Session E4: Energy Audi1ng
Energy Audits In Ac1on Lonnie Russell, CEM
Energy Audits in Ac/on by EnergyMan LLC
Plan of A8ack
The goal is to try to make the biggest impact possible with little or no
investment. Start with the largest
electrical loads and gas users.
Includes HVAC and hot water
50%
30%
20%
Building Energy Usage: Non Industrial Environmental Control Ligh1ng Other
Important Question: Why is this operating with no one here? Must do some of audit during non-occupied times
These items were found on 24/7 during non-occupied times. Programmable thermostat in override and set to
68F in the summer
Boiler
10 Air handlers with a combined horsepower of 68.5
This is equipment in the cabana; only used
seasonally, but it was all on; 3 refrigerators were empty and on, stove had it’s pilot light on and hot water heater was not turned off.
The auditorium is a very large space to leave the HVAC system running when the room is not in use
Computer monitors leS on
The current IT PC policy is not helping with PC power consump/on, as can be observed by the
hundreds of PC’s that are leS on 24/7.
At an absolute minimum, the monitors should be set to to go to standby. Leaving these all on puts a heavy load on the HVAC
system, which may not have been originally designed for this large a load.
8 cents / kWh 11 cents / kWh1 kW $611 $96410 kW $7,008 $9,63625 kW $17,520 $24,09050 kW $35,040 $48,1801 Hp $680 $93410 Hp $6,796 $9,34425 Hp $16,989 $23,36050 Hp $33,978 $46,720
Cost per YearMotor Size
Ini/al motor cost is only about 5% of the total lifecycle cost, so always buy an efficient motor!
Chiller and associated equipment
Cooling Towers
Why does equipment not get turned off?: • Lack of control of building during off hours, especially in buildings with mul/ple users • System was set up that way from the beginning and no one on site knows how to correct it. • It has always been that way so no one no/ces. • We tried that once but…. • You can’t turn that off. It may not turn back on (my personal favorite).
This is not limited to smaller
facilities. Here are some sizable loads at a large
facility.
Chiller Primary and Secondary pumps
Cooling Tower Pumps
Now that the schedule is op/mized how do we make our HVAC system more efficient? • Tighten up the building and ductwork • Control the outside air (preferably with demand controlled
ven1la1on) and Economize, if possible • Install VFD’s where possible • Ligh1ng • Energy efficiency products • Minimize, or eliminate reheat • Op1mize the set points (room temp, chill water, hot water, non-‐
occupied, occupied etc…) • ASHRAE states that 80% of all occupants will be comfortable at temperatures of 68F to 74F in the winter and 73F-‐78F in the summer at no > 60% RH.
SCGSAH 1st year Results (opera/onal changes only!) Electricity Usage
100,000150,000200,000250,000300,000350,000
Dec Jan Feb Mar Apr May Jun Jul
Time
KW
H
20082009
Natural Gas Usage
1,000
6,000
11,000
16,000
Dec Jan Feb Mar Apr May Jun Jul
Time
Ther
ms
20082009
YTD Electricity Cost
0
50000
100000
150000
2008 2009
Time
Dol
lars
YTD
YTD Natural Gas Cost
0
50000
100000
150000
2008 2009
Time
Dolla
rs
YTD
Reduc/on of 60.4%
Reduc/on of 51.7%
Reduc/on of 28.6%
Reduc/on of 18.4%
Building Envelope Improvement This building had many major air leaks that needed to be addressed. Major leaks included:
• Exhaust fans with no dampers so they would be wide open when not running
• Overhead doors with no seals • Bathroom exhaust fans that never shut off
• Large gaps around fan shrouds
• Large louvers that were open to the outside
BackdraS Damper Installa/ons Open Exhaust Duct
Air infiltration repair (Overhead doors)
Before Before (sunlight leaking in) ASer
Curtain for frequently used door
Brush seal
Brush Seal
Missing InsulationFaulty Duct Insulation
Open Roof Access
Building Envelope and Leaky ductwork examples
OA damper stuck open
Ductwork insulation in bad shape
No floor insulation in crawl space
Negative Pressure from Bathroom Exhaust Fans Bathroom Exhaust fans were on 24/7. When HVAC equipment was shut down, these fans
exhausted 2000 cfm and pulled air in from outside causing humidity to rise at night.
Fan switches were hidden and always leS on
Sensors were installed to automate the bathroom exhaust fans so they would run for 15 minutes when the bathroom became
unoccupied and then shut off.
