Introduction
The objective of this research was to investigate the life
cycle cost impact of upgrading Nebraska’s
residential energy code to the 2000 IECC (International Energy Conservation
Code). Two other code conditions were
used for comparison: the 1983 MEC (Model
Energy Code), the current statewide minimum, and the Nebraska
average currently being required by jurisdictions in the state. This average condition was determined by a
2002 survey of Nebraska code
officials conducted by the Nebraska Energy Office. The study considered the reduction in energy
costs associated with upgrades to the energy code, and compared those savings
against any increases in costs of construction required to meet the code. Weather conditions, construction costs and
utility rates were considered for four cities:
McCook, Omaha, Norfolk
and Chadron.
Computational models of four houses were developed for the
study. These include a ranch style
house at the 20th percentile size being constructed in Nebraska,
a ranch style house and a two story house at the median home size, and a two
story house at the 80th percentile size. Occupancy and usage patterns were modeled based
on national average usage data. The
impact of setback thermostats and an alternate occupancy profile were also
investigated.
Selection and specification of houses modeled
House size and type
Based on the survey of Nebraska building code officials,
the calculated average Nebraska home built in 2002 was 1,870 square feet (sf)
in size. Unfortunately, data on floor
area are not recorded in Omaha, and we believe many of the state’s larger houses are
built in its larger communities. The
average new home in Lincoln was approximately 2,200 sf, which supports this assumption.
Also, average house sizes have been rising, so a larger area of 2,100-2,200
sf is also relevant as an estimate of the “average” Nebraska home.
These data agree well with published U.S. census data1.
For 2001, the median new home in the area defined as "Midwest"
had 1,965 sf, and the average new "Midwest" home had 2,209 sf (very
large homes skew the average higher). The
census data also include some information on the distribution of sizes.
This was used to estimate the 20th and 80th percentile
house sizes for this study. The 20th percentile Nebraska home is larger than 20 percent of new homes built in Nebraska. Likewise, the 80th
percentile home is larger than 80 percent of new Nebraska homes. By interpolation
of the census data, the 20th percentile home in the "Midwest" is approximately 1,450 sf, and the 80th percentile
is about 2,900 sf.
Four houses were modeled using these sizes:
a ranch house at the 20th percentile, a ranch house at the
mean size determined by the survey of Nebraska code officials, a two story house between the median and
average sizes for Midwest homes according to the U.S. Census data, and a two story
house at the 80th percentile. Plans
and estimating kits were supplied by Design Basics, an Omaha building plan service that supplies plans for 15,000 houses
per year. The actual houses modeled,
their square footages, and other characteristics are shown in Table 1.
The decision to model both smaller homes as ranches
was based on the survey of code officials, which identified 69% of new homes
built in the state as ranch style. The split entry style, which is also likely
to be used for smaller homes accounted for only 13% of the total. Two story homes accounted for 18% of the statewide
total, and undoubtedly are more common for larger homes. The larger “average” home and the
80th percentile home were both modeled having two stories.
|
House
|
Plan area
|
Style
|
Ceiling height (range, ft)
|
Above grade exterior wall area
(sf)
|
Door area (sf)
|
Window area (sf)
|
|
20th percentile
|
1,453 sf
|
ranch
|
7.5-10.0
|
1,530
|
42
|
160
|
|
Surveyed mean
|
1,852 sf
|
ranch
|
7.5-10.0
|
2,070
|
70
|
160
|
|
Midwest mean
|
2,103 sf
|
2 story
|
7.5-9.0
|
2,620
|
88
|
229
|
|
80th percentile
|
2,932 sf
|
2 story
|
7.5-12.7
|
2,540
|
86
|
477
|
Table
1. Characteristics of houses modeled.
According
to the survey, 92% of Nebraska houses have basements, and 26% of these are finished basements.
All four houses were modeled with conditioned basements.
The survey found that when records on the type
of heating and cooling systems installed are recorded, 67% of new homes have
gas-fired forced air furnaces and central air conditioning systems, 24% reported
“electric heat and air conditioning,” and only about 4% reported
using heat pumps of various types. We
suspect that the “electric heat and air conditioning” category may
actually contain both electric resistance heating and heat pumps. Because both were in the minority, all four
homes were modeled using forced air heating with gas-fired furnaces and central
air conditioning.
An air infiltration rate of 0.5 air change per
hour was used in modeling the above ground portions of all four houses under
all three code conditions. Basements
located below grade are modeled with 0.2 air change per hour to reflect their
reduced tendency toward air exchange with the outdoors. Air infiltration rates in US houses vary by
up to a factor of 10, and have been shown to vary by approximately 15% in
identical houses constructed at the same time by the same contractor2. The rate of 0.5 air change per hour was selected
for the model because it is the median annual infiltration value measured
in a study of 312 US houses of “newer, energy efficient construction”3.
Occupant information
Occupant behavior and heat gains associated with people and
their activities influence the energy required for heating and cooling. This study assumes a family of four living in
each house, and two different occupancy conditions were modeled. In the first, one adult and one child are
home during the day while the other adult and child are away from home during
the workday. The second condition assumes
that both adults work full-time outside the home and both children are away from
home during the workday. The heat gain
from each adult occupant was modeled as 250 Btu/hr sensible and 200 Btu/hr
latent3. The two children
were modeled as having 75% of this heat gain.
Two occupant schedules were used. In the first, one adult and one child are
away from home during the day for work or school and a second adult and child
are home during the day. The first two
occupants are modeled as being away from home between 8:00 a.m. and 6:00 p.m.
on weekdays and between 10:00 a.m.
and 5:00 p.m. on weekends. This occupancy schedule was specified to
produce the number of “at home” hours as are recommended by the Environmental
Protection Agency’s Exposure Factors Handbook5 for a working
American adult. The other two occupants
are assumed to have the same weekend activities as the others and to spend two
hours each weekday outside the house.
Their schedule places them away from home between 2:00 p.m. and 4:00 p.m.
on weekdays and between 10:00 a.m.
and 5:00 p.m. on weekends.
The second occupant schedule changes in that all four
occupants are modeled as being away from home for work or school during the
day. Their activities follow the same
schedule as for the first two occupants described above.
Thermostat settings
Occupants’ use of setback thermostats also influences
heating and cooling energy consumption.
This model assumes a thermostat setpoint of 70°F in the winter and 76°F
in the summer. These conditions are
within the American Society of Heating, Refrigerating, and Air Conditioning Engineers
(ASHRAE) comfort ranges for people seasonally dressed. Simulations were conducted with two sets of
conditions. The first assumes that
thermostat setbacks are not used. The
second assumes that the thermostat setting is reduced to 62°F between 10:00 p.m. and 6:00
a.m. in the winter for both occupancy scenarios. For the occupancy condition in which no one
is home during the day, this scenario also assumes a setback to 62°F between 8:00 a.m. and 5:00
p.m. in the winter and an increase to 80°F for these same hours
during the summer.
Appliance loads
Sensible internal heat gains include the occupants
themselves (discussed above), appliances, and lighting. Heat gains for some appliances, such as
refrigerators, are generally independent of occupant activities. The usage of other appliances, such as
televisions, depends on occupant activity.
Sensible loads for appliances were computed primarily based on national
residential statistics published by the Energy Information Administration (EIA)4. This report shows that the average American
home consumes approximately 34.6 million Btu annually for appliances that
contribute to internal heat gain. These
gains were broken into two categories:
those related to occupants and their activities, and those that are
nearly constant. The occupancy-related
sources account for 18.2 million Btu, and are (in decreasing order of
magnitude): hot water, lighting, clothes
dryers, color televisions, cooking, dishwashers, microwave ovens, personal
computers, VCRs, clothes washers, stereos, and laser printers. Sources that are independent of occupancy
account for 16.4 million Btu and are (in decreasing magnitude): refrigerator, freezer, waterbed heaters,
ceiling fans, aquariums, answering machines, battery chargers, cordless phones,
fax machines, and residual items. The contribution of each item to energy use
is weighted to account for their frequency of occurrence in the nation’s
housing stock.
Internal heat gains are also related to house size. The EIA reports median energy expenditures
based on number of rooms. These were
divided by the median national household energy expenditure to obtain a factor
that was used to scale the non-occupancy related heat gains. The occupancy related heat gains are more
likely to be related to the number of occupants than the size of the house, so
they were not scaled.
To coincide with occupant activities, the occupancy-related
sources were scheduled to occur from 6:00 a.m.
to 8:00 a.m. and from 6:00 p.m. to 10:00
p.m. on weekdays, and from 8:00 a.m.
to 10:00 a.m. and 5:00 p.m. to 10:00 p.m. on weekends, for a total of 2,288
hours per year. Heat sources that are
independent of occupancy were modeled as constant over the entire year. Table 2 summarizes the internal heat gain
values used for the analysis.
|
House size (sf)
|
# of rooms
|
% US
average energy cost
|
Occupant related gains (Btu/hr)
|
Non-occupant related gains (Btu/hr)
|
|
1,453
|
5
|
96
|
7,955
|
1,790
|
|
1,852
|
6
|
111
|
7,955
|
2,069
|
|
2,103
|
8
|
143
|
7,955
|
2,668
|
|
2,932
|
9
|
182
|
7,955
|
3,413
|
|
U.S.
Average
|
N/A
|
100
|
7,955
|
1,872
|
Table 2. Internal sensible heat gains from equipment.
Latent loads also contribute to a home’s cooling energy
consumption. For an average family of
four, Canada’s Institute for Research in Construction6 recommends
the following latent loads: respiration from the occupants themselves, 5,760
Btu/day for occupancy related activities (including showering, bathing,
dishwashing, cooking, and cleaning), and 5,760 Btu/day from other sources
(including construction moisture, seasonal storage, basements and crawlspaces,
rain penetration and unknown sources).
Latent loads from the occupants themselves were modeled according to the
occupancy schedules. To achieve the
daily rates above, latent loads from occupant activities were modeled using the
same schedule as for occupancy-related sensible loads at a rate of 960
Btu/hr. The other latent loads were
modeled as constant throughout the day at a rate of 240 Btu/hr.
Codes
Three different energy codes were modeled.
