5.6. SR 10-04-2004
Item 5.6.
E~
River
Police Department
MEMORANDUM
TO:
FROM:
DATE:
SUBJECT:
Pat Klaers, Mayor and City Council
Jeffrey A. Beahen, Chief of Police
September 30, 2004
Update on Public Safety Building
I have received a response from Scott Rudie, the consulting mechanical engineer from
Nelson-Rudie and Associates - the firm who designed the geo-thermal system for our public
safety facility. I have attached the report for your review.
In short, Mr. Rudie states that our natural gas usage is appropriate and within range for the
predicted usage as specified for a building our size, considering the current heating systems
within, and the flow of fresh air into the building - something required in new construction.
Geo-thermal only provides twenty-four percent (24%) of our total heat based on the
information provided by Mr. Rudie. The remaining heat is provided by gas fired units.
Natural gas costs for the building, at current gas pricing, should be around $16,948 a year.
Having geo-thermal provide part of the heat is a savings of $4,237 a year in natural gas
pnces.
To provide additional savings, we are talking to Econ-Air, a local geo-thermal provider,
about potentially replacing the roof-top building ventilation system with a geo-thermal unit.
That could provide another $6,406 a year in gas savings off of the projected $16,948 a year
we are predicted to spend for natural gas.
Gary Lore and I will be present at the council meeting to discuss this or any other building
issues that you may have.
.
.
.
Nelson-Rudie & Associates, Inc.
Structural - Mechanical - Electrical
Consulting Engineers
2575 University Ave. West
Suite 135
St. Paul, MN 55114
September] , 2004
Mr. Jeffrey A. Beahen
Chief of Police
City of Elk River Police Department
13077 Orono Parkway
Elk River, MN 55330
Re: Elk River Public Safety Building
Elk River, MN
NRA Project No.: 02-009
Dear Jeff:
We have reviewed your letter dated July 20, 2004 along with the gas utility bills and the
Commercial/Industria] Energy Audit dated April] 7, 2004 which you sent to us. You indicated
that you had some difficulties with your geo-thermal heating system during the winter months
and that your biggest concern is the "massive amount of natura] gas that the building is
consuming especially since gas is not being used as a primary source of fuel for the heating
system. "
We reviewed the original design ofthe heating system for the building and although the building
is heated with a geo-thermal system which uses electricity as its energy source, a significant
amount of heating for the building is being supplied by natural gas. The total connected heating
load for the geo-thermal heat pumps is approximately 680 MBH. The total connected load ofthe
natural gas heating system is 2] 58 MBH, not including the gun range unit. This total includes
665 MBH for heating in the Apparatus Bay and Garages, 743 MBH for the Apparatus Bay and
Garage Make-up Air units, and 750 MBH for the Budding Ventilation Unit.
Table A below indicates our estimate of the natural gas the building will consume and the
associated costs based on the current cost of $0.86 per CCF of gas used. As you can see from the
Table, the worst month would be January with an estimated gas usage of39]2 CCF and a cost of
$3,364.52 and the annual estimated total would be ]9,707 CCF with an estimated cost of
$] 6,948.32. These estimates do not include the consumption and costs for the gun range
ventilation system which will be operated periodically during the year.
Dennis A. Nelson, P.E.
Scott F. Rudie. P.E.
Andrew N. Erdmann, P.E.
Joseph M. Pearce, P.E.
M~hael D. WoeMe, P.E.
Tel: (651) 644-2400
Fax: (651) 647-4120
WNW.nelsonrudie.com
.
.
.
September 1, 2004
Mr. Jeffery A. Beahen
Elk River Public Safety Building
NRA Comm. No. 02-009
Page 2
TABLE A
I ..... ...... I. .~~i"'1~~~l<oup . . .' . - ..-. . . .
...... I' up . - ~. . -_..: . .
I. --- . -- . Heat'
I M~':' . . I MA~ I '. . MBH I CCF . I COST-
n';v.' Hr CCF 1<, "~F MAl< Hr CCF CCF ,,-
Jan 1592 750 24 2278 746 6 567 335 24 1018 50 3912 $ 0.86 $ 3,364.52
Feb 1330 750 24 1903 746 6 473 335 24 850 50 3277 $ 0.86 $ 2,817.88
Mar 1068 750 24 1528 746 6 380 335 24 683 50 2641 $ 0.86 $ 2,271.25
April 565 750 24 809 746 6 201 335 24 361 50 1421 $ 0.86 $ 1,221.80
Ma, 243 750 24 348 746 6 86 335 24 155 50 640 $ 0.86 $ 549.99
June 51 750 24 73 746 6 18 335 24 33 50 174 $ 0.86 $ 149.41
Jutv 7 750 24 10 746 6 2 335 24 4 50 67 $ 0.86 $ 57.60
Aua 20 750 24 29 746 6 7 335 24 13 50 99 $ 0.86 $ 84.73
Sept 166 750 24 238 746 6 59 335 24 106 50 453 $ 0.86 $ 389.34
Oct 477 750 24 683 746 6 170 335 24 305 50 1207 $ 0.86 $ 1,038.20
No' 953 750 24 1364 746 6 339 335 24 609 50 2362 $ 0.86 $ 2,031.32
Dee 1404 750 24 2009 746 6 500 335 24 897 50 3456 $ 0.86 $ 2,972.28
Total 7876 750 24 11271 746 6 2803 335 24 5034 600 19707 $ 0.86 $ 16,948.32
*
Based on 113 averages for the City of Minneapolis
Excluding service charges and taxes
**
You also sent us copies of gas utility bills for the building which we have summarized in Table B
below. These bills included three periods as identified on the Table. There appears to be an
error in the billings or a problem with the operation of the systems for the April 04 period. This
billing indicates a usage of5049 CCF which tr8ns!ates to a usage which is an order of magnitude
higher than the other two periods based on a usage per degree day of heating (a measure of the
energy utilization based on outside temperature).
