sustainable energy benchmarking and greenhouse gas accounting

Sustainable Energy Benchmarking and Greenhouse Gas Accounting for Municipal

Government Operations

Prepared by,

Lyndsay Hazen, Graduate Student

Dr. Anu Ramaswami, Professor and Director, Program on Sustainable Urban Infrastructure

University of Colorado Denver

Spring 2009

City of Durango, Colorado

Sustainable Energy Benchmarking and Greenhouse Gas Accounting: City of Durango Municipal Government Operations

University of Colorado Denver, IGERT, Program on Sustainable Infrastructure

Acknowledgements:

Thanks to Greg Caton, Nancy Andrews, and the many City of Durango staff members that helped collect the vast

amounts of data required for this project.

La Plata Electric Association: Susan Maxwell and Ray Pierotti

Atmos Energy: Pennelin Fugate



Contents

Executive Summary ......................................................................................................................... 5

Introduction to Sustainable Energy Futures ................................................................................... 9

The Business Case for Sustainable Energy: ............................................................................. 9

Sustainable Energy Planning and Greenhouse Gas Accounting: ............................................. 9

Greenhouse Gases (GHGs): ..................................................................................................... 9

Developing a Sustainable Energy Plan: ................................................................................. 10

2. Goals & Objectives: City of Durango’s Municipal Operations ................................................. 12

City of Durango Municipal Operations Overview:................................................................. 13

3. GHG Inventory Method ............................................................................................................ 15

Method and Scopes: .............................................................................................................. 15

4. Municipal Government Energy and GHG Analysis.................................................................... 18

Reporting Year ....................................................................................................................... 18

4.1 Buildings and Facilities Sector ............................................................................................. 18

Buildings and Facilities Energy Consumption and Energy Intensity ...................................... 18

Buildings and Facilities Sector Energy Flow Overview: ......................................................... 19

Buildings and Facilities Emission Factors ............................................................................... 20

4.2 Transportation Sector ......................................................................................................... 22

Vehicle Fleet Fuel Consumption and Fuel Economy/Energy Intensity: ................................ 22

Transportation Emission Factors: .......................................................................................... 23

Employee Commute Emissions: ............................................................................................ 23

4.3 Materials and Waste Sector ................................................................................................ 25

Annual Material Flow for Materials and Waste: ................................................................... 25

Emission Factors for Materials and Waste: ........................................................................... 25

5. Green Power ............................................................................................................................ 28

6. Conclusions: .............................................................................................................................. 29



Status of Durango’s Path toward Greening Government Goals: .......................................... 29

Works Cited ................................................................................................................................... 30

List of Figures:

Figure 1. Breakdown of Durango’s Municipal Government Greenhouse Gas Emissions by Sector

......................................................................................................................................................... 6

Figure 2. Durango’s Municipal Government Greenhouse Gas Emissions by Energy Source ........ 6

List of Tables:

Table 1. Durango Government Operations Overview ................................................................. 13

Table 2. Buildings and Facilities Sector Benchmarks ................................................................... 19

Table 3. Building Sector Emissions Summary .............................................................................. 21

Table 4. Transportation Benchmarks ........................................................................................... 22

Table 5. Transportation Energy Flow Emissions ........................................................................... 23

Table 6. Employee Commute Material Flow and Emissions Summary: ...................................... 24

Table 7. Materials and Waste Summary Table ............................................................................ 27

Table 8. Green Power Offsets ...................................................................................................... 28

Table 9. Greening of Government Goals ..................................................................................... 29

Acronyms:

CO2e: carbon dioxide equivalent

GHG: Greenhouse Gases

ICLEI: Local Governments for Sustainability

IPCC: International Panel on Climate Change

GWP: Global Warming Potential

EIA: Energy Information Administration

EF: emission factor



Executive Summary

The City of Durango governs 9.8 square miles (25.5km) of land, operates over 318,000 square

feet of buildings and facilities, and serves approximately 18,000 people. The City seeks to

develop a sustainable energy plan for its municipal government operations that leverages

energy efficiency, energy conservation and renewable energy with economic savings and

business opportunities. To accomplish this plan, the City of Durango seeks to implement the

three steps described in this report:

Greenhouse Gas Emissions Inventory: The first step in developing a sustainable energy

plan is to develop a greenhouse gas emissions (GHG) inventory. The greenhouse gases

included in this report are carbon dioxide, methane and nitrous oxides, represented as

carbon dioxide equivalents or CO2e. A GHG emissions inventory provides a consolidated

accounting of the emissions from city government’s use of fossil fuel energy.

Sustainable Energy Goals: Once a GHG inventory is complete, the next step is to

establish realistic goals and timeframes for energy use and emissions reductions.

Sustainable Energy Action Matrix: Using the GHG Inventory and the Sustainable Energy

Goals for guidance, targeted actions to reduce the GHG emissions from municipal

operations are evaluated and compiled into an Action Matrix. The Sustainable Energy

Action Matrix will be a working document used to provide preliminary insight into the

“how” component of implementing a sustainable energy plan and achieving emission

reductions.

Results from Durango’s municipal government GHG emissions accounting are summarized next.

GHG Emissions Inventory: In 2008, Durango’s total municipal government GHG footprint was

14,582mt-CO2e. The buildings and facilities sector contributes about 75% of the total

emissions, transportation 18%, and materials and waste seven percent. Figure 1 shows the

City’s municipal government emissions subdivided into local government sectors. The greatest

emission sources were from buildings and facilities (38%), followed by the wastewater

treatment plant and pumps (15%), and the city vehicle fleet (13%). Figure 2 shows Durango’s

municipal operations GHG emissions by energy source. Electricity usage is the greatest source

of emissions, representing 63% of all emissions, followed by natural gas at 11%. The footprint

results show that the bulk of Durango’s GHG emissions are associated with buildings and

facilities energy use.



