“Hypocrites! How dare you say the Sierra Club could support building tens of thousands of housing units, when you’ve fought for decades to block developments like Koa Ridge?” Yup, we’ve heard the critique of our opposition to the 3,500-unit Mililani suburb to be planted on one of the most productive food farms in Hawaii after the Supreme Court gave it the thumbs up last week.

Our answer is simple: it’s about what kind of housing and where.

We know Hawaii’s population is expanding by 14,000 people a year and that most of the new arrivals are local babies, not malihinis. If we Just Say No to all development, house prices will continue to soar and those who suffer won’t be wealthy outsiders, but local families turned economic refugees, fleeing to the mainland. If we want to avoid a society ever more divided into gated communities and homeless encampments, we have to build. The state Department of Business Economic Development & Tourism says we need 21,000 new affordable rentals in less than 10 years.

OK. But that doesn’t mean we throw our principles out the window.

We believe an equal priority is to protect our farmlands and countryside. This isn’t vacuous tree-huggerism. We have a moral obligation, enshrined in the Constitution, to preserve the ‘aina for future generations. But there are also vital security and economic imperatives at stake.

Our biggest industry depends on the beauty of our islands. A chief complaint from tourists is sprawl — the vastness of the conurbation they have to traverse to reach the North Shore and the unrelenting loss of green space. Ironically, the jobs the tourist industry generates are filled by the very people who most desperately need affordable housing — which is precisely why hospitality unions typically join us in opposing unfettered development.

The U.N. predicts another 2.4 billion mouths to feed on planet Earth in just 34 years and that climate change-induced disruption of global agriculture will lead to food price inflation and scarcities. Already we grow barely 10 percent of the food we eat in Hawaii. Strengthening our food resilience is essential: efforts to preserve ag lands and boost farming are not a luxury.

Our opposition to greenfield developments is balanced by an alternative strategy: building taller and denser in the urban core. It’s precisely because we understand the need for affordable housing that we support the rail project — a transit corridor around which to cluster dense housing. We have no patience for the building moratorium in parts of the city that the City Council is now considering. In this housing crisis, that’s nuts.

By taller we don’t mean 40-story buildings: six to eight stories translate well into a dense, yet human scale. We support organizations like Better Block Hawaii that are trying to figure how to build affordable housing at a neighborhood scale rather than vertical and horizontal sprawl.

Is such housing more expensive than single family homes in the ’burbs? It doesn’t have to be, especially if you remove the requirement for two parking spaces per unit — each spot typically increases monthly rents by $100 to $200. Encouraging people to walk, bike and use mass transit has major impacts on affordability. The average annual cost to own a car is $8,700. If a family moves to a unit near the rail and gets rid of one car, the savings would be $725 a month. Not to mention the nightmare commutes that are destroying family life.

Those who allege that environmentalists disrespect low-income folks by blocking suburban developments (and the congested commutes that go with them) rarely live in the suburbs and rarely commute three hours a day. They weep crocodile tears.

The Sierra Club doesn’t use the permitting process to delay or make developments more expensive. We use the process to try to kill inappropriate development and we would like the death sentences to be delivered much more swiftly.

Nor have we been the force behind inclusionary zoning — the requirement to build income-qualified units to secure permits for large developments. That tool has been wielded by politicians because so few developers have shown interest in building affordable projects.

There are notable exceptions — Stanford Carr, for example — but his Halekauwila project demonstrates that even with free land and drastically reduced permit review, low-income housing still needs government support.

It’s true that long, contentious permitting battles can add to costs. One solution might be to create special districts with a rapid approval process. I believe environmentalists could support such an idea, but only if the districts were in parts of the urban core where they belong: Moiliili, McCully, Iwilei, Kalihi, Waipahu … and only if accompanied by a process to preserve ag land and rent it to food farmers on long leases.

But if you want to speed the permitting process to build new suburbs on ag-land, be prepared for a fight.