Cost Details
Gas Infrastructure
Costs are applied as cost savings for an all-electric home when compared to a mixed fuel home. For this analysis an average of the new subdivision and infill development costs was used, representing 80% of the new subdivision and 20% infill.
The tables of costs present total costs for each scenario as well as reduced costs after deductions are applied per the Utility Gas Main Extensions rules. These rules specify that the developer has the option to only pay 50% of the total cost for a main extension after subtraction of allowances for installation of gas appliances. This 50% refund is applied to the main extension cost and the appliance allowance deductions are accounted for in the service extensions costs in the table. This analysis assumes these rules will remain in place through the 2022 code cycle and that the cost savings to the developer are passed along to the customer. The deductions were applied under the On-Bill methodology.
It is assumed that there are no required upgrades to the electrical panel, and that a 200 Amp panel is typically installed for both mixed fuel and all-electric homes.
Appliances
Space Heater: Replacement costs for the heat pump are based on a 17.5-year lifetime for the gas furnace and air conditioner and a 15-year lifetime for the heat pump. Residual value of the gas furnace/AC at the end of the 30-year analysis period was accounted for to represent the remaining life of the equipment.
Water Heater: Replacement costs account for a 15-year HPWH lifetime and a 20-year lifetime for the gas tankless water heater. Residual value of the gas tankless at the end of the 30-year analysis period was accounted for to represent the remaining life of the equipment.
A high efficiency HPWH that meets the Northwest Energy Efficiency Alliance (NEEA)11 Tier 3 rating was also evaluated. This is representative of most HPWHs that are on the market today. Aligned with prior recent reach code studies the first equipment cost for the 2.0 UEF HPWH was assumed to be 90% of that for a NEEA Tier 3 HPWH. No replacement costs are applied for the NEEA Tier 3 relative to a 2.0 UEF as it’s assumed that in 15 years’ time efficiency standards will have met up with the NEEA Tier 3 standard.
Clothes Dryer and Range: The cost difference between gas and electric resistance equipment for clothes dryers and stoves is negligible and the lifetimes of the two technologies are also similar.
Electric service upgrade: The 2022 Title 24 code requires electric readiness for gas appliances; as a result, the incremental costs to provide electrical service for electric appliances are minimal. The incremental costs accounted for in this study are calculated as the cost to install 220V service for the electric appliances less the cost for the electric ready requirements and for installing 110V service for the comparable gas appliance. Incremental costs are applied for the space heater, water heater, and cooking range. It’s assumed that in a typical mixed fuel home both electric and gas service are provided to the dryer location and therefore no incremental costs for the dryer were applied. Costs assume 50A service for the range and 30A service for the space heater and water heater.
In-house gas infrastructure (from meter to appliances): Installation cost to run a gas line from the meter to the appliance location was estimated at $580 per appliance. An average cost per appliance of $580 was determined. Costs are assumed to be the same for the single family and ADU analyses.