Figure 1. Breakdown of Durango’s Municipal Government Greenhouse Gas Emissions by Sector

About 75% of Durango’s municipal government emissions are associated with buildings and facilities (shown in shades of blue). The City and Airport vehicle fleet (including Durango Transit and the Police Dept.) and employee commute (shown in red) contribute 18%. About 7% of Durango’s emissions (shown in green) are associated with the embodied energy of materials (including paper, cement, asphalt, and fertilizer) used by the City.

Figure 2. Durango’s Municipal Government Greenhouse Gas Emissions by Energy Source

Buildings and Facilities

38%

Airport9%

Streetlights/Traffic Lights/Park Lights/

Irrigation6%

Water Treatment/ Pumps

7%

Wastewater Treatment/ Pumps

15%City and Airport Vehicle Fleet

13%

Employee Commuting

5%

Waste and Recycling

2%

Fugitive Emissions from Wastewater

Treatment1%

Materials4%

2008 GHG Emissions by Local Government Sector

2008 Emissions: 14, 438 mt-CO2ePer-Person Served Emissions: 0.8 mt-CO2e/person

Natural Gas Usage11%

Electricity Usage63%

Gasoline7% Diesel

6%

Propane0%

Employee Commute (gasoline&

diesel)5%

Embodied Energy of Key

Materials (upstream production emissions)

7%

2008 GHG Emissions by Energy Source



Sustainable Energy Goals: For step two, the City of Durango has adopted Colorado’s Greening

of Government Goals: a 20% reduction in energy use and a 25% reduction in transportation

fuel use by June 1st, of 2012.

Sustainable Energy Action Matrix:

The Sustainable Energy Action Matrix is a valuable tool for tracking the progress and assessing

and comparing the cost-benefits of various sustainable energy strategies.

Current Actions: The GHG Inventory reports the City’s energy consumption and emissions

status as of 2008. Since 2008, the City of Durango has undertaken a number of actions to

reduce energy consumption and improve the efficiency of municipal operations. A few of the

actions that are currently being implemented include: instituting an energy efficient computer

power policy, purchasing smaller replacement vehicles, and installing renewable energy

technologies at the Wastewater Treatment Plant and the Recreation Center. The City of

Durango’s current initiates have been included in the Action Matrix as a strategy for tracking

progress during the timeframe between GHG Inventory Reports.

Next Steps: The Sustainable Action Matrix provides a preliminary assessment and comparison

of the cost-benefits for the City’s “Next Steps”. A summary of the Actions assessed is provided

below.

Buildings and Facilities:

Increasing the efficiency of the City’s lighting was a major target for the Climate Action

Matrix. It is recommended the City transition its buildings and facilities to LED tube lighting

which uses 50% less energy than T12s and 30% less energy than T8s. The City’s indoor lighting

could be further retrofitted by installing motion sensors and identifying opportunities to

decrease the lighting wattage in buildings. Estimated Savings: $40,000 annually in electricity

costs and a 3.0% reduction in GHGs (from the 2008 baseline).

It is also recommended that City replace its current streetlights with LED streetlights,

which are 25% more efficient. Estimated Savings: $4,000 annually in electricity costs and a

1.7% reduction in GHGs.

A four-day work week for four of the City’s buildings (City Hall, River City Hall, Carnegie

Building, and General Services) was assessed. Estimated Savings: $4,000 annually in electricity

and heating costs and a 0.31% reduction in GHGs.



Other recommendations include performing a detailed building retrofit analysis for all

City buildings, particularly the Recreation Center (the City’s largest energy consumer). A

detailed technical analysis for the City’s water/wastewater pumps and motors is also

recommended.

Transportation:

A low cost initiative to improve the City’s vehicle fleet economy is to provide Eco-Driving

Training for employees. Studies indicate driving the speed liming, accelerating properly, and

reducing idling can improve vehicle fuel economy by 12%. Estimated Savings: $49,000 annual

in fuel costs and a 1.5% reduction in GHGs.

For the City’s existing diesel engine vehicles, it is recommended the engines be

retrofitted with new smart valve technology, which has been proven to improve fuel economy

by 20%. Estimated Savings: $30,000 annually, a 0.9% reduction in GHGs.

It is suggested the City seek opportunities to improve the fuel economy of the Police

Fleet. Strategies include using hybrid-electric vehicles and downsizing to 6-cylinder vehicles

where appropriate. Such strategies could improve the fuel economy of the Police fleet by 55%.

Estimated Savings: $36,000 annually in fuel costs, and a 1.7% reduction in GHGs.

The City should also seek opportunities to replace its solid waste and recycling fleet with

hydraulic-electric hybrids. Considering the stop and go nature of trash trucks, hybrid-electrics

could potentially improve the fuel economy of the Solid Waste & Recycling fleet by 20%.

Estimated Savings: $12,000 annually in fuel costs and a 0.3% reduction in GHGs.



Introduction to Sustainable Energy Futures

Sustainability is widely understood to encompass the three E’s: Economics, Environment and

Equity. In the context of the environment, sustainability refers to more efficient use of scarce

natural resources such as water, energy and minerals, as well as reducing or avoiding emissions

of toxic pollutants such as heavy metals, harmful pesticides, and carcinogens. Sustainability

entails facilitating human activities that simultaneously promote economic development,

environmental protection, and social equity.

