Sustainable Construction 

in Indian Country

Energy Efficiency Evaluation and Recommendations

November 27, 2012

Cocopah Indian Housing 

and Development

Somerton, AZ 

14380 S. Farm Road Multifamily Housing
Table of Contents

Introduction ........................................................................................................................................................... 1

Cocopah Tribe Location and Climate ................................................................................................................ 2

1. Site and Building Description ............................................................................................................................ 4

1.1 Building Envelope ....................................................................................................................................... 5

1.2 HVAC .......................................................................................................................................................... 5

1.3 Domestic Hot Water .................................................................................................................................... 6

1.4 Lighting ........................................................................................................................................................ 6

1.5 Additional Plug Loads ................................................................................................................................. 6

2. Energy Analysis Approach ................................................................................................................................ 7

3. Energy Consumption and Analysis ................................................................................................................... 9

3.1 Utility Consumption Benchmarking ............................................................................................................. 9

3.2 Energy Consumption Profiles .................................................................................................................... 10

3.3 Breakdown of Annual Energy Consumption ............................................................................................. 11

4. Energy Cost Reduction Measures .................................................................................................................. 12

4.1 ECRM 1: Lighting Upgrade ....................................................................................................................... 12

4.2 ECRM 2: Replace Old Refrigerators ......................................................................................................... 13

4.3 ECRM 3: Exterior Window Shade Upgrade .............................................................................................. 13

4.4 ECRM 4: Triple Pane Low-E Window Upgrade ........................................................................................ 16

4.5 ECRM 5: HVAC Upgrade .......................................................................................................................... 16

4.6 ECRM 6: Radiant Barrier Upgrade ............................................................................................................ 16

5. Renewable/Sustainable Measures ................................................................................................................. 17

5.1 ECRM 7: Solar Thermal Domestic Hot Water .......................................................................................... 17

5.2 ECRM 8: Photovoltaic Array ..................................................................................................................... 17

5.3 ECRM 9: Geothermal System ................................................................................................................... 18

5.4 Package of Recommended ECRMs ......................................................................................................... 18

6. Leveraging Energy Cost Reduction Measures with Utility Resources ............................................................ 19

7. Develop an Energy Management Strategy ..................................................................................................... 20

8. Conclusions and Recommendations .............................................................................................................. 21

Attachment A ...................................................................................................................................................... 22
1 

Introduction 

The Cocopah Indian Tribe, in southwestern Arizona, is committed to providing its members 

with safe, affordable, healthy, and energy efficient housing. This vision should encourage 

members living on the Reservation to remain and encourage members’ now living offReservation to return.1

 As part of this vision, the Cocopah Indian Housing and Development 

(CIHAD) decided to explore various options to retrofit an existing 2 story 8 unit garden 

apartment building with more energy efficient sustainable features. 

The Cocopah Reservation is located in a low-lying desert with an extremely hot-dry climate. 

Geographical location and weather directly influences energy consumption and costs in 

buildings. For the Cocopah Tribe, the largest category for energy consumption and cost is 

space cooling. Utilities costs are the second largest costs for households after mortgages and 

rents. Any retrofitting to make homes more energy efficient and affordable creates a win 

situation for the Tribe and household occupants. 

This assessment provides information on the most economically feasible upgrade options for 

this garden apartment building. This assessment provides information and strategies on how to 

reduce the annual operation costs through load reductions, energy efficiency improvements, 

and renewable energy resources. It presents an energy assessment analysis on the Building’s 

design and load consumption before and after the installation of energy efficient sustainable 

features. The comparison provides information for determining which of the energy efficiency 

strategies would likely result in the most effective savings on energy consumption and cost and 

makes recommendations for upgrades based on project payback periods. 

CIHAD participated as a demonstration project under HUD’s Sustainable Construction in 

Indian Country initiative (SCinIC). SCinIC, under the HUD Office of Policy Development and 

Research, promotes the enhanced use of sustainable materials and technologies in Native 

American housing communities through technical assistance, training, and promotional 

materials. 

 

1

 Cocopah Indian Housing and Development Web Page: www.ontherez.org 
2 

Cocopah Tribe Location and Climate 

The Cocopah Reservation is located in southwestern Arizona, near the Town of Somerton in 

southern Yuma County approximately 13 miles south of Yuma, 15 miles north of San Luis, 

Mexico and 180 miles east of San Diego. The Reservation's unique geographical location 

borders the United States, Mexico, Arizona and California. The Reservation consists of 6,565 

acres in three sections: North, West and East. 

