HomeMy WebLinkAboutAngoon Low-income Housing Pellet District Heat Project - Final Technical Analysis Report - Dec 2015 - REF Grant 7081113Alaska Energy Engineering LLC Technical Memorandum
25200 Amalga Harbor Road Tel/Fax: 907.789.1226 December 17, 2015
Juneau, Alaska 99801 jim@alaskaenergy.us
to: Craig Moore, Tlingit-Haida Regional Housing Authority
subject: Final Report
project: AkWarm Energy Model Analysis
EXECUTIVE SUMMARY
The Tlingit-Haida Regional Housing Authority has developed a Final Technical Report dated
July 30, 2015 that includes an energy use assessment of their housing facilities. The energy use
predictions in that report were based on AkWarm energy models of the buildings, which were
also used to evaluate investments in energy efficiency measures.
Alaska Energy Engineering LLC compared the AkWarm predictions with actual energy use.
Energy data was gathered directly from the suppliers and utilities for 42 THRHA apartment
buildings. The actual energy use was compiled into a spreadsheet and then compared to AkWarm
predictions for 18 of the buildings.
Discrepancies were found between the actual and predicted consumption. The models were
reviewed and in many cases the discrepancies were due to incorrect modeling parameters. The
program developer also provided insight into appropriate methods of modeling the buildings. The
corrected models are more accurate in predicting energy use, validating the use of AkWarm
energy models. The models also led to investigation into why a few buildings are using higher
than predicted energy use.
ACTUAL ENERGY USE
The energy use for 42 THRHA apartment buildings is summarized in the Appendix. The energy
use is normalized by the Energy Use Index (EUI) in kBtu/sqft and Energy Cost Index ($/sgft) to
provide a metric for comparing the buildings. The following table shows the average EUI—the
most valuable metric for comparing building energy use —and the breakdown between
heating/DHW energy and non -heating electric loads.
Average Building Energy Use Index EUI), kBtu/sqft
EUI Percent
Heat and Domestic Hot Water 47 78%
Electric Loads 14 22%
Total 61 100%
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The data shows that 78% of the energy is used for heat and domestic hot water. The buildings
consume nearly 15,000 MMBtu at an annual cost of $600,000 per year.
Heating and DHW Energy Use Index
A review of the energy data revealed that some of the buildings have relatively higher EUIs. The
following buildings should be investigated to determine why they have heat/HW EUIs that are
significantly above the average:
• Angoon Triplex 7A, 7B, & 7C
• Haines Senior Center
• Hoonah Senior Center
• Juneau Granite Drive 4063/4067
• Juneau Kanat'a Deyi (most buildings)
• Petersburg Housing
The Yakutat Senior Center has a low heat EUI because it is also heated with cordwood, which
was not included in the total energy use. The Kasaan duplexes also have low EUI's, which is due
to both a highly efficient envelope and the likely use of wood heat.
Non -heat EUI
Some of the buildings have higher non -heating EUIs. The following buildings should be
evaluated to determine why they have non -heating EUIs that are significantly above the average:
• Hoonah Senior Center
• Juneau Granite Drive
• Juneau Kanat'a Deyi (4468-4470; 4480-4482)
• Kasaan Duplex 3A/3B
AKWARM COMPARISON
During development of the Final Technical Report, THRHA recognized that some buildings had
significant discrepancies between the AkWarm energy predictions and actual energy use. A
review of the AkWarm models was undertaken for the following buildings:
• Angoon Low Rent
• Haines Senior Center
• Hoonah Senior Center
• Juneau Fireweed Place
• Juneau Granite Drive
• Juneau Kanat'a Deyi
• Juneau Valley Boulevard
• Kasaan Duplexes
• Ketchikan Fairview
• Saxman Senior Center
• Yakutat Sunrise Apartments
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Energy Modeling
The nature of an energy model is to predict energy use by inputting assumptions for building use
and system efficiency. Since modeling the specific use of a building can be both difficult and
tedious, an energy model is generally developed based on reasonable or average use of the
building. This is effective when predicting differences in energy consumption for various options.
It is less reliable as a predictor of actual energy use, which can vary widely with occupant use and
system efficiency.
To account for these modeling realities, the total energy use of all the buildings was compared
with the total energy use predicted by the AkWarm models. Reasonable adjustments were then
made to bring the predicted and actual energy consumption in close agreement as a group.