The Business Case for Sustainable Energy:

There has been much interest nationally, in the State of Colorado, and in several Colorado cities

in developing sustainable energy plans. These plans are motivated by the projected increase in

global demand for limited oil and gas resources, the increasing world-wide cost of fossil fuels,

our dependence on foreign oil which impacts national energy security, and our understanding

of the global and local environmental impacts of using fossil energy. These impacts include

local-scale air pollution from petroleum use in automobiles, local-scale air pollution from coal-

fired power plants, and global impacts of greenhouse gas emissions that is projected to have

local impacts in Colorado, including impacts on the snow pack, water supplies and local

agriculture. Looking toward a future with increased cost and reduced availability of fossil

energy, cities are embarking on sustainable energy plans that save money through energy and

resource conservation, generate jobs in the new green energy economy focused on energy

efficiency and renewable energy, and promote community-wide economic development.

Sustainable Energy Planning and Greenhouse Gas Accounting:

We use fossil fuel for almost all human activities – for cooling and heating our buildings, for

transportation, and for industrial production. An accounting of CO2 emissions from burning

fossil fuel promotes a comprehensive understanding of our fossil energy use. In addition, such

Greenhouse Gas accounting is also useful to represent human impact on climate.

Greenhouse Gases (GHGs):

The internationally recognized Greenhouse Gases (GHGs) include carbon dioxide (CO2),

methane (CH4), nitrous oxide (N2O) and three replacements for chloroflorocarbons—HFCs ,

PFCs , and sulphur 9exafluoride (SF8). The first three GHGs are dominant and account for more

more than 90% of GHGs emitted nationally (1). Carbon dioxide (CO2) is produced primarily



from the burning of fossil fuels and is the largest contributor to global warming. Methane (CH4)

is

produced largely from biodegradable waste

decomposition (naturally or in landfills) and

from fugitive emission in natural gas pipelines.

Nitrous oxide is often emitted from fertilizers,

combustion, and wastewater treatment plant

effluent. HFC, PFC, and SF6 are often found in

vehicle and building air conditioning units and

refrigerators and generally contribute trivially.

The different GHGs have different one hundred

year global warming potentials (ability to trap

heat in the atmosphere over time). For

example, according to the IPCC’s 2nd Assessment

Report, methane is twenty-one times better at

trapping heat than carbon dioxide. Nitrous

oxide is 310 times better at trapping heat than carbon dioxide. The GHGs are reported

together on a common standardized basis as metric tons (mt) of CO2e, called carbon dioxide

equivalents.

Developing a Sustainable Energy Plan:

Developing a sustainable energy plan for a community includes:

Kyoto Protocol/Internationally

Recognized Greenhouse Gases

100-Year Global Warming Potential

(GWP)

Carbon dioxide (CO2) 1

Methane (CH4) 21

Nitrous Oxide (N2O) 310

HFCs Varies: 140-11,700

PFCs Varies: 6,500-9,200

Sulphur Hexaflouride (SF8)

23,900

*The GWPs from the International Panel on Climate Change (IPCC) Second Assessment Report were used in this report as recommended by ICLEI Local Government Operations Protocol 2008, p166.



Conducting an inventory of CO2e emissions to understand fossil fuel use and associated GHG emissions in basic human activity sectors

Developing a matrix of actions that can be taken in each of the sectors to promote energy efficiency, conserve resources, save money and/or create business opportunity while mitigating CO2e emissions

Choosing and prioritizing among the available action options based on local economics, culture, civic engagement and political support to develop a practical sustainable energy action plan suited for implementation.

Developing an implementation plan for the prioritized actions, with outcomes assessment protocols

Some communities are also focusing on adaptation strategies such as, planning to adapt to water supply variation, peak oil prices, or other anticipated future trajectories.



2. Goals & Objectives: City of Durango’s Municipal Operations

The City of Durango seeks to be a leader in sustainable energy planning and has identified a

number goals and objectives for the local municipal operations.

In accordance with the Governor of Colorado’s Greening of Government Executive Orders,

Durango’s government operations and facilities will seek to achieve the following five goals by

June 30, 2012 (2):

-20% reduction in energy use

20% reduction in paper use

-10% reduction in water consumption

- 25% volumetric reduction in state vehicle fuel consumption

In Spring of 2009, Durango contracted with the IGERT Program on Sustainable Urban

Infrastructure at the University of Colorado Denver to assist in developing a sustainability plan

for the City of Durango’s Municipal Government Operations, based on the business case of

advancing the three E’s of sustainability. The objectives of the study were to:

Conduct an inventory of municipal government CO2e emissions, to understand fossil fuel

use and associated GHG emissions from the three main sectors of the City of Durango’s

Municipal Government Operations: buildings and facilities, transportation, and

materials.

Develop a matrix of sustainable energy actions that can be taken in each of the activity

sectors to promote energy efficiency, conserve resources, save money and/or create

business opportunities while mitigating CO2e emissions.

In this section we present background information about the City of Durango’s Municipal

Government Operations, after which Section 3 describes the methodology used and Section 4

develops the GHG inventory for Durango’s Municipal Government Operations.



