BERLIN — A sizzling heat wave this week is fueling a shift in attitude in Europe to the once foreign concept of air conditioning, as successive brutally hot summers have forced Europeans to reckon with a ceaseless spike in global temperatures from climate change.

With France tallying a record-high temperature of 114.6 degrees (45.9 Celsius) on Friday, Europeans are reconsidering their traditional opposition to air conditioning that has made them among the lowest users of the cooling machines in the world.

In Germany, you can — quite literally — feel the change in the air.

Residents are sharing maps on social media of air-conditioned buildings and cafes in their area, fans and portable cooling systems are sold out, employers are worried the lack of cooling is killing productivity, and at least one Berlin air-conditioning installer suspended its phone service because of a flood of calls, according to a recorded voice message.

“We’re being inundated with requests,” said another air-conditioning installer, Maximilian Schichtl, in Munich.

These scenarios would be unusual anywhere in air-conditioning-skeptical Europe, but they’re especially rare in Germany, where sweaty locals have long puzzled over Americans’ love for excessively cold air conditioning.

Until now, fewer than 5 percent of all European households have been air-conditioned, compared with 90 percent in the United States. But Europe’s air-conditioner stock is estimated to roughly double within the next two decades, according to the International Energy Agency (IEA), as record heat becomes more frequent and prolonged because of climate change.

On a continent that has long shrugged off air conditioning as unnecessary and where doctors still debate its potentially harmful side effects, this week’s quest to find cooler air may foreshadow a drastic change in Europeans’ relationship to the air conditioner. Dirk Trembich, the head of the Berliner Klima air-conditioning company, said interest began to surge in April 2018 — ahead of a record-hot summer. Demand still hasn’t faded.

Even over Christmas, Trembich said, people kept calling to have units installed. His company’s waiting list grows by up to 50 customers per day, he said.

Companies have shown a growing interest in installing air conditioning, fearing high temperatures are affecting productivity, saying employees are more likely to make errors if they’re hot.

For residents, the growing acceptance of air conditioning in their homes is an acknowledgment of a worrisome fact: Climate change is here to stay.

Last week, after predictions of the impending heat wave, sales of fans and air conditioners surged across Europe, including in France and Austria. In Germany, the U.S. military said it was examining whether new temperature records would require the installation of new air conditioners, Stars and Stripes reported.

Those changes may come close to a cooling revolution in Europe. But by a global standard, the movement toward cooling is marginal.

Europe’s estimated increase in overall demand in the coming years is expected to be dwarfed by demand in other parts of the world, especially India, Indonesia and China. Fans and air conditioners already account for 10 percent of electricity consumption, but the IEA predicts that the associated energy demand could triple over the next three decades, unless units become significantly more energy efficient.

European air conditioners are already among the world’s most efficient. Still, their environmental footprint could make Europe’s debate over the need for better cooling even more heated than it has been in the past. By trying to escape the impact of climate change, its critics argue, air-conditioner consumers may end up making global warming worse.

Air conditioners’ energy consumption was among the reasons cited when German officials in the city of Düsseldorf recently rejected proposals to install cooling systems. Like most buildings in Germany, one of the world’s richest nations, schools are not usually air-conditioned, which means that students are sent home early on especially hot days.

People jump into Lake Geneva on a hot summer day at sunset in Saint Saphorin, Switzerland, on June 26. (Jean-Christophe Bott/Keystone/AP)

But the hesitancy among some Germans to embrace air conditioning is justified, said Veit Bürger, deputy energy and climate action head of Germany’s Institute for Applied Ecology. Periods of heat often coincided with stiller-than-usual air, resulting in less wind energy being produced and an increased demand for polluting coal energy instead, he said. This combination could make air conditioning during the summer especially challenging, given European targets to cut emissions.

Instead, he urged a more concerted effort to design “buildings in a way that minimizes the need” for air conditioning, through better insulation.

Air conditioning’s unpopularity in Europe is not entirely based on climate change concerns. For some, it is simply not worth the effort. On most days, summers in some parts of Europe can still feel more like mild winters to Texas or Arizona residents.

Then there are the health concerns. German health insurance providers and doctors frequently caution that air conditioning can make humans more vulnerable to catching colds and may expose people suffering from allergies to mold. One of Germany’s largest health insurance providers, Barmer, released a warning last year and compared air conditioners’ “cold shock” to “weather extremes,” such as thunderstorms, which may worsen “sleep disorders, headache or circulatory problems.”

Instead, public health officials said, Germans should consider opening their windows in the morning, dress accordingly and drink sufficiently.

But Trembich, the air-conditioning installer, said that well-maintained and appropriately programmed systems were designed to avoid such side effects. Unlike in the United States, for instance, German systems usually lower the temperature by a few degrees, to avoid exposing consumers to drastic temperature changes and to save energy.

Record-hot summers — including a heat wave that killed 15,000 people in France in 2003 — have prompted reconsideration.

Schichtl, the cooling-system salesman, said consumers were increasingly concluding “that relying on ACs is actually healthier” than battling the heat without one.

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