The region is one of low-lying desert with the Colorado River bordering North Cocopah. The 

reservation is less than 300 feet above sea level, the area has an extremely hot, dry climate 

typical of the Sonoran Desert. The year round temperature averages 74 degrees with 

summertime highs frequently exceeding 110 degrees. Winter lows seldom go below 40 

degrees. The area averages slightly less than three inches of precipitation per year. 2

The geographical location of a community is very much impacted by its sources of energy, 

consumption patterns, and costs. This is because weather directly influences energy 

consumption and costs in homes and buildings. 

Figure 1: Map of the Cocopah Tribal Lands

 

2

 Tiller’s Guide to Indian Country: Economic Profiles of American Indian Reservations; Cocopah Tribe, pgs. 293-

294. 
3 

Figures 2 & 3: Traditional Cocopah Home
4 

1. Site and Building Description 

Constructed in 2003, the site has three eight-unit buildings and a community building, figure 4. 

The buildings are arranged on the site in the shape of a rectangle with a building at each 

corner. Two of the apartment buildings face south (including building B), and the other 

housing building and community center are oriented to the north with parking located in the 

center of the rectangle. Each of the 24 units is approximately 855 to 1,107 square feet, 

making each building approximately 8,532 square feet. Each of the two-bedroom units has a 

full bathroom, living room, dining room and kitchen. The three-bedroom units have two full 

bathrooms, living room, dining area, kitchen, and storage room. The laundry facilities are in 

the shared community building on site. For the focus of this energy assessment, building B 

energy consumption and costs will be examined. 

Figure 4: Cocopah Site Image
5 

1.1 Building Envelope 

Figure 5: Building B

Walls: The typical wall construction from the inside to outside is 5/8” gypsum board, 2x6 wood 

stud construction at 16” on center with R-19 fiberglass batt insulation, 60 MIL building paper, 

and 7/16” oriented strand board sheathing with stucco and mesh. It is estimated that the wall 

assembly has a thermal resistance rating (R-value) of R-22.

Roof: The roof is gabled with a 4:12 slope. It is constructed with 2x6 pre-engineered wood 

trusses at 24” on center, covered in 7/16” oriented strand board, #15 felt, and 240# fiberglass 

shingles. There is R-32 blown insulation above the ceiling. 

Floor: The main floor is a 5” reinforced concrete slab on 2” of clean sand. The second floor is 

2x10 wood floor joists at 16” on center with 3⁄4” gypsum concrete subfloor and 3⁄4” tongue and 

groove CDX plywood. The bedrooms, hall, dining room, and living room are carpeted. The 

kitchen, storage, and bathrooms are vinyl composite tile. 

Windows: All windows are operable and have clear double pane glazing.

1.2 HVAC 

The plan of the building places all HVAC equipment in a closet central to each unit. 

Heating/Cooling: The units have Amana split system heat pumps that are 3 to 3.5 ton (1000 

to 1200 cubic feet per minute or CFM) depending on unit size. According to plan there is an 

ambient temperature 115 °F cooling, 40 °F heating and minimum SEER of 12.0.

Ventilation: Ventilation air will be provided by infiltration and operable windows. Each 

bathroom also has an exhaust fan rated at 100 CFM. 
6 

1.3 Domestic Hot Water 

The units have 40 gallon electric water heaters (Whirlpool E1F40RD045V) with an energy 

factor (EF)3 of 0.92. 

1.4 Lighting 

When day-lighting from the windows is insufficient, lighting in the building is provided by 

incandescent light fixtures throughout each unit. Table 1 indicates fixture locations, wattage, 

estimated operating hours, and kilowatt-hour (kWh) usage. It was assumed that 60 watt (60W) 

incandescent lamps were used in each fixture throughout each unit of the building. 