City of Durango Municipal Operations Overview:

The GHG Inventory includes all City Municipal Operations and Facilities as well as the Durango-

La Plata Airport. (Buildings not included are cited in Table 1.) The City of Durango’s population

was estimated to be 15,559 in 2005 and 16,169 in 2008 (3). However, due to a year-round

tourism industry and a fluctuating student population from Fort Lewis College, a more realistic

population served by city government services was estimated to be approximately 17,000 in

2005 and 18,000 in 2008 (4). The number of City employees (full-time and part-time) grew

from 395 in 2005 to 425 in 2008. In 2005, the City of Durango owned and operated fifteen

buildings, totaling 270,736. Between 2005 and 2008, the Three Springs Police-Sub Station and

the LEED Library were built; expanding the City’s building square footage by 18 percent to

318,513 square feet. Table 1 lists key indicators for tracking local government’s growth.

Table 1. Durango Government Operations Overview

Municipal Government Overview:

Key Indicators: 2005 2008

Population (# of residents) 15,959 16,169

Population Served* (residents + part-time residents & students/tourists) 17,000 18,000

Total Land Area (square miles) 9.77 9.84

Full-Time Equivalent Employees** 280 310

Total City Employees 438 478

Full-time 258 284

Part-time/Temporary 179 193

Cooling Degree Days 108 165

Heating Degree day 7856 8368

Buildings and Facilities:

Number of City Buildings*** 15 17

Total Building Square Footage

270,736 318,513

Number of Servers 25 30

Number of Computers 298 302

Number of CRT Monitors NA 302



Airport:

Annual Arriving and Departing Passengers

210,000

270,000

Full-Time/Part-Time Employees 14/0 14/2

Water/Wastewater Treatment Plants

Population Served 17,000 18,000

Number of Customers 5335 5561

Water Treated (million gallons) 1294 1283

Wastewater Treated (million gallons) 722 735

Ave/Max Daily Load (million gallons) 2.0 / 3.0 2.0 / 3.0

Biosolids (short tons per year) 415 369

Streetlights

Total 762 863

100 Watt 18 22

175 Watt 55 115

250 Watt 542 579

400 Watt 147 147

Parks

Number 31 32

Parks (acres) 250 268

Open-Space (acres) 786 935

Percent Irrigated 71%

Vehicle Fleet (does not include airport fleet)

Total Fuel Consuming Units NA 213

Gasoline 120

Durango Transit NA 12

Police Department NA 21

Toyota Prius/Hybrid NA 2

Staff Car 2x2 NA 4

Staff Car 2x4 NA 4

Pickup 2x2 NA 10

Pickup 2x4 NA 20

MiniVan NA 12

Misc. Equipment/Surplus Equip NA 35

Diesel 80

Durango Transit 9

Dumptrucks/Recyle/SolidWaste/Street Sweepers etc. 60

Diesel Trucks (4x4) 6

Diesel Trucks (4x2) 5

Propane 5

Natural Gas 8

Durango Transit/Public Bus

Miles Served NA 77.5

# of Annual Passengers 296,269 365,048

Bike Paths and Lanes (miles) NA 11

*Population served includes a percentage of tourists and Fort Lewis students that are not included in standard population data. **Full-time equivalent number was approximated by the Human Resource Dept. ***The energy consumption from the City owned, but rented Silver Peaks Condo, Pingrey Daycare, and La Plata Youth Services were not included in the GHG Inventory.



3. GHG Inventory Method

Method and Scopes:

The GHG inventory is conducted using the advanced method developed by Ramaswami et al

(2008) (5). The method uses the standardized ICLEI protocol to report GHG emissions from in-

boundary activities. Out-of-boundary activities critical for Municipal Government Operations –

such as the purchasing of copier paper, cement, asphalt, fertilizer, and employee commute –

are added on to the in-boundary activities to yield a more holistic GHG footprint. The inclusion

of additional out-of-boundary (WRI Scope 3) activities is highly recommended by EPA’s Climate

Leaders Program. The Ramaswami et al (2008) inventory-footprint method for GHG

accounting was first pioneered by UCD with the City of Denver, and since by other cities such as

Portland, OR, Seattle, WA, Arvada, CO, Austin, TX, Minneapolis, MN. This is the first application

of the methodology to municipal government operations.

In-boundary activities include the following energy uses and are required to be reported by all

cities as per ICLEI and WRI guidelines (6).

BUILDINGS and FACILITIES–Emissions from the use of electricity and natural gas in municipal buildings and operations.

TRANSPORT –Emissions from the use of gasoline, diesel, and propane fuels in city owned vehicles.

Formally, the GHGs emitted directly from burning natural gas in buildings and gasoline/diesel in

vehicles are termed Scope 1 emissions by WRI, while CO2e emissions from power plants to

produce the electricity used within our community is termed Scope 2 emissions. Scope 1-2

plus solid waste emissions from in-boundary landfills are included in the “In-boundary”

activities and are required to be reported in a city’s GHG inventory as per ICLEI protocols.

Out-of-boundary activities designated by the WRI as Scope 3 are optional, but are highly

recommended by the EPA as they can lead to win-win strategies for GHG mitigation. The

following out-of-boundary activities, when added to in-boundary activities, yield a more holistic

account of a municipal governments CO2e footprint:



EMBODIED ENERGY OF CRITICAL URBAN MATERIALS: The associated GHG

emissions from the energy used to produce critical urban materials (fuel,

paper, asphalt, concrete, fertilizer) and from the waste and recycling that is

transported out-of-boundary.

Energy Use Sectors: To better communicate a municipal government’s overall energy use and

GHG emissions, classifying end-use of energy into three different sectors is useful (versus the

WRI in-boundary and out-of boundary activity classification). In this report, we consistently

report energy use and GHG emissions in the following three sectors:

Buildings and Facilities– Energy use in local government buildings and facilities.

