### Bill Calculation

This page describes how the Energy Estimates generated by the Home Energy Saver enegy calculations are use to estimate cost estimates.

#### 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.

State Electricity Price Natural Gas Price LPG Price Fuel Oil Price Table 2. Default Energy Prices 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