Table 1: Existing Building Incandescent Lighting Information

Location Fixture Type Watts Operating

Hours kWh Usage

(4) 2 Bedrooms 2‐lamp 60W   960 365 350

(4) 3 Bedrooms 2‐lamp 60W 1,440 365 526

(8) Kitchen   1‐lamp 60W   480 365 175

(8) Living room 1‐lamp 60W   480 365 175

(4) 1 Bathroom 3‐lamp 60W   720 730 526

(4) 2 Bathrooms 3‐lamp 60W   1,440 730 1,051

(8) Hall 1‐lamp 60W   480 2,190 1,051

Totals per Building:    6,000 5,110 3,854

3,854 kWh * 13 cents = $501.02

Table 2 indicates the estimated savings from replacing all of the 60W incandescent lamps with 13W 

compact fluorescent lamps (CFLs). 

Table 2: Upgrading Lighting to CFLs

Location Fixture Type Watts Operating

Hours kWh Usage

(4) 2 Bedrooms 2‐lamp 13W   224 365 82

(4) 3 Bedrooms 2‐lamp 13W   336 365 123

(8) Kitchen   1‐lamp 13W   120 365 44

(8) Living room 1‐lamp 13W   120 365 44

(4) 1 Bathroom 3‐lamp 13W   180 730 131

(4) 2 Bathrooms 3‐lamp 13W   360 730 263

(8) Hall 1‐lamp 13W   120 2,190 263

Totals per Building:    1,460 5,110 949

949 kWh * 13 cents = $123.37 $377.65 savings over 60W incandescent

1.5 Additional Plug Loads 

Additional plug loads in the building include typical residential appliances such as task lighting, 

TVs, and standard kitchen equipment (refrigerators, stove, and microwaves). 

 

3

 EF is the energy efficiency of water heater and accounts for energy loss of heating and storing the water. 
7 

2. Energy Analysis Approach 

The approach used to develop this report involved several steps. First, initial information was 

collected from the CIHAD about building B’s design, occupancy data, energy consumption, 

and energy costs. This included the following: 

 Building plans 

 Utility consumption data for the last 12 months 

 Geographical location and climate data 

 Details about unit occupancy, mechanical equipment, HVAC systems, and lighting 

fixtures from interviews with CIHAD staff during a site visit 

Utility consumption was then compared with annual heating and cooling degree day data to 

determine any correlation between energy usage and climate conditions; the results were 

examined for anomalies. Data, observations, and photos were recorded during a site visit 

conducted from April 2-4, 2012. 

A baseline energy model was constructed in computer modeling software that performs 

building energy simulations. The HVAC load design and analysis software e-QUEST version 

3.64 was used to model the building. This modeled data is calibrated to match the actual 

building energy usage as shown by the utility bills and then used as a baseline for evaluating 

the energy cost reduction measures (ECRMs). The program calculates the amount of energy 

(and the resulting utility cost of that energy) the building is expected to use over an entire 

typical weather year. Model inputs are taken from information collected during the site visit 

and information provided by the tribe. The weather file for e-QUEST was taken from the 

Yuma, Arizona, weather station. Assumptions made for the e-Quest model include: 

 The building type and daily operation schedules are significant factors in energy 

consumption and costs. The type of occupants and income levels are also a 

significant factor in energy usage. Senior and disabled residents tend to occupy 

homes for longer periods and family developments generally have more 

occupants. It is assumed that 40 people will be living in each building (two 

people per bedroom). While occupancy is highly dependent on the individual 

lifestyles of the families it is assumed that half of the household will spend most 

of their time at home. Therefore it is assumed that the families will primarily be in 

the units 75 percent of the time during the week (approximately 126 hours/week). 

 Air changes per hour (ACH) of 0.5. 

 Non-ENERGY STAR appliances. 

 Lighting power density of approximately 0.76 W/ft2

 for the building. 

A computer analysis of the ECRMs was performed. The baseline model is changed to reflect 

the implementation of theses ECRMs and the computer model generates the expected energy 
8 

consumption and utility costs. When necessary, some ECRMs are evaluated outside of the 

modeling software using spreadsheet calculations. 

Finally, the estimated savings and additional costs of implementing ECRMs are evaluated in a 

life cycle cost analysis. This analysis assumes a 20-year life cycle and calculates the internal 

rate of return (IRR) and the net present value (NPV) of each ECRM and a package of ECRMs. 

IRR is essentially the annual yield on an equivalent investment. A project is a good investment 

if its IRR is greater than the rate of return that could be earned by an alternative investment 

(other projects, bonds, bank accounts, etc.). For this project, 5 percent is assumed as the 

minimum acceptable rate of return. The NPV calculation uses a discount rate to find the 

present value of savings occurring at a future date. The discount rate is your minimum 

acceptable rate of return, or your time value of money. Again, 5 percent is assumed. 

