No more office space until there are affordable places for the new workers to live -- that's the goal of a March 2020 ballot initiative.

One of the most important – and desperately needed – land-use measures in years could be on the March, 2020 ballot.

The Yerba Buena Neighborhood Consortium is promoting an initiative that would directly link new office approvals to affordable housing growth. It’s such a simple concept: The city would not be able to approve new office space when there’s no place for the new workers to live.

The problem is obvious. According to the city’s own figures, for every 875,000 square feet of new office space that’s built and occupied, 3,676 new workers are attracted to the city, and need 1,785 housing units.

That’s the amount of new space allowed every year under the 1986 growth-control measure Prop. M. It’s about the size of one new big project; the Transamerica Building has about 600,000 square feet

As the consortium points out, 33.5 percent of those new units need to be affordable to low, moderate, and middle-income workers. That’s 598 affordable units.

According to a consortium statement, the city is failing to meet the state-mandated needs for affordable housing:

After three years, San Francisco has produced 215 percent of the market-rate/luxury housing needed for this growth, but unly 68 percent of the affordable housing. We can’t go on like this. The consequences of the 32 percent affordable housing production shortfall are devastating the city. Low-income and working-class residents of the city are being pushed out of their long-time neighborhoods and many middle-income residents can no longer afford to live here.

Under the “Balanced Development Act, the amount of allowable office space would be reduced by the same amount that the city falls short of affordable housing. In the current situation, only 68 percent of the 850,000 square feet a year could be built.

That, of course, would give developers who get very rich building and leasing office space an incentive to help with the affordable housing crisis. And if they don’t? Then office growth will slow, and at least the situation won’t get worse.

(It fits with what I call the Hippocratic Oath of housing policy: First, do no harm. You could also call it the Theory of Holes – when you are stuck in a hole, stop digging. Or as John Elberling, who runs Todco, has said to the Planning Commission, it’s time to stop pouring gasoline on the fire.)

But this is the first time in the current housing crisis that a serious policy proposal has come forward to address the “demand” side of the “supply and demand” equation that the Yimbys love to talk about. Rather than attracting huge numbers of new residents to a city that already has a housing crisis, and then later trying to scramble (at considerable expense) to catch up, why not make sure that when new tech companies move here or expand here, there’s enough housing built in advance (or at the same time) to accommodate the needs?

That would seem to be the essence of what is kindly called “city planning.”

The concept polls well: The consortium reports that a recent survey of likely voters supports the idea of a limit on office space until affordable housing is available by a 2-1 margin.

That, of course, is before the developers and the tech industry start pouring millions of dollars into misleading ads that will talk about damaging the city’s economy. We’ve heard that over and over whenever there are growth-limit measures.

But this new measure doesn’t need to block new office space. It just says that housing has to be available for the new workers – before the buildings go up.

It’s a model that could be exported to places like Mountainview and Palo Alto, which love tech office space but not housing. It’s a much more logical approach to the problem that the Scott Wiener policy direction.

And like many smart policies, it could be starting in San Francisco.