVAC
MEDIUM
WATER/STEAM
USES
HEATING
AIR
COOLING
Components of HVAC
• 3 components
• Generation
• Distribution
• Utilization
• This presentation deals with how to
optimize all components of HVAC
system at zero cost.
Do you know your annual costs per
square foot?
• You cannot manage without
measurement.
• What is your annual fuel and power cost per
square feet?
• If you have A research campus in North East,
your annual cost for fuel and power should not
be more than 6/square foot
• For a commercial property the cost should be
less than $4/square foot
Do you know your annual costs per
square feet?
• Actual annual costs of a research center (2009)
•
•
•
•
Gas
$3,390,916
Electric
$4,086,465
Total Charges
$7,477,381
Gross Square Feet
1,491,418
• Cost/SQFT
• Cost / MMBTU
$5.014
$11.193
Let your fingers do the savings
• Once you know your cost per square foot, try to subdivide
these costs for heating, cooling and power
• Electrical and cooling
costs are around 75% to
80% of your annual
costs.
• If heating cost is more
than benchmark of say
20% to 25% then
something is wrong
Heating:
20% - 25%
Cooling:
35% - 40%
Electric:
35% - 40%
We are all in energy business
Please tell me what is wrong with the
next slide
Case: Air flow through AHU
How energy is wasted??
OAT: 45
Temp Set: 56
Actual
Temp: 58
Mixed Air
Temp: 54
Valve leak, Pre
heat temp: 59
Overheating of air
Cooling Valve: 42%
open to cool air to
set temp.
Read your logs -Temperatures
• What is your short temperature difference?
• The chillers installed during the past 10 years are
designed for less than 2 degree difference between
refrigerant temperature and water temperatures.
• More than 2 degree differential indicates inefficiencies.
– Possible causes…
 Inadequate refrigerant
 Foul tubes
 Inadequate flow
Evaporator approach
• The temperature
difference between the
leaving chilled water
and the refrigerant
temperature
• Nominal: 2 deg F
• Questionable: 4 deg F
• Bad: 6 deg F or higher
Condenser approach
• The temperature
difference between the
leaving cooling water and
liquid refrigerant.
• Nominal: 2-3 deg F
• Questionable: 4-5 deg F
• Bad: 6 deg F or higher
Refrigerant Charge & Approach
• Approach increases
when the unit is either
overcharged or
undercharged.
Typical Operating Log
•
Inefficient
evaporator
Evaporator
approach: 47 – 34
= 13ºF. (>>2ºF)
Chilled Water Delta T:
49 – 47 = 2ºF.
Typical Operating Log
•
Efficient
Evaporator
Evaporator
approach: 42 – 41
= 1ºF. (<2ºF)
Condenser
approach: 92.2 –
82.1 = 10.1ºF.
•
Inefficient
Condenser
Read your logs
• What is your condenser water temperature and
flow?
Load
%
100%
90%
80%
kW/Ton
• The chillers are designed for 85 degree temperature for
peak load.
• Many chiller plants are designed for 2 gpm/ton - Trane
Recommendations
Chiller Performance at varying ECWT
• Peak load happens for
1.6
only 200 hours a year.
1.4
Additional cooling tower
1.2
capacity is available for use.
1
• Lower condenser water
0.8
temperatures and/or higher
0.6
flow will improve
0.4
85
83
81
79
77
75
73
71
69
67
efficiency and reduce
Entering Condenser Water Temperature,
operating costs.
deg F
70%
60%
50%
40%
30%
20%
65
Read your logs
• What is your chilled water delta T?
• Poor chilled water Delta T reduces chiller operating
capacity and forces operation of additional equipment.
• Use of additional equipment further reduces operating
efficiencies.
• You may not be able to improve the delta T overnight
• However, you can always increase the flow through
chiller to compensate for low delta T and increase the
chillers operating capacity.
• Always try to operate chillers at 70% or higher loading
Lost Chiller Capacity Due to Poor ΔT
Ideal Design Conditions
150 L/sec
(2,400 gpm)
150 L/sec
(2,400 gpm)
13°C (55.5°F)
55.5°F
No Flow
Through
Decoupler
5°C (41°F)
5°C (41°F)
150 L/sec
(2,400 gpm)
150 L/sec
(2,400 gpm)
Chiller sees a ΔT of 8°C (14.5°F) at a flow of 150 L/sec (2,400 gpm)
The chiller capacity is therefore 5,000 kW (1,450 tons)
Lost Chiller Capacity Due to Poor ΔT
Case 1: Mixing Through Decoupler Line
150 L/sec
(2,400 gpm)
75 L/sec
(1,200 gpm)
9°C (48.25°F)
13°C (55.5°F)
75 L/sec
(1,200 gpm)
at
5°C (41°F)
5°C (41°F)
5°C (41°F)
150 L/sec
(2,400 gpm)
75 L/sec
(1,200 gpm)
Chiller sees a ΔT of 4°C (7.25°F) at a flow of 150 L/sec (2,400 gpm)
The chiller capacity is therefore 2,500 kW (725 tons)
Lost Chiller Capacity Due to Poor ΔT
Case 2: Poor Building Return Temperature
150 L/sec
(2,400 gpm)
150 L/sec
(2,400 gpm)
9°C (48.25°F)
9°C (48.25°F)
No Flow
Through
Decoupler
5°C (41°F)
5°C (41°F)
150 L/sec
(2,400 gpm)
150 L/sec
(2,400 gpm)
Chiller sees a ΔT of 4°C (7.25°F) at a flow of 150 L/sec (2,400 gpm)
The chiller capacity is therefore 2,500 kW (725 tons)
Small Loss in ΔT Rapidly Reduces
Chiller Capacity
At a design ΔT of 14.4°F:
Chiller Capacity
100%
Chiller capacity
80%
60%
40%
20%
0%
14.5
13
11.5
10
Delta T, deg F
8.5
7
How do you improve delta T?