Investments have a positive NPV when the IRR is greater than the discount rate. Therefore 

projects with IRR greater than the discount rate and a positive NPV are considered to be good 

investments and are recommended. 
9 

3. Energy Consumption and Analysis 

3.1 Utility Consumption Benchmarking 

Utility data was provided for the eight units of building B for the 2011 calendar year. The 

Cocopah Tribe receives their electricity through Arizona Public Service (APS) Electric and it is 

delivered at an estimated rate of $0.13 per kWh. This rate includes meter fees and taxes. The 

estimated annual energy use intensity (EUI) of the building is 43 kBtu/ft2

/yr. The estimated 

annual energy cost intensity (ECI) is $1.67 /ft2. These two values can be used to benchmark 

the energy performance of the current building against similar buildings. The charts below 

show the difference that changing from incandescent lamps to CFLs can make. The EUI 

drops to 41 kBtu/ft2/yr and the ECI becomes $1.58/ft2/yr. This results in a $506 savings from a 

simple and inexpensive energy upgrade. 

Utility Consumption Analysis Building B 

Average Annual Consumption Annual Costs Average Unit Cost 

Electricity 70,509 kWh $9,295 100% 0.13 $/kWh 

Natural Gas therms $/therm 

Total: $9,295 

Total Conditioned Area 5,574 ft2 

Electricity Use Intensity 13 kWh/ft2/yr Natural Gas Use Intensity Therms/ft2/yr

Energy Use Intensity 43 kBtu/ft2

/yr Energy Cost Intensity $1.67 $/ft2/yr 

Electricity is provided by APS Electric 

Utility Consumption Analysis Building B after CFL Upgrade 

Average Annual Consumption Annual Costs Average Unit Cost 

Electricity 67,604 kWh $8,789 100% 0.13 $/kWh 

Natural Gas therms $/therm 

Total: $8,789 

Total Conditioned Area 5,574 ft2 

Electricity Use Intensity 12 kWh/ft2/yr Natural Gas Use Intensity Therms/ft2/yr

Energy Use Intensity 41 kBtu/ft2

/yr Energy Cost Intensity $1.58 $/ft2/yr 
10 

3.2 Energy Consumption Profiles 

The SCinIC team analyzed one year of electric data provided by the housing authority. The 

utility data covers the months from January 2011 through December 2011. The building was 

then modeled using the closest weather station, Yuma, Arizona, which recorded 1,182 heating 

degree days and 4,848 cooling degree days. 4 Degree days are indicative of the duration and 

intensity of the heating and cooling seasons and are used in this analysis to track how 

electricity usage corresponds to seasonal weather changes. 

Figure 6. Electricity Consumption vs. Cooling Degree Days & Heating Degree Days 

Figure 6 compares the Cocopah Building B electricity usage with cooling degree days, heating 

degree days, and the modeled electricity usage. Electricity is used for lighting, heating, 

cooling, domestic hot water, plug loads, fans, and pumps. The base electrical load for the 

building is just over 4,000 kWh per month. The building uses this amount of electricity 

regardless of weather. The graph shows that additional electricity use does correspond with 

the cooling degree days and heating degree days. The modeled electricity use comes within 4 

percent of the metered annual electricity use. 

 

4

 Heating and cooling degree day data was obtained from: http://www.degreedays.net/
11 

3.3 Breakdown of Annual Energy Consumption and Costs 

Using the modeled energy data, an energy consumption profile was created for the Cocopah 

Building B. Figure 7 shows the energy consumption and cost breakdown for the building. The 

largest category of energy usage is space cooling (32 percent) costing $2,852. The second 

largest is interior lighting (29 percent) costing $1,885, and then miscellaneous plug loads (20 

percent) costing $1,645. 

Figure 7. Annual Energy Consumption & Cost Breakdown 
12 

4. Energy Cost Reduction Measures 

Energy conservation is best achieved through a multifaceted approach that involves load 

reduction, efficiency improvements, and renewable generation. Addressing any one of these 

pathways will save energy. 