These included the 1983 Model Energy Code (the current Nebraska Building
Energy Conservation Standard), the 2000 International Energy Conservation
Code, and the Nebraska average being enforced across the state. This average was calculated based on the Nebraska
Energy Office’s survey of state code officials, concluded in December
2002. Table 3 summarizes the required
component values for the three cases.
|
Component
|
1983 MEC (note a)
|
2000 IECC
(note b)
|
Nebraska average
|
|
Glazing U-factor
|
Note
a
|
0.40
- 0.35
|
0.45
|
|
Ceiling R-value
|
25
|
38
- 49
|
33
|
|
Wall R-value
|
5.6
|
18
- 21
|
11
|
|
Floor R-value
|
12.5
|
21
|
21
|
|
Opaque door U-factor
|
Note
a
|
0.35
|
0.25
|
|
Basement wall R-value
|
0
|
10
- 11
|
8
|
|
Glazing SHGC
|
none
|
none
|
none
|
|
Forced air furnace
|
78%
AFUE (note c)
|
80%
AFUE
|
80%
AFUE
|
|
Central air conditioning
|
6.8
SEER
(note
c)
|
10.0
SEER
|
10.0
SEER
|
Table
3. Component requirements by building
code.
Note a: R-values for walls and ceilings using the 1983
MEC are to include the effects of windows, doors, and skylights. Consistent with the published rules of LB755,
the statewide average of 6,500 degree days is used to determine the 1983 MEC’s
requirements for the entire state.
Note b: The ranges shown reflect the fact that Nebraska includes four of the degree day ranges specified
in the 2000 IECC, and requirements vary across the state.
Note c: Although 78% Annual Fuel Utilization Efficiency
(AFUE) and 6.8 Seasonal Energy Efficiency Ratio (SEER) are the minimum requirements
for the 1983 MEC, 80% AFUE and 10.0 SEER that are locally available and widely
installed. These higher values were
used for the 1983 MEC case for the energy and cost analysis.
There is no Solar Heat Gain Coefficient (SHGC)
requirement for glazing in climates with more than 3,500 degree days.
For modeling, a default SHGC of 0.66 was used.
This is the default value found in Table 102.5.2(3) of the 2000 IECC
for double glazed clear fenestration with operable metal frames or fixed nonmetal
frames.
The 1983 MEC wall insulation values are for the
composite wall, and include the effects of doors and windows.
In our model, we used door and window U-factors equal to those required
by the Nebraska average code, and then calculated the required wall insulation
R-value, which varied from 7 to 9 depending on the house. For 2000 IECC and the Nebraska average code
condition, the R-values shown for ceilings, walls, and floors apply to insulation
only, and the codes specify that other parts of the wall section, including
framing, drywall, sheathing, and siding are not to be counted toward this
value. From this perspective, these updated codes are
actually easier to apply than the 1983 MEC, since less calculation is needed.
In the model, resistances of other wall components were specified based
on materials indicated in the plans.
In the model, basements were considered conditioned
space. The 2000 IECC requirement is
for conditioned basement walls to be insulated. If the basement wall is not a conditioned space,
the 2000 IECC allows for the insulation to be placed in the floor cavity between
the basement and first floor.
The requirements shown above in Table 3 are associated
with the “simplified prescriptive track” of each code, which is
the easiest and most often used means of code compliance. The codes also contain “performance tracks”
that allow homeowners to trade off upgraded components in one area to allow
flexibility in other areas. Therefore,
the actual codes can be more flexible than is implied by the table, but the
simplified prescriptive track is used by most builders.
Climates
Four cities were chosen to
represent the climate variation in Nebraska. These cities were
chosen to represent the heating degree day categories used in the 2000 IECC to
specify required thermal performance of envelope components. The National Oceanic and Atmospheric Administration
(NOAA) publishes a list of annual degree days that includes approximately 140
cities and towns in the state of Nebraska. The heating degree
days (65°F base) in the state range from 5,552 to 7,862. This includes four categories specified in
the 2000 IECC, and one city from each of these categories was chosen for
modeling. Table 4 summarizes the degree
day categories, the selected cities, and their actual numbers of degree
days. Note that the state’s second
largest city, Lincoln, has nearly the same climate as Omaha (6,119 vs. 6,153 degree days). Numbers of degree days for other code
jurisdictions not shown can be found in Table A4 in the appendix to this
report. Also shown in Table 4 are the
component criteria for thermal performance in each of the four climate zones.
|
Degree day range
|
City
|
Annual degree days
|
Max. glazing U-factor
|
Min. ceiling R-value
|
Min. wall R-value
|
Min. floor R-value
|
Min. basement wall R-value
|
|
5,500-5,999
|
McCook
|
5,967
|
0.40
|
38
|
18
|
21
|
10
|
|
6,000-6,499
|
Omaha
|
6,153
|
0.35
|
38
|
18
|
21
|
10
|
|
6,500-6,999
|
Norfolk
|
6,766
|
0.35
|
49
|
21
|
21
|
11
|
|
7,000-8,499
|
Chadron
|
7,021
|
0.35
|
49
|
21
|
21
|
11
|
Table
4. Cities, their climates, and 2000 IECC
component criteria.
Cost analysis
RS Means Residential Cost Data7 were used
to determine installed cost for the building components considered in the
study. This step required that the
code-specified U-factors and R-values be translated into defined building
components for which costs could be compared.
Only the costs for components that differ between energy codes were
included in the construction cost calculation.
In some instances, Means did not provide as much detail as was needed
to differentiate the components (for example, window types), so quotes from
local vendors were used to supplement the estimates, as described below. The total price for each component includes
purchase price, installation, overhead, and profit. This is the total installed cost to the customer.
Local cost adjustment factors from Means were then used to adjust each
of the costs to the four locations: Omaha, Norfolk, McCook, and Chadron.
The calculated energy cost for each house includes
electricity used by the HVAC system fan year round, electricity needed for
cooling, and gas used for heating. Rates were obtained in May 2003 from local utilities
serving the four geographical areas (see Tables 9 and 10).
Windows
Base prices for windows were taken from Means values for
premium quality vinyl clad windows. A
few of the windows listed on the house plans were not exactly the same size as
those found in Means, and in these cases the next largest size or a window with
the same glass area was used.
The window U-factors required by the different codes
vary. U-factor is usually decreased by
adding either an insulated air or argon space, adding a low-e coating, or
improving frame performance. However,
the Means data does not include cost differences for these upgrades. The Means prices are for double glazed
insulating glass with ½ inch air space and no coating, a combination that
provides U = 0.50. We then obtained
costs from local vendors to upgrade to argon fill and low-e coating. An upgrade to low-e glass with e = 0.40 was
estimated at $25.00 per window, and an upgrade to low-e glass with e = 0.15 was
priced at $30 per window. Argon gas fill
requires an additional cost of $15.00 per window. Table 5 below shows the four window U-factor
requirements of the various codes and the glass type and coating combinations
needed to comply with each. U-factors of
various combinations were obtained from a thermal engineering text8.
|
U-factor (Btu/hrft2ºF)
|
Glass type
|
Coating
|
|
0.50
|
Double glazed, ½” air space
|
none
|
|
0.45
|
Double glazed, ½” air space
|
Low-e (0.40)
|
|
0.40
|
Double glazed, ½” air space
|
Low-e (0.15)
|
|
0.35
|
Double glazed, ½” argon fill
|
Low-e (0.15)
|
Table
5. Types of windows used to meet
U-factor requirements.
Exterior wall insulation
Wall insulation base prices were also obtained from
Means7 and insulating values not specified by Means taken from
a thermal engineering text8. All four house plans have 2 by 4 stud walls,
but some of the higher wall insulation requirements could not be obtained
using only 3 ½ inch batt insulation. In
these cases, the R-value requirement was met by placing 3 ½ inch batt insulation
between the studs and a layer of rigid insulation used as sheathing.
The houses with R-11 or lower walls have an outer
layer of plywood to which the siding would be nailed. For higher R-value walls, homebuilders may use
rigid insulation of up to ½ inch in place of this plywood layer (with plywood
for shear bracing at corners). Since
rigid insulation is slightly less expensive than plywood, this allows a more
insulated wall to be constructed at approximately the same cost. R-18 walls can be achieved with a 2 by 4 stud
wall if higher density R-15 fiberglass batts are used. To obtain an R-21 wall, 2 by 6 construction
is necessary. Therefore, the costs
for the R-21 walls include the incremental cost increase necessary to convert
the houses to 2 by 6 construction.
Table 6 shows the wall insulation combinations
that were used to meet the code R-value requirements. For easy use, most of the codes specify wall
insulation values that apply only to the insulation. However, the 1983 MEC code specifies composite
wall insulating values that include the effects of doors and windows.
Therefore, the required insulation value for those cases depends on
the number of and type of doors and windows in each house.
For our analysis, we modeled the 1983 MEC cases with a glazing U-factor
of 0.45 Btu/h.ft2F and an opaque door U-factor of 0.25 Btu/h.ft2F. With this combination, the insulation requirements
for the four houses ranged from 7.0 to 8.9 ºFft2hr/Btu. An R-value of 11 ºFft2hr/Btu was
used for all of these cases, since this was the closest reasonable insulation
choice.
|
R-value (ºFft2hr/Btu)
|
Wall insulation type
|
|
7.0
|
3-½” R-11 fiberglass batts
|
|
7.9
|
3-½” R-11 fiberglass batts
|
|
8.1
|
3-½” R-11 fiberglass batts
|
|
8.9
|
3-½” R-11 fiberglass batts
|
|
11
|
3-½” R-11 fiberglass batts
|
|
18
|
3-½” R-15 fiberglass batts plus
½” isocyanurate rigid insulation
|
|
21
|
5-½” R-19 fiberglass batts plus
½” isocyanurate rigid insulation
|
Table
6. Wall insulation combinations used to
meet code requirements.