Total Energy Use
The AkWarm models predicted total energy use for all of the buildings that was 35% higher than
actual energy use. A single building (Juneau Fireweed Place) accounted for a majority of the
error. However, a review of the AkWarm models revealed inaccurate inputs for occupancy,
system efficiencies, load definitions, and tenant preferences. These were corrected as noted later
in this report. The most common corrections were:
• Boiler seasonal efficiency (AFUE) was set at 70% for most of the buildings. Most models
used a higher AFUE. A 70% value is more reasonable (it may even be lower) for boilers
that are sized for a peak design load plus a peak domestic hot water load, effectively
oversizing them significantly for average loads. Good information on boiler seasonal
efficiency is not readily available. So, this inaccuracy is to be expected.
• Indirect hot water heater efficiency was set at 65% to account for the boiler efficiency
and a 5% loss factor for the hot water tank.
• The ventilation rate was set to correspond to the size of the ventilation systems.
• Electric use was changed from medium to low use, which is appropriate for multi -family
apartments of modest size (as opposed to single family houses), especially in
communities with high electric rates.
After making the corrections to the models, the predicted total energy use came into close
agreement at 0.4% higher than actual, a remarkable result. The following table compares total
actual energy use for all buildings with the original AkWarm predictions and the corrected
predictions.
Comparison of Actual Energy Use and AkWarm Predictions —All Bldgs, MMBtu
Energy Actual Original AkWarm Corrected AkWarm
Heat/DHW Energy 3,930 3,400 (-13%) 3,870 (-2%)
Non -heat Energy 2,900 5,790 (+99%) 2,990 (+3%)
Total Energy 6,830 9,190 (+35%) 6,860 (+0.4%)
The results show that AkWarm is a highly accurate tool for predicting energy use. However, this
is only true if the models are developed based on a thorough understanding of building use and
system efficiency. Making experience -based changes to the models and then verifying the
changes with the actual bills obtained this level of precision. Modelers may not have the benefit
of such feedback.
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Building Comparisons
After correcting the models so they accurately predict "typical use", the model predictions are a
valuable tool for identifying energy use anomalies that may be related to tenant use or the energy
systems.
A comparison of the individual building energy use with the corrected AkWarm models revealed
that variations between actual and predicted use of +/-25% is reasonable. The following buildings
have actual energy use that is more than 25% higher than the prediction:
• Angoon Bldg. 7 (triplex): The fuel oil use is 44% higher than the prediction.
• Juneau Granite Drive 4060-4064: The electric use is 70% higher than the prediction. The
low electric use results in less heat gain, causing the fuel oil use to be 149% higher than
the prediction.
• Juneau Granite Drive 4063-4067: The electric use is 41% higher than the prediction.
• Juneau Kanat'a Deyi 4481-4483: The fuel oil use is 32% higher than the prediction.
• Saxman Senior Center: The fuel oil use is 57% higher than the prediction.
• Yakutat Sunrise Apart. A: The actual fuel oil use is 269% lower than the prediction. This
indicates that the supplier fuel oil records are not accurate.
• Hoonah Senior Center: The waste heat use is 52% higher than the prediction.
• Kasaan Duplexes: Electricity use is 23% and 68% higher than predicted.
These buildings should be evaluated for potential issues related to energy use.
SUMMARY
The Final Technical Report based its findings on energy savings predicted by AkWarm energy
models. The models were found to contain inaccurate representations of building use and system
efficiency. While the inaccuracies may lead to inaccurate energy use predictions, the inaccuracies
tend to cancel when comparing energy use between two options, so any adjustments are likely to
produce only slight changes in energy savings.
Actual energy use is also not a good metric for comparing energy efficiency measures because it
is based on the current use, which may differ greatly from average use. For housing buildings,
average use is a more valid metric since tenants come and go. Thus, an energy model, despite its
potential limitations, is the better tool for energy savings predictions.
AkWarm was found to be a valid tool for predicting "typical" energy consumption, provided that
reasonable accuracy is applied to modeling the building use and system operation and
efficiencies. This is essentially the art of modeling which is to have an inherent understanding of
energy systems and the important parameters that must be carefully determined.
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AKWARM MODEL ADJUSTMENTS
Angoon Low Rent Housing
Description
• Eight buildings —four duplexes, two triplexes, two 4-plexes
• Heat: Fuel oil boiler for each apartment, except one of the 4-plexes, which has a single
boiler; fuel oil consumption data from supplier.