Load reduction, whether no cost or low cost, should be the first step. Load reduction involves 

managing energy consumption by simply turning things off when not needed or implementing 

control systems to help manage unnecessary energy use. Examples of load reduction include 

using nighttime thermostat setbacks or turning off lights in well-lit areas on sunny days to 

reduce lighting loads. Envelope upgrades such as adding insulation or window shades can 

result in load reduction but usually require large capital expenditures. 

Energy efficiency improvements should be considered next. While typically more expensive 

than load reduction, energy efficiency improvements are more cost effective than implementing 

renewable energy generation. Efficiency improvements involve replacing old or failing systems 

with modern technologies which perform the same function while consuming less energy. 

Examples of energy efficiency improvements include installing boilers with greater heating 

efficiencies, installing lighting with increased luminous efficacy, and installing energy efficient 

appliances such as ENERGY STAR refrigerators. 

The final step is energy generation. This step offsets a portion of the remaining energy 

consumption with onsite energy generation. Onsite energy generation is purposefully 

recommended after load reduction and efficiency improvements. Accomplishing the first two 

steps makes it possible to install lower capacity, therefore less expensive, generation systems. 

This section addresses all three approaches. 

4.1 ECRM 1: Lighting Upgrade 

Lighting is currently provided by incandescent light fixtures throughout the building. A 60W 

incandescent lamp in each fixture calculates to a lighting power density of 0.76 W/ft2. By 

replacing the 60W incandescent lamps with 13W CFLs, 2,171 kWh may be saved annually, 

resulting in an annual cost savings of $282. The lifespan of lighting is calculated at 5 years. 

The replacement of the incandescent lamps with CFLs will pay back in just over a year, 

therefore implementation of this measure is highly recommended. 

Table 3: Lighting Upgrade Energy Savings 

ECRM 1: CFL Lighting Upgrade 

Annual Savings Economic Analysis 

kWh Cost % Energy Investment IRR5 NPV6 Simple Payback 

(years) 

2,171 $282 3% $395 66% $788 1.40 

 

5

 Internal Rate of Return: Rate of return on investment for project 

6

 Net Present Value: Shows project earns this amount more or less than the desired rate of return (5 percent) 
13 

4.2 ECRM 2: Old Refrigerator Replacement 

Refrigerators consume the most energy of all household appliances due to the 24 hour a day/ 

7 day a week operational schedule. With recent improvements in insulation and compressor 

technology, new refrigerators use much less energy than older models. ENERGY STAR 

qualified refrigerators are in fact required by the U.S. Department of Energy to use 20 percent 

less energy than models not labeled with the ENERGY STAR logo. The refrigerator currently 

in use in each of the eight units of the building is a 1995 GE CTX18CAX which costs $112 

annually to run. An equivalent new ENERGY STAR model would only cost $51 annually to 

run. Table 4 shows the savings for upgrading to ENERGY STAR refrigerators in Building B. 

Refrigerator replacement is a highly recommended measure. 

Table 4: Energy Star Refrigerator Replacement 

ECRM 3: Refrigerator Upgrade 

Annual Energy Savings Economic Analysis 

kWh Cost % Energy Investment IRR NPV Simple Payback 

(years) 

3,754 $488 6% $3,200 9% $541 6.56 

4.3 ECRM 3: Exterior Window Shade Upgrade 

Preventing the sun from heating a space may be best accomplished by adding shading 

devices to the exterior on the south of the building. Using interior window shades is helpful but 

allows the heat to enter through the window while exterior shades prevent some of the solar 

radiation from reaching the window and therefore entering the building. 

The windows on the south side of the building currently have no exterior shading device other 

than the 2’ overhang for the windows on the second floor. By adding 4’ louvered shades (as 

seen in figures 8 & 9) above the windows on the south side of the building, 1,860 kWh may be 

saved annually resulting in an annual cost savings of $242. 

Figure 8: Building B with 4' Louvered Window Shades
14 

Figure 9: Building B with 4' Louvered Window Shades

If 8’ decks (as seen in figures 10 & 11) were added for the second floor that shaded the 1st

floor windows, 2,240 kWh could be saved annually resulting in an annual cost savings of $291. 

Figure 10: Building B with 8' Decks for Window Shades 
15 

Figure 11: Building B with 8' Decks for Window Shades 

The lifespan of the shading is calculated at 20 years. The additional 4’ shading will pay back in 

far less time than the 6’ decks which will pay back in just over the 20 year lifespan. 

Implementation of this measure using exterior window shades is highly recommended. 