Outside air control opportuni/es Some places, such as churches and auditoriums, have high outside air requirements
because of the per person ASRAE ven/la/on requirements. This is partly to prevent the “sick building syndrome” issues that occurred when buildings did not ven/late
adequately in the past.
Sanctuary Outside Air Intake
Using CO2 monitoring, and controlling the outside air intake based on that, allows for proper outside air intake. Otherwise, you could be bringing in the outside air requirement for
hundreds of people no ma8er how small the occupancy is. This technique is called “demand controlled ven/la/on”. The price to do this type of control has dropped substan/ally in the last few years, with CO2 sensors now barely over $100.00 and damper controllers for about
the same.
Demand Controlled Ven/la/on
AHUs were initially set at 10% - 15% OA damper open at all times. Especially in the hot humid summers of South Carolina, this can unnecessarily load the
system. CO2 sensors were installed and set to open the OA dampers if CO2 levels rise to levels > 1000 ppm.
Outside Air Dampers
Economizer possible for 2309 to 3961 hours. High bays maybe an addi/onal 1000 hours.
Make outside air your friend! Economize (frequently called free cooling) for your winter heat loads. Able to shut down all but the air moving parts of the HVAC
systems (chillers, pumps, compressors etc…).
Outside air damper can only be open or closed: cannot be modulated.
Installed Modulator
Return air had no damper, therefore
ra/o of return versus outside air cannot be
controlled.
Installed Modula/ng Damper
Equipment Modifica/ons/Requirements to Economize
HVAC systems are generally built for the 10 hoYest and 10 coolest days of the year. There is generally overcapacity for all other condi[ons. VFD’s offer the ability to match the system to
the load, offering tremendous energy savings and extending equipment life.
A 50% reduction in flow actually reduces horsepower requirements by 87.5%
Advantages of a Variable Frequency Drives (VFD’s)
Pumping power is wasted (valves are par/ally closed) making the pumps good VFD (variable frequency drive) candidates. The pumps (2) also run con/nuously.
Variable Frequency Drive HVAC Applica/ons
40 Hp high bay air handler. 30 Hp high bay air handler. Cooling Tower Pump VFD: Since the small chiller only needs 900 gpm and the
exis/ng pump supplies 2000 gpm, a VFD was far more efficient than a thro8le
valve (see previous slide).
AHU’s: Original owner of Bldg. needed 100% OA for the manufacturing space. New owner did not need that so VFDs were used to thro8le these drives down significantly. This also allowed for dehumidifica/on control (by moving the air very slow and lowering the chill water temperature) and reduced load on the chiller and boiler.
Filter
Reheat Reduc/on using variable airflow
Fan Reheat
Coil Cooling
Coil
RA damper
OA damper
Fast Airflow
Air Temp
Fan Reheat
Coil Cooling
Coil
RA damper
OA damper
Slow Airflow
Air Temp
Air Temp
Filter
Original Line-up (simplified with no exhaust): Air moved at max CFM across the cooling coil that had 42F chilled water going through it. This dropped the temperature. This colder air was then passed across a reheat coil that had 180F water going through it. This brought the air to a normal discharge temperature of 55F – 65F.
65F
New De-humidification line-up (simplified with no exhaust): Air moved at min CFM across the cooling coil that had 42F - 47F chilled water going through it. This drops the temperature significantly, condensing more water therefore reducing humidity. The need for reheat is reduced or eliminated. The reduced airflow helps keep the space from getting too cold, but a little reheat may be required if that occurs. As you can see the low discharge air temperature means the supply air duct definitely has to be insulated.
50F
Air Temp
Elimina/ng reheat required the high bay ductwork to be insulated because the discharge air temp would drop and swea/ng could occur. This was an
$18,000 investment with a payback of about 1 month!