• Electricity: Supplied by Inside Passage Electrical Cooperative; data from utility
Energy Use
Actual energy use varies for the buildings. There is no correlation with building size or number of
apartments. The variations are the likely due to tenant lifestyle and equipment efficiency.
AkWarm Models
The AkWarm prediction of energy use varies widely from 67% to 120% of actual energy
consumption. One consistent trend is that the models over predict electricity consumption by an
average of 156%.
The models were reviewed and the following adjustments were deemed appropriate to more
accurately model the buildings:
• Fuel Type: Changed from #1 to #2 fuel oil
• Boiler: The boiler was modeled with 82% seasonal efficiency and measured combustion
efficiency. These were replaced with a seasonal AFUE efficiency of 70%. A 70% AFUE
is appropriate for an oversized boiler supplying space heating and intermittent domestic
hot water loads.
• HW Heater: The hot water heater was modeled without accounting for the boiler AFUE.
An energy factor of 65% was added which takes into account the boiler AFUE and an
additional 5% tank loss.
• Miscellaneous Electric Use: Reduced from medium to low. A reasonable adjustment
given Angoon's high electric rates.
R e-idYS
The modeled electric use remains high at 119% of actual. This is likely because of high electric
rates of 65¢ per kWh, which would cause occupants to use electricity more frugally. The model
treats electric use as a heat gain, effectively reducing the heating load. This is not an equal trade-
off in overall energy consumption because the boiler produces heat at 70% efficiency.
The adjustments to the model were beneficial to bringing the energy predictions into closer
agreement with the actual. Modeled energy consumption is 99% of actual, which is well within
the accuracy of the energy model.
Bulking Name
Sin
sgft
Annuel EwW Coneumptlon
Fuel Oil FJect is ty Waste Heat: Propane
gallons kWh ; MMBtu gallons
AMM CompaAson • Ori M Yodel
Fuel UI Oectridry
gallons %ofacualE kWh E%ofactuaf
Taal
kBtu
AkYYum cavubon • Certew Model
Fuel Oil lile&dry ToW
9albns E%ofactuall kWh :%ofachuaF I6lu
AngoonDuplexlAendl6
2,688
1,148 f0,848
940 82Yo i3.103
126% E
90%
1.036 90%
10.276
95%
91%
AngoonRom 2Aand 28
Z688
933 14,195 ;
940 101% E 13.556
95% E
99%
1,062 114%
E 10.432
73%
103%
AngoonDupkx3Aand 38
Z250
738 9,621
848 I 115% 13,190
131% E
120%
886 120%
E 9,650 E
100%
115%
Prom Duplex 4A and 48
Z250
851 7,042
848 100% 13,012E
185%
114%
968 E 114%
10.007
142% €
119%
argoon4-plex5A585C5D
3680
t,325 14,702
988 75% ; 24.911
169%
95%
1,185 89%
18.993 €
129%
98%
Angoon4�lex6A686C6D
3680
1294 13,485
1,048 E 81% 24,916
185% ?
102%
1,112 91%
18.997
141% €
101%
ArgoonTAplex7A787C
1,794
1,171 9,463
521 44% 17.157
181%
67%
655 S6%
E 13.324
141% E
70%
AngoonTdplex9A969C
Z250
728 ! 8,69
615 E 84% 17,206E
198%
110%
747 103%
? 13.311
153% E
11/%
Totals
21,28g
8.188 ; 88.046
6.748 82% : 137,681
156%
98%
7,711 94% E 104.990
119%
99%
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Haines Low Rent Housing
Description
• Building: 12-unit multi -family housing
• Heat: Two fuel oil boilers; fuel oil consumption data from supplier.
• Electricity: Supplied by Alaska Power Company; data from utility
Energy Use
The building consumes 4,314 gallons of fuel oil and 22,480 kWh of electricity.
AkWarm Models
The AkWarm model predicts energy use of 2,277 gallons of fuel oil and 67,125 kWh. The high
electric prediction is treated as heat gain by the model, which is contributing to the low fuel oil
prediction. The model was reviewed and the following adjustments were made to more accurately
model the buildings:
• Ventilation: Changed continuous ventilation airflow from 309 to 600 cfin.
• Boiler: Added 68% AFUE which is reasonable for an oversized boiler.
• HW Heater: Added 63% energy factor with accounts for the boiler AGUE of 68% and an
additional 5% tank loss.