Table 5: Exterior Window Shade Upgrade Energy Savings 

ECRM 4: Exterior Window Shade Upgrade 

Options 

Annual Savings Economic Analysis 

kWh Cost % Energy Investment IRR NPV 

Simple 

Payback 

(years) 

4’ Window Shades 1,860 $242 3% $2,000 10% $965 8.27 

Decks/Window 

Shades 2,240 $291 3% $6,000 0% -$2,258 20.60 
16 

4.4 ECRM 4: Triple Pane Low-E Window Upgrade 

The current windows of the building are typical double pane windows with clear glazing. By 

replacing them with triple pane window that have low emissivity, 2,100 kWh may be saved 

annually resulting in an annual cost savings of $273. The lifespan of windows is calculated at 

20 years. The window replacement with triple pane windows will pay back in just over the 20 

year lifespan. Implementation of this measure is recommended. 

Table 6: Triple Pane Low-E Window Upgrade Energy Savings 

ECRM 5: Triple Pane Low-E Window Upgrade 

Annual Savings Economic Analysis 

kWh Cost % Energy Investment IRR NPV Simple Payback 

(years) 

2,100 $273 3% $6,000 -1% -$2,474 21.98 

4.5 ECRM 5: HVAC Upgrade 

The HVAC system currently in use in each of the eight units of the building is a split system 

single zone with an air source heat pump. It has a cooling efficiency of 12 SEER, and a 

heating efficiency of 3 coefficient of performance (COP). If this system was replaced with an 

ENERGY STAR rated system with a 14.5 SEER and a 3.6 COP, 4,720 kWh may be saved 

annually resulting in an annual cost savings of $614. The lifespan of HVAC is calculated at 20 

years. This upgrade will not pay back during its lifespan: therefore, implementation of this 

measure is recommended only when the current units are in need of replacement. 

Table 7: HVAC Upgrade Energy Savings 

ECRM 2: HVAC Upgrade 

Annual Savings Economic Analysis 

kWh Cost % Energy Investment IRR NPV Simple Payback 

(years) 

4,720 $614 7% $16,000 -2% -$7,955 26.08 

4.6 ECRM 6: Radiant Barrier Upgrade 

The existing attic insulation is blown-in R-32. By adding a radiant barrier with additional attic 

insulation of R-11 (a combined total of R-43), heating and cooling losses may be minimized. 

The calculations below use $1.20/ sq. ft. for insulation and labor. If this cost could be reduced 

to under $0.40/sq. ft. the additional insulation would pay for itself within its 25-year lifespan. 

Table 8: Radiant Barrier Upgrade Energy Savings 

ECRM 6: Radiant Barrier Upgrade 

Annual Savings Economic Analysis 

kWh Cost % Energy Investment IRR NPV Simple Payback 

(years) 

450 $59 1% $4,608 -7% -$3,603 78.77 
17 

5. Renewable Energy-Related Measures 

5.1 ECRM 7: Solar Thermal Domestic Hot Water 

Building B currently uses around 9,200 kWh to heat water per year. Evacuated-tube solar 

collectors could offset most of the electricity used for heating hot water. Panels are available 

capable of producing 28,000 British thermal units (BTUs)/day in the southern Arizona region. 

The panel size is around 55ft2 (varies by manufacturer) and the building would need two to 

produce all of the building’s hot water needs. The panels would have a first cost of nearly 

$3,000. The economics of this are favorable with a 4-year payback before incentives. 

There are Federal tax credit incentives and also Arizona Public Services incentives available, 

which could lower the cost. If the 30 percent federal tax credit and the $0.50/kWh saved APS 

incentive (up to half of the project cost) can be taken advantage of, the cost would be reduced 

to $600 and would pay back in less than a year. Another consideration is the large amount of 

space required for installation. A storage tank may also be necessary for the hot water loop. 

Consulting with a system designer to establish the best setup for the building is recommended. 

Table 9 summarizes the analysis of this measure. 

Table 9: Solar Thermal Energy Savings 

ECRM 7: Solar Thermal 

Annual Savings Economic Analysis 

kWh Cost % Energy Investment IRR NPV Simple Payback 

(years) 

6,465 $840 10% $3,000 28% $8,424 3.57 

With tax credit and incentive: $600 140% $10,710 0.71 

5.2 ECRM 8: Photovoltaic Array 

The purpose of a photovoltaic array (PVs) is to reduce the use of traditional energy sources. 

