A COMPARISON OF INDUSTRIAL ENERGY CONSUMPTION
AMONG U.S. AND MEXICAN MANUFACTURERS IN THE
BORDER REGION
PROJECT NUMBER E-01-2
HARVEY BRYAN, ARIZONA STATE UNIVERSITY
PATRICK E. PHELAN, ARIZONA STATE UNIVERSITY
NARRATIVE SUMMARY
This report consists of a research plan developed to undertake the comparison of
energy consumption in industrial facilities in the southwest border region. In Mexico,
the industrial sector’s energy use accounts for 58% of the national electricity sales.
The sector’s demand for electricity has been growing at 8% per year (Friedmann
and Sheinbaum 1998). Due to the lack of information on the relative importance of
energy use in Mexican industries, it is difficult to initiate cost effective energy
conservation measures. Hence, this study conducts a comparative analysis of
energy consumption among U.S. and Mexican industries in the U.S.-Mexican border
region. This study consists of five components:
1. A comparison of current energy efficient building design practices.
2. A comparison of relevant energy practices applicable to U.S. and Mexican
industries.
3. A comparison of energy consumption and costs among U.S. and Mexican
industries.
4. Undertaking energy audits of a few comparable industrial facilities.
5. Making recommendations as to how the energy practices can be improved.
Like many developing countries with state-owned utilities, Mexico is undertaking a
series of policy reforms designed to gradually lift energy subsidies to various endusers. Paralleling this policy, agencies like the Comisión Nacional para el Ahorro de
Energía (CONAE) have become aware of the potential energy savings in various
sectors and have embarked on several energy conservation programs and sought
technical assistance from the United States. These programs are beginning to reap
benefits, however information is lacking to evaluate the effectiveness of existing
energy conservation programs or support the evolution of an energy efficiency
infrastructure.
This project provides, apparently for the first time, an examination and comparison of
energy practices among Mexican and U.S. firms in the U.S.-Mexican border region.
Due to the rising cost of industrial electricity in the Mexican border region, improving
energy efficiency in the maquiladoras will prove vital to maintaining their
competitiveness relative to other locations around the world, such as in China or
Southeast Asia. The examination of the maquiladoras’ energy practices provided as
part of this study enables an accurate assessment of their energy efficiency, and
thus ultimately how to improve their energy efficiency.
The energy forecasting model developed in this project provides an accurate tool for
predicting the impact of implemented energy efficiency measures, or conversely, the
effect of not implementing such measures. This tool has already been provided to an
official of the Mexican government, who requested it after the presentation at the
Border Energy Forum in Saltillo, Coahuila. It is the Investigators’ desire that the tool
will prove useful for energy policy formulation.
2
A COMPARISON OF INDUSTRIAL ENERGY CONSUMPTION
AMONG U.S. AND MEXICAN MANUFACTURERS IN THE
BORDER REGION
PROJECT NUMBER EN-01-2
HARVEY BRYAN, ARIZONA STATE UNIVERSITY
PATRICK E. PHELAN, ARIZONA STATE UNIVERSITY
INTRODUCTION
This report consists of a research plan developed to undertake the comparison of
energy consumption in industrial facilities in the southwest border region. In Mexico,
the industrial sector’s energy use accounts for 58% of the national electricity sales.
The sector’s demand for electricity has been growing at 8% per year (Friedmann
and Sheinbaum 1998). Due to the lack of information on the relative importance of
energy use in Mexican industries, it is difficult to initiate cost effective energy
conservation measures. Hence, this study conducts a comparative analysis of
energy consumption among U.S. and Mexican industries in the U.S.-Mexican border
region. This study consists of five components:
6. A comparison of current energy efficient building design practices.
7. A comparison of relevant energy practices applicable to U.S. and Mexican
industries.
8. A comparison of energy consumption and costs among U.S. and Mexican
industries.
9. Undertaking energy audits of a few comparable industrial facilities.
10. Making recommendations as to how the energy practices can be improved.
Like many developing countries with state-owned utilities, Mexico is undertaking a
series of policy reforms designed to gradually lift energy subsidies to various endusers. Paralleling this policy, agencies like the Comisión Nacional para el Ahorro de
Energía (CONAE) have become aware of the potential energy savings in various
sectors and have embarked on several energy conservation programs and sought
technical assistance from the United States. These programs are beginning to reap
benefits, however information is lacking to evaluate the effectiveness of existing
energy conservation programs or support the evolution of an energy efficiency
infrastructure.
The study was initiated by conducting a comparison of U.S. and Mexican energy
efficient building design practices. This was done to determine how effective are the
recently developed CONAE building energy standards, how extensively are they
being used and how well are they being enforced. The results of this phase should
give us a good understanding of the level of energy efficient building design practice
in Mexico.
3
This was followed by conducting a comparison of energy conservation practices in
U.S. and Mexican industries. Here a typical Mexican industrial facility was modeled
using the energy conservation requirements outlined in the CONAE standards. The
results of this phase will help to prioritize energy conservation strategies for this
building type, suggest areas for further standard investigation as well as identify
potential energy savings that can be achieved within this sector.