• Electric Loads: Changed from medium to low use and eliminated the electric range and
eliminated the electric dryer and range
R eSul is
The modeled electric use remains high at 137% of actual. This is likely because of high electric
rates of 25¢ per kWh, which would cause occupants to use electricity more frugally. The model
treats electric use as a heat gain, effectively reducing the heating load. This is not an equal trade-
off in overall energy consumption because the boiler produces heat at 68% efficiency and electric
loads produce heat at 100% efficiency.
The adjustments to the model were beneficial to bringing the energy predictions into closer
agreement with the actual. Modeled energy consumption is 99% of actual, which is well within
the accuracy of the energy model.
Annual Energy Consumption I AkWarm Comparison • Original Model AkWarm Comparison • Cor WW Model
Building Name sin Fuel00 Ek�hiaty3WasleHeat Propane FuNQI Fleooidly Total Fuel0il Elentn ty Total
sdft oalloisi kWh MMk dalkms I gallons %of add kWh N of xl al: kBtu oallons : m of actual kWh % of actual? katu
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Hoonah Low Rent Housing
Description
Building: 12-unit multi -family housing
Heat: Two fuel oil boilers; fuel oil consumption data from supplier.
Electricity: Supplied by Alaska Power Company; data from utility
Energy Use
The building consumes 639 MMBtu of waste heat and 55,000 kWh of electricity.
AkWarm Models
The AkWarm model predicts energy use of 258 MMBtu and 68,000 kWh. The high electric
prediction is treated as heat gain by the model, which is contributing to the waste heat prediction.
The model was reviewed and the following adjustments were made to more accurately model the
buildings:
• Ventilation: Changed continuous ventilation airflow from 327 cfm, which is the code -
required minimum.
• Heat: Changed to district heat with 95% efficiency to account for heat exchanger losses.
• HW Heater: The model would not accept a hot water heater connected to the district heat
system. The hot water load was modeled as an electric hot water heater at 90%
efficiency, which accounts for the heat exchanger efficiency of 95% and an additional 5%
tank loss. The predicted how water energy was manually converted from electric energy
to MMBtu.
• Electric Loads: Changed from medium to low use.
Results
The modeled electric use is appropriate at 96% of actual. The modeled heating load is 50% of
actual. There is concern that the waste heat Btu meter is not properly calibrated. The calibration
will be verified.
Modeled energy consumption is 82% of actual due to the low waste heat projection.
Annual Energy Consumption I AkWarm Comparison • Original Model I AkWarm Comparison • Corrected Model
�� NamSae Fuel Q ; Electnty ?Hasse Hea< Propane Waste Heat EecO aty Total Waste Heat Electnaty TotaBlai
salt gallons i kWh' MMBtu gallons MMBtu %of acWal kWh `', of " k8tu MMBtu % of actual; kWh %of actual; kStu
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Juneau Fireweed Place Senior Housing
Description
• Building: Residential apartment building; 65 units
• Heat: Electric baseboard
• Electricity: Supplied by Alaska Electric Light & Power; data from utility
Energy Use
The building has a house meter and individual apartment meters. Energy use and demand for the
house meter has been reasonably consistent at 425,000 kWh per year and 79 kW demand per
month. Use and demand increases in the winter months due to electric heating.
AkWarm Models
The AkWarm prediction of energy use is 1,140,000 kWh. The model was developed for the entire
building. The model was modified to only capture the house loads and to more accurately model
the building:
• Perimeter: Reduced the wall, roof, floor, and window areas to reflect the areas served by
the house meter.
• Water Heaters: The apartment water heaters were removed from the model. Steady state
efficiency was reduced from 100% to 95% to account for tank losses that are not being
beneficial to heating the building.
• Ventilation: Reduced the air flow to 8,000 cfm; reduced fan power to 9500 watts
• Lighting: Removed the apartment lighting.
R eSul is
The modeled electric use is 109% of actual. This is a reasonable result given the unknowns about
ventilation flow rates, heat recovery effectiveness, and weather variations.
Annual Energy Consumption
AkWarm Comparison • Original Model
AkWarm Corparison • Comeded Model
Building Name Size
Fuel Oil Electricity Waste Heat Propane
Fuel01 Elednoty Tonal
Fuel Oi Ele,*dly Total
sgft
gallons kWh MMBW E gallons
gallons Nofaclual; kWh %ofactuali kBtu
gallons '%ofactualkWh E%ofatal k8tu
Juneau Fireweed Place 54,323
: 423,920 ;
:1.139.510: 269% 269`h
: 462.705 109% 109%
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Juneau Granite Drive Housing
Description
• Duplex housing building
• Heat: Fuel oil boiler; fuel oil consumption data from supplier.