This system captures solar energy and converts it to electricity for use in the home which cuts 

down on the amount of energy that must be purchased from the utility company. When 

analyzed using the PV Watts calculator, the following results indicate that a 4.0 kW array in the 

Somerton, AZ, area will produce 6,221 kWh annually. The investment cost is calculated with 

the $8,400 federal/state tax credit and the $800 state utility rebate. With the tax credit, the 

calculator shows that this array would pay back within the photovoltaic 25-year lifespan. The 

measure is recommended for implementation. 

Table 10: Photovoltaic Array Energy Savings 

ECRM 8: Photovoltaic Array Upgrade 

Annual Savings Economic Analysis 

kWh Cost % Energy Investment IRR NPV Simple Payback 

(years) 

6,221 $809 9% $17,800 1% -$6,097 22.01 
18 

5.3 ECRM 9: Geothermal System 

The purpose of a geothermal system is to reduce the use of traditional energy sources. This 

system uses the temperature of the earth to heat and cool buildings. There is a federal tax 

credit (30 percent of measure cost) available for implementing a geothermal system. When 

analyzed in the e-Quest model, the following results indicate this measure should not be 

implemented as the measure will not pay off in its lifetime (20 years). 

Table 11: Geothermal System Energy Savings 

ECRM 9: Geothermal System Upgrade 

Annual Savings Economic Analysis 

kWh Cost % Energy Investment IRR NPV Simple Payback 

(years) 

-940 -$122 -1% $48,000 -$47,165 -392.8 

with 30% Federal Tax Credit: $33,600 -$33,478 -269.8 

5.4 Package of Recommended ECRMs 

The purpose of this package is to combine the ECRMs recommended for implementation, and 

calculate the combined energy savings for these measures. This package includes CFL, 

refrigerator, and exterior window shades. There is an additional calculation with the addition of 

the photovoltaic array and solar thermal. When analyzed in the e-Quest model, the following 

results indicate these measures should be implemented as the package of ECRMs will pay off 

well within the lifetime of the photovoltaic array and solar thermal (25 years). 

Table 12: Package of ECRMs Energy Savings 

Package Upgrade 

ECRMs 

Annual Savings Economic Analysis 

kWh Cost % Energy Investment IRR NPV 

Simple 

Payback 

(years) 

Package 7,785 $1,012 12% $5,595 17% $6,683 5.53 

with Photovoltaic 

Array & Solar 

Thermal 

20,471 $2,661 30% $23,995 9 $8,733 9.02 

After implementing the ECRM package, the utility consumption analysis would be estimated as: 

Utility Consumption Analysis of Building B after Upgrade 

Average Annual Consumption Annual Costs Average Unit Cost 

Electricity 50,038 kWh $6,505 100% 0.13 $/kWh 

Natural Gas therms $/therm 

Total: $6,505 

Total Conditioned Area 5,574 ft2 

Electricity Use Intensity 9 kWh/ft2/yr Natural Gas Use Intensity Therms/ft2/yr

Energy Use Intensity 31 kBtu/ft2

/yr Energy Cost Intensity $1.17 $/ft2/yr 
19 

6. Leveraging ECRMs with Utility Resources 

Local utility companies may offer energy efficiency incentives and on-site energy assessments 

of buildings to eligible customers. The Database of State Incentives for Renewables & 

Efficiency: http://www.dsireusa.org/ provides a summary of available and eligible state and 

utility resources. 

APS provides a Multifamily Energy Efficiency Program (MEEP). The program provides a free 

on-site energy assessment to identify areas of upgrade for energy savings, free energy cost 

reduction measures (ECRMs), and technical and field support to assist with installation to 

eligible building owners. In May 2012, the Tribe requested an on-site energy assessment of 

Building B to determine eligible ECRMs. In June, MEEP installed, at no cost the following 

ECRMs: 

 24 Kitchen Faucet Aerators and 36 Bathroom Faucet Aerators 

The aerators use 1.5 gallons per minutes using 31 percent less water compared to the 

standard 2.5 gallons per minute faucet. By using a lower flow faucet, less energy is 

used for heating hot water for everyday use. 