In the next phase, an energy consumption and costs analysis was conducted for the
textile/apparel, automotive components, and electronics/appliances sectors. After
this data was collected, two forecasting models were developed, one for U.S.
manufacturers and the other for the maquiladoras. The U.S. model was used to
statistically validate the maquiladora model. Causal variables were selected (i.e.,
establishments, number of employees, value of shipments, electricity cost, and
natural gas cost), data sets were gathered, observation gaps were filled, and time
series forecasts were conducted. Alternatively, a multiple regression analysis was
performed using the original data sets, and a regression equation was derived using
the regression coefficients. Both models achieved acceptable statistical behavior
and energy and environmental impact analysis was conducted as an implementation
example. Using the forecast for the current conditions, electricity consumption
savings, electricity demand savings, installed capacity savings and emission
reductions for carbon dioxide, methane and nitrous oxides were predicted. Such
output proves the usefulness of the proposed model, since this kind of information
serves as the ultimate tool to validate energy policy changes, as well as to persuade
authorities and industry about the consequences of energy-efficient practices.
After completing the forecasting models, energy audits of several industrial facilities
were undertaken. Since Arizona State University’s (ASU) Industrial Assessment
Center (IAC) had completed over 270 industrial energy audits and had access to
over 9,000 more through the IAC database, U.S. side audits were not needed. Thus
the focus was on conducting several on-site energy audits in Mexico. Energy audits
were undertaken in two industrial facilities in Mexicali, Baja California; one was an
electronic assembly plant and the other was an auto parts/accessory plant. The
results of this phase give us a good comparison of energy use between countries for
these specific industries.
In the final phase, a series of recommendations that public agencies, industrial
associations, utilities and individual manufacturers might consider in reducing energy
consumption in industrial buildings in the southwest border region will be generated.
A COMPARISON OF ENERGY EFFICIENT BUILDING DESIGN PRACTICES
A Comparison of Building Energy Standards
In commencing this project, a comparison was conducted of U.S. and Mexican
building practices with a particular focus placed on the understanding of the energy
practices being used in the design of industrial facilities. To accomplish this, the
researchers needed to identify appropriate building energy standards being used in
4
both countries. The investigation found that although the United States has had
building energy standards in place since 1975, Mexico has been late in generating
similar standards. The following is a brief review of both U.S. and Mexican energy
standards that have been generated to date.
U.S. Energy Standards
The first U.S. building energy standard was developed some 25 years ago by the
American Society of Heating, Refrigerating and Air-Conditioning Engineers
(ASHRAE). ASHRAE 90-1975 was a hurried attempt to respond to the 1973 OPEC
oil embargo. It was based on determining the severity of the climate in which a
building is located and not on the building’s load profile. While appropriate for
residential scale buildings (i.e., envelope dominated buildings), the standard proved
inappropriate for large commercial and institutional buildings (i.e., internal load
dominated buildings). This resulted in buildings that had limited glazing area as well
as being over insulated. Realizing problems associated with this standard, ASHRAE
proposed in 1989 a major revision of this standard. ASHRAE 90.1-1989 overcame
most of the earlier problems by splitting the standard into separate residential and
non-residential portions. It further broke the standard into two compliance paths: one
prescriptive and the other performance oriented, which allowed for much more
flexibility than did ASHRAE 90-1975. Most state and building code writing bodies
have incorporated into their code most if not all of ASHRAE 90.1-1989. California is
one of the few states that has generated its own energy standard, called Title 24.
While Title 24 is similar in many ways to ASHRAE 90.1-1989 most experts in the
field view it as being a slightly stricter standard.
Mexican Energy Standards
In 1994, the United States Agency for International Development (USAID)
contracted with the Department of Energy’s (DOE) Lawrence Berkeley National
Laboratory (LBNL) to assist CONAE in developing a series of energy standards
appropriate to Mexico. To date, over twenty energy efficiency standards or Normas
Oficiales Mexicanas (NOM) have been generated, and of these, five relate closely to
non-residential building design practices. They are:
 NOM-007-ENER-1995: Energy Efficiency for Lighting Systems in NonResidential Buildings
 NOM-008-ENER-2001: Energy Efficiency in Non-Residential Building
Envelopes
 NOM-009-ENER-1995: Energy Efficiency in Thermal Insulation for Industrial
Buildings
 NOM-011-ENER-1996: Energy Efficiency in Central Air Conditioning Systems
 NOM-018-ENER-1997: Thermal Insulation for Buildings
NOM-007-ENER-1995: Energy Efficiency for Lighting Systems in Non-Residential
Buildings – the objective of this NOM is to establish energy efficiency levels in terms
of electric power use that the lighting systems must comply with in new nonresidential buildings or in renovations of existing buildings. It establishes a method of
determining the Lighting Power Density of the lighting system in order to verify the
5
compliance with the prescript Lighting Power Density outlined in this NOM. This
NOM is applicable to exterior and interior lighting systems for use in new or existing
non-residential buildings with a connected load greater than 20kW. This NOM also
promotes the use of lighting control equipment and systems such as occupancy
sensors, dimmers, daylight sensors, timers, combined controls, etc. by allowing the
Lighting Power Density to be increased by a prescribed factor depending on the
lighting control being used.