Natural gas consump/on has been the largest success of our energy management efforts. Overall Results:
• Dekatherms reduced by 87.8%
• Cost reduced $239,728 for a cost reduc/on of 89.2%
Natural Gas Consumption
0
500
1000
1500
2000
2500
1 2 3 4 5 6 7 8 9 10 11 12
Month
Deka
ther
ms
200620072008
228 CDD
231 CDD
320CDD
Though Nov08 was very cold, with a 28% increase in CDD, gas usage only increased 12.8%
Natural Gas Consump/on Results
• Electronic Timers should be installed on electric water heaters. • Many facili/es have water heaters that are grossly oversized • NG should be used if available (Far less expensive to heat with than electric resistance) • Tankless NG systems are ideal for low or variable occupancy applica/ons • Heat Pump water heaters are good for hot kitchens
Domes/c Hot Water
When water heaters are turned off, their associated recircula/on pumps need to be turned off also. If not, they will cause the piping system to act as a large
radiator, removing heat from the hot water tank, causing the water heater to use more energy on start-‐up (to reach set point). This energy loss is in addi/on to the
energy use to operate the pump
HW recircula/on pumps
• Install Vending Miser on soda machines: h8p://www.usatech.com/energy_management/energy_vm.php
• Shuts down the compressor and lights when people are not in the area
• Can have a payback of less than one year • Simple to install requiring li8le technical skills • Some/mes soda vendor will supply for free • Soda s/ll stays cold
Vending Misers
Many opportuni/es for vending and cooler misers
“\` Many drink coolers have very bad seal
leaks
A vendor supplies these coolers to this golf resort, but the resort s/ll has to pay the u/lity bill! These are basically opera/ng with the door leS open.
Use of a programmable receptacle can reduce water
fountain power use by 30%
Refrigerated Water Fountains
The hood should overhang 6” over the cooking equipment. Either the equipment needs pushed back a li8le more or extensions need
installed on the hood.
Dishwasher sani/zing heaters, such as these two 36 kW models, can consume up to 30% of a restaurants total power use. Should consider
a NG unit or a chemical dishwasher
Dishwasher exhaust is on when dishwasher is not opera/ng. Best fix is
an interlock
Idle /me needs to be reduced whenever possible
Pilot lights should be shut off whenever
possible
Pilot lights are leS on con/nuously
Assume 1,250 BTUs for commercial pilot. This is a two-‐fold savings: natural gas or propane to fuel the pilot and the electricity saved by not having to remove the heat with the HVAC system. A 4 burner stove (they are usually larger) would require 10 tons of
cooling to remove the heat from the pilots!
Example of a plas/c
curtain that would work well in the walk-‐in
coolers and freezers
No curtains
Walk-‐Ins
Ligh/ng Opportuni/es
Most painless energy project! Replace
incandescent exit signs with LED signs. About a 6 month payback and no
complaints!
Too much aisle light
Incandescent Auditorium Lights
500 T12 lights on at 0100 in the morning in a large library
Many /mes hallways are over-‐illuminated. Rarely should a 4 bulb fixture be used in a hallway. The Illumina/ng Engineering Society of
North America (IESNA) maintains that 10-‐20 fc is adequate for hallways and aisles. These were 50 fc or higher.
This is an inexpensive way to secure ligh/ng that does not have switches. This example is for high bay ligh/ng (uses much more energy than office ligh/ng). The breakers we labeled and security was trained to turn them off when they are not needed. This reduced the off-‐shiS load by 35 – 50 KW with no capital required, just labeling and a procedure. The lifespan of the breakers was inves/gated and it was found
that they should last over 11 years if they are cycled twice a day.
Reduced Ligh/ng Plan on the cheap
Ligh/ng Upgrades
This hi bay was converted from 250w HPS to T8 fluorescent. 32 fixtures were replaced with 16 4’s and 16 6’s. This reduced wa8age by 3,242 wa8s and HVAC by 1902 tons. This project was done in conjunc/on with installing switches that allowed for all but 6 lights to be off when the space was not in use. This allowed for a 1.4 yr payback and allowed for a much be8er work environment. The 5000K ligh/ng made reading prints and assembly work much easier than the yellowish HPS. It helps to sell a ligh/ng retrofit if switches can be added in. Also, do not forget to calculate the HVAC savings, which can be substan/al. New ligh/ng can be “brighter” but the foot candle readings may be
lower; be more concerned about the recep/on of the ligh/ng.
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This spreadsheet is a very handy tool in obtaining buy-‐in for ligh/ng projects. Be sure to research any available rebates: they can be very lucra/ve.
These 2 graphs (water and sewer) track together very closely, but they should not. Sewage should only be charged for water that goes down the drain, not water for irriga/on or, in this case, water that is being evaporated in a cooling tower. For the small price of installing an irriga/on meter ($340.00) the sewer bill will drop
at least 50%.
U/lity Bill Analysis Findings
Water and Sewer The sewer bill at this facility is based on water consump/on. At one /me, when the previous owner had the plant, the water used for the cooling tower and the irriga/on system was
deducted from the total (since this water never went to sewage). The meters below were read by the County Water and Sanita/on Department monthly so the values could be deducted
from the usage amount reported by the City Water System.
