With the Penny for Pinellas local sales tax on the books for another 10 years, a stream of funding will be available for developing affordable housing, and there is a dire shortage. Rising rents are forcing low-income residents to spend a growing share of their money just to keep a roof over their heads. This is one of the area’s most critical needs, and county commissioners should make a concrete commitment to devoting more money to reducing that pressure.Pinellas voters last fall overwhelmingly approved renewing the 1-cent-on-the-dollar sales tax, which is expected to generate $2 billion over the next decade. The proceeds will be shared among the county and its 24 cities. In selling the plan to voters, the county provided broad outlines of how its share would be spent, including $165 million on economic development and affordable housing. That was a reasonable commitment, but it leaves a little too much wiggle room for shorting the housing needs if the political winds shift in the next few years.A coalition of more than 40 Pinellas congregations known as FAST — Faith and Action for Strength Together — has a reasonable request of the commission: pass an ordinance that reaffirms that half of that $165 million will go to affordable housing. That $82.5 million would go a long way toward assembling land, leveraging state and local housing dollars, offering incentives to developers to build affordable units and building out infrastructure. FAST also wants new multifamily properties to set aside units for working families making below the median income, which is a proven model.Pinellas County Commission chair Ken Welch, who plans to attend the FAST meeting at 7 p.m. Monday at Tropicana Field, says he supports the organization’s request for an ordinance. While future commissions could change direction even with an ordinance on the books, Welch calls an ordinance "a little bit of insurance’’ and expects the commission to enact one. That’s encouraging.In the 2018-19 state budget passed this week by the Florida Legislature, lawmakers swept $182 million from the trust funds that are supposed to go to affordable housing. It redirected the money for other budget needs in what has become an annual raid in Tallahassee. However, they also agreed to spend $223 million on housing programs, including $44.5 million to aid local governments. That’s also encouraging.The share of low-income renters in Tampa Bay grew by 35 percent in 10 years, but the area’s affordable housing stock is not keeping up. Housing is a basic need, and when full-time working adults struggle to pay for it, that’s a serious problem. Pinellas commissioners can help address it by passing an ordinance that commits the needed funds and beginning to spend them now.