NOM-008-ENER-2001: Energy Efficiency in Non-Residential Building Envelopes –
the objective of this NOM is to control the heat gain being transmitted through the
building envelope. It applies to all new buildings and renovations of existing buildings
excluding buildings that are primarily residential or industrial. This NOM lists the
specifications for the building envelope of a reference building and establishes a
testing method to evaluate the heat gain through the envelope of the proposed
building. An energy budget calculation is to be performed so as to determine that the
heat gain through the envelope of the proposed building must be equal to or less
than the heat gain that occurs through the envelope of the reference building. Heat
gain by both conduction and solar radiation are to be included in this calculation.
NOM-009-ENER-1995: Energy Efficiency in Thermal Insulation for Industrial
Buildings – the objective of this NOM is to control within industrial buildings the
losses of energy which may occur either due to dissipation of heat to the
environment in the case of systems that operate at high temperatures or because of
gain of heat in systems that work at low temperature by means of the adequate
insulation. This NOM establishes general layouts for selection, design,
specifications, installation and inspection of thermal insulation systems. It includes
minimum requirements for the application of low and high temperature insulation
within a range of –75C to 815C. The use and application of thermal insulation
would address the purpose of process temperature control, energy conservation,
personnel protection as well as anti-condensation.
NOM-011-ENER-1996: Energy Efficiency in Central Air Conditioning Systems – the
objective of this NOM is to establish the minimum level of energy efficiency that air
conditioners must possess and specifies the testing method that must be used to
verify the compliance with these levels. It also defines the requirements that must be
included in the labels as consumer information so as to protect them from low quality
products and excessive energy consumption. This NOM applies to new centralized
air conditioners, package units, or split systems that operate with electric energy and
have cooling capacities of 10,540W to 17,580W that work by mechanical
compression and include an air-cooled evaporative coil, a compressor and either an
air or water-cooled condensing coil.
NOM-018-ENER-1997: Thermal Insulation for Buildings – the objective of this NOM
is to specify the characteristics that insulation sold in Mexico must possess as well
as establishes testing methods to evaluate their thermal resistance, apparent
density, permeability to water vapor, and moisture absorption properties. It is
6
applicable to the materials, products, components and thermal insulation elements
that possess thermal insulation properties for roofs, ceilings and walls in buildings
and includes both materials made in Mexico and those imported from other
countries. It also states that the manufacturer or distributor/retailer must provide an
instruction booklet that will indicate the specifications for the proper use and
installation of the material.
RESEARCH FINDINGS
After the appropriate U.S. and Mexican energy standards were identified, a detailed
comparison was performed. Several comparative techniques were used, such as the
COMcheck program, which is an energy code compliance tool, developed by DOE’s
Pacific Northwest National Laboratory (PNNL), as well as traditional side-by-side text
comparison. The results from these comparisons suggest that the Mexican NOMs
are for the most part close to the ASHRAE 90.1-1989 standard. Where deficiencies
in the NOMs exist they are offset in areas where they provide better performance.
Comparisons like this can never take into consideration all the dynamics that exist in
any standard nor all the ongoing changes that are in progress. Recently, ASHRAE
has updated its energy standard with the release of ASHRAE 90.1-1999, however
most states have yet to adopt it. CONAE has also updated its NOMs and future
updates are expected. Thus, as far as building energy standards are concerned, the
Mexican NOMs are at parity with U.S. building energy standards.
Survey of Design Professionals
Having in place building energy standards is only one of several prerequisites
needed for good energy efficient building design practices. Other factors, such as
awareness, training, and enforcement can be as important as the standard itself. To
achieve a better understanding of these issues a survey was conducted to
determine the level of knowledge of the five NOMs. A questionnaire was generated
to gather the following information:
 Knowledge of the five NOMs
 Use of these NOMs in projects
 Enforcement of these NOMs
 Typical energy savings strategies applied to projects
The questionnaire was sent to architects, civil engineers, industrial engineers, and
other building industry professionals who work in the border area of Mexico. Sixty
professionals responded to this questionnaire, of which 41 were architects, 11 civil
engineers, five industrial engineers, and three others. The first three questions were
rather straightforward, however the fourth question required the design professional
to respond to a list of typical energy savings strategies that they have applied to
projects, including:
 Insulated walls and roof
 Shading devices
 Light color surfaces
 High efficiency lighting
 Microclimatic site design
7




Solar energy
Double-glazing windows
High efficiency A/C
Environmental control systems
Summary of Survey
Knowledge of NOMs among all professions
30.00%
25.00%
20.00%
15.00%
%
10.00%
5.00%
AP
PL
IE
D
IN
PR
C
ED
JE
C
O
O
M
N
EN
FO
R
TS
18
-0
11
N
O
M
-0
09
N
O
M
-0
08
-0
O
M
N
N
O
M
-0
07
0.00%
NOM-018 was the most known NOM among the five. Approximately 27% of the
professionals surveyed had knowledge of this NOM, 20% knew about NOM-007,
approximately 17% knew about NOM-008, and only 15% knew about the NOM-009
and NOM-011. Thus, ‘Thermal Insulation for Buildings’ was the most known energy
saving strategy, while ‘Energy Efficiency in Central Air Conditioning Systems’ was
the least known codes among the NOMs surveyed.
