Slowly but surely, Oahu’s inventory of affordable rentals is growing, with a new 26-unit, three-story walk-up for low-income renters now open in Makiki. It’s not a lot of units, but the project was touted for successfully using the city’s “Bill 7” law, which relaxes development standards and provides incentives such as a decade of property tax exemptions for qualifying projects. One hopeful aspect: This Ernest Street housing was built in about nine months, using prefabricated concrete. That’s pretty quick — once city permits were approved, of course.