• Ventilation: Heat recovery ventilator
• Electricity: Supplied by Alaska Electric Light & Power; data from utility
Energy Use
The Granite Drive apartment buildings have high energy use when compared to other THRHA
apartments. Actual energy use varies for each building due to tenant lifestyle and equipment
efficiency. It is anticipated, however, that the modeled energy use will be in close agreement with
average building energy use.
AkWarm Models
The AkWarm predictions of fuel oil and electricity energy use varies widely from the actual. The
models were reviewed and the following adjustments were made to each model to more
accurately model the buildings:
• Occupants: Changed occupancy of each 3-bedroom apartment form 6 to 4.
• Boiler: The boiler efficiency was reduced from 82% seasonal efficiency to 70%. A 70%
AFUE is appropriate for a boiler oversized to meet high, intermittent domestic hot water
loads.
• HW Heater: The hot water heater was modeled without accounting for the boiler AFUE.
An energy factor of 65% was added which accounts for the boiler AFUE and the tank
losses of 5%.
• Temperature: Turned off night setback control.
• Miscellaneous Electric Use: Reduced from medium to low.
Results
The 4060/4064 duplex has a much higher electricity use (kWh/sgft) than other THRHA
apartments. This high use causes that building to use less heating energy because of heat gain
form the electric appliances. Disregarding this anomaly, the AkWarm prediction is within 5% of
overall actual use.
Annual Energy Consumption
AkWorm Comparison • Original Model
AkWann Comparison - Corrected Mode
Building Name
sin
Fuel oilE Elecmaty ?Neste HeafE Prol
Fuel 01 Elecowty
Total
Fuel Oil Electricity Total
sqM
gallons kWh WOW gallons
gallons �4; of actual; kWh N of actual;
i
gallons °a of actual€ kWh %ol actual': kBlu
Juneau Granite Drive 4060.4064
2,120
681 ; 35,677 i
1.378 i 202% 13,716 i t
110%
1,6 t 249% i 10.582 i 1
Juneau Grdnee l) im 4063-0087
2,694
1,826 E 18,827
1456 [ 80% i 14,634 f 78% i
79%
1,797 i 98% f 11,180 I 59% ¢ 91%
Totals
4.814
2,507 54,504
2,634 113% 28.350 5Yh s
92%
3A92 139% 21762 40% 105%
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Juneau Kanat'a Deyi Housing 4481-4483
Description
• Duplex housing building
• Heat: Fuel oil boiler; fuel oil consumption data from supplier.
• Ventilation: Heat recovery ventilator
• Electricity: Supplied by Alaska Electric Light & Power; data from utility
Energy Use
The Kanat'a Deyi apartment buildings have relatively high energy use when compared to other
THRHA apartments. Actual energy use varies for each building due to tenant lifestyle and
equipment efficiency. It is anticipated, however, that the modeled energy use will be in close
agreement with average building energy use.
AkWarm Models
The AkWarm prediction of fuel oil and electricity energy use is 5 1 % and 127% of actual,
respectively. The models were reviewed and the following adjustments were made to each model
to more accurately model the buildings:
• Fuel Type: Changed from #1 to #2 fuel oil
• Boiler: The boiler efficiency was reduced from 82% seasonal efficiency to 70%. A 70%
AFUE is appropriate for a boiler oversized to meet high, intermittent domestic hot water
loads.
• HW Heater: The hot water heater was modeled without accounting for the boiler AFUE.
An energy factor of 65% was added which accounts for the boiler AFUE and the tank
losses of 5%.
• Temperature: Turned off night setback control.
• Miscellaneous Electric Use: Reduced from medium to low.
Results
The modeled fuel oil use is low at 68% of actual. The modeled electricity use is in close
agreement at 108% of actual. The reason for the low fuel oil prediction cannot be explained. The
other buildings show similar fuel oil use so life style does not appear to be the cause.