8
Percentage within each profession that applied NOMs or had them
enforced
40.00%
35.00%
30.00%
25.00%
20.00%
15.00%
10.00%
5.00%
0.00%
Architects
Civil Engineers
Industrials Engineers
APPLIED IN PROJECTS
Other professions
ENFORCED
A total of 28% of the professionals surveyed had applied one or more NOMs in their
projects and 27% have had these NOMs enforced. Among these, 34% of the
architects applied them and 32% had them enforced, 18% of the civil engineers
applied them and 27% had them enforced, none of the industrial engineers applied
them or had them enforced and 33% of the other professionals applied them and
none of these had them enforced.
9
Percentage of Professionals who applied these various Energy Saving
Strategies (as per survey)
11%
7%
37%
2%
4%
4%
15%
4%
16%
insulated walls and roof
Shading devices
Light color surfaces
High efficiency lighting
Microclimatic site design
Solar energy
Double glazing windows
High efficiency A/C
Environmental control systems
A total of 38% of the professionals surveyed had applied walls and roof insulation in
their projects. Shading devices, high efficiency lighting, environmental control
systems, high efficiency A/C, light color surface, microclimate site design, solar
energy, and finally, double glazing windows were of the order of importance of the
energy saving strategies applied.
10
Comparison of the knowledge of the NOMs within the different
professions. (Percentages are of the total within the professions)
35.00%
30.00%
25.00%
20.00%
15.00%
10.00%
5.00%
0.00%
NOM-007
Architects
NOM-008
NOM-009
Civil Engineers
NOM-011
Industrials Engineers
NOM-018
Other professions
The most known NOMs among the:
 Architects: 29% of this group were aware of NOM-018, while only 12% were
aware of NOM-008
 Civil Engineers: 27% of this group were aware of NOM-008 while NOM-009
and NOM-011 were the least known with only 9% awareness
 Industrial Engineers: 20% of this group were equally aware of all the NOMs
except NOM-011, of which none were aware
 Other professions: 33% of this group were equally aware of all the NOMs (this
might have been caused by this group having such a small sample)
The low general awareness of these NOMs among design professionals suggests
that CONAE will need to embark on an aggressive education/training campaign.
U.S. experience in the energy standards area has found that good energy design
practice is very dependent on education/training and it is clear that this component is
missing in the Mexican case. The survey responses to the enforcement question
also suggest that these NOMs are not being enforced. Thus CONAE also needs to
embark on an aggressive education/training effort targeted to municipal building
officials.
A Comparison of Energy Conservation Practices in U.S. and Mexican Industries
Since the maquiladoras are major energy consumers in the border region, it was
deemed important to explore the potential energy savings that could be achieved
when Mexican industrial buildings do conform to the recently established NOMs.
Although most new U.S. buildings now conform to ASHRAE energy standards, it
took 25 years of effort to achieve this level of compliance. It would be expected that
11
energy improvements to the Mexican building stock would go through a similar
process. Thus, the researchers propose to analyze in this section how incremental
energy changes to a typical Mexican industrial building would help to improve the
energy performance of this sector’s building stock.
A typical Mexican industrial building was modeled using the DOE-2 program. The
DOE-2 program is a widely used building energy simulation model that uses hourly
weather data to simulate a building’s energy use dynamics. The building that was
chosen for analysis was a 90,000-ft2 factory building with a 56,000-ft2 double-height
factory floor and a 34,000-ft2 two-story attached office block. The building
performance criteria assumed for this base case factory was that it was built to preNOM standards. The factory floor was assumed to be evaporatively cooled while the
office area was to be air-conditioned. No energy was assumed for plant operations,
thus this analysis considers predominantly envelope factors. Using a series of
parametric runs, the base case factory building was incrementally upgraded to
present NOM standards by changing the wall insulation, roof insulation, including
daylighting sensors, improving glazing type and lighting power density.
Illustration of the 90,000-ft2 base case factory building
Parametric runs were undertaken for four different locations within the southwest
border region. These locations represent areas within the southwest where industry
is quite active as well as varying climatically. They are: Phoenix, Arizona; San Diego,
California-Tijuana, Baja California; El Paso, Texas-Ciudad Juárez, Chihuahua; and
Nogales, Arizona-Nogales, Sonora.
The order of the parametric runs were as follows:
1. Base case
2. Wall insulation
3. Roof insulation
4. Daylight sensors
5. Without skylights
12
6.
7.
8.
9.
Daylight sensors without skylights
Glazing type (office, factory, and skylight)
Lighting power density
Horizontal shading devices
The various parameters were compared with each other for maximum benefit and
the cumulative benefits of all the parameters were finally compared for different
locations. The comparisons are presented below.