Subdivided into the following local government sectors:


Airport

Streetlights and Traffic Signals (park irrigation included here)

Water Treatment and Distribution

Wastewater Treatment and Collection

Transport – Energy use to operate the City and Airport vehicle fleet and energy use for

employee commute. Generally termed Pump-to-Wheels (P2W) energy use.

City and Airport Vehicle Fleet

Employee Commute

Materials and Waste-- Energy use and associated GHG emissions from producing critical urban

materials and from waste disposal.

Upstream Fuel Production

Paper

Asphalt (Street Maintenance Division)

Concrete (Street Maintenance Division)

Fertilizer

Solid Waste and Recycling

Fugitive Emissions from the Wastewater Treatment Plant



Annual Energy Consumption/Material Flow Data: The annual Material/Energy Flow Analysis

tells us how much the municipal government is consuming. For energy (or materials use) in

each of the three main sectors, the following datasets were gathered: total kWh of electricity

consumed annually, total natural gas use consumed annually, and fuel consumed annually. By

benchmarking these consumption data on a per community member served, per square foot of

building space or other metrics, we can represent how efficient the municipal government’s

consumption patterns are.

GHG Emission Factors: GHG emissions factors tell us how clean our energy or materials are in

terms of how much CO2e is emitted per unit of the product consumed. For example, kg CO2e

emitted per unit kWh of electricity consumed.

Total emissions are computed as the product of how much is consumed and the GHG emissions

per unit of the product consumed. In the next section, consumption data and emission factors

for all three sectors are reported and an overall municipal government GHG inventory and

footprint is developed.



4. Municipal Government Energy and GHG Analysis

Reporting Year: This section reports energy (or materials) consumption data and associated

GHG emissions factor for 2005 and 2008 for the three main sectors:

Buildings

Transport (Tailpipe emissions)

Materials and Waste

For each sector, raw consumption data are presented first, the data are then normalized and

compared with benchmarking metrics after which emission factors are used to quantify GHG

emissions. The total GHG emissions from each sector are consolidated and reported in an

overall municipal government operations summary in Table 12. GHG emissions are reported in

terms of metric tons (mt) of carbon-dioxide equivalents, shown as CO2e.

4.1 Buildings and Facilities Sector:

Buildings and Facilities Energy Consumption and Energy Intensity:

The buildings sector energy use reports electricity and natural gas consumed in City buildings,

Airport buildings, Street lights and Traffic signals, Water Treatment/Distribution, and

Wastewater Treatment/Distribution. City buildings included in the building and facilities sub-

sector include: City Hall, River City Hall, Old Library, Mason Center, Communications Centers,

Recreation Center, Police Department, the Three Springs Police Substation, the Recycling

Center and various other smaller facilities such as cemeteries and Chapman Hill Ice Rink.

Electricity data was obtained from La Plata Electric Association (LPEA) for 2005 and 2008.

Natural gas data was obtained from Atmos Energy for City buildings and Source Gas for the

Airport. Based on the square footage of Durango’s city buildings (building data obtained from

the City of Durango), energy use intensity can be computed in terms of electricity and natural

gas use per kBTU used per square foot. These intensity numbers for buildings in Durango can

then be benchmarked with similar energy intensity metrics reported by the Energy Information

Agency (EIA) for commercial spaces in the Rocky Mountain region.



Table 2. Buildings and Facilities Sector Benchmarks

Buildings and Facilities Sector Benchmarks:

Commercial Buildings: City Hall

Durango Police

Department Rec.

Center

CBECS Mountain Census Division

CBECS National

Electricity (kWh/sq.ft) 72.8 18 105.8 15 14

(therm/per sq. ft) 0.55 0.37 2.38 1 0.9

(kbtu/per sq. ft. ) 128 99 344 NA 93

*Commercial Buildings Energy Consumption Survey (CBECS), 2003.

Buildings and Facilities Sector Benchmarks:

Water Treatment Plants: Durango

2005 Durango

2008 City of Denver

gallons treated per person/per day 209 195 150

watts per gallon of water treated 0.75 0.76 0.5

Wastewater Treatment Plants:

watts per gallon of wastewater treated 3.84 3.68 1

*Water/Wastewater people served: 17,000 in 2005 and 18,000 in 2008.

*City of Denver, GHG Inventory, 2007

Buildings and Facilities Sector Energy Flow Overview:

In 2008, the City of Durango consumed 10,773,073 kWh of electricity and 361,508 therms of

natural gas. Electricity use (kWh) increased by 10% and natural gas use (therms) increased by

15% between 2005 and 2008. A number of factors contribute to the increase in electricity and

natural gas use including an increase in building square footage and an increase in both cooling

and heating degree days in 2008 (see Table 1) (7).

To compare total energy usage, the electricity and natural gas data was converted to kBtus.

For electricity, one kWh is equivalent to 3,412 Btu. For natural gas, one therm is equivalent to

100,000 Btu. When measured in kBtus, the City of Durango’s total energy usage increased by



12% between 2005 and 2008. The Buildings and facilities sector energy use increased by 21%

while the other sectors total energy usage decreased between 2005 and 2008.1

Electricity by Sector: The City of Durango’s total electricity consumption continues to increase.