• Controlling the chilled water flow through the
chillers
• Use of new control technology at AHUs.
Control Logic
• Master Control
Maintain HX water supply temperature or steam
pressure by modulating HTHW water control valve.
• Sub Master Control
Maintain HTHW return temperature and float HX
water supply temperature or steam pressure. The
amount of float depends on requirements at users. i.e.
animal room vs. class room vs. office space.
Control Modification
Existing control: Maintain water
supply temperature from heat
exchanger
Additional control: Maintain
HTHW return temperature
Maintain Range
Controller
eg: 180 - 185ºF
New York Presbyterian Hospital
• Applied revolutionary control logic
Log Data
~ 20F
T
PA State Capitol Complex – CHW ΔT
Field Implemented Improve CHW
Operation: Wyeth Bio-TEch
• Original design for 1 primary pump per chiller
• Actual operation: standby pump operating at all times
• Operating more pumps increases the flow through the
chillers decreasing delta T and chiller performance.
• Flow reduction by 1/3 increased delta T and chiller
efficiency.
• The increased efficiency allows the chiller to consume less
energy and the increased capacity allows less chillers to
run saving more energy.
Field Implemented Improve CHW
Operation: Wyeth Bio-Tech
Chiller 3 completely
used duringshut
peakdown, Chiller 1
efficiency increased, Chiller 2 operating
hours decreased after modification
Valve “OPEN”
Valves “OPEN”
“CLOSED”
After Modification
Existing Pumps “ON”
What is the cost for this
?? Nothing
Pump “OFF” After
Modification
Existing Pump “OFF”
What is the annual savings
after
modification??$190,000
Read your logs
• What is your chilled water pump pressure drop?
Benchmark Pressure Drop
Chiller
Plant:
45 ft.
Distribution:
50-80 ft.
Building:
45-55 ft.
– Total pumping head during peak load should not be more than 180 feet
to 200 feet.
– Higher pressure drop than bench mark indicates additional resistance
Balancing is the biggest crime in a dynamic hydronic system
Biotech Firm – Action Taken
Plant B
120 psi
(Discharge
)
21 psi
(Suction)
Biotech Firm – Action Taken
Plant B
• Found a bottleneck in the system.
AMGEN From Client
HP
Voltage
Kw
Description
Hours per
Year
100
480
74.6
B29 P-01
8760
653,496
0.12
0.85
$
92,258
100
480
74.6
B29 P-02
8760
653,496
0.12
0.85
$
92,258
100
480
74.6
B29 P-03
8760
653,496
0.12
0.85
$
92,258
40
480
29.84
B25 P-01
8760
261,398
0.12
0.85
$
36,903
40
480
29.84
B25 P-02
8760
261,398
0.12
0.85
$
36,903
40
480
29.84
B25 P-03
8760
130,699
0.12
0.85
$
18,452
150
480
111.9
B30 P-5251
8760
980,244
0.12
0.835
$
140,873
150
480
111.9
B30 P-5252
8760
980,244
0.12
0.835
$
140,873
150
480
111.9
B30 P-5253
8760
490,122
0.12
0.835
$
70,437
B38
30
480
22.38
B38-08-P1
8760
98,024
0.12
0.85
$
13,839
30
480
22.38
B38-08-P2
8760
98,024
0.12
0.85
$
13,839
B27
20
480
14.92
B27-01
8760
130,699
0.12
0.85
$
18,452
20
480
14.92
B27-02
8760
130,699
0.12
0.85
$
18,452
B14
50
480
37.3
B14-CW-P0001
8760
326,748
0.12
0.83
$
47,241
50
480
37.3
B14-CW-P0002
8760
326,748
0.12
0.83
$
47,241
B15
60
480
44.76
B15 -P001
8760
392,098
0.12
0.85
$
55,355
60
480
44.76
B15 -P002
8760
392,098
0.12
0.85
$
55,355
B33
7.5
480
5.60
B33 -P01
8760
49,012
0.12
0.83
$
7,086
7.5
480
5.60
B33 -P02
8760
49,012
0.12
0.83
$
7,086
40
480
29.84
B32-P001
8760
261,398
0.12
0.902
$
34,776
40
480
29.84
B32-P002
8760
261,398
0.12
0.902
$
34,776
40
480
29.84
B32-P003
8760
261,398
0.12
0.902
$
34,776
Location
B29
B25
B30
B32
Total
1,325
KwH per Year Price per KwH
7,841,952
Annual
Savings
Power Factor
$
1,109,488
Boilers
• Stack Temperature
− Stack temperature for boilers should commonly lie in
range of 300 – 350 ºF
− A high stack temperature may suggest the building up of
soot or scale inhibiting the heat transfer or the rupture in a
refractory baffle wall.