Table 1. Spreadsheet summary of results from the four locations
Table 2. Summary of annual energy performance for the four locations
Place
Phoenix
San Diego
Actual
Consumption
(KWh)
1488922
1436260
13
Simulated
Consumption
(KWh)
1025904
881805
Cumulative
Saving
31%
39%
Nogales
El Paso
1459845
1466859
964141
1013689
34%
31%
Findings
The most effective strategy for reducing energy use in a typical Mexican industrial
facility is by upgrading the lighting power density in both the factory area and office
area to NOM-007. The second best strategy is to introduce daylighting sensors (also
mentioned in NOM-007). All areas of energy performance: annual energy use, peakcooling tonnage, annual Heating, Ventilation and Air Conditioning (HVAC) demand,
and overall electricity demand all benefit by using these strategies. If all these
strategies were employed, a typical energy reduction of 30-40% could be achieved.
While these savings are significant, increased savings could be accomplished by
upgrading NOM-007. NOM-007-ENER-1995: Energy Efficiency for Lighting Systems
in Non-Residential Building was the first and is currently the oldest (dating from
1995) of the building-related NOMs developed by CONAE. Significant advances
have been made in energy efficient lighting technology in the last eight years, which
should be incorporated into this NOM. If the lighting power density presently in
ASHRAE 90.1-1999 were used in the previous analysis, an additional 10-15%
improvement could have been achieved.
Overall building energy performance increases on the order of 40-50% are very
close to levels achieved between pre and present-day building energy standards for
U.S. buildings. Thus, given current trends, it would not be unexpected that over the
next several years for Mexico to achieve similar energy performance increases in
their building stock.
A Comparison of Energy Consumption and Costs among U.S. and Mexican
Industries
A quantitative comparison was made for the three industrial sectors most relevant
for the Mexican border region’s maquiladoras: textiles/apparels, auto equipment and
components, and electronics/appliances. However, only the auto equipment and
components industrial sector will be discussed here. Information was drawn from a
variety of sources, including DOE’s Energy Information Agency (EIA) and the
Industrial Assessment Center (IAC) database. Due to the lack of information
available, data were gathered for industries on the U.S. side of the border, and
conclusions regarding Mexican industries had to be based on those data. The
details of the approach as well as material on the other industrial sectors can be
found in the MS thesis generated as a result of this project (Flores, 2002).
Only representative results for the auto equipment and components sector are
presented here, for other sectors and for more detailed results see Flores (2002).
Industries in the auto equipment and components manufacturing subsector
manufacture products to be assembled at the downstream car assembly industry.
Examples of such equipment and parts include (NAICS, 2002):
 Gasoline Engine and Engine Parts
 Lighting Equipment
14






Electrical and Electronic Equipment
Brake System Manufacturing
Steering and Suspension Components
Metal Stamping
Transmission and Power Train Parts
Air Conditioning
In this sector, electricity (40%) and natural gas (46%) play the most important roles
as energy sources (Figure 1 A & B). Boiler usage is less intense than the national
average or the textile/apparel sector since it does not involve raw material
transformation of properties. Most of the energy is utilized in direct process and nonprocess activities in the same pattern as the entire manufacturing industry.
The national average for this sector indicates that as companies become larger,
energy productivity ratios as well as energy cost ratios decrease (Figure 2 A & B).
This pattern is not clear for the U.S. border, most likely due to the small sample size
and its effect on variability and the mean of the values. However, if the outlier point
of the $50-99 million-industry size is eliminated, it could be said that the border
region is more efficient in energy usage (less energy used per dollar produced)
compared to the U.S. national average, although the energy cost per output is higher
than the national average for the same sector.
15
30%
9%
21%
Indirect Uses-Boiler Fuel
Direct Uses-Total Process
Direct Uses-Total Nonprocess
End Use Not Reported
40%
A) Energy Consumption By End-Use
B) Energy Consumption Breakdown For End Use
Figure 1 A & B Energy Consumption and Breakdown for the U.S. Auto
Equipment/Components Sector (EIA, 2001)
16
$0.025
$0.020
$0.015
$0.010
$0.005
$0.000
Under 20
20-49
50-99
100-249
Ind ust ry Siz e ( M illio n D o llars)
National
A) Energy Consumption Per Dollar
Value Of Shipments
US Border
B) Energy Cost Per Dollar Value Of
Shipments
Figure 2 A & B Energy Consumption and Energy Cost Per Dollar Value of
Shipments for the U.S. Auto Equipment/Components Sector (EIA, 2001 & IAC,
2002)
Maquiladora Energy Forecasting Model
An economic model was developed for forecasting the future electrical energy use of
the Mexican maquiladora facilities located in the border region. This model utilized
regression analysis, and for comparison, a similar model was developed for U.S.
industries. The causal variables adopted for consideration were the number of
establishments, the number of employees, the value of shipments, the cost of
electricity, and the cost of natural gas. Future values of the causal variables were
forecast by time series, and then regression was applied to predict the electrical
energy consumption out to the year 2010. This model enabled the prediction of
energy savings generated by implementing energy efficiency measures. The details
of the approach can be found in the MS thesis generated as a result of this project
(Flores, 2002).
