This tool is intended to provide you with a comparison that reflects an estimate of the cost differences between the energy your home currently uses and various alternatives. Individual results and costs savings may vary.

Estimates generated are based upon back-end processing from the SIMPLE energy modeling tool and on a number of user-specific inputs, such as your geographic location, electric provider, square feet, year in which your home was built, number of windows, number of residents, stories, and current heating equipment information. The SIMPLE algorithm combines this information about the structure and the location of your home along with the nearest TMY2 weather station data, current natural gas rates, and as applicable the current average electric rates or current average oil rates from three local oil providers in the Portland area to estimate a home’s energy usage and in turn costs.

The resulting comparison and information are estimates only and provided as-is, without warranty or guarantee, for the convenience of the user. The estimates are not designed to duplicate or replicate an individual user’s actual bills, and the estimates provided may differ from an individual’s actual energy usage or actual energy bill amounts and should not be conclusively relied upon by the user.


CakeSystems software has been verified for accuracy and consistency through three 3rd party studies, including:

Field Assessment of Energy Audit Tools for Retrofit Programs - U.S. Department of Energy - 2013

Home Energy Performance Scores: Efforts to Date with Modeling Tool Comparison and Summary of Key Issues. - MetaResource Group - 2012

Energy Performance Score Pilot – Prepared for Energy Trust of Oregon - Earth Advantage Institute and Conservation Services Group - 2008

Energy Trust of Oregon authorized energy auditors, when rating an existing home, to use the SIMPLE algorithm, provided by CakeSystems. CakeSystems implementation of the tool also allows for specific fuel rates by utility to calculate costs relative to the amount of energy being used by the home. Other tools, such as the US DOE Home Energy Score use a statewide average rate for fuel costs.


The following represent the basic assumptions included in the energy use modeling, which in turn impact the calculation of energy usage and cost comparison estimates. Because of the nature of the assumptions, the estimates do not reflect, should not be assumed to reflect, and may differ from an individual’s actual energy usage and actual energy bills. Average hot water usage is determined by the number of occupants selected.