Basement wall insulation
The cost analysis was performed
with the assumption that the basements are conditioned. Generally, energy codes require insulation
between the house and basement if the basement is not conditioned space, and
basement wall insulation if the basement is conditioned. In this case, two of the energy codes require
basement wall insulation. Our cost
analysis obtains R-8 with polystyrene rigid insulation, which can be placed on
the exterior of the basement wall. R-10
and R-11 would more likely be obtained with interior insulation. Here, we have priced 3 ½” R-11 fiberglass
batts. Table 7 shows the basement wall
insulation combinations used to meet the code requirements. Depending on the code official, the use of
interior insulation may also involve finishing of the interior wall. Such finishing has other benefits and
increases value to the homeowner in ways that go beyond energy efficiency. For all of these reasons, the costs of
furring and drywalling the interior basement walls was not included in the life
cycle cost analysis.
|
R-value (ºFft2hr/Btu)
|
Basement wall insulation type
|
|
8
|
2” expanded polystyrene rigid
insulation (applied to exterior)
|
|
10
|
3 ½” R-11 fiberglass batts
|
|
11
|
3 ½” R-11 fiberglass batts
|
Table
7. Basement wall insulation combinations
used to meet code requirements.
Ceiling insulation
Most of the ceiling area for the
four house plans is beneath attics.
Where attics are present, fiberglass batt insulation was used with a
layer of blown-in insulation above it if needed to meet the R-value
requirement. One floor plan also
contains a small amount of cathedral ceiling (about 5% of the overall roof
area) directly beneath a sloped roof supported by 2 by 10 inch joists. For these sections, batt insulation was used
between the joists. When more insulation
is required, foamed in place polyurethane is substituted. Table 8 summarizes the roof/ceiling
insulation combinations that were used to meet the codes.
|
R-value (ºFft2hr/Btu)
|
Insulation location
|
Insulation type
|
|
25
|
Cathedral ceiling
|
9” fiberglass batts
|
|
32
|
Cathedral ceiling
|
9 ¼” blown in cellulose
|
|
33
|
Cathedral ceiling
|
9 ¼” blown in cellulose
|
|
38
|
Cathedral ceiling
|
9 ¼” foamed in place urethane
(approx. R-6 per inch)
|
|
49
|
Cathedral ceiling
|
9 ¼” foamed in place urethane
(approx. R-6 per inch)
|
|
25
|
Attic floor
|
9” fiberglass batts
|
|
32
|
Attic floor
|
5-½” fiberglass batts plus 6”
blown-in fiberglass insulation
|
|
33
|
Attic floor
|
5-½” fiberglass batts plus 7”
blown-in fiberglass insulation
|
|
38
|
Attic floor
|
5-½” fiberglass batts plus
8-1/2” blown-in fiberglass insulation
|
|
49
|
Attic floor
|
5-½” fiberglass batts plus 13-½”
blown-in fiberglass insulation
|
Table
8. Roof and ceiling insulation
combinations used to meet code requirements.
Exterior doors
Doors meeting the code U-factor
requirements for opaque exterior doors were also identified and priced through
local suppliers and rated using a thermal engineering text8. Installation costs were taken from Means7. As mentioned above, the 1983 MEC cases were
modeled with U=0.25 Btu/hrft2ºF, which was also the requirement for
the Nebraska average case. This
requirement was met with a 1 ¾ inch thick polyurethane core fiberglass door
with a thermal break. All locations for
the 2000 IECC code required a door U-factor of 0.35 Btu/hrft2ºF. This was met using a door identical to that
above, except that it is constructed of steel.
The steel door is slightly less expensive and less insulating.
Mechanical equipment
Price data for gas furnaces and central air conditioning
units were also obtained from Means. Because Means only lists a few sizes for each,
we consulted with vendors to determine the commonly available size increments
and interpolated the Means cost data to these sizes. This allowed us to model a more realistic range
of equipment capacities and to specify equipment that more closely meets the
design loads for the houses studied.
The 1983 MEC allows gas furnaces
with AFUE as low as 78% and air conditioning systems as low as 6.8 SEER. Upon consultation with local vendors, we
learned that these efficiencies are no longer being widely installed. The least efficient systems typically being
used are 80% AFUE furnaces and 10.0 SEER air conditioning systems. These are required for the Nebraska average and 2000 IECC codes. Therefore, all of the code conditions were
modeled with the same efficiencies, and the only difference in system cost for
the codes occurs if increased insulation reduced the design load and equipment
could be downsized.
Utility costs
Table 9 shows current rates
charged by Nebraska utilities for natural gas.
These rates were used to determine heating cost. Since all of the house and code combinations
have gas service and use some gas, the minimum and customer charges were not
included in the cost analysis since they will be the same for each house.
|
City
|
Gas rate in dollars per
therm (100,000 BTU).
|
Gas supplier
|
|
McCook
|
$0.909
|
Kinder Morgan Choice Gas
|
|
Omaha
|
$0.6928
|
Metropolitan Utilities
District
|
|
Norfolk
|
$0.81283
|
Aquila
|
|
Chadron
|
$0.909
|
Kinder Morgan Choice Gas
|
Table
9. Nebraska gas rates.
Table
10 shows the rates currently charged in Nebraska for electricity. Both
Nebraska utilities charge different rates for winter and summer.
Winter rates are charged between October 1 and May 31 and summer rates
are charged June 1 through September 30. Since
the decision to have electrical service is independent of the energy code,
the base monthly charge was not included in the analysis.
Furthermore, use of these rates in the cost analysis is more complicated,
since electrical rates are tiered. As
a customer uses more energy, a lower rate is charged. Since the goal of this analysis is to determine
the cost of electricity used for cooling and to operate the fan year-round,
it is necessary to estimate the customer’s other electricity use so that
the correct costs can be applied.
|
Cities
|
|
Electrical power rate
|
Power supplier
|
|
McCook
Norfolk
Chadron
|
Base charge (monthly)
|
$13.00
|
Nebraska Public Power District
|
|
First 750 kWh (summer)
|
8.51 Cents/kWh
|
|
After 750 kWh (summer)
|
6.98 Cents/kWh
|
|
First 750 kWh (winter)
|
6.26 Cents/kWh
|
|
After 750 kWh (winter)
|
3.74 Cents/kWh
|
|
Omaha
|
Base charge (monthly)
|
$5.15
|
Omaha Public Power District
|
|
First 1000 kWh (summer)
|
7.61 Cents/kWh
|
|
After 1000 kWh (summer)
|
7.25 Cents/kWh
|
|
First 100 kWh (winter)
|
6.88 Cents/kWh
|
|
100 to 1000 kWh (winter)
|
5.87 Cents/kWh
|
|
Above 1000 kWh (winter)
|
3.65 Cents/kWh
|
Table
10. Nebraska electricity rates.
Customers’ electrical use for activities other than thermal
conditioning were estimated from the same data used to calculate the internal
sensible heat gains from equipment.
Table 11 shows the hourly internal heat gains from appliances and
lighting that were used in the energy analysis of the four houses. The occupancy-related usage occurs during
2,288 hours per year, or 191.7 hours per month.
The non-occupancy related gains occur 8,760 hours per year, or 730 hours
per month. With these usage frequencies,
a total monthly heat gain due to equipment was calculated and converted to
electricity use in kWh, since these appliances convert virtually all of their
energy input into heat.
Using these values for each house’s base electricity usage,
all of the space conditioning electricity cost for the NPPD houses (McCook, Norfolk,
and Chadron) was calculated at the lower rate for usage above 750 kWh. Likewise, the entire space conditioning electricity
cost for the two larger OPPD houses (Omaha)
was calculated at the lowest rate for usage above 1000 kWh. For the two smaller OPPD houses, the first
170 or 110 kWh needed each month for space conditioning were calculated at the
below 1000 kWh rate, and the remaining usage occurs at the lowest (above 1000
kWh) rate.
|
House size (sf)
|
Occupancy related gains (Btu/hr)
|
Non-occupancy related gains (Btu/hr)
|
Total monthly
equipment heat gain (Btu)
|
Electricity use (kWh)
|
|
1,453
|
7,955
|
1,790
|
2,831,674
|
830
|
|
1,852
|
7,955
|
2,069
|
3,035,344
|
890
|
|
2,103
|
7,955
|
2,668
|
3,472,614
|
1,018
|
|
2,932
|
7,955
|
3,413
|
4,016,464
|
1,177
|
Table 11. Internal sensible heat gains from equipment.
Life cycle cost analysis
Life cycle cost analysis was performed over a 30 year period
to determine the present value of mortgage payments and energy costs for the
different options studied.
A mortgage payment amount for the construction upgrades was
estimated using an average rate published by the Federal Housing Finance Board
for the previous year9. For
2002, this source reports an effective interest rate of 6.43% for 30 year
mortgages on new single family housing.
This rate was used to convert the construction costs into equal mortgage
payments.
The present value of these mortgage payments was then
computed using the methodology published by the U.S. Department of Energy (DOE)
for Life Cycle Cost (LCC) analysis of energy conservation projects10. This methodology forms the basis for the
National Institute of Standards and Technology (NIST) Building Life Cycle Cost
(BLCC) program, which is used to calculate life cycle costs for government
projects. The BLCC program was not used
directly because it does not allow time periods greater than 25 years to be
studied. In this calculation, the April
2003 discount rate of 3.0% for DOE projects related to energy conservation
(based on the current rate for T-bills), and a long term average inflation rate
of 2.1% were used.
The present value of the annual energy costs was also
calculated using the DOE BLCC method, with price indices and discount factors
published for April 200310.
These are based on the same 3.0% discount rate and projected cost
increases for electricity and natural gas in the Midwest
census region, which includes Nebraska.
Results
Annual energy simulations and
life cycle cost analysis were performed for the four houses under the three
code conditions to determine their impact on Nebraska homeowners. This
section compares the design heating and cooling loads and construction cost for
the three codes in the four climate zones.
Annual energy use and life cycle cost for a family of four with two
occupants at home during the daytime is then compared in detail for all of the
code and climate combinations. The
sensitivity of the analysis to several key issues relevant to Nebraska homeowners are also investigated, including: the effects of finished basements, alternate
occupancy profiles, and thermostat setbacks.
Finally, future economic impacts for Nebraska are discussed.