The data table on which the regression model for the Mexican border region’s
maquiladoras energy consumption was based is provided in Table 3. A similar table,
although with data for a greater number of years, was generated for comparison for
U.S. manufacturers.
The results of the regression model are displayed in graphical form in Figure 3,
which also includes the confidence intervals for 95% confidence. As expected, the
confidence intervals broaden as the forecast is made further into the future. Although
these results are of interest by themselves in that they enable a quantitative
17
prediction of future maquiladora electrical usage, of even greater utility is the ability
to predict the effects of implementing various energy efficiency measures on annual
electricity consumption.
This report considers implementation of energy efficiency measures in two areas:
motor systems, including compressed air systems, and lighting, both of which are
commonly found in industrial facilities and consume a very significant fraction of the
total electricity consumption. A graph presenting the “business as usual” scenario,
without implemented energy efficiency measures and a curve showing the effect of
implementing such measures, is presented in Figure 4. Note that the measures are
assumed to be implemented gradually, over the 9-year forecast period, so that the
maximum savings are achieved at the end of the forecast period (2010). A table
providing a breakdown of the usage and demand cost savings is given in Table 4.
PROBLEMS/ISSUES ENCOUNTERED
Certainly one significant problem concerned the lack of quantitative data available
on industrial energy consumption for the Mexican maquiladoras. As briefly described
above, some information had to be drawn from comparable industries on the U.S.
side of the border, and then the results extrapolated to the maquiladoras.
18
Table 3. Data Matrix for the Border Region’s Maquiladora Energy Consumption Model
(INEGI, 2002)
Response Variable
Independent Variables
Energy Consumption
Year
6
Establishments
Value of Shipments
Electricity Cost
Natural Gas Cost
(Pesos)
(Pesos/kWh)
($/1000 Cuft)
Employees
(10 kWh)
1990
1,392.10*
1,527
422,021
$
3,138,350
$
0.12
$
2.11
1991
1,602.40*
1,693
399,558
$
3,719,469
$
0.16
$
1.68
1992
1,886.10*
1,828
468,304
$
4,236,668
$
0.18
$
1.87
1993
2,169.80*
1,848
473,542
$
5,837,951
$
0.18
$
2.16
1994
2,453.50*
1,801
505,673
$
6,694,261
$
0.17
$
1.95
1995
2,737.20*
1,776
550,247
$
14,600,005
$
0.20
$
1.49
1996 3,159.55
1,974
645,779
$
21,038,169
$
0.28
$
2.29
1997 3,422.03
2,204
769,892
$
28,428,204
$
0.36
$
2.44
1998 3,912.89
2,367
852,602
$
42,582,716
$
0.39
$
2.35
1999 4,522.28
2,552
939,055
$
47,910,911
$
0.44
$
2.50
2000 5,480.35
2,759
999,018*
$
53,059,153*
$
0.50
$
4.19
2001 5,115.96
2,834
1,058,980*
$
58,522,174*
$
0.54*
$
3.87*
(*) Values Estimated Using The Double Exponential Smoothing Method (Time Series)
Figure 3 Forecast Confidence Intervals for Border Region’s Maquiladora Industry
Electricity Consumption Model
19
9,000
Electricity Consumption
106 kWh
8,500
8,000
7,500
7,000
6,500
6,000
5,500
5,000
4,500
4,000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
Year
Current Conditions
With Policy
Figure 4 Comparative Annual Electricity Consumption Chart: Current Conditions
Vs. Recommended Scenario
20
Table 4 Electricity Savings and Environmental Impact Results for Implementing
Energy Efficiency Measures in the Border Region’s Maquiladora Industries
21
Undertake Energy Audits of a Few Comparable Industrial Facilities
Energy audits were conducted at two Mexican maquiladora industrial facilities,
located near Mexicali. These audits followed the approach employed by the ASU
Industrial Assessment Center in its audits of U.S. manufacturing firms, in that the
audits consisted of a walk-through tour of the facility, an extensive question-andanswer session with the plant manager and other facility representatives, data
gathering by the audit team, and finally, analysis and report generation back at ASU.
Energy practices between the two facilities that were audited were found to be, in
general, similar to those for U.S. manufacturers. This is probably due to the fact that
the maquiladoras are owned by international firms, which would tend to employ an
international standard of energy efficiency, and to the fact that the cost of electricity
(for industrial users) is approximately the same on both sides of the U.S.-Mexican
border. This suggests that, with regard to energy costs, there is no advantage to
locating a facility in Mexico, although of course labor costs will be reduced by doing
so. Energy costs, however, are apparently of some concern. One plant manager
expressed the view that, in the future, his company might locate future plants outside
of Mexico, such as in southeast Asia, not only for the even greater labor cost
savings relative to Mexico, but also partially because of the relatively high energy
costs in Mexico.
