He looks at me and says: “broken doors.” In his country house, my grandfather’s door opens in half: bottom leaf, top leaf, each with its own hinge. Every time I see it I think of cowboy movies, the logo of saloon from some after-dinner western. I imagined: “of course, for the cat.” Nothing to see. history class. The idea of the split door is not only from La Mancha or Toledo, it is the same principle as the Dutch doors or stable doors from four centuries ago. According to the definition itself, the first dutch doors They date from the mid-17th century, around period 1640-1650. From here they became a practical solution in farms and rural houses in the Netherlands and the United Kingdom, in order to let air and light in while keeping out animals, dust and some of the cold. The chronology itself can be found in Dutch paintings of the time, such as ‘Young Woman at a Dutch Door’, from 1645 and attributed to Samuel van Hoogstraten, a painter in Rembrandt’s workshop. Its use became popular in the American colonial era and its fame decreased towards the end of the 18th century, in favor of more robust, secure and single-leaf doors. A tunnel of cold and cleanliness. At that time, the word air conditioning did not exist, but there was a concern for hygiene: when you open only the upper half, the door works like a large window, releasing pollution from cooking smoke, which, being less dense, always accumulates at the top. And thus a small renewal current was created with the lower leaf closed. If the house had another opening on the opposite façade, the effect was amplified: cross ventilation is generated that brings in cooler air on one side while hot air leaves on the other. A simple but very effective formula if activated first thing in the morning or in the late afternoon, when the sun sets. And in winter? Well, the same door allows the opposite: opening only the lower part for a few minutes to ventilate without the entire pocket of hot air stuck to the ceiling escaping, reducing thermal losses in houses without modern insulation and where the heat was produced from braziersglories (under the floor) or low chimneys. In winter you open the bottom part to ventilate without losing the warmth that gets trapped on top. In summer, quite the opposite: you open the upper part so that the hot air can escape while the ground floor remains in darkness. If you light a fire in the kitchen, just open the top so that the smoke comes out through natural convection —chimney effect pure and hard—while the lower leaf continues to act as a barrier against the cold that comes from outside, usually the corral or the orchard. Thick walls, slow summers. The split door works because it works in tandem with another ancient technology: fat walls. So thick that they do not allow the electromagnetic radio waves that make WiFi to work. In the traditional architecture of the Meseta it is not uncommon to find enclosures more than fifty centimeters thick, chambers made of stone, rammed earth or solid brick, with a thermal inertia similar to that of a cave. The physics behind it couldn’t be simpler: the more mass the wall has, the longer it takes the outside heat to pass through it. Meanwhile, the interior remains relatively cool, as happens in any church where the sun takes hours to show itself or sometimes not even that. The same wall, in winter, absorbs part of the heat from braziers and stoves and slowly releases it when night falls, reducing thermal fluctuations in homes without radiators. What we call today “passive comfort management” is this very thing. And without IoT sensors or apps. Grandparents know it all. Silos: fresh but dry. The third lesson is taught to us silos and traditional barns. To store grain, a dry and cold microclimate must be created, in order to stop fungi, bacteria and insects that can rot the grain. When the grain is wet, the dough breathes, generates heat and creates pockets where the temperature rises and moisture condenses; If there is no ventilation, the pile becomes a breeding ground that can ruin tons of harvest. The solution is as simple as creating aeration ramps at the base and airlocks – small windows – along the walls that allow air to travel through the bulk, equalizing temperatures and removing steam upwards. It is the chimney effect but on the contrary: if you leave the ventilation openings open, the hot outside air enters through these ducts, rises through the mass of grain and heats it from within, forcing the openings to be sealed well once the cereal is dry and cold. Domestic science, with convection c. This whole repertoire of split doors, thick walls, and silos with eyes works because it takes advantage of three basic ideas of fluid physics: hot air rises, cold air falls, and air moves from areas of higher pressure to areas of lower pressure. End. The cross ventilation —that is, opening opposite openings so that air crosses the home—relies on pressure differences between facades and the orientation of the wind, while the chimney effect uses vertical corridors (patios, stairs, door openings) so that hot air rises and sucks in cooler air from below. In research On traditional patio houses, it has been measured how two patios with different temperatures activate a convection current that keeps the main rooms within comfortable ranges, without a single air conditioning machine. Each and every passive ventilation strategy involves some cooling, because “convection helps dissipate the heat accumulated inside as long as the openings and volumes are well thought out.” In the end, my grandfather’s split door didn’t hack anything, it was just properly installed. Two hundred years ago there were no engineers INTA in San Pablo de los Montes or in Quintanar de la Orden, but there were people with heat … Read more