The Streetlights, Park Lights, and Irrigation Sector experienced the greatest increase, 32%, in

electricity usage between 2005 and 2008. The increase is most likely contributed to the

installation of 137 400 watt street lamps at Rivergate Drive, which, in itself, increased the kWh

usage by approximately 195,000 kWh annually. Electricity usage at the Airport increased by

226,359 kWhs (18%). A portion of the Airport’s electricity increase can be contributed to the

installation of a new air conditioning unit. For the buildings and facilities sub-sector, electricity

usage increased by 367,535 kWh (9%), likely contributable to standard service expansion

including the addition of two buildings to the City’s inventory: the LEED Library and the Three

Springs Police Station. At the Water Treatment Plant, electricity usage increased by four

percent and the Wastewater Treatment Plant experienced a three percent increase. Although

the Wastewater Treatment Plant has stabilized electricity consumption, it continues to be a

substantial electricity consumer, representing 25% of the City’s total electricity consumption.

Natural Gas by Sector: The buildings and facilities natural gas usage increased by 70,148

therms or 9%. The Recycling Center, River City Hall, and the Bodo Facility experienced the

greatest percent increases in natural gas consumption. Chapman Hill Ice Rink’s natural gas

consumption decreased by 66%, a likely result of the building being enclosed. City Hall’s

natural gas usage decreased by 15%, reflecting the efficiency of the building’s recently installed

boiler.

Buildings and Facilities Emission Factors:

The 2008 GHG emission factor for electricity (0.83 kg-CO2e/kWh) was calculated from Tri-State

Generation’s (LPEA’s parent company) 2007 energy mix ratio (8). An emission factor of 1.0 kg-

CO2e per kWh produced was used for the percent of electricity produced from coal. An

emission factor of 0.5 kg-CO2e per kWh produced was applied to the percent of electricity (9)

produced from natural gas. The emission factor for natural gas (5.3 kg-CO2e/therm) is from the

ICLEI protocol (10). These emission factors are in line with those reported by the EPA and EIA

Although the data indicates the Airport Terminal building’s natural gas consumption decreased by 36% between 2005 and 2008, it is hypothesized that the gas meter is inaccurate.

1



for the Rocky Mountain Region (11). Using the electricity and natural gas emission factors (EF)

and the annual energy use data, a total of 10,854 mtCO2e was calculated for the Building and

Facilities Sector in 2008 as shown in Table 5.

Table 3. Building Sector Emissions Summary

Buildings and Facilities Emissions Totals:

Buildings and Facilities Sector

2005 Emissions (mt-CO2e)

2008 Emissions (mt-CO2e)

05-08 % Change

(mt-CO2e)

% of Total 2008 GHG Emissions


4,770

5,448 14% 38%

Airport Facilities

1,263

1,367 8% 9%

Street Lights, Park Lights, & Irrigation

672

885 32% 6%

Water Treatment Plant/Pumps

989

1,010 2% 7%

Wastewater Treatment Plant/Pumps

2,113

2,144 1% 15%

Total

9,807

10,854 11% 75%



4.2 Transportation Sector

Vehicle Fleet Fuel Consumption and Fuel Economy/Energy Intensity:

Fuel use for gasoline, diesel, biodiesel, and propane was obtained from the City of Durango

General Services Department and the Durango-La Plata Airport. Fuel data sub-divided by

department/division was not available. Fuel consumption data from City employees’ commute

was obtained from an online survey distributed by the IGERT program in Spring of 2009.

Table 4. Transportation Benchmarks

Transportation Benchmarks:

Sectors: City of

Durango National Average

Durango Transit:

Loop/Trolley Gasoline (mpg) 8/7.5 varies

Loop/Trolley Diesel (mpg) 10/11.0 varies

Police Fleet:

Aspen Traditional.

Patrol Car*/Highlander

Hybrid

Police Fleet (mpg) 9 12.9/21.73

Employee Commute:

Drive to Work Alone 85% 77%

Average One-Way Commute (miles) 13 16

Average Fuel Vehicle Fuel Economy (miles) 22 21

*Source :http://www.aspenpitkin.com/depts/53/hybrid.cfm

*State of Colorado Employee Commute Survey, 2007

**U.S. Census Bureau, 2005



Transportation Emission Factors:

Emission factors for gasoline and diesel were obtained from GREET for pump-to-wheels

analysis, appropriate for vehicle operations (12). The emissions factors of 9.3 kg for gasoline

and 9.5 kg for diesel are in-line with those in ICLEI and IPCC. The emission factor for propane,

5.74 was from ICLEI (10) and the emission factor for B20 biodiesel was from the EIA-1605 (9).

The emissions factor for transportation fuels was combined with the total material flow

resulting in the total transport sector tailpipe emission at 1,439 mt CO2e for 2005 and 1,848

mt-CO2e for 2008. Details are provided in Table 7 below.

Table 5. Transportation Energy Flow Emissions

City and Airport Vehicle Fleet Summary Table:

Fuel

2005 Total MFA (gallons)

2008 Total MFA

(gallons)

2005 Vehicle

Fleet Emissions

Total (mt-CO2 e)

2008 Vehicle

Fleet Emissions

Total (mt-CO2 e)

2005 to 2008 % Change

in Emissions

2008 % of Total

Emissions

Gasoline 61,939 102,760 576 956 66% 6.62%

Standard Diesel 62,629 93,344 595 887 49% 6.14%

Biodiesel 32,000 0 260 0 0.00%

Propane 1,403 980 8 6 -30% 0.04%

Total 1,439 1,848 28% 12.80%

Sources: City of Durango, General Services; Durango La-Plata Airport

Employee Commute Emissions:

The ICLEI GHG Inventory Protocol recommends emissions from employee commutes are

included in a local government’s GHG inventory. Using the average full-time equivalent

employee, the average employee commute, and the average fuel economy of employee

vehicles the emissions from the City employees’ commute were estimated at 699 mt-CO2e for

2005 and 786 mt-CO2e for 2008.