Annual Energy Consumption
AkWarm Comparison • Original Model
AkWarm Comparison • Corrected Model
Sim
Fuel Oil ElectriatyWaste HeaC Propane
Fuel01 Beftly Total
FuelOi Electraty Total
Building Name
sgft
gallons kWh i MMBtu E gallons
gallons Nofactual: kWh Nofactual: kBtu
gallons i%ofaclualkWh :%ofactua k8lu
Juneau KanafaDeyi 44814483 Z266
1,381 10,185
707 51% 1ZO 127% 63%
NO 68% 10,961 108% 74%
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Juneau Valley Blvd 8414, 8416, 8418, 8420
Description
• 4-plex apartment building
• Heat: Fuel oil boiler; fuel oil consumption data from supplier.
• Ventilation: Heat recovery ventilator
• Electricity: Supplied by Alaska Electric Light & Power; data from utility
Energy Use
The Valley Blvd apartments have relatively low energy use, when compared to other THRHA
housing. However, modeled use is much higher than actual, ranging from 130% to 173%.
AkWarm Models
The AkWarm prediction of fuel oil and electricity energy use is 160% and 173% of actual,
respectively. The models were reviewed and the following adjustments were made to each model
to more accurately model the buildings:
• Fuel Type: Changed from #1 to #2 fuel oil
• Boiler: The boiler efficiency was reduced from 82% seasonal efficiency to 70%. A 70%
AFUE is appropriate for a boiler oversized to meet high, intermittent domestic hot water
loads.
• HW Heater: The hot water heater was modeled without accounting for the boiler AFUE.
An energy factor of 65% was also which takes into account the boiler AFUE and the tank
losses of 5%.
• Ventilation: The building has a 120 cfm HRV that serves the four apartments. The model
showed 120 cfin being supplied to each apartment. The ventilation rate was lowered from
120 cfm to 30 cfm.
• Temperature: Turned off night setback control.
• Miscellaneous Electric Use: Reduced from medium to low.
R ecnits
The modeled fuel oil use is low at 68% of actual. The modeled electricity use is in close
agreement at 108% of actual. The reason for the low fuel oil prediction cannot be explained. The
other buildings show similar fuel oil use so life style does not appear to be the cause.
Annual Energy Consumption
AkWarm Comparison • Original Model
AkWarm Comparison • Corrected Model
Building Name size
Fuel Qi Eke may *asse Heat propane
Fuel Oil Geckle ToW
Fuel Oil Elednnty T:4
W
gallons kWh MMBW gallons
gallons %ofaclual; kWh ;%ofacWel; kBW
gallons %ofaul? kWh :%OfaCtual: K31
Juneau valley Boulevard 84"20 4,560
1.634 11,460
Z608 i 160% 28,372 1 248% 1rA
Z157 132% i 21.448 187% E 1W.
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Kasaan Duplexes
Description
• Duplex apartment buildings
• Heat: Toyo Stove and wood stove; fuel oil data from supplier.
• Domestic Hot Water: Propane hot water heater; propane data from supplier.
• Ventilation: Heat recovery ventilator
• Electricity: Supplied by Alaska Power and Telephone; data from utility
Energy Use
The Kasaan Duplexes have relatively low energy use, when compared to other THRHA housing.
However, building 3A/313 has much higher electricity use than the other two buildings.
AkWarm Models
The AkWarm prediction of energy use is 118% and 66% of actual for buildings 2A/213 and
3A/313, respectively. The models were reviewed and the following adjustments were made to
each model to more accurately model the buildings:
• Ventilation: Increased to 50 cfm per apartment
• Miscellaneous Electric Use: Reduced from medium to low.
D,.-- —
The modeled energy use is 116% of actual for apartments 2A/213 and 76% for apartments 3A/313.
The predominant discrepancy is that actual electricity use in 3A/313 is very high.
Animal Emrgy AkWann ComparBon • "Iril l Mod" MW4sm Contprhon • Ca rectod Mod"
Mukifuel Buildings SW ONropaneE Eletlnary FONropane i Eleuncily Total FDRropane i Elecaialy i Energy lulu
sgfl k8tu i kWh kBtu i%of actualkWh i%of actual: kBlu k8tu 1%of actali kWh of actual i Actual Mod"ed Ou
Kesaen Duple: 2A and 2B 1.792 48.969 E 9.180 61.397 I 125% l 9,736 E 106% E 118% 69,430 E 142% E 7.032 E 77% E B0,291 ? 93AD E 116%
hasaan Duple: 3A and 38 1,792 60.956 i 21.966 59.106 97% 1 9.114 f 41% f 66% 74,618 i 122% i 6.930 i 32% i 135.903 98.263 i 72%
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Ketchikan Fairview Housing
Description
• 4-plex apartment building
• Heat: Electric baseboards
• Ventilation: Exhaust only ventilation
• Electricity: Supplied by Ketchikan Public Utilities; data from utility
Energy Use
The building has moderate energy use when compared to other THRHA apartments.