 38 Low-Flow Showerheads 

The low-flow showerheads use 1.5 gallons per minute using 20 percent less water than 

the standard 2.5 gallons per minute showerheads. It is estimated that $246 in utility bills 

and 8,212 gallons of water per year will be saved. 

 360 Compact Fluorescent Lamps 

The energy consumption models shows that, for Cocopah residents, household lighting 

accounts for over 20 percent of their total energy use.7

 Switching to energy-efficiency 

lighting is one of the fastest ways to cut energy bills. CFLs last about 10 times longer 

and use about 75 percent less energy than traditional incandescent bulbs. A typical CLF 

lamp can pay for itself in energy savings in less than 9 months and can continue to cut 

energy costs each month. 

 Incentives are offered for solar thermal domestic hot water, and photovoltaic array 

installation. 

 

7

 http://www.energysavers.gov/tips/indoor_lighting.cfm 
20 

7. Develop an Energy Management Strategy 

Organizations that adopt and practice an energy management strategy are rewarded with 

lower energy use. These plans are very effective and are considered low cost. The United 

States Green Building Council (USGBC) recommends using an energy management plan to 

save 10 percent of energy use. The SCinIC team recommends this plan to CIHAD. Here are 

the steps that describe an energy management strategy offered by ENERGY STAR.8

1) Make a Commitment: Recognize that the economic, environmental, political, and social 

impacts of energy consumption are sufficient motivation to change our energy use patterns. 

2) Assess performance: Make a personalized accounting of energy use and costs. 

Benchmark your site by comparing its energy performance with similar sites. 

3) Set Goals: Review your objectives and constraints. Establish priorities and set 

measurable goals with target dates. 

4) Create an Action Plan: Define the technical steps. Apply proven methods to increase 

energy efficiency or get specialized guidance. Assign roles and resources. Consider 

rolling savings from earlier efforts into future, more complex initiatives. 

5) Implement Action Plan: Install equipment and change operational procedures. Establish 

a maintenance schedule. Train equipment operators and building occupants on the 

changes. Track and monitor conditions. 

6) Evaluate Progress: Compare current performance to established goals. Understand 

what worked well in order to identify best practices. Adjust procedures, goals, and 

schedule the next evaluation. 

7) Recognize Achievements: Provide internal recognition for the efforts and achievement of 

individuals, teams, and facilities. Seek external recognition from government agencies, 

media, or third party organizations. 

The quickest, easiest, and cheapest way to reduce loads during peak hours is to ensure 

that lights and equipment are turned off whenever they are not required. This could be 

achieved by developing better occupancy habits by the residents. Savings can also be 

achieved by changing the thermostat settings to minimum cooling during the peak day time. 

Thermostat should be set to 78 °F for occupied zones. 

 

8

 For more information on the ENERGY STAR energy management strategy: 

http://www.energystar.gov/index.cfm?c=guidelines.guidelines_index 
21 

8. Conclusions and Recommendations 

In summary, this report provides information and strategies on how to reduce the annual 

operation cost through load reduction, energy efficiency improvements, and renewable energy 

sources. Table 13 includes a summary of the quantified results. 

Table 13: Summary of ECRMs

Energy Cost 

Reduction Measure 

(ECRM) 

 Number 

of ECRMs 

Annual Energy Savings Economic Analysis 

kWh Cost % 

Energy Investment IRR NPV 

Simple 

Payback 

(years) 

CFLs 79 2,171 $282 3% $395 66% $788 1.40

Refrigerators 8 3,754 $488 6% $3,200 9% $541 6.56

Window Shades 20 1,860 $242 3% $2,000 10% $965 8.27

Window Shades 2 4 2,240 $291 3% $6,000 0% -$2,258 20.60

Triple low-e windows 20 2,100 $273 3% $6,000 -1% -$2,474 21.98

HVAC Upgrade 8 4,720 $614 7% $16,000 -2% -$7,955 26.08

Radiant Barrier 3,840 ft2 450 $59 1% $4,608 -7% -$3,603 78.77

Solar Thermal 2 6,465 $840 10% $600 140% $10,710 0.71

Photovoltaic Array 4 KW 6,221 $809 9% $17,800 1% -$6,097 22.01

Geothermal 32 wells -940 -$122 -1% $48,000 0% -$47,165 -392.80

All Recommend 

ECRMs 20,471 $2,661 30% $23,995 9% $8,733 9.02
22 

Attachment A