Basically, general recommendations can be dangerous when it comes to keeping windows closed or ventilating them during the day, because several factors must be taken into account.
When we are hot, we sweat and release moisture into the room. The humidity in the apartment increases – especially if the apartment is well insulated. In addition, the humidity is inherently higher in summer because the warm air can absorb more moisture. Whether ventilation is a sensible measure to reduce humidity in the room also depends on “whether and how the humidity in the indoor and outdoor air differs and how strong the air circulation is,” says Gudrun Laschewski from the Center for Meteorological Medicine research at the German Weather Service in an interview with #factfox from BR24.
For example, if the humidity outside is lower than the humidity inside, ventilation can reduce the humidity in the room, especially with stronger air circulation. However, if the humidity inside is lower than the humidity outside, ventilation would contribute to increasing the humidity in the room. In addition to the humidity in the room, the temperature and air circulation are also important for sweating well.
Why does humidity play a role in sweating?
When it’s hot, the body tries to compensate for the direct effect of the heat. This happens through sweating and a massive increase in cardiac output: “This means that the circulatory system has to work incredibly harder to activate the body’s air conditioning,” says Professor Martin Scherer, director of the Center for Psychosocial Medicine at the University Hospital Hamburg-Eppendorf in the #Faktenfuchs interview.
Sweat is there to cool the body. When humidity increases, perspiration becomes more difficult: “The production of sweat puts greater pressure on the body, especially in the elderly. And depending on the underlying disease and medication of the elderly, the temperature tolerance of the elderly is also reduced by four degrees,” explains Scherer.
If the body can no longer withstand this increased stress to compensate for the heat, the person dies. Before death, there are omens related to heat and Symptoms such as fatigue, dizziness, fever and clouding of consciousness.
A difficult question: ventilate during the day or close the windows?
The question of whether you should ventilate during the day in hot weather depends on several factors: General practitioner Martin Scherer talks in the #Faktenfuchs interview about the “common sense” that you should apply to this question. According to him, you should look at where the sun is shining and what the air temperature is outside. He sums it up as follows: “Whenever the outside air temperature is cooler than the inside air temperature, ventilation makes sense. If it is warmer outside than inside, you should keep the windows closed.”
There is no clear rule for the question: “Open window or closed window?” According to Scherer, this does not exist. However, the data suggest that it makes sense to ventilate at night because then the temperature drops. The Federal Environment Agency recommends that windows should be closed at least on the sunny side and, if possible, darkened with blinds or curtains, for example. But says Hans-Guido Mücke from the expert group for environmental medicine and health assessment at the Federal Environment Agency: “Humans live on fresh oxygen, which means that fresh air should be supplied to the rooms every day through natural ventilation via free ventilation.”
Measures may include opening the windows slightly, but still blocking the scorching sun with blinds. It is ideal if you have the option of creating a draft, i.e. opening two opposite windows. Ultimately, there are no general recommendations to follow dogmatically, as many factors come into play.
Take care of the elderly!
It’s important to care for vulnerable people, such as young children and the elderly. Blocking the windows of your grandmother’s apartment and leaving her alone during the day is neglect. “Elderly people or people with other health conditions need to get out of hot homes. They need to find air-conditioned spaces where they can cool off,” says Texas A&M University professor Andrew Dessler. Since there’s not always an option to escape the heat, you may need to consider measures like air conditioning to protect those at risk.