At one facility, which shall remain anonymous for reasons of confidentiality, a total of
four energy efficiency measures were recommended:
 Reduce compressor air pressure
 Install variable frequency drives
 Install occupancy sensors
 Use brazer exhaust to heat water
The total potential annual cost savings if these measures are implemented is
estimated as $50,315, or 0.7% of the total facility energy cost of $6,912,242. In
terms of energy consumption, this amounts to 880.3 MMBtu each year, or 1.2% of
the facility’s total energy usage.
In many cases, the air is compressed to a higher pressure than the air-driven
equipment actually requires. By determining the minimum required pressure, one
may find that the pressure control setting on the compressor can be lowered. This is
done by a simple adjustment of the pressure setting and applies to both screw and
reciprocating compressors. The air pressure control setting could be reduced on the
125 hp air compressor from 100 psig (114.7 psia) to 90 psig (104.7 psia) to
decrease the energy consumption of the compressor. Implementation of the reduced
air pressure will result in approximately $5,505 in savings annually.
The next energy conservation opportunity (ECO) involves application of variable
frequency drives on the cooling tower motors. Energy savings result from reduced
power consumption by the motors. As the system power requirements are reduced,
22
the power consumed by the equipment can be reduced by an amount significantly
greater than can be achieved with the existing controls. This change will result in
possible savings of $43,777 per year.
During the site visit it was observed that at present the hot flue gas from the
generator is thrown out to the atmosphere and consequently the heat content of the
gas is lost to the surroundings. It is proposed that a heat exchanger be incorporated
into the system to heat up the cold water to get hot water to be used for the washing
process using the heat contained in the hot flue gas going out of the brazer. An
estimated savings of $303 per year will result from training employees to run the
machine only when it is needed.
Another important energy-savings idea is installing occupancy sensors in office
areas. By wiring occupancy sensors or timers into the lighting circuits, lighting usage
can be eliminated during unoccupied periods. These units turn lights on when both
technologies detect motion and remain on as long as one of the technologies
detects motion. It was estimated that installing occupancy sensors could contribute
$730 per year to the overall facility savings.
Except for the coastal area around Tijuana, the majority of the southwest border
region is typically characterized as being a hot/dry climate. Most of the maquiladoras
that were observed used some type of evaporative cooling strategies in the factory
area. While this cooling strategy is a very effective low energy solution that avoids
the use of expensive air-conditioning (those systems that use vapor compression) it
does not offer very good comfort control. It would be beneficial if these facilities
begin to investigate the use of alternative evaporative cooling technologies such as
indirect evaporative cooling, evaporative condensers, etc. as a means to improve
better comfort and still avoid the use of energy intensive air-conditioning.
Recommendations
Mexican NOMs were found that for the most part to be in parity with U.S. building
energy standards. Unfortunately education/training of design professionals and
building officials on the use of these NOMs and the rigor of their enforcement was
woefully inadequate. Thus, it is of critical importance that CONAE embark on an
aggressive education/training effort. CONAE could also make available for a
Mexican audience compliance tools like those developed in the United States, which
greatly helped design professional to become skilled in complying with ASHRAE
90.1.
23
The energy audits of two maquiladora facilities in Mexicali showed that, in general,
energy practices are similar to those encountered at U.S. industrial facilities. The
cost of electricity for industrial energy users in the Mexican border region has been
steadily increasing, to the point where now the cost is roughly the same on either
side of the border. This means that it is just as important for the maquiladoras to
implement energy efficiency measures, as it is for U.S. manufacturers.
As stated elsewhere, due to the lack of detailed data for Mexican industries, an
analysis was applied to U.S. manufacturing data, with emphasis given to firms in the
U.S-Mexican border region. For the three analyzed industrial sectors, which
represent the three largest sectors among all Mexican maquiladoras, it was found
that the cost of electricity is related to the size of the company, as measured in the $
value of shipments: the larger the company is the lower its energy cost per $ value
of shipments. The predominant energy sources are electricity and natural gas. This
energy mix is similar for the three sectors and for both sides of the border, although
maquiladoras substitute natural gas with propane gas in those areas where the
distribution grid does not reach the company. The Mexican government, however, is
committed to enlarging the distribution grid and promoting natural gas usage;
therefore propane gas usage is going to be gradually reduced.
Electricity consumption forecasts, based on time series and regression models, were
obtained for both the U.S. manufacturing industry and for the Mexican border
region’s maquiladora industry. Confidence intervals were generated that show how
the Mexican model’s confidence interval broadens more than its counterpart, as a
consequence of the shorter data set and the variability of the causal variables,
included as randomness when calculating the forecast’s mean and upper and lower
limits. To prove the usefulness of the maquiladora model an energy and
environmental analysis was conducted. Annual savings for the border region’s
maquiladora industry were calculated based on the forecasted electricity
consumption. Electricity consumption, electricity demand, installed capacity, and
emissions reduction for carbon dioxide, methane and nitrous oxides were
forecasted, validating the benefits of adopting energy efficient measures in the areas
of lighting, compressed air systems, and motor-driven systems. These data, the
generated savings, reduced electricity consumption and demand, and emissions
reduction fulfills one of the goals of this project: validate energy studies and aid
agencies to promote such implementation of energy-efficiency measures.
