Home Heating Operating Cost Estimator Approach & Assumptions

The goal of this site is to help users compare estimates of the potential operating costs of several different home heating options within NW Natural’s service territory. Actual and individual home energy costs vary; the operating cost estimates provided by the Home Heating Cost Estimator are just that – an estimate, meaning an approximation of yearly operating costs. The estimates are not a guarantee or promise of cost or pricing for any home heating source and do not include all potential costs associated with any particular home or home heating source.

Calculation of the estimated operating costs are driven by regression analysis of the Northwest Energy Efficiency Alliance’s (NEEA) RBSA II Combined Database drives the calculation of operating cost estimates. Using the regression analysis, the estimated load needed to heat a home us determined based on identifiable characteristics of a home and its heating system. These characteristics include home type, foundation, and estimated efficiency of a given heating system.

Once the estimated heating load is determined, then the cost of fuel is applied. More information on regression analysis can be provided upon request. Email Furnace@nwnatural.com for more information.

How are energy costs determined?

Twice a year, the rates for each utility are updated. These rates reflect the prices as of the most recent update (November 1, 2024). Any rate changes made after the most recent update are not incorporated. The Heating Operating Cost Estimator does not project or forecast what rates may be in the future.

The cost per kWh is obtained from the base energy rate of each electric utility. Using the publicly reported prices of each energy utility, we apply the cost per kWh to estimate the annual cost to heat a home, based on the user’s provided information.

The cost per therm of natural gas is based on NW Natural’s Rate Schedule 2 (Residential Sales Services) filed in Oregon and Washington and is applied based on the user-provided zip code.

The initially provided oil price is based on the price per gallon of residential heating oil as publicized by the U.S. Energy Information Administration at the time of the most recent site update of utility rates. However, the price of oil changes often, and varies from location to location, so the user is given the opportunity to adjust the price per gallon to reflect a known price.

How are unknown inputs determined?

To help make the site easier to use, the requested information from users is limited to variables that most homeowners are familiar with about their property. However, in recognition that not all homeowners know the details of their current equipment setup (type of equipment, its age, etc.), users are also given the opportunity to choose “I’m not sure.”

If “I’m not sure” is chosen, the most common equipment for the provided energy type and its average age are applied to the calculations. The most common equipment and/or its respective age was determined using data in NW Natural’s service territory as reported by CoreLogic. The equipment data provided by CoreLogic is sourced from real property information and obtained via public sources, RMLS listings and information provided by CoreLogic clients.

Users are provided the opportunity to adjust their inputs – including those previously marked as “I’m not sure” – on the results page. They can then change their inputs to see how different information affects the estimated home heating operating cost. All inputs are at the discretion of the user and they use any Home Heating Cost Estimator results at their own risk and voluntarily.