AkWarm Models
The AkWarm prediction of electricity energy use is 94% of actual. The models was reviewed and
was found to be an accurate representation of the building.
Results
The modeled electricity use is within 6% of actual, which is acceptable.
hAW EW Canna j" AkWarm Comparison • Original Model AkWarm Comparison • Corrected Model
BWkIq Sias Fud 01 1 Becbidlir 6* Heat propene Fuel UI 6 ecoiaty Total Fuel 011 dectno Total
We
SO AM kWh i Mlft i 9l Am Nofadual; kWh Nolactual'; kBtu gallons %ofwWalkWh %of actuaii kBtu
Kelfikan ill IM 164,951 : 61,320 94% 94% 61,320 94% 94%
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Saxman Low Rent Apartments
Description
• 12 unit apartment building
• Heat: Fuel oil boiler; fuel oil consumption data from supplier.
• Ventilation: Exhaust only
• Electricity: Supplied by Alaska Electric Light & Power; data from utility
Energy Use
The model is predicting fuel oil use that is 39% of actual and electricity use that is 106% of
actual.
AkWarm Models
The models was reviewed and the following adjustments were made to more accurately model the
buildings:
• Boiler: The boiler was modeled with 82% seasonal efficiency and measured combustion
efficiency. These were replaced with a seasonal AFUE efficiency of 70%. A 70% AFUE
is appropriate for a boiler oversized to meet high, intermittent domestic hot water loads.
• HW Heater: The hot water heater was modeled without accounting for the boiler AFUE.
An energy factor of 65% was added which takes into account the boiler AFUE and the
tank losses of 5%.
Results
The modeled fuel oil use increased to 43% of actual. The reason for the low fuel oil prediction is
not apparent.
Annual Ene W Coamplion AkWarm Comparison • Original Model AkWarm Comparson • Corrected Model
Buildin Name Size Fuel01 Bectio Waste Hea Propare Fuel01 Beftty Total Fuel Oil Deco Total
9 so go" i kWh MMBtu gallons ga'bns of actual; kY1'h `: of actual: kBtu gallons `ro of acwal kYVh %af adua' kBlu
Saman Senior Cenler 31,300 3,693 : 64,980E 1,422 39% ; 69,009 : 106% : 59% 1,589 43% : e9,099 : 106% : %
I I Alaska Energy Engineering LLC
Page 15
YAKUTAT SUNRISE APARTMENTS
Description
• 12 unit apartment building
• Heat: Fuel oil boiler; fuel oil consumption data from supplier.
• Ventilation: Exhaust only
• Electricity: Supplied by City of Yakutat; data from utility
Energy Use
The models are predicting fuel oil use that is 422% of actual and electricity use that is 270% of
actual.
AkWarm Models
The models were reviewed and the following adjustments were made to more accurately model
the buildings:
• Boiler: The boiler was modeled with 82% seasonal efficiency and measured combustion
efficiency. These were replaced with a seasonal AFUE efficiency of 70%. A 70% AFUE
is appropriate for a boiler oversized to meet high, intermittent domestic hot water loads.
• HW Heater: The hot water heater was modeled without accounting for the boiler AFUE.
An energy factor of 65% was added which takes into account the boiler AFUE and the
tank losses of 5%.
• The apartments are individually meters; their energy use is not included in this analysis.
The model was modified to only include exterior lighting and laundry loads that are on
the house meter.
Results
The modeled fuel oil use comes to 369% of actual use. A review of the supplier energy data
shows no consistency over the past 3-years. It is apparent that the supplier data is not reliable.
The electric use is within 9% of actual, which is a reasonable estimate of use.
IAnu*1
Enargy Constrmptlon I AkWarm Comparison -original Model I MWann Coprparlson - Cometed Model
Building Name Size Fuel Oil ; Elecl 'Waste Heat Propane Fuel QI � FJeot6dly `. Taal Fuei Od ( Electncity i Total
sett gallons kWh MMBtu galons galons ihOfactual: kWh i%oleCtual k8tu gallons °pofaG4lali kWh i%otactual l
by:
Jim Rehfeldt, P.E.
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