Bill 25 has divided those seeking to keep construction costs low, and those seeking to save the environment. Currently the City and County is working from the 2003 International Building Codes. There’s a stand-off.

Is saving the planet worth increasing the costs of new construction? At the core, Bill 25 requires new construction to be pre-wired for electric cars and a pathway to add rooftop solar. Building industry groups argue that it will drive up construction costs, while the environmentalists cite global warming, sea level rise, and the state’s 2045 target of 100% renewable energy.

Housing is already sky-high; can Oahu’s residents afford Bill 25?

Once a luxury or novelty, many electric cars now cost less than owning a Toyota Camry or Honda Accord. The electricity that charges their batteries is one-third the cost of gas per mile driven; plus they don’t require much of the regular maintenance, such as oil changes, coolant flushing and belts.

Bill 25 requires new construction be prewired for the 220 volts that electric vehicles require to charge. During construction, a wire costing $1.18 per linear foot is run from the electrical panel to the garage or carport.

This is the same wiring used for a dryer. The distance can vary greatly, depending on the layout of the home, so precise costs depend on the design. The wiring is then charge-ready once a 30 amp, two-pole breaker ($10.58 at the hardware store) and a dryer-type outlet ( $10.48) are installed. The estimated total time is one-two hours for a journeyman electrician earning $40 per hour, when installed during construction.

The second main feature of Bill 25 is preparing homes for rooftop solar. These panels have become very common on Oahu, but now that expensive storage batteries are required, are they cost-effective? A $46,500 residential solar system offered by a well-known company consists of 40 panels and three batteries, allowing it to produce and manage $400 of electricity every month.

While such a system may sound out of the reach for most families, there are several attractive financing options, including the city’s Solar Loan Program that offers loans to lower-income families. The city’s website calculates the payment for the above system at $193.75 per month. For non-low-income families, many credit unions offer 20-year financing at 5%, which would be $307 per month. Either way, it is less than $400, the cost of electricity from the grid.

Bill 25 also requires a pathway connecting future solar panels to the main electric box. What are the total estimated costs of this installation — for materials such as wire and metal tubing, plus electrician labor? Several hundred dollars. What are the potential savings for a family that chooses an electric car and a solar system? Hundreds of dollars each month, plus tens of thousands in tax credits.

Most electric cars qualify for a $7,500 federal tax credit and and all solar systems qualify for up to a $5,000 state credit and a 26% federal credit. The above-described $46,500 solar system qualifies for $17,090 in tax credits. Tax credits work like tax refunds. As long as you paid that much in taxes, you will get it back once you file.

The building industry and environmentalists are fighting the wrong battle. It is not about the environment or keeping construction costs down — it is about building housing that is affordable to live in month to month, year after year. That’s what will keep Oahu’s families together and its workers employed.

R.J. Martin is head of Green Homes Hawai‘i and a Realtor associate.