Zero Cost: $176,000 a year savings
From: Paul Schwabacher [mailto:pschwaba@nyp.org]
Sent: Monday, July 15, 2002 4:39 PM
To: hmehta@wmgroupeng.com; Santo Saglimbeni; martray@nyp.org; Michael
Shallo; Joseph R. Castellano
Subject: Re: Economizer is working.
Thanks everyone, this is great news. 3.2% improvement x $5.5 million annual gas
expense will save $176,000 a year. Not bad for closing a damper.
Ray: Please keep damper manually closed at all times and monitor flue gas
temperature. We should only be using boilers that have functioning economizer -other boilers should be for stand-by only.
Mehta: is there any risk of sulfur or acid condensing when burning gas?
Joe & Mike: Please track list of energy conservation measures completed and
planned w/estimated savings.
HVAC – Case Study
• Steam trap survey along
with a regularly scheduled
testing schedule during
2007 retro-cx
• Location: The Vanguard
Chelsea
• High Rise Residential
Building survey of only
common area steam traps
in the basement resulted
in annual energy savings
of approx.$11,000 with
payback period of 4
months.
HVAC – Case Study
• During 2007 Retro-cx
• Location: The Vanguard
Chelsea
• Installing variable
frequency drive on cooling
tower that was previously
a constant speed fan
resulted in annual savings
of $22,000 with a payback
period of 6 months
HVAC – Case Study
• Resetting domestic
hot water set point
from 135 F to 120 F
• Location: The
Vanguard Chelsea
• Results: Annual
Energy Cost Savings
of $10,000 with no
implementation cost,
done by in-house
staff.
HVAC Practical Examples
• Installation of Carbon
Monoxide Sensor for
operation of indoor
garage exhaust
• Location: Dish
Network Satellite
office
• Results: Annual
Energy Savings of
$2,500 and payback
period of 1 months
HVAC – Case Study
• Replacing faulty sensor on
rooftop unit that was
preventing unit from
operating economizer
mode during 2009 retro-cx
– outside air dampers were
fully open all the time.
• Location: Fordham
University
• Results: Annual Energy
Cost Savings of $37,600
with payback period of 1
month
HVAC – Case Study
• Conversion of dual
duct air system to
variable air volume
system, per air
handler, during 2009
retro-cx
• Location: Fordham
University
• Results: Annual
Energy Cost Savings
of $20,000 to $80,000
with average paypack
period of 4 ½ years
HVAC – Case Study
• Installation of demand
control ventilation
system on air
handlers
• Location: Fordham
University
• Results: Annual
Energy Cost Savings
of $135,000 with
average payback
payback of 4 ½ years
HVAC – Case Study
• Increasing chilled water
set point from 42 F to 45 F
to match chilled water coil
design inlet temperatures
on air handlers
• Location: Fordham
University
• Results: Annual Energy
Cost Savings of $9,000
with no implementation
cost, done by in-house
staff
HVAC – Case Study
• Replacing chilled
water valves that were
leaking by – in two
campus buildings
during retro-cx 2009
• Location: Fordham
University
• Results: Annual
Energy Cost Savings
of $41,000 with
paypack period of 2
months
HVAC – Case Study
• Temperature
calibration of faulty
thermostat on fan coil
units
• Location: Fordham
University
• Results: Annual
Energy Cost Savings
of $11,500 with
paypack period of 2 ½
months
HVAC – Case Study
• Implementation of
outside air / hot water
reset schedule on
existing building
management system
• Location: Fordham
University
• Results: Annual
Energy Cost Savings
of $92,000 with
payback period of 3
months
Summary
• You as a facility manager are too busy to take care
the needs of your bean counters
• You must empower your plant operators.
• It is not difficult to change their culture by teaching.
• This will only make them proud of their work.
• Hire an expert if you have to.
• Teach them to read what they record on logs.
• As engineers we can really make a difference
• Go bust energy and make our planet better for our
kids
Thank You
Hemant Mehta, P.E.
President
WMGroup Engineers, P.C.
(646) 827-6400
hmehta@wmgroupeng.com
www.wmgroupeng.com