RECOMMENDATIONS FOR FURTHER RESEARCH
One area that this project partially addressed is the lack of data and information
regarding energy practices among Mexican industrial firms. The focus here was on
the border region’s maquiladoras, but the lack of data appears to be endemic
throughout Mexican industry. More comprehensive data gathering is needed,
including additional on-site energy audits, such as those that were conducted as part
of this study.
24
Although, strictly speaking, this recommendation does not concern research,
additional training of Mexican design professionals in current energy-efficiency
practices is critical. The goal would be to encourage the formation of an energy
services industry in Mexico, which would enable Mexican industry to develop its own
approaches to energy efficiency.
Finally, the development of software tools targeted to Mexico, i.e., in Spanish and
Metric, is also desirable. Such tools would focus on energy efficiency measures, and
could readily be adapted from existing software tools available in the US, such as
various DOE’s building simulation tools like DOE-2 or the Federal Emergency
Management Program’s (FEMP) tools like Motor Master.
Implementation/Dissemination Strategies
Results of the industrial forecasting model were presented at the 9th Border Energy
Forum in Saltillo, Coahuila on October 24 – 25, 2002. The results of the entire study
were presented at the 10th Border Energy Forum in Austin, Texas on October 23-24,
2003. The audience for both of these presentations included government, private
industry, and academic representatives from both sides of the border.
In addition, one journal article on the industrial energy forecasting model has been
accepted for publication in the International Journal of Energy Research, and
another journal article on the comparison of industrial energy practices in the border
region is in preparation.
RESEARCH BENEFITS
This project provides, apparently for the first time, an examination and comparison of
energy practices among Mexican and U.S. firms in the border region. Due to the
rising cost of industrial electricity in the Mexican border region, improving energy
efficiency in the maquiladoras will prove vital to maintaining their competitiveness
relative to other locations around the world, such as in China or Southeast Asia. The
examination of the maquiladoras’ energy practices provided as part of this study
enables an accurate assessment of their energy efficiency, and thus ultimately how
to improve their energy efficiency.
The energy forecasting model developed in this project provides an accurate tool for
predicting the impact of implemented energy efficiency measures, or conversely, the
effect of not implementing such measures. This tool has already been provided to an
official of the Mexican government, who requested it after the presentation at the
Border Energy Forum in Saltillo. It is the Investigators’ desire that the tool will prove
useful for energy policy formulation.
ACKNOWLEDGMENTS
Professor Manual Ochoa, the researchers’ collaborator from the School of
Architecture at the Universidad de Sonora was very knowledgeable about the NOMs
and undertook the survey of Mexican design professionals. Gustavo Carmona, a
graduate student in Architecture was very helpful in translating the NOMs. Carlos
25
Flores, who received his MS degree for his work on developing the energy
forecasting model, deserves the utmost appreciation, as does his co-advisor,
Professor Jong-I Mou of the Department of Industrial Engineering, Arizona State
University. Finally, César Martínez, a PhD student of Industrial Engineering at ASU
and a member of the ASU Industrial Assessment Center staff, helped arrange the
audits of maquiladora plants in Mexicali, for which the researchers are most
appreciative.
This work was sponsored by the Southwest Consortium for Environmental Research
and Policy (SCERP) through a cooperative agreement with the U.S. Environmental
Protection Agency. SCERP can be contacted for further information through
www.scerp.org and scerp@mail.sdsu.edu.
REFERENCES
American Society of Heating, Refrigerating and Air-Conditioning Engineers
(ASHRAE). 1989. ASHRAE 90.1-1989, Energy Efficient Design of New Buildings
Except New Low-Rise Residential Buildings
Energy Information Administration (EIA). 2001. Manufacturing Energy Consumption
Survey: 1998 Energy Consumption by Manufacturers. Retrieved on Jan 10, 2002
from http://www.eia.doe.gov/emeu/mecs/mecs98/datatables/contents.html.
Flores, C. 2002. “Analysis Of Industrial Electricity Consumption For the U.S.A. and
for the Mexican Border States’ Maquiladoras.” MS thesis, Department of Industrial
Engineering, Arizona State University, Tempe, Arizona, USA.
Friedmann, R. and C. Sheinbaum. 1998. “Mexican Electric End-Use Efficiency:
Experiences to Date.” Annual Review of Energy and Environment 23: 225 – 252.
Industrial Assessment Center (IAC). 2002. Database Files. Retrieved on June 24,
2002 from http://oipea-www.rutgers.edu/database/db_f.html.
National Institute of Statistics, Geography and Informatics (INEGI). 2002. Retrieved
on March 03, 2002 from http://www.ineg.gob.mx.
North American Industry Classification System (NAICS). 2002. 1997 NAICS
Definitions: 3363 Motor Vehicle Parts Manufacturing. Retrieved on Jan 14, 2002
from http://www.census.gov/epcd/naics/NDEF336.HTM#N3363.
26
27