Bill Calculation

The basic calculation of energy bills is given in the following equation:

Annual Cost = Annual site energy * utility conversion[resource] * price[resource]

    Where resource is one of electricity ,natural gas ,fuel oil, or lpg

The site units and conversion factors are given in table 1.

Table 1. Site Cost Units and Utility Conversion Factors
Fuel Primary Units
Utility Units US
Conversion US
electric kWh kWh 1
demand watts kW 0.001
natural gas kBtu therms 0.01
lpg kBtu gallons 0.01092
fuel oil kBtu gallons 0.00722
cold water gallons gallons 1
hot water gallons gallons 1
carbon lbs co2 lbs co2 1
currency $ $ 1
heat flow kBtu kBtu 1
all N/A N/A 0
source kBtu mBtu 0.001

When a building is first created default energy prices are assigned based on the state in which their ZIP code is located. The defaults energy prices are presented in table 2 below. Users have the option of overriding these values with their own utility rates. The default energy prices are the most recent available state averages from either 2009 (for electricity and natural gas) or 2007 (for LPG and fuel oil). Energy price data are from the U.S. DOE's Energy Information Administration (US DOE 2007, 2009a, 2009b, 2011), and U. S. EPA 2009, 2012.

Table 2. Default Energy Prices
State Electricity Price Natural Gas Price LPG Price Fuel Oil Price
Alabama 0.113 1.581 2.342 1.957
Alaska 0.176 0.889 3.069 2.503
Arizona 0.111 1.587 2.824 2.459
Arkansas 0.091 1.153 2.171 1.994
California 0.152 0.992 2.566 2.516
Colorado 0.113 0.813 2.073 2.111
Connecticut 0.181 1.493 2.915 2.637
Delaware 0.137 1.512 2.571 2.422
Florida 0.117 1.789 3.096 2.390
Georgia 0.111 1.517 2.252 2.344
Guam 0.347 4.450 4.572 2.422
Hawaii 0.347 4.450 4.572 2.422
Idaho 0.079 0.895 2.260 2.171
Illinois 0.118 0.939 1.849 2.290
Indiana 0.101 0.862 2.148 2.342
Iowa 0.105 0.957 1.807 2.237
Kansas 0.106 1.054 1.890 2.223
Kentucky 0.091 1.002 2.269 2.237
Louisiana 0.091 1.173 2.581 1.957
Maine 0.154 1.414 2.907 2.501
Marshall Islands 0.347 4.450 4.572 2.422
Maryland 0.134 1.244 2.836 2.621
Massachusetts 0.148 1.453 3.008 2.488
Michigan 0.131 1.132 2.323 2.222
Minnesota 0.110 0.876 1.943 2.266
Mississippi 0.101 1.019 2.565 2.014
Missouri 0.098 1.166 1.864 2.200
Montana 0.098 0.864 1.921 2.053
Nebraska 0.093 0.895 1.615 2.227
Nevada 0.116 1.225 2.720 2.484
New Hampshire 0.165 1.446 2.605 2.377
New Jersey 0.162 1.284 3.195 2.573
New Mexico 0.110 0.963 2.332 1.976
New York 0.183 1.404 2.806 2.605
North Carolina 0.103 1.250 2.480 2.365
North Dakota 0.086 0.808 1.640 2.216
Ohio 0.114 1.113 2.474 2.247
Oklahoma 0.095 1.113 1.859 2.207
Oregon 0.096 1.249 2.543 2.132
Palau 0.347 4.450 4.572 2.422
Pennsylvania 0.134 1.290 2.719 2.470
Puerto Rico 0.347 4.450 4.572 2.422
Rhode Island 0.145 1.648 3.503 2.542
South Carolina 0.111 1.303 2.623 2.390
South Dakota 0.093 0.877 1.684 2.195
Tennessee 0.098 1.046 2.556 2.259
Texas 0.113 1.081 2.419 2.000
Utah 0.090 0.822 2.036 2.148
Vermont 0.163 1.614 2.771 2.749
Virgin Islands 0.347 4.450 4.572 2.422
Virginia 0.107 1.273 2.660 2.302
Washington 0.083 1.224 2.161 2.653
Washington DC 0.134 1.353 2.755 2.571
West Virginia 0.094 1.139 2.565 2.401
Wisconsin 0.131 1.034 1.987 2.211
Wyoming 0.091 0.858 2.148 2.134