Design heating and cooling loads
Table 12 shows the heating design loads in MBH (1MBH=1,000
Btu/hr) for each of the house/city/code combinations. The table is arranged to show the codes in decreasing
order of stringency for each city. For
each house in a specific city, the heating design load increases from the 2000
IECC to the 1983 MEC code, typically by more than 20%. These differences are large enough to allow
smaller equipment to be installed, depending on the actual values in relation
to the available equipment sizes.
As would be expected, heating design loads are lowest in
McCook, and increase with the number of heating degree days in Omaha,
Norfolk, and Chadron. Heating design loads also generally increase
with house size. The design loads for
the 1,852 sf ranch are usually slightly larger than those for the 2,103 sf two
story house. This is due to infiltration
effects. Both houses have full
basements, but because the ranch house has a larger footprint, the volume of
its basement is larger. Infiltration
effects for this much larger basement increase the load for the house. Also, the floor to ceiling height for the
ranch house is about 1 foot higher than for the two story house, which also
increases its volume and thus its infiltration load slightly.
|
Combinations
|
Heating design load
(MBH)
|
|
Code
|
City
|
1,453 sf ranch
|
1,852 sf ranch
|
2,103 sf
2 story
|
2,932 sf
2 story
|
|
2000 IECC
|
McCook
|
30
|
37
|
36
|
50
|
|
NE average
|
McCook
|
32
|
40
|
39
|
55
|
|
1983 MEC
|
McCook
|
37
|
48
|
44
|
63
|
|
2000 IECC
|
Omaha
|
31
|
40
|
39
|
54
|
|
NE average
|
Omaha
|
34
|
43
|
43
|
59
|
|
1983 MEC
|
Omaha
|
39
|
51
|
47
|
67
|
|
2000 IECC
|
Norfolk
|
33
|
40
|
40
|
56
|
|
NE average
|
Norfolk
|
37
|
46
|
45
|
63
|
|
1983 MEC
|
Norfolk
|
42
|
55
|
50
|
72
|
|
2000 IECC
|
Chadron
|
32
|
40
|
39
|
55
|
|
NE average
|
Chadron
|
36
|
45
|
44
|
62
|
|
1983 MEC
|
Chadron
|
41
|
54
|
50
|
71
|
Table 12. Heating design load.
Table 13 shows cooling design loads for the house/city/code
combinations. The design cooling loads
show many of the same general trends, with load increasing for warmer climate
and larger houses. Note that Omaha,
while its winters are colder than McCook, also has warmer summer weather.
|
Combinations
|
Cooling design load
(Tons)
|
|
Code
|
City
|
1,453 sf ranch
|
1,852 sf ranch
|
2,103 sf
2 story
|
2,932 sf
2 story
|
|
2000 IECC
|
McCook
|
2.8
|
3.1
|
3.5
|
3.7
|
|
NE average
|
McCook
|
2.7
|
3.1
|
3.5
|
3.8
|
|
1983 MEC
|
McCook
|
2.8
|
3.2
|
3.6
|
3.9
|
|
2000 IECC
|
Omaha
|
2.8
|
3.2
|
3.5
|
3.8
|
|
NE average
|
Omaha
|
2.9
|
3.3
|
3.7
|
4.0
|
|
1983 MEC
|
Omaha
|
2.9
|
3.5
|
3.7
|
4.2
|
|
2000 IECC
|
Norfolk
|
2.7
|
3.1
|
3.4
|
3.6
|
|
NE average
|
Norfolk
|
2.8
|
3.2
|
3.6
|
3.9
|
|
1983 MEC
|
Norfolk
|
2.8
|
3.3
|
3.6
|
4.1
|
|
2000 IECC
|
Chadron
|
2.7
|
3.1
|
3.4
|
3.6
|
|
NE average
|
Chadron
|
2.8
|
3.2
|
3.6
|
3.9
|
|
1983 MEC
|
Chadron
|
2.8
|
3.3
|
3.6
|
4.0
|
Table 13. Cooling design load.
Construction cost
The calculated construction cost includes purchase and
installation of all construction items associated with meeting the different
code situations. For walls, this includes
cavity wall insulation, either exterior plywood sheathing or rigid insulation
as needed to achieve the required R-value, and the incremental cost of
upgrading to 2 by 6 stud wall construction if necessary. Also included are exterior doors, windows,
ceiling/roof insulation, gas furnaces, and central air conditioning units.
The more stringent code requirements naturally involve
increased costs for most of these components.
The HVAC equipment is an exception.
Since availability dictated that the same efficiency equipment be used
for all of the code cases, the only difference in cost occurred when more
stringent codes allowed the equipment size to be decreased. This provided a small cost reduction in some
cases. Exterior doors, which make up a
small portion of the overall cost, are another exception since the 2000 IECC
allows a slightly less expensive and less insulating door than is required by
the current Nebraska average.
Figure 1 shows a typical distribution of these costs among
the construction items. For the 2,103 sf
two story house located in Omaha
meeting the Nebraska average code
requirements, the construction cost for code-related items is approximately
$21,500. Exterior doors contribute 2% of
this cost, HVAC equipment 21%, insulation 32%, and windows 45%.
Figure 1. Typical construction cost distribution
Table 14 shows the location-adjusted costs for these construction
components for each house for each code.
Location adjustments were made using location factors published in the
2003 Means Residential Cost Data11 (Means). Means established costs in McCook at 78% of
the national average, Omaha at 92%,
Norfolk at 84%, and Chadron at
73%. As would be expected, construction
costs usually increase as the code becomes more stringent. However, in a few cases, the upgraded
insulation allows the HVAC equipment to be downsized, which reduces the cost
impact of the 2000 IECC. Exterior doors,
though a small portion of the total cost, are also slightly less expensive for the
2000 IECC compared to the Nebraska
average.
|
Combinations
|
Construction cost
in 2003 dollars
|
|
Code
|
City
|
1,453 sf ranch
|
1,852 sf ranch
|
2,103 sf
2 story
|
2,932 sf
2 story
|
|
2000 IECC
|
McCook
|
$13,601
|
$14,726
|
$18,147
|
$31,062
|
|
NE average
|
McCook
|
$13,711
|
$14,880
|
$18,226
|
$31,371
|
|
1983 MEC
|
McCook
|
$11,942
|
$12,840
|
$16,698
|
$28,577
|
|
2000 IECC
|
Omaha
|
$16,355
|
$17,755
|
$21,735
|
$37,309
|
|
NE average
|
Omaha
|
$16,172
|
$17,536
|
$21,571
|
$37,062
|
|
1983 MEC
|
Omaha
|
$14,086
|
$15,103
|
$19,732
|
$33,706
|
|
2000 IECC
|
Norfolk
|
$15,097
|
$16,347
|
$19,752
|
$34,014
|
|
NE average
|
Norfolk
|
$14,803
|
$16,045
|
$19,695
|
$33,810
|
|
1983 MEC
|
Norfolk
|
$12,928
|
$13,789
|
$18,025
|
$30,787
|
|
2000 IECC
|
Chadron
|
$13,120
|
$14,206
|
$17,166
|
$29,560
|
|
NE average
|
Chadron
|
$12,832
|
$13,914
|
$17,116
|
$29,382
|
|
1983 MEC
|
Chadron
|
$11,235
|
$11,984
|
$15,664
|
$26,566
|
Table 14. Construction cost for code-related items.
Table 15 translates the construction costs shown in Table 14
into annual mortgage payments for a 30 year fixed mortgage at a rate of 6.43%,
based on Federal Housing Finance Board data.
This represents the annual cost to the homeowner for the construction of
these items. In all cases, any
additional cost associated with an upgrade to the 2000 IECC code from the
current Nebraska average is less
than $25 annually.
|
Combinations
|
Annual mortgage
payment in dollars
|
|
Code
|
City
|
1,453 sf ranch
|
1,852 sf ranch
|
2,103 sf
2 story
|
2,932 sf
2 story
|
|
2000 IECC
|
McCook
|
$1,024
|
$1,109
|
$1,366
|
$2,339
|
|
NE average
|
McCook
|
$1,032
|
$1,120
|
$1,372
|
$2,362
|
|
1983 MEC
|
McCook
|
$899
|
$967
|
$1,257
|
$2,152
|
|
2000 IECC
|
Omaha
|
$1,232
|
$1,337
|
$1,637
|
$2,809
|
|
NE average
|
Omaha
|
$1,218
|
$1,320
|
$1,624
|
$2,791
|
|
1983 MEC
|
Omaha
|
$1,061
|
$1,137
|
$1,486
|
$2,538
|
|
2000 IECC
|
Norfolk
|
$1,137
|
$1,231
|
$1,487
|
$2,561
|
|
NE average
|
Norfolk
|
$1,115
|
$1,208
|
$1,483
|
$2,546
|
|
1983 MEC
|
Norfolk
|
$973
|
$1,038
|
$1,357
|
$2,318
|
|
2000 IECC
|
Chadron
|
$988
|
$1,070
|
$1,293
|
$2,226
|
|
NE average
|
Chadron
|
$966
|
$1,048
|
$1,289
|
$2,212
|
|
1983 MEC
|
Chadron
|
$846
|
$902
|
$1,180
|
$2,000
|
Table 15. Annual mortgage payment for code-related
items.
Energy use
Annual energy consumption for heating and cooling was
determined using an annual hourly calculation performed using Energy Plus. Because the orientation of the house impacts
the energy consumption, each of the house/city/code conditions was simulated
with the house facing due North, South, East, and West, and these four results
averaged to obtain one energy consumption value for each condition. Energy costs for gas, summer electricity, and
winter electricity were determined using local utility rates and summed to
obtain a single energy cost for each house (See Appendix).
Figure 2 shows the distribution of these costs for the Nebraska
average case in McCook and Chadron, the warmest and coldest cities
studied. Nebraska
homeowners spend a significant amount of money on both heating and
cooling. The average homeowner in McCook
spends approximately $275 for electricity in the summer used for cooling, and
approximately $450 on gas in the winter for heating. In Chadron, the same house will require
approximately $225 in electricity for summer cooling, but $550 in gas for
winter heating.
Figure 2. Typical annual heating and cooling cost
distribution (NE average code).
