More on passive design strategies… Crossed Ventilation

As you have noticed, I recurrently write about passive design strategies. These strategies are in few words, the part of the architecture that dedicates its studies and proposals for innovative construction techniques, based on passive traditional practices to resolve the needs of comfort, hygiene, and safety in the shelter for human activity.

With the understanding that each area and building requires special consideration for geological, geographical,geo biological, geo morpholigical matters in addition to climatic conditions, is the aim of the passive strategies to lower the possible environmental impact.

Geotecture was born in ancient and vernacular building traditions which trough trial and error and lot so f observation over millions of years, forged techniques and procedures to obtain shelter. In the Costa Rica case, the first who used these strategies were our natives from Talamanca. After a while, around the same area, europeans imported their victorian style. The local afroamerican communities tranformed it into what we know as vernacular architecture. One of such techniques used in this kind of architecture, was Crossed Ventilation. This is basically a concept to define ventilation on buildings.

 

 

 

 

Depending on each site and time of the day, there are typical winds that generate high pressure zones and low pressure zones. You should promote open windows and interior doors located specially to let the air flow generated by the 2 pressure zones, to all over the house, as homogeneous as possible. Doors and windows should be located diagonally in the space.

 

In reference literature specialists Givoni, Izard, Guyoy or Olygay recoomend crossed ventilation for warm temperate climates to wet tropical moist, like Costa Rica, as a strategy for passive cooling of buildings. This strategy should be used with the combination of shade and surrounding environment meaning walls and ceilings, whose surface temperature is similar to room temperature. This is closely related to roof design and wall insulation.

While the outside temperature does not exceed 30’34 degrees celsius with a relative humidity of 70’90%, we can achieve crossed ventilation. Outside these ranges the croos-ventilation strategy will be less effective. Fortunately, most areas in  Costa Rica fall within these parameters, that’s why I tend to promote Crossed Ventilation on all my projects.

I truly believe on not spending not even one more dollar or colon on air conditioned. Unless you have a special computer or medical room. Ac pumps heat and harmful gasses into the external environment, thus contributing to global warming, so we need more air conditioning. The classic ‘ vicious circle” effect. The power required to run it consumes fossil fuel, depleting reserves and again, adding to global warming. Is it good for us to sit breathing recirculated air which consists of other people’s farts, body odour, tobacco fumes and food smells?

Open your minds and windows…

 

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