A million people in a low-rise, well-served city

• Four times as many people live in the low-rise, well-served city as it seemed

  By census section, the areas with high proximity and low height added up to 127 sections with 256,083 people. Looking block by block, many low-rise blocks appear inside taller sections: 7,640 residential city blocks of 2 stories or fewer in the two quintiles with the most proximity, home to 1,045,183 people. The potential to densify close to services is much larger than the first estimate suggested.

• They are self-built working-class neighborhoods with small lots

  63.4% of those city blocks are stratum 1 or 2, the average lot measures 122 m², and in only 3.7% are most properties held as condominiums. Densifying here does not mean large projects on assembled lots: it means each household being able to build one or two more stories on its own lot.

• The POT allows almost all growth up to 3 stories, but little beyond

  We calculated how much could be built if every house on these city blocks rose to 3, 4 or 5 stories, and then checked what height the POT allows on each lot. Zoning allows three quarters of the growth up to 3 stories, but only half of what 4 stories would achieve and a third of what 5 would. With what it allows today, between 399,000 and 565,000 more people would fit. The main reason is that almost four in ten of these city blocks are in comprehensive upgrading zones, where an ordinary lot can reach 3 stories.

• Where growth could be greatest is not where zoning allows the most

  At 4 stories, the greatest physical capacity is in Ciudad Bolívar, Engativá, Kennedy and San Cristóbal. Once the height the POT allows is applied, the order changes: Engativá, Rafael Uribe Uribe, Ciudad Bolívar and Kennedy lead, and San Cristóbal drops out of the top places.

• At three floors, about 400,000 people under current rules

  If every lot in the candidate blocks rose to 3 floors, 18.1 million m² would be added; with the height the Land Use Plan allows, 13.6 million, enough for about 398,574 people at 34 built m² per person.

• Beyond four floors, the rules hold growth back

  At 4 floors the Land Use Plan allows 17.6 million of the 35.0 million physical m² (50.4%); at 5 floors, 19.2 of 52.8 million.

• The low-rise city is already dense

  Three-floor blocks have 626 people per hectare and two-floor blocks, 453: one more floor adds population without extending the city.

Allow stepped heights in integral-improvement areas for lots that can support them and back lot-by-lot growth with technical assistance and structural reinforcement, after checking the candidate blocks against landslide and flood hazard and network capacity.

Within its well-served city, Bogotá has room for hundreds of thousands of people; half depends on the rules and the other half on integral improvement.