The section is the first drawing. Not the floor plan, not the elevation — the section. The cut through the building tells you how it lives: how tall the rooms are, where the light enters and at what angle, how you move vertically, where the building compresses before it releases. La sección como relato — the section as the story of the building.
In Mexico, at latitudes between 15 and 23 degrees north, the sun is the most powerful design force. Managing it through section geometry is not optional. It is the fundamental act of design.
What the section reveals that the plan cannot
A floor plan shows area and adjacency. A section shows experience. It shows:
- The height of the ceiling at each point in the sequence
- Where natural light enters the room and from what angle
- Whether the structure reads as presence or disappears
- How the building relates to the ground — buried, elevated, hovering
- Where compression and release happen as you move through space
Experienced architects read sections intuitively. Clients reading a section for the first time see the building in a way that a floor plan never provides. This is why in MÉTODO we present sections before plans in every design review.
Asoleamiento: the sun mapped onto the section
Asoleamiento is the practice of drawing the sun's path on the section. For a given latitude, compass orientation, and time of year, you can calculate the exact angle at which sunlight enters any opening. This calculation drives the geometry of:
- Overhangs: The projection needed to shade a south-facing window at the summer solstice while admitting winter sun
- Clerestories: The height at which a high north-facing window delivers consistent diffuse light without glare
- Light wells and skylights: The proportions of a vertical light shaft that illuminates the base without admitting direct sun to a space that cannot tolerate it
- Interior light courts: The proportions of an atrium that distribute reflected light to surrounding galleries
For Mexico City at approximately 19 degrees north latitude, the midday summer sun is nearly overhead (roughly 73 degrees elevation). A one-meter horizontal overhang provides meaningful shade at noon. The midday winter sun is at approximately 47 degrees — the same overhang admits significant direct light. This variation is the instrument. The overhang depth is the adjustment.
We draw the winter and summer noon sun angles on every section that includes a significant opening. The overhang, brise-soleil, or fin geometry is derived from these lines, not selected from a catalog.
The section as ventilation strategy
In Mexico's warm climates, the section is also a ventilation instrument. Stack effect — the natural rise of warm air — is driven by the height differential between the lowest air intake and the highest exhaust opening. A section that provides:
- Low openings on the windward side (northeast is typical for much of Mexico)
- High-level openings or operable clerestories on the leeward side or above
...creates passive ventilation without fans or mechanical systems. The temperature differential between the cool low intake and the warm stratified ceiling air drives airflow through the building continuously when there is a height differential.
This means the section must be designed to produce the height differential. Flat-plate buildings with uniform ceiling heights and no high-level openings cannot use stack effect ventilation regardless of window area.
Section in a cultural pavilion
The daylighting strategy for a cultural pavilion or gallery differs from residential work. Key requirements:
- No direct sun on displayed work: UV exposure damages art and artifacts. South and west-facing glazing requires solar control; north-facing clerestories deliver diffuse light without direct sun.
- Even illumination across the floor: Wall-washing from high openings, combined with reflected ceiling light, produces even horizontal illuminance without harsh shadows.
- Flexibility for changing exhibitions: A daylighting strategy that works with portable artwork requires more careful calibration than one designed for fixed installations.
In MÉTODO, cultural pavilion sections are analyzed for illuminance distribution at multiple times of day and year before the section geometry is fixed. This is computational work (using daylighting simulation tools) layered onto the hand-drawn section analysis.
Section in residential design: a specific example
Consider a house on a sloped site in Morelos. The slope falls north to south. The best view is to the south, but south-facing rooms must manage afternoon heat.
The section strategy: the living level is raised above the road to capture the south view. A deep covered terrace faces south — the terrace roof provides shade from the high summer sun while framing the view. Below the terrace, the slope is excavated to provide a lower-level service and sleeping zone that is partially bermed into the hillside for thermal stability.
The section reads as: compressed entry at grade, rising to the main living level with the view, descending to the private lower level. Three zones, three ceiling heights, three relationships to light and landscape. The floor plan organizes this section, not the other way around.
Próximos pasos
The section is not a technical document — it is the spatial argument for how your building works. Reviewing it carefully at the schematic stage, before the plan is fully developed, is the highest-value design activity in the project.
Conoce el método de MÉTODO to see how the section drives every design decision from the first site analysis through construction supervision.