Table 6. Employee Commute Material Flow and Emissions Summary:

Employee Commute Summary Table:

Employee Commute Data 2,005 2,008

2008 % of Total

Emissions

FTE Employees 280 310

Average One-Way Commute 13 13

Total Annual Commuting Miles 1,644,829 1,830,578

Gallons of Fuel Consumed

Gasoline 71,344 79,869

Diesel 3,725 4,599

Total Emissions 699 786 5.44%



4.3 Materials and Waste Sector

Annual Material Flow for Materials and Waste:

Annual Consumption of Key Materials: Consumption of transportation fuels was determined

from total fuel flow as summarized in Table 7. The consumption of paper for 2005 and 2008

was provided by the City of Durango’s Purchasing Division. The 2008 consumption of asphalt

and cement was provided by the City of Durango’s Street Maintenance Division. The 2008

consumption of fertilizer was provided by the City of Durango’s Parks Division. The 2005

consumption data for asphalt, cement, and fertilizer was assumed the same as 2008.

Annual Municipal Waste and Recycling: The annual tonnage of waste and recycling collected

from each City building and facility was estimated based on the size of the container, how full

the container generally is when it is serviced, and how many times a week the building is

serviced. The waste and recycling data was provided by the City’s Department of Sustainable

Services and the Solid Waste Division. Waste and recycling data for the Durango-La Plata

Airport was provided by the Airport. In 2005, Durango’s waste was transported to the Bondad

Landfill, which was approximately 20 miles from the Durango Transfer Station. In 2008,

Durango’s waste was transported to the Crouch Mesa Landfill in New Mexico, approximately 45

miles from the Durango Transfer Station. Currently, neither landfill uses a methane collection

and flaring system.

Annual Fugitive Emissions from Wastewater Treatment Plant: The daily amount of digester

gas (ft3/per day) produced at the wastewater treatment plant was provided for 2008. The 2005

digester gas was estimated based on an average of 2007 and 2008 data. Site specific daily

nitrogen load data (kg-N/day) was available for both 2005 and 2008. The wastewater data was

provided by the City’s Wastewater Division. Fugitive emissions from the Durango-La Plata

Airport wastewater treatment process (lagoons) were minimal and were not included in this

report.

Emission Factors for Materials and Waste:

Emission Factors of Key Materials: The GHG emission factors for producing transport fuels

were obtained from the Argonne National Laboratory’s GREET Model Well-To-Pump analysis as

2.0 kg-CO2e/per gallon for gasoline and 2.5 kg-CO2e/per gallon for diesel respectively (12). The

upstream emission factor for propane was obtained from the IPCC as 1.15 kg-CO2/per gallon

respectively (does not included CO2e) (13).



The emission factor for paper was obtained from the Global Warming Initiative as 2.95 kg-

CO2/per ream (14) (CO2e not calculated). The emission factors for 30% and 100% post-

consumer recycled paper, bleached chlorine free was calculated based on the Reach for

Unbleached organization’s estimation of a 37% reduction in greenhouse gas emissions from

100% recycled paper (15). The emission factor for asphalt was obtained from EIO-LCA and is

1.92 g-CO2e/per dollar, where all expenditures are in 1997 $ (16). The percent of cement in

concrete (10%) was obtained from the City’s local supplier. The emission factor for cement is

one mt-CO2e/per metric ton of cement and was obtained from the National Renewable Energy

Laboratory’s Life-Cycle Inventory Database (17).

Emission Factors for Waste and Recycling: The emission factors for waste and recycling were

obtained from the EPA WARM Model. The waste emission factor was 0.37 mt-CO2e/per short

ton of waste disposed at a landfill 45 miles away with no methane capture and flaring system

(18). The emission factors (mt-CO2e/per short ton) for individual recyclable materials were as

follows: aluminum,-3.73; glass, -0.08; mixed office paper,-0.93; and mixed plastics, -0.42.

Emission factors for the fugitive emissions sources of wastewater treatment plants were

calculated using the site specific data provided by the Wastewater Division and calculations

from the ICLEI Local Government Protocol (10). The nitrogen effluent emission factor is 1.55

kg-CO2e/per kg-N. The ICLEI calculation assumes approximately 1% of the methane captured at

wastewater treatment plants is not completely flared. Applying these emission factors to the

consumption data, the total GHG emissions from the material and waste sector are as shown in

Table 9.



Table 7. Materials and Waste Summary Table

GHG emissions from waste disposal and recycling and manufacture of key urban materials used and for the City of Durango are summarized in the table below.

Material

2005 Annual

Material/ Energy Flow

2008 Annual

Material/ Energy

flow

Total 2005 GHG

emitted MFA x EF (mt-CO2e)

Total 2008 GHG

emitted MFA x EF (mt-CO2e)

2005-2008 % -

/+

2008 % of Total

Emissions

Waste

505 727

677 727

5.04% (short tons)

(short tons) 7.39%

Recycling

145 154

-448 -507

-3.51% (short tons)

(short tons) 13.17%

Wastewater Treatment Plant

Fugitive Emissions

(CH4)+(N2O)

45,390 44,146

71 80

0.55%

cubic feet/ per

day

cubic feet/ per

day 12.68%

37 56

g N/per day

g N/per day

City Vehicle Fuel

Production (W2P) (same as Scope 1)

(same as Scope 1) 324 425

2.95% 31.33%

Paper 4,036 3,693

11 7

0.05% (reams) (reams) -36.65%

Asphalt

2,385 2,385

207 207

1.43% (metric

tons) (metric

tons)

Cement in Urban Concrete

25 25

5 5

0.03%

(cubic yards of

concrete)

(cubic yards of

concrete)

Fertilizer (18-18-18)

4 4

6 6

0.04% (tons) (tons)

Emissions Total: 1,551 1,736 11.93% 12%



5. Green Power

In 2005, the City of Durango purchased 63 blocks of green power for the months of November

and December. One block of green power equates to 100 kilowatt hours of electricity, and

costs roughly .80 cents. The cost includes 100 kilowatt hours of electricity as well as a

contribution to renewable energy rebate programs for local residents. In 2008, the City of

Durango further expanded its green power purchases. The green power program purchases

were subtracted from the City’s total emissions. Without the green power purchases total

emissions increased by 11%. Including the green power purchases, results in a 40% reduction in

total emissions between 2005 and 2008.