TABLEB
Period Erid Readioo . P~iiodStai1Readlnn .... .. . . ....
, Therni , Dog
P~ricx1 Date: ReadlnQ .. Dale ReadhY! .. CCF Factor Therms $/Therm Colt Da.. Thenl\lDD
Mav-June 04 6/25/2004 34272 4/22/2004 33618 654 1.11 726 $ 0.8255 $ 599.29 536 1.4
April 04 4/22/2004 33618 312212004 28569 5049 1,103 5569 $ 0.7312 $ 4,072.09 531 10.5
Dee 03 Mar 04 3/2212004 28569 12/3/2003 21316 7253 1.104 8007 $ 0.7999 $ 6,405.05 4835 1.7
.
.
.
September], 2004
Mr. Jeffery A. Beahen
Elk River Public Safety Building
NRA Comm. No. 02-009
Page 3
In the Commercial/]ndustrial Custom Energy Analysis prepared by Minnegasco, Table 2
indicates the Natural Gas Summary for your building. This Table also indicates a much higher
than normal usage for the 3/22/04 period. The reasons for this are unknown based on the
information we have received to date. We are not sure where the balance ofthe usage readings
indicated in the Table came from. The billings which you sent us do not indicate these readings.
If we reduce the 3/22/04 value to a more normal amount of$2,300 as indicated in our estimates,
the annual total for the building would be approximately $]4,436 which compares favorably to
our estimate of $16,948.
As you can see from Table A, the largest amount of gas (57%) is used by the Building Make-up
Air Unit. This unit is used to supply outside (ventilation) air to the building heat pumps located
throughout the building. The air is brought in from the outside and heated or cooled and ducted
to the inlet of each heat pump. Based on the printouts that you sent us of the control system
operational screens, it appears as though the discharge air setpoint on the unit is approximately
70oF. This means that the unit will heat the outside air with natural gas to 700F during the
heating season. If heat pumps are operating in the cooling mode, the 700F discharge air may be
higher than necessary. If heat pumps are in the heating mode, some of the space heating may be
accomplished by the make-up air unit in lieu ofthe heat pump. We would recommend that air
from the make-up air unit be discharged at approximately 600F in the heating season (outside air
temperatures below 500F) and 750F in the cooling season (outside air temperatures above 500F).
This should reduce the gas consumption of this unit. In addition, this unit is scheduled to operate
twenty four hours per day to provide ventilation air to the building continuously. Ifthere are
periods of time when the building is essential1y un-occupied, the unit could be cycled off.
We were not aware that you had a problem with the heat exchanger on the Building Make-up Air
Unit. This unit is designed to operate continuously. The specifications require that the unit have
a one year warranty on materials and labor and a nine year extended warranty on the heat
exchanger.
We were concerned with the statement in your letter that said "the local (geo-thermal) provider
has briefly looked at the system and their conclusions are that the pump brand/type and size are
all wrong for how we intend to have the system heat and cool the building." The geo-thermal
system is properly designed and matched to the building requirements. Any statement to the
contrary is simply not tme.
We believe that your systems are operating as intended and that the gas usage that you have
experienced are in line with what we would expect based on the assumed operating profiles of
the equipment. We have to keep in mind, when comparing this building to previous City Hal1
and Police Building, that this is a larger building with a significantly improved ventilation
system that is currently operating twenty four hours per day. Modifications to system setpoints
and operating profiles can help to reduce the costs, but this building wil1 continue to consume a
significant amount of natural gas which is increasing in cost as natural gas prices continue to
rise.
.
.
.
September 1,2004
Mr. Jeffery A. Beahen
Elk River Public Safety Building
NRA Comm. No. 02-009
Page 4
We hope this helps you to better understand the building systems and how they operate. We
would be happy to meet with you and your staff to discuss this in greater detail and to help you
improve the operation of your facility.
Yours very truly,
( ;' ,/<<~d:S
\SC-ot . Rudie, P.E.
cc: Dan Pellinen
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