What’s the best way to create drafts in your home during a heat wave, according to science

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With its ups and downs, the price of energy continues to skyrocket, making air conditioning a luxury. The heat wave is also affecting areas of the Iberian Peninsula that are less accustomed to high temperatures and therefore do not have this type of equipment. Fortunately there are alternatives, one of them is to open the windows and let the wind in. But this option requires some skill if we do not want the heat from the street to flood our home.

Moving air.
Air is a gas and is governed by some basic rules. The physics of fluids is complex, but it is enough to take into account some intuitive notions to be able to take full advantage of domestic ventilation. First of all, knowing that air tends to occupy voids, that is, if there is air “escaping” from one side, surely a windy effect will introduce it from another. The second idea that we must take into account is that hot air is less dense and therefore will go up, while the cold, dense air will go down. As the air heats up it will tend to rise.

Different types of ventilation.
These movements allow us to distinguish three types of ventilation: unilateral, crossed and thermal shot. Unilateral ventilation is the least efficient, especially in the summer. It is the one that occurs when we open a single window in a room or when all the windows that we open in a house face the same facade. They will generate some current if there is difference between indoor and outdoor temperatures, and also because the insulation of our house is not perfect.

The second type of ventilation is cross ventilation. This is the one that occurs when opening windows on opposite facades of the building. The existence of wind can facilitate the appearance of these currents, but they will also occur naturally due to the difference between the air pressures between the facades and the interior of our house.

The third type of ventilation is thermal draft, although it is also known as chimney effect. This denomination allows us to understand it better: the hot air passes into a vertical corridor (an interior courtyard, a stairwell…) and rises. This creates a windy effect that draws in air from cooler areas. As the air heats up it continues to rise up the corridor, creating a current.

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For health.
During the Covid pandemic much insistence on ventilation rooms, but it is advice that can still be useful. Ventilating our home can not only help us to better maintain our thermal comfort, but it can also improve our health.

Ventilation reduces home humidity. This is especially important in kitchens and bathrooms where it can affect the walls of the building. Humidity also allows the accumulation of allergens and particles that can affect our health. In addition to this, it will allow us to avoid the accumulation of smoke from the kitchen, not to mention the importance of avoiding other smoke such as tobacco in the home.

Know your house.
Before starting to ventilate the house it is a good idea to get to know it better. Open Google Maps or some other similar application and see what the orientation of your house is, if it is near the sea, some air corridor (such as a river or an avenue in a city); and which way (north, south, east, or west) each of the windowed facades faces. You should also get an idea of ​​which windows are opposite each other and if they are exterior windows or open onto a patio.

To be more familiar with our surroundings, we can also open the weather application on our mobile (or better yet, go outside) and check which way the wind is blowing. Taking advantage of the wind is not always easy, but when it is not there we can create it.

Strategies for optimal ventilation.
Before starting to generate currents, yes, we must ask ourselves if it is the right time to ventilate our house. The first hours of the day are best for ventilation, although we can also take advantage of those after sunset. In any case, doing it during the hottest hours of the day can be counterproductive.

To get the most out of ventilation, windows should be opened at opposite ends of the house. This will allow cross ventilation. This air current will cool everything in its path, so we want this tour to be as long as possible. For this we can create a diagonal between the windows that we open.

It is possible that our house does not have windows on both sides of the building. In this case, the interior patios can also serve us. Here we will be taking advantage in part of the “chimney effect”, since the hot air will come out of the window to go up through the patio. Another way to take advantage of these currents will be if our house has several floors or if we have the possibility of opening windows at different heights.

Open windows, but not in any way.
It is convenient that we open the windows partially and that more or less the opening that we leave to the air inlet is similar to the outlet, but the latter a bit older. We can go experimenting with different combinations of windows to cool the maximum number of rooms in the home. It is also advisable to keep the rest of the rooms closed.

Ventilation reduces humidity in the home, that is precisely one of our intentions, but sometimes the resulting environment can be too dry. In these cases we can put a container with water that evaporates when the air passes, always carefully, since high humidity can increase the thermal sensation.

Other tips.
Not only on ventilation will our thermal comfort depend and with it our comfort in general. Heat can also affect our health directly or indirectly. We must always keep in mind that cooling our house is the tool, the objective is to keep us at a comfortable temperature. For this, it is advisable to wear fresh clothes, stay in the shade and hydrate well.

Other measures that we can take at home are, for example, proper management of electronic devices, being careful with which ones we keep on, and changing old light bulbs for low-consumption ones are also appropriate strategies. Another aspect that we must take care of is proper sleep, a difficult thing but of vital importance for health and well-being.

Image | Charlotte May

With its ups and downs, the price of energy continues to skyrocket, making air conditioning a luxury. The heat wave…

With its ups and downs, the price of energy continues to skyrocket, making air conditioning a luxury. The heat wave…

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