Table 8. Green Power Offsets

Major Sector

2005 (mt-

CO2e) 2008

(mt-CO2e)

2005-2008 % Change

2008 % of Total

Emissions

Buildings & Facilities

9,807

11,015 11% 75%

Transportation

2,137

2,635 23% 18%

Materials and Waste

852

950 11% 7%

Total

13,001

14,582 11%

Green Power Purchases (mt-CO2e) 0.5

6,784

Total w/G. Power Offsets (mt-CO2e) 12,796

7,654 -40%



6. Conclusions:

Status of Durango’s Path toward Greening Government Goals:

Table 9. Greening of Government Goals

Greening Government State Goal

City of Durango Status

(2005-2008)

Energy use: 20% Reduction 11% Increase

Vehicle fuel consumption: 25% Reduction 25% Increase**

*Water data is city-wide (not isolated for municipal government operations).

**Based of combined gallons of gasoline, diesel, and propane.

By performing a Sustainable Energy Benchmarking Analysis and Greenhouse Gas Inventory, the

City has undertaken the first step to reducing greenhouse gas emissions. The GHG Inventory

for 2005 and 2008 provides valuable baseline data for the City to assess and identify strategic

focal areas for emission reduction initiatives. The next step in the sustainable energy planning

process is to prioritize actions for a Climate Action Plan.



Works Cited

1. EPA. Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2005. Table: 1-5. [Online]

2007. http://www.epa.gov/climatechange/emissions/usinventoryreport.html.

2. Colorado, State of. Greening of State Government Executive Orders D011 07 and D012 07.

http://www.colorado.gov. [Online] 2007.

3. DOLA. Colorado Department of Local Affairs. Information and Publications/ Population

Data/Estimates. [Online] 2009.

http://www.dola.state.co.us/dlg/demog/population/estimates/Table5-07final.pdf.

4. Durango, City of. [Online] 2009.

5. Ramaswami, Anu. A Demand-Centered, Hybrid Life-Cycle Methodology for City-Scale

Greenhoue Gas Inventorie. Environmental Science and Technology. 2008, Vol. 42, 17, pp. 6455-

6461.

6. WRI. The Greenhouse Gas Protocol: A Corporate Accounting and Reporting Standard.

[Online] 2004. http://www.ghgprotocol.org.

7. NCDC. National Climatic Data Center. Land-Based Data. [Online] 2009.

http://www7.ncdc.noaa.gov/CDO/CDODivisionalSelect.jsp#.

8. Tri-State Generation . Electricity Generation Energy Mix. s.l. : Jonathan Beyer, 2007.

9. EIA. EIA 1605 Instructions: Voluntary Reporting of Greenhouse Gas Emissions. Appendix H of

Form EIA-1605: Fuel Emission Factors . [Online] 2007.

http://www.eia.doe.gov/oiaf/1605/pdf/EIA1605_Instructions_10-23-07.pdf.

10. ICLEI. International Local Government GHG Emissions Analysis Protocol. [Online] September

2008. http://www.iclei.org/index.php?id=8154.

11. eGRID. Emissions and Generation Resourse Integrated Database. [Online] 2006.

http://www.epa.gov/cleanenergy/energy-resources/egrid/index.html.

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Energy Use in Transportation. [Online] 2005.

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Report: Information on Greenhouse Gases Sources and Sinks in Canada (1990-2005). [Online] .

http://www.ec.gc.ca/pdb/ghg/inventory_report/2005_report/a3_2_eng.cfm.



14. GWI. The Green PDF Revolution. [Online]

http://www.greenpdf.com/graphics/TheGreenPDFRevolution.pdf.

15. RFU. Clean Paper Consumer Information. Reach for Unbleached Foundation. [Online]

http://www.rfu.org/cp/paperguide.htm.

16. EIO-LCA. Economic Input-Output Life Cycle Assessment; . [Online] Green Design Institute,

Carnegie Mellon University: Pittsburgh, PA , 2006. http://www.eiolca.net.

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http://www.nrel.gov/lci/database/.

18. WARM. WAste Reduction Model. [Online] U.S. Environmental Protection Agency.

http://www.epa.gov/climatechange/wycd/waste/calculators/Warm_home.html.

19. NCDC. National Climate Data Center. Durango and 14th Street Weather Station. [Online]

2009. http://www4.ncdc.noaa.gov/cgi-win/wwcgi.dll?wwDI~StnSrch~StnID~20003376.

20. IPCC and McCann. Annex 3.2 Methodology for Industrial Processes. National Inventory

Report: Information on Greenhouse Gases Sources and Sinks in Canada (1990-2005). [Online]

http://www.ec.gc.ca/pdb/ghg/inventory_report/2005_report/a3_2_eng.cfm.

sustainable energy benchmarking and greenhouse gas accounting

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