Table 16 summarizes the annual energy cost for heating and
cooling all of the house/code combinations in 2003 dollars. This is the predicted energy cost for the
first year of operation. In every case,
energy code upgrades result in decreased energy cost for the homeowner. For a given house and city, the difference in
energy cost between the 1983 MEC house and the 2000 IECC house is hundreds of
dollars. This illustrates the very real
financial effect that timely upgrades to energy codes have on homeowners. The data also show that an upgrade from the
current state average to the 2000 IECC will save homeowners between $39 and
$137 annually, depending on location and house size.
|
Combinations
|
Annual energy cost in
2003 dollars
|
|
Code
|
City
|
1,453 sf ranch
|
1,852 sf ranch
|
2,103 sf
2 story
|
2,932 sf
2 story
|
|
2000 IECC
|
McCook
|
$581
|
$728
|
$712
|
$976
|
|
NE average
|
McCook
|
$622
|
$787
|
$779
|
$1,055
|
|
1983 MEC
|
McCook
|
$813
|
$1,067
|
$1,079
|
$1,408
|
|
2000 IECC
|
Omaha
|
$579
|
$710
|
$700
|
$940
|
|
NE average
|
Omaha
|
$618
|
$763
|
$760
|
$1,007
|
|
1983 MEC
|
Omaha
|
$800
|
$1,015
|
$1,037
|
$1,332
|
|
2000 IECC
|
Norfolk
|
$595
|
$755
|
$746
|
$1,033
|
|
NE average
|
Norfolk
|
$665
|
$849
|
$843
|
$1,154
|
|
1983 MEC
|
Norfolk
|
$862
|
$1,134
|
$1,148
|
$1,513
|
|
2000 IECC
|
Chadron
|
$587
|
$744
|
$721
|
$1,006
|
|
NE average
|
Chadron
|
$665
|
$849
|
$827
|
$1,143
|
|
1983 MEC
|
Chadron
|
$858
|
$1,135
|
$1,129
|
$1,483
|
Table 16. 2003 Annual energy cost.
The accepted economic method for performing cost comparison
of alternatives is to complete a life cycle cost analysis. This is shown in the following section. However, we recognize that home sales are
often made on the basis of first year cost.
This practice is based on the assumption that the owner’s income is
likely to rise while the mortgage payment will stay the same. Therefore, a buyer trying to obtain as much
house as he/she can afford might be concerned about the trade-off between
mortgage increase and energy savings in the first year, rather than whether he/she
will save money over the life of the house.
Table 17 shows a comparison of the first year mortgage costs
and energy savings that would result from an upgrade from the current Nebraska
average code to the 2000 IECC code. This
is the change that the average homeowner in Nebraska
would experience. For all sixteen
house-city combinations shown, the first year energy savings is greater than
the annual mortgage cost increase. This
means that these homeowners begin to see cost savings in the first year. Note that for the houses in McCook, the mortgage
increases shown are negative, meaning that the 2000 IECC house actually costs
less to build. This happens when
downsizing of HVAC equipment and/or the less expensive exterior doors save more
money than is required to increase the amount of insulation used.
|
1,453 sf ranch
|
1,852 sf ranch
|
2,103 sf 2 story
|
2,932 sf 2 story
|
|
City
|
Mortgage
increase
|
Energy
savings
|
Mortgage
increase
|
Energy
savings
|
Mortgage
increase
|
Energy
savings
|
Mortgage
increase
|
Energy
savings
|
|
McCook
|
-$8
|
$41
|
-$12
|
$59
|
-$6
|
$67
|
-$23
|
$79
|
|
Omaha
|
$14
|
$39
|
$17
|
$53
|
$12
|
$60
|
$19
|
$67
|
|
Norfolk
|
$22
|
$70
|
$23
|
$94
|
$4
|
$97
|
$15
|
$121
|
|
Chadron
|
$22
|
$78
|
$22
|
$105
|
$4
|
$106
|
$13
|
$137
|
Table 17. First year mortgage cost-energy savings
comparison – upgrade from Nebraska
average to 2000 IECC.
Table 18 compares the first year mortgage cost and energy
savings associated with an upgrade from the 1983 MEC, the current statewide
minimum, to the 2000 IECC. In all
sixteen cases, the first year energy savings exceed the annual mortgage
increase. The first year savings to the
homeowner ranges from $50 to $295, and is usually more than $100. A code upgrade would therefore provide an
even greater benefit to homeowners in jurisdictions where the state minimum
code is still being enforced.
|
|
1,453 sf ranch
|
1,852 sf ranch
|
2,103 sf 2 story
|
2,932 sf 2 story
|
|
City
|
Mortgage
increase
|
Energy
savings
|
Mortgage
increase
|
Energy
savings
|
Mortgage
increase
|
Energy
savings
|
Mortgage
increase
|
Energy
savings
|
|
McCook
|
$125
|
$232
|
$142
|
$339
|
$109
|
$367
|
$187
|
$432
|
|
Omaha
|
$171
|
$221
|
$200
|
$305
|
$151
|
$337
|
$271
|
$392
|
|
Norfolk
|
$163
|
$267
|
$193
|
$379
|
$130
|
$402
|
$243
|
$480
|
|
Chadron
|
$142
|
$271
|
$167
|
$391
|
$113
|
$408
|
$225
|
$477
|
Table 18. First year mortgage cost-energy savings
comparison – upgrade from 1983 MEC to 2000 IECC.
Tables 17 and 18 show clear cost benefits associated with
upgrading the state energy code. These
benefits can be realized in the first year of home ownership. Over the life of the house, mortgage costs
will remain fixed while energy costs continue to rise. Therefore, owners will experience even
greater savings in subsequent years.
Life cycle cost
Life cycle cost analysis is a method of comparing
alternatives that have differing first and long-term costs. The method is commonly used to determine if
higher initial costs can be justified by reducing long-term operating
costs. The life cycle cost is reported
in terms of 2003 dollars, with future payments adjusted to account for these
effects. Therefore, the life cycle cost
for each code/city/house combination is the present value (in 2003 dollars) of
payments on a 30 year mortgage plus the present value of 30 years of energy
costs. These are shown in Table 19 in
2003 dollars, and graphically in Figure 3.
In all sixteen cases, the life cycle cost of the 2000 IECC
is the lowest of the three code conditions.
This echoes the earlier observation that even in the first year, before
any utility rate increases, the 2000 IECC case produces more energy savings
than are needed to pay the increased mortgage costs. In subsequent years mortgage costs remain
constant while energy prices escalate, bringing even greater savings to the
homeowner.
|
Combinations
|
Life cycle cost in
2003 dollars
|
|
Code
|
City
|
1,453 sf ranch
|
1,852 sf ranch
|
2,103 sf
2 story
|
2,932 sf
2 story
|
|
2000 IECC
|
McCook
|
$26,366
|
$30,530
|
$33,911
|
$53,432
|
|
NE average
|
McCook
|
$27,322
|
$31,873
|
$35,336
|
$55,358
|
|
1983 MEC
|
McCook
|
$29,100
|
$35,123
|
$39,507
|
$59,194
|
|
2000 IECC
|
Omaha
|
$29,259
|
$33,396
|
$37,538
|
$59,499
|
|
NE average
|
Omaha
|
$29,853
|
$34,210
|
$38,548
|
$60,571
|
|
1983 MEC
|
Omaha
|
$31,068
|
$36,434
|
$41,892
|
$63,166
|
|
2000 IECC
|
Norfolk
|
$28,293
|
$32,835
|
$36,346
|
$57,827
|
|
NE average
|
Norfolk
|
$29,380
|
$34,391
|
$38,213
|
$60,018
|
|
1983 MEC
|
Norfolk
|
$31,155
|
$37,510
|
$42,345
|
$63,704
|
|
2000 IECC
|
Chadron
|
$26,004
|
$30,335
|
$33,078
|
$52,483
|
|
NE average
|
Chadron
|
$27,268
|
$32,116
|
$35,132
|
$55,028
|
|
1983 MEC
|
Chadron
|
$29,306
|
$35,648
|
$39,484
|
$58,644
|
Table 19. Life cycle cost.
Figure 3. Life Cycle Cost.
Other effects on construction cost
and energy use
This study is based on assumptions about how houses will be
built and how they will be used by the occupants. Whenever possible, these assumptions are
based on statistical information published by U.S.
government sources so that they will represent the average citizen as
accurately as possible. However, there
is value in investigating the study’s sensitivity to a few key variations
likely to be of interest to Nebraska
homeowners.
What impact would finished basements have?
None of the code options studied require basements to be
finished, although some require basement wall insulation. If this insulation is applied to the inside
of the wall, some code officials might also require the basement wall to be
finished. Finished basements offer a
number of benefits to the homeowner, increasing the livable space in the house and
potentially increasing its value. Therefore,
basement wall finishing is unlike the other construction cost items considered
because it is not entirely an energy related cost.
Table 20 shows the estimated cost to add furring and drywall
to the basement walls of each house.
This estimated cost does not include the cost of any finish applied to
the drywall, such as paint or wallpaper, since these would be selected for
other reasons, and would not be required or specified by a code official. The costs in Table 20 are shown both as total
construction cost, and the additional annual mortgage payment on a 30 year
mortgage with the same rate as was used for the previous analysis.
|
Combinations
|
Costs and payments
in 2003 dollars
|
|
Cost
|
City
|
1,453 sf ranch
|
1,852 sf ranch
|
2,103 sf
2 story
|
2,932 sf
2 story
|
|
Construction cost
|
McCook
|
$1,241
|
$1,385
|
$1,052
|
$1,673
|
|
Omaha
|
$1,464
|
$1,633
|
$1,241
|
$1,974
|
|
Norfolk
|
$1,337
|
$1,491
|
$1,133
|
$1,802
|
|
Chadron
|
$1,162
|
$1,296
|
$985
|
$1,566
|
|
Annual mortgage payment
|
McCook
|
$93
|
$104
|
$79
|
$126
|
|
Omaha
|
$110
|
$123
|
$93
|
$149
|
|
Norfolk
|
$101
|
$112
|
$85
|
$136
|
|
Chadron
|
$87
|
$98
|
$74
|
$118
|
Table 20. Costs for finished basement walls.