These had not been read since the new owner had purchased the building. You can see this by looking at the huge increases occurring during the summer months, when the irriga/on and cooling tower load were at their max. When the Sewer Department was contacted, they did not want to do the readings again and
offered to compromise with a flat rate. This resulted in an annual savings of over $20,000.00.
This school district’s newer elementary school was using more than 40% more energy than the state average, and far more than older schools in the same district. Met with the Energy Management System contractor and spent the day watching
this system operate in detail.
60 Hp Boiler (2) 250 Ton Chiller 50 Ton Chiller
• Chillers were operated by a flow calcula/on that did a very poor job. The small chiller never ran at all.
• No low OA lock-‐out for chiller and high OA lock-‐out for boiler. Large chiller came on when it was 47F outside
• Only one call for heat would turn on the whole hea/ng system • Set-‐points need to be variable • Simultaneous hea/ng and cooling needs to be eliminated or greatly reduced
30 Hp CHW Pumps
10 Hp HW Pumps
CHW Pump Control Pkg.
CHW Pump VSDs (different speeds?)
Pumps had their own control package: they were not controlled by the EMS. Pumps would not shut down and ran at different speeds at the same /me.
Air Handler Blower Coil Units
• Though EMS showed units to be scheduled off, many were s/ll opera/ng due to hardware communica/on issues.
• OA should be minimized; why run dedicated systems when the building is unoccupied
• Thermostat set points were way too loose. Need to use ASHRAE standard
EMS (or BAS) U/liza/on Many /mes an EMS is used for nothing more than a fancy /me-‐ clock. This is a missed opportunity and waste of money. Control strategies can reduce energy use significantly. Examples: • Op/mum Start/Stop • SA/DA reset • Sta/c reset • HW reset • CHW reset • Demand Controlled Ven/la/on • OA lockouts • Humidity control strategies • Advanced scheduling • Variable override /mers
The heat from the walk in refrigerator and freezer condensers ejects right into the HVAC condensers.
Poor Installa/on
Condensers are much to close to each other and to the walls. There is very li8le room for them to dissipate heat effec/vely.
This valve was opened a few years ago to compensate for a “water hammer” issue that occurred by accident. Power readings taken on the pump with this valve open and closed showed an increase from 66KW to 82KW. The pump consumed 16 more KW with this valve
open. Shuung this valve saved $7,140.00 a yr.
Improper Valve posi/on Example
Single Point Bulle/ns A good tool to drive energy awareness
Man-‐fan example This man-‐fan was running 24/7 though the area was only occupied about 90 hours a week. This equates to just over $300.00 a year. Remember man-‐fans do not lower the room temperature, they are only helpful if you are there to feel their benefit. How many of these have you seen running in a non-‐occupied space? Many man-‐fans at this facility use more power than this one.
Compressed Air Leak examples Let’s assume these leaks add up to a 1/8” leak (probably very conserva/ve). A con/nuous 1/8” leak costs and unbelievable $7,000.00 a year. This is totally
preventable. Maintenance usually repairs these within one day if they are no/fied. The next /me you hear the hissing sound, remember it sounds like money!
Ligh/ng example If the ligh/ng override is used, it should be turned off when no longer needed and not allowed to /me out. Some of these /mers are 2 hours and some of these zones can cost up to $15.00 for just one hour of opera/on. Knowing your zone helps
prevent the waste associated with turning every zone on, just to make sure you get the right one (this does happen).
Exhaust fan example This exhaust fan can cost over $50.00 a month to operate, not to men/on the cost of
the condi/oned air that is being pumped outside the building. This fan was not turned off when produc/on ended.
Space Heaters
• They are a fire hazard • They consume very large amounts of energy • They affect other employees comfort by causing the HVAC system to work
harder in the summer (making it colder for those without the heaters) and less in the winter (having a thermostat meet temperature when the whole room may not be warm).
Personal fans, on the other hand, do not change building temperature, just airflow, and do not use much electricity.
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To sell an energy project, think like a life insurance salesman, only backwards!
When selling a policy for $275.00 a year it is presented as cos/ng only $.75 a day. When working with energy and jus/fying a project, think the opposite (annually)! This is especially easy when looking at loads that run 24/7, such as an exit sign.
40 wa8s – 4 wa8s = 36 wa8s * 8760 hrs (hours in a year) = 315360/1000 (wa8s in a kilowa8) = 315.4 kWH * $.11 (price per kilowa8 hour) = $34.69 a yr in savings
Doesn’t that sound be8er than saving 9.50 cents a day?
Ques/ons?
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