The additional mortgage payment required is approximately
$100, depending on the size of the basement.
Table 21 shows the impact on life cycle cost if finished basement walls
are included in the two cases that require basement wall insulation. For all of the houses, the life cycle cost
for the 2000 IECC with finished basement walls is less than the 1983 MEC case
with unfinished basement walls. Both the
2000 IECC and the Nebraska
average code condition require basement insulation, so they must be compared
with the same wall treatment. The 2000
IECC case has the lowest life cycle cost both with and without the basement
insulation included in the life cycle cost calculation.
|
Combinations
|
Life cycle cost in
2003 dollars
|
|
Basement
walls
|
Code
|
1,453 sf ranch
|
1,852 sf ranch
|
2,103 sf
2 story
|
2,932 sf
2 story
|
|
Unfinished
|
2000 IECC
|
$29,259
|
$33,396
|
$37,538
|
$59,499
|
|
NE average
|
$29,853
|
$34,210
|
$38,548
|
$60,571
|
|
1983 MEC
|
$31,068
|
$36,434
|
$41,892
|
$63,166
|
|
Finished
|
2000 IECC
|
$30,872
|
$35,201
|
$38,903
|
$61,685
|
|
NE average
|
$31,466
|
$36,014
|
$39,912
|
$62,756
|
Table 21. Life cycle cost including finished basement
walls in Omaha.
How sensitive are the results to occupancy profile?
The occupancy profile used to generate the results in this
section was based on a family of four, with two members who were away from home
for work or school during the day, and two members who were usually at home
during the day. Simulations were also
conducted for a family of four in which all four occupants were away from home
during the daytime hours. Occupant
related internal gains were again based on national averages and assumed to be
the same as for the base case, except that they are shifted to evening and
weekend hours. Therefore, the difference
in energy consumption is due to changes in the timing of the loads. In the summer, this occupancy pattern would
decrease the peak load in the afternoon when outdoor temperatures are
highest. In the winter, the shifting of
load to evening hours may have little overall effect at times when heating is
needed all of the time. However, the
lower daytime load during milder weather in the spring and fall may cause the
house to require more heating at these times.
Table 22 shows the change in life cycle cost when the
different occupancy profile is used in the analysis. A positive change indicates an increase in
cost associated with the new occupancy profile, and a negative change indicates
a decrease. Whether the change is
positive or negative seems generally to be related to house design, with two of
the houses usually showing increases and two usually showing decreases. Variations on the order of several hundred
dollars over 30 years can be attributed to a change in occupancy schedule. However, the average for all of these cases
is only a reduction in life cycle cost of about $90 over the 30 year
period. Therefore, these results should
be broadly applicable to Nebraska
homeowners, although individual results in a particular house may vary.
|
Combinations
|
Change in life cycle
cost in 2003 dollars
|
|
Code
|
City
|
1,453 sf ranch
|
1,852 sf ranch
|
2,103 sf
2 story
|
2,932 sf
2 story
|
|
2000 IECC
|
McCook
|
-$129
|
$31
|
-$141
|
$178
|
|
NE average
|
McCook
|
-$235
|
$85
|
-$97
|
$265
|
|
1983 MEC
|
McCook
|
-$532
|
-$101
|
-$280
|
-$15
|
|
2000 IECC
|
Omaha
|
-$425
|
-$231
|
-$315
|
-$91
|
|
NE average
|
Omaha
|
-$617
|
-$186
|
-$290
|
-$36
|
|
1983 MEC
|
Omaha
|
-$1,058
|
-$479
|
-$585
|
-$400
|
|
2000 IECC
|
Norfolk
|
-$11
|
$122
|
$4
|
$237
|
|
NE average
|
Norfolk
|
-$70
|
$192
|
$67
|
$324
|
|
1983 MEC
|
Norfolk
|
-$431
|
-$65
|
-$190
|
-$11
|
|
2000 IECC
|
Chadron
|
$29
|
$185
|
$1
|
$280
|
|
NE average
|
Chadron
|
$18
|
$265
|
$84
|
$369
|
|
1983 MEC
|
Chadron
|
-$268
|
$71
|
-$124
|
$169
|
Table 22. Variations in life cycle cost with occupancy
profile.
How would energy use be impacted by thermostat setbacks?
Another issue that may be interesting to many people is the
use of setback thermostats. Setback
thermostats are not currently required by state energy code, nor are they
included in the 2000 IECC. Furthermore,
they may not be appropriate for all homeowners.
However, many people set their thermostats back at night and when they
are away from home to save energy, and their effects on the cost analysis may
be interesting for that reason. Figures
4-7 compare the first year energy cost for occupancy profile #1 (two people at
home during the day) and occupancy profile #2 (no one at home during the day)
without and with night setback thermostats.
Significant savings are obtained for both occupancy
profiles, but the savings are larger for occupancy profile #2. This is because the setback thermostat for
that occupancy profile operates both at night and on weekdays when the
occupants are not home. The setback
thermostat for occupancy profile #1 operates only at night, since two of the
occupants are home during the day.
Depending on the city, average energy cost savings vary from 20 to 25%
for occupancy profile #1 and from 35 to 40% for occupancy profile #2.
The first year energy savings are quite favorable,
considering that an automatic programmable setback thermostat costs
approximately $30. For all four houses,
the lowest annual savings occur for occupancy profile #1 (night setback only)
in Omaha with the 2000 IECC
code. The greatest annual savings occur
for occupancy profile #2 (day and night setbacks) in Chadron with the 1983 MEC
code. Owners of the 20th
percentile home (1,453 sf ranch) would save a minimum of $120 and a maximum of
$384. For the median Nebraska
homeowner, the 1,852 sf ranch home experiences savings between $146 and $485
and the 2,103 sf 2 story home saves between $105 and $387. The 80th percentile home (2,932 sf
2 story) experiences annual energy savings between $166 and $567.
Figure 4. Energy cost impact of thermostat setbacks -
McCook.
Figure 5. Energy cost impact of thermostat setbacks - Omaha.
Figure 6. Energy cost impact of thermostat setbacks - Norfolk.
Figure 7. Energy cost impact of thermostat setbacks -
Chadron.
Setback thermostats will impact life cycle cost by changing
the annual energy use. Tables 23 and 24
show life cycle costs associated with setback thermostats and the two occupancy
profiles. Setback thermostats do not
change the construction cost, but reduce the energy use. The reduction in energy use gained by setback
thermostats, as was seen in Figures 4-7, is largest for the less restrictive
codes. Therefore, the use of setbacks
acts to reduce the life cycle cost penalty associated with energy use in less
restrictive codes.
If a night setback is used with the occupancy profile in
which two occupants are at home during the day (Table 23), the IECC 2000 case
has the lowest life cycle cost in all sixteen house/city combinations. This means that the code upgrade will also be
beneficial to homeowners who choose to use night setback thermostats to
conserve energy.
The 2000 IECC case is the lowest cost option in thirteen of
the sixteen cases when setback thermostats are used both at night and on
weekdays (Table 24). The 1983 MEC has a
slightly lower life cycle cost for the smallest house in McCook, Omaha,
and Norfolk. In McCook and Norfolk
the difference is very small, less than $200 over 30 years. The difference is somewhat higher in Omaha
due to lower utility rates and higher construction costs there. This is a very conservative thermostat
scenario that is unlikely to be followed for an entire 30 year period. Even so, the 2000 IECC provides the lowest
costs in most of the houses and all of the “average” sized houses. Furthermore, the 2000 IECC provides a lower
life cycle cost than the current state average code in every case except
one. In that case, the difference is
only $19 over 30 years.
|
Combinations
|
Life cycle cost in
2003 dollars
|
|
Code
|
City
|
1,453 sf ranch
|
1,852 sf ranch
|
2,103 sf
2 story
|
2,932 sf
2 story
|
|
2000 IECC
|
McCook
|
$23,206
|
$26,596
|
$31,090
|
$49,000
|
|
NE average
|
McCook
|
$23,649
|
$27,659
|
$32,249
|
$50,634
|
|
1983 MEC
|
McCook
|
$24,063
|
$29,214
|
$34,885
|
$52,544
|
|
2000 IECC
|
Omaha
|
$26,879
|
$30,496
|
$35,444
|
$56,191
|
|
NE average
|
Omaha
|
$27,076
|
$31,089
|
$36,253
|
$56,995
|
|
1983 MEC
|
Omaha
|
$27,117
|
$32,111
|
$38,472
|
$58,184
|
|
2000 IECC
|
Norfolk
|
$25,499
|
$29,308
|
$33,831
|
$53,847
|
|
NE average
|
Norfolk
|
$26,042
|
$30,531
|
$35,373
|
$55,653
|
|
1983 MEC
|
Norfolk
|
$26,606
|
$32,152
|
$38,145
|
$57,577
|
|
2000 IECC
|
Chadron
|
$22,692
|
$26,184
|
$30,083
|
$47,817
|
|
NE average
|
Chadron
|
$23,318
|
$27,506
|
$31,704
|
$49,841
|
|
1983 MEC
|
Chadron
|
$23,974
|
$29,281
|
$34,407
|
$51,378
|
Table 23. Life cycle cost with night setback thermostat
(Occupancy profile #1).
|
Combinations
|
Life cycle cost in
2003 dollars
|
|
Code
|
City
|
1,453 sf ranch
|
1,852 sf ranch
|
2,103 sf
2 story
|
2,932 sf
2 story
|
|
2000 IECC
|
McCook
|
$21,639
|
$24,772
|
$29,566
|
$46,852
|
|
NE average
|
McCook
|
$22,053
|
$25,765
|
$30,659
|
$48,439
|
|
1983 MEC
|
McCook
|
$21,471
|
$26,141
|
$32,265
|
$48,840
|
|
2000 IECC
|
Omaha
|
$24,863
|
$28,208
|
$33,623
|
$53,644
|
|
NE average
|
Omaha
|
$24,844
|
$28,727
|
$34,335
|
$54,347
|
|
1983 MEC
|
Omaha
|
$23,882
|
$28,460
|
$35,383
|
$53,945
|
|
2000 IECC
|
Norfolk
|
$23,739
|
$27,151
|
$32,116
|
$51,263
|
|
NE average
|
Norfolk
|
$24,180
|
$28,237
|
$33,537
|
$52,919
|
|
1983 MEC
|
Norfolk
|
$23,603
|
$28,480
|
$35,089
|
$53,136
|
|
2000 IECC
|
Chadron
|
$21,143
|
$24,323
|
$28,560
|
$45,570
|
|
NE average
|
Chadron
|
$21,721
|
$25,528
|
$30,095
|
$47,468
|
|
1983 MEC
|
Chadron
|
$21,416
|
$26,098
|
$31,697
|
$47,558
|
Table 24. Life cycle cost day and night setback
thermostat (Occupancy profile #2).
Economic impacts for Nebraska
These results can be generalized for the entire state by
considering the number of houses built annually in each of the climate
regions. The four modeled cities were
chosen to represent the four heating degree day ranges throughout the state. Table 25 shows these degree day ranges, the
city used to represent it, and the number of 2001 permits issued in each
region. The information on number of
homes built was taken from the survey of code officials conducted by the Nebraska
Energy Office.
As Table 25 shows, the vast majority of houses being
constructed in the state, nearly 90%, are in the weather region represented by Omaha. This region includes the state’s seven
largest code jurisdictions in terms of 2001 building permits: Omaha,
Lincoln, Bellevue,
Sarpy County,
Gretna, Papillion, and Cass
County. The region represented by Norfolk
accounts for nearly 8% of the state’s total, with Kearney,
Norfolk, and North
Platte the largest jurisdictions in this area. Seward and Seward
County are the largest
jurisdictions represented by the McCook region with 1.4% of the state
total. Chadron represents the smallest
region, with Sidney, Wayne, and Chadron the largest jurisdictions in that
area. A full list of all code
jurisdictions in the state, their numbers of heating degree days (HDD), and the
city used to represent them is included in the appendix (Table A4).
|
Heating degree days
|
Modeled city
|
Number of permits
|
% of total
|
|
5,500-5,999
|
McCook
|
78
|
1.4
|
|
6,000-6,499
|
Omaha
|
5,142
|
89.5
|
|
6,500-6,999
|
Norfolk
|
456
|
7.9
|
|
7,000-8,499
|
Chadron
|
67
|
1.2
|
|
Nebraska total
|
|
5,743
|
|
Table 25. Number of homes represented by each region.
Using the percentages for each region shown in Table 25 it
is possible to calculate a weighted average savings for homeowners across the
state. Table 26 shows the weighted
average mortgage increase, first year energy cost, and first year net savings
to homeowners if the state energy code is increased from the current average
being enforced in the state to the 2000 IECC.
For all four houses, the mortgage increase is smaller than the energy
savings, producing a net first year savings to the homeowner. This will be the effect on the average Nebraska
homeowner if the 2000 IECC is adopted statewide. Note that this is most likely a conservative
estimate, since nearly 90% of the state is represented by Omaha. As was seen previously, Omaha
has higher construction costs and lower gas utility rates than other areas in
the state. Some jurisdictions with
climates similar to Omaha may have
lower construction and higher gas costs, which would produce greater first year
energy savings in these areas.
House
|
Mortgage increase
|
Energy savings
|
Net first year savings
|
|
1,453 sf ranch
|
$14
|
$43
|
$29
|
|
1,852 sf ranch
|
$17
|
$57
|
$40
|
|
2,103 sf 2 story
|
$11
|
$64
|
$53
|
|
2,932 sf 2 story
|
$18
|
$72
|
$54
|
Table 26. Weighted average first year savings to Nebraska
homeowners – upgrade from Nebraska average
to 2000 IECC code.
Table 27 uses the same weighting method to show the mortgage
increase, energy savings, and net first year savings associated with an upgrade
from the 1983 MEC to the 2000 IECC.
Here, the net first year savings to the homeowner are larger. These are the benefits that would be realized
by homeowners in jurisdictions that are enforcing only the state minimum
code.
|
House
|
Mortgage increase
|
Energy savings
|
Net first year savings
|
|
1,453 sf ranch
|
$169
|
$225
|
$56
|
|
1,852 sf ranch
|
$198
|
$312
|
$114
|
|
2,103 sf 2 story
|
$148
|
$343
|
$195
|
|
2,932 sf 2 story
|
$267
|
$400
|
$133
|
Table 27. Weighted average first year savings to Nebraska
homeowners – upgrade from 1983 MEC to 2000 IECC code.
The aggregate energy savings for the state can be estimated
based on the number of houses built in each size range. For this estimate, it is assumed that the
smallest 20% of Nebraska houses
can be represented by the 1,453 sf ranch and the largest 20% can be represented
by the 2,932 sf 2 story house. The 1,852
sf ranch and 2,103 sf 2 story houses each represent 30% of houses built in the
state. If 5,743 houses are built
annually in the state, an upgrade from the current state average to the 2000
IECC code provides a $340,000 aggregate energy savings to homeowners of these
houses in the first year. The net cash
savings to homeowners in the first year is $254,007. In terms of life cycle cost, the houses built
during a single year will provide their owners with a $5.5 million net savings
in 2003 dollars over the next 30 years.
This means that if the 2000 IECC is adopted by the state of Nebraska,
the houses built before 2015 will provide their owners with a net savings of
more than 59.6 million 2003 dollars over their lifetimes, even if there is no
housing growth during this period.
A more detailed look at where these savings come from shows
an even greater benefit for Nebraska’s
state economy. Thus far, construction
costs have been dealt with primarily in terms of mortgage payment increase,
since this is how the vast majority of homeowners finance construction. However, the entire construction cost is paid
to builders at the time of construction.
Table 28 shows the construction cost increase associated with an upgrade
from the current state average energy code to the 2000 IECC. Note that the McCook houses, again, show a
negative increase, meaning that the 2000 IECC actually costs less to build in
that region. For houses constructed in
the first year, the aggregate construction cost increase in the state is 1.13
million dollars. This money enters the
state economy during the year of construction, benefiting Nebraska
businesses and workers.
|
City
|
Construction cost
increase in dollars
|
|
1,453 sf ranch
|
1,852 sf ranch
|
2,103 sf 2 story
|
2,932 sf 2 story
|
|
McCook
|
-$110
|
-$154
|
-$79
|
-$309
|
|
Omaha
|
$184
|
$219
|
$165
|
$247
|
|
Norfolk
|
$293
|
$302
|
$57
|
$205
|
|
Chadron
|
$288
|
$292
|
$50
|
$178
|
|
Wtd. Average
|
$189
|
$221
|
$151
|
$235
|
Table 28. Construction cost increase – upgrade from Nebraska
average to 2000 IECC code.
In contrast, a substantial portion – an estimated 80 percent
– of energy dollars spent in Nebraska
leave the state:
* Virtually all the natural gas used is imported;
*More than 95 percent of fuels used to generate electricity
come from outside the state12.
The aggregate annual energy cost savings for houses built in
a single year with an upgrade from the current state average to the 2000 IECC
code will be $340,000. Of this, $43,800
is electricity, for which 95.6% of the purchased fuels are from out of state.
The remaining $295,600 is for gas, which is at least 60% out of state.
Therefore, less than $120,200 of this expense remains in the state.
Conclusion and recommendations
The findings of this study strongly support adoption of the
2000 IECC as the Nebraska
statewide residential energy code.
Four houses ranging from the 20th to 80th
percentile size were studied in four cities that cover the range of climates
experienced in the state. For all
sixteen house-city combinations, the upgrade to the 2000 IECC from the 1983
MEC, the current state minimum, resulted in first year energy savings greater
than the annual mortgage increase. This
means that the first year energy savings was greater than the annual mortgage
increase required to build houses to the stricter code. The difference was large enough to save most Nebraska
homeowners $100 or more during the first year.
For all sixteen house-city combinations, the upgrade to the
2000 IECC from the Nebraska average
resulted in first year energy savings greater than the annual mortgage
increase. This means that the average Nebraska
homeowner would also see savings in the first year of home ownership, and would
see even greater savings with future increases in utility prices. The aggregate projected savings for all
homeowners in the state is $254,000 in the first year. Over the next thirty years, the houses built
during a single year will provide their owners with a $5.5 million in net
savings. These savings will be
compounded in future years as more and more of Nebraska
housing stock is built to the upgraded standard.
The study also investigated the effects of setback
thermostats and found that Nebraska
homeowners can realize substantial savings if they are used. The change in energy use associated with
setback thermostats can begin to close the gap between mortgage cost and energy
savings associated with moving to a more restrictive energy code. However, in all of the cases, there is still
a lower life cycle cost associated with the 2000 IECC code for houses using
night setbacks. Even with a very
conservative and unlikely night and day setback scenario, most of the cases
still experienced lower life cycle cost with the 2000 IECC.
Other benefits to the state include additional investments
in construction cost, which translates to approximately 1.13 million dollars in
the first year and benefits local builders and suppliers. The mortgage payments on this additional construction
cost are traded against roughly $340,000 in annual energy savings, less than
35% of which remains in the state.
Finally, every effort has been made to use realistic cost
and occupancy assumptions. When future
costs are projected, U.S.
government statistics and projections are used to predict items such as
inflation and energy cost increases.
These projections are often based on past data, and should be regarded
as estimates. In particular, the energy
cost increases used here are modest.
Larger savings would be obtained if energy costs were to increase
suddenly in the future. Adoption of the
2000 IECC would give Nebraska
homeowners peace of mind by helping to insulate them from future fluctuations
in energy rates.
REFERENCES
1 US Census Data http://www.census.gov/const/C25Ann/sftotalsqft.pdf
2 Musser, A. and G. Yuill (1999). "Comparison of Residential
Air Infiltration Rates Predicted by Single Zone and Multizone Models."
ASHRAE Transactions 105(1).
3 ASHRAE (2001). ASHRAE Handbook of Fundamentals. Atlanta,
GA, American Society of Heating, Refrigerating,
and Air Conditioning Engineers.
4 EIA (1997). A look at residential energy consumption in 1997.
Washington, DC, US
Department of Energy, Energy Administration:
310.
5 USEPA (1997). Exposure Factors Handbook, National
Center for Environmental Assessment,
United States Environmental Protection Agency.
6 Quirouette, R. (1983). Moisture Sources in Houses. Building
Science Insight '83, NRC Canada.
7 RS Means 2003
Residential Cost Data, 22nd Annual Edition. Kingston, MA.
8 Kuehn, T., J. Ramsey, J. Threlkeld. 1998.
Thermal Environmental Engineering.
3rd ed. Prentice-Hall,
Inc. New York. 740 pgs.
9 Federal Housing Finance Board.
10 Rushing, A. and S. Fuller.
2003. Energy Price Indices and
Discount Factors for Life-Cycle Cost Analysis – April 2003. NISTIR 85-3273-18. April, 2003.
Building and Fire Research Laboratory, National Institute of Standards
and Technology. Gaithersburg,
MD.
11 RS Means 2003
Residential Cost Data, 22nd Annual Edition. Kingston, MA.
12 Energy Information Administration, U.S. Department of Energy, Washington, DC. And Nebraska Energy Office, Lincoln, NE.
Appendices
Annual summer electricity consumption
(kWh)
|
Combinations
|
Annual summer
electricity consumption kWh
|
|
Code
|
City
|
1,453 sf ranch
|
1,852 sf ranch
|
2,103 sf
2 story
|
2,932 sf
2 story
|
|
2000 IECC
|
McCook
|
3,242
|
3,678
|
4,373
|
4,948
|
|
NE average
|
McCook
|
3,264
|
3,766
|
4,510
|
4,993
|
|
1983 MEC
|
McCook
|
4,270
|
5,083
|
6,129
|
6,925
|
|
2000 IECC
|
Omaha
|
3,763
|
4,349
|
5,038
|
5,877
|
|
NE average
|
Omaha
|
3,770
|
4,424
|
5,166
|
5,931
|
|
1983 MEC
|
Omaha
|
5,021
|
6,015
|
7,049
|
8,198
|
|
2000 IECC
|
Norfolk
|
3,310
|
3,755
|
4,475
|
5,090
|
|
NE average
|
Norfolk
|
3,338
|
3,867
|
4,611
|
5,160
|
|
1983 MEC
|
Norfolk
|
4,388
|
5,220
|
6,248
|
7,103
|
|
2000 IECC
|
Chadron
|
2,754
|
3,034
|
3,720
|
4,026
|
|
NE average
|
Chadron
|
2,761
|
3,109
|
3,807
|
4,070
|
|
1983 MEC
|
Chadron
|
3,533
|
4,113
|
5,082
|
5,373
|
Table A1. Annual summer electricity consumption (kWh).
Annual winter electricity consumption
(kWh)
|
Combinations
|
Annual winter
electricity consumption kWh
|
|
Code
|
City
|
1,453 sf ranch
|
1,852 sf ranch
|
2,103 sf
2 story
|
2,932 sf
2 story
|
|
2000 IECC
|
McCook
|
1,015
|
1,166
|
1,413
|
1,499
|
|
NE average
|
McCook
|
1,052
|
1,264
|
1,499
|
1,455
|
|
1983 MEC
|
McCook
|
1,205
|
1,425
|
1,821
|
1,802
|
|
2000 IECC
|
Omaha
|
1,170
|
1,349
|
1,575
|
1,636
|
|
NE average
|
Omaha
|
1,210
|
1,380
|
1,651
|
1,723
|
|
1983 MEC
|
Omaha
|
1,407
|
1,547
|
2,059
|
2,117
|
|
2000 IECC
|
Norfolk
|
1,223
|
1,432
|
1,650
|
1,746
|
|
NE average
|
Norfolk
|
1,249
|
1,468
|
1,772
|
1,759
|
|
1983 MEC
|
Norfolk
|
1,457
|
1,698
|
2,192
|
2,286
|
|
2000 IECC
|
Chadron
|
949
|
1,087
|
1,274
|
1,247
|
|
NE average
|
Chadron
|
1,016
|
1,150
|
1,372
|
1,249
|
|
1983 MEC
|
Chadron
|
1,057
|
1,193
|
1,619
|
1,457
|
Table A2. Annual winter electricity consumption (kWh).
Annual gas consumption (Therm)
|
Combinations
|
Annual gas
consumption (Therm)
|
|
Code
|
City
|
1,453 sf ranch
|
1,852 sf ranch
|
2,103 sf
2 story
|
2,932 sf
2 story
|
|
2000 IECC
|
McCook
|
348
|
471
|
390
|
632
|
|
NE average
|
McCook
|
391
|
525
|
450
|
717
|
|
1983 MEC
|
McCook
|
517
|
725
|
641
|
943
|
|
2000 IECC
|
Omaha
|
339
|
468
|
400
|
656
|
|
NE average
|
Omaha
|
392
|
535
|
469
|
743
|
|
1983 MEC
|
Omaha
|
508
|
723
|
650
|
954
|
|
2000 IECC
|
Norfolk
|
392
|
540
|
458
|
754
|
|
NE average
|
Norfolk
|
475
|
645
|
560
|
895
|
|
1983 MEC
|
Norfolk
|
616
|
869
|
775
|
1,146
|
|
2000 IECC
|
Chadron
|
395
|
540
|
455
|
747
|
|
NE average
|
Chadron
|
478
|
647
|
561
|
893
|
|
1983 MEC
|
Chadron
|
629
|
883
|
785
|
1,159
|
Table A3. Annual gas consumption (Therm).
Number of permits and heating degree
days by code jurisdiction
Jurisdiction
|
Permits
|
HDD
|
Modeled
City
|
Jurisdiction
|
Permits
|
HDD
|
Modeled
City
|
|
Albion
|
7
|
7087
|
Chadron
|
Louisville
|
3
|
6292
|
Omaha
|
|
Alliance
|
5
|
6823
|
Norfolk
|
McCook
|
7
|
5967
|
McCook
|
|
Alma
|
3
|
6203
|
Omaha
|
Mead
|
1
|
6570
|
Norfolk
|
|
Ashland
|
32
|
6379
|
Omaha
|
Milford
|
6
|
5779
|
McCook
|
|
Auburn
|
6
|
5765
|
McCook
|
Minden
|
3
|
6398
|
Omaha
|
|
Beatrice
|
35
|
6151
|
Omaha
|
Nebraska City
|
9
|
6023
|
Omaha
|
|
Bellevue
|
300
|
6153
|
Omaha
|
Norfolk
|
65
|
6766
|
Norfolk
|
|
Blair
|
56
|
6455
|
Omaha
|
North Platte
|
53
|
6766
|
Norfolk
|
|
Bloomfield
|
1
|
7057
|
Chadron
|
Ogallala
|
12
|
6672
|
Norfolk
|
|
Cass County
|
121
|
6292
|
Omaha
|
Omaha
|
2136
|
6153
|
Omaha
|
|
Central
City
|
1
|
5834
|
McCook
|
O’Neill
|
4
|
7246
|
Chadron
|
|
Ceresco
|
1
|
6613
|
Norfolk
|
Palmyra
|
3
|
6337
|
Omaha
|
|
Chadron
|
9
|
7021
|
Chadron
|
Papillion
|
142
|
6153
|
Omaha
|
|
Columbus
|
60
|
6411
|
Omaha
|
Plainview
|
2
|
6485
|
Omaha
|
|
Cozad
|
7
|
6303
|
Omaha
|
Plattsmouth
|
20
|
6153
|
Omaha
|
|
Crete
|
10
|
5811
|
McCook
|
Ralston
|
2
|
6153
|
Omaha
|
|
Dakota City
|
7
|
6600
|
Norfolk
|
Sarpy County
|
281
|
6153
|
Omaha
|
|
David City
|
7
|
6237
|
Omaha
|
Saunders County
|
47
|
6613
|
Norfolk
|
|
Douglas County
|
42
|
6153
|
Omaha
|
Scottsbluff
|
19
|
6742
|
Norfolk
|
|
Elkhorn
|
64
|
6153
|
Omaha
|
Seward
|
24
|
5779
|
McCook
|
|
Falls City
|
1
|
5795
|
McCook
|
Seward County
|
22
|
5779
|
McCook
|
|
Fremont
|
40
|
6444
|
Omaha
|
Sidney
|
35
|
7092
|
Chadron
|
|
Gering
|
32
|
6742
|
Norfolk
|
South Sioux City
|
23
|
6600
|
Norfolk
|
|
Grand Island
|
101
|
6385
|
Omaha
|
Superior
|
1
|
5552
|
McCook
|
|
Gretna
|
166
|
6379
|
Omaha
|
Sutton
|
2
|
6347
|
Omaha
|
|
Hall County
|
24
|
6385
|
Omaha
|
Tekamah
|
4
|
6564
|
Norfolk
|
|
Hastings
|
59
|
6211
|
Omaha
|
Valley
|
4
|
6570
|
Norfolk
|
|
Holdrege
|
8
|
6482
|
Omaha
|
Wahoo
|
13
|
6570
|
Norfolk
|
|
Kearney
|
116
|
6652
|
Norfolk
|
Washington Cty.
|
79
|
6455
|
Omaha
|
|
Keith County
|
50
|
6672
|
Norfolk
|
Waverly
|
15
|
6119
|
Omaha
|
|
LaVista
|
115
|
6153
|
Omaha
|
Wayne
|
11
|
7143
|
Chadron
|
|
Lancaster County
|
34
|
6119
|
Omaha
|
Wymore
|
5
|
6151
|
Omaha
|
|
Lexington
|
7
|
6303
|
Omaha
|
York
|
19
|
6338
|
Omaha
|
|
Lincoln
|
1140
|
6119
|
Omaha
|
Yutan
|
4
|
6570
|
Norfolk
|
Table A4. 2001 Residential Permits by Nebraska code
jurisdiction.
This report was prepared with the support of the U.S.
Department of Energy (DOE)
Grant
#DE-FG48-02R803105. The findings,
conclusions and recommendations herein are those of the author and do not
necessarily reflect the views of DOE.
