I May Be a Troglodyte, but I’m Staying Cool

https://www.nytimes.com/2019/07/06/opinion/sunday/france-heat-wave-caves.html

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VOUVRAY, France — The early-morning procession began during the last week of July 2018. From my kitchen window, I watched as people made their way up the steep incline toward the caves in the cliff. Most were older, except for some younger women with children. A few cars dropped people near the summit.

We were in the middle of a “canicule,” a heat wave that would break records. The village mayor had repurposed one of her family’s caves to be a cooling station where the vulnerable could escape the heat. The hottest day in the normally temperate Loire Valley last year came on Aug. 6 in the town of Chinon, nearly 40 miles southwest of here, where the temperature reached 101 degrees Fahrenheit. Last year ended up being the hottest in France since at least 1900, when modern meteorological measurement began.

This year may prove to be even worse. On June 28, the town of Gallargues-le-Montueux in southern France hit 114.6 degrees, a record high for this country. To date, at least four deaths in France have been attributed to the heat wave. The World Meteorological Organization reports that 2015-2018 were the four warmest years ever recorded for the world. Projections for 2019 suggest the trend will continue.

A week after the 2018 heat wave began, I received an email from Jérôme and Audrey, a young couple from Olivet, near Orléans, about 80 miles northeast, asking to stay in my holiday rental cottage. They were in search of air-conditioning. Any kind would do.

My air-conditioning is unconventional: I live in a cave, or actually a group of interconnected caves, known in local parlance as a “maison troglodyte.” My troglodyte comprises five caves of varying size, one of which — my “cottage” — I rent out each summer.

My caves and others in the Loire Valley, a wine-growing region about 150 miles southwest of Paris, occupy caverns left by a limestone quarrying operation active for several centuries beginning in the late Middle Ages. During the 1950s, the first nonquarrying owner of the five-cave warren that is my home turned it into a modern residence, opening interior hallways through limestone walls several yards thick and installing electricity and plumbing. The habitable part of my cave measures about 1,700 square feet.

Jérôme, Audrey and their new baby, Daphné, were in desperate need of a cooling system. Every air-conditioned lodging from Paris to Bordeaux was booked. The nighttime temperature in their own apartment, Jérôme said, had not dipped below 86 degrees for over a week and the baby would not eat or sleep. Normally, he told me, the average temperature at that time of year was around 77 degrees.

In my house, air-conditioning is built in to the geology. Last summer, the inside temperature did not exceed 72 degrees.

My maison troglodyte is a fully equipped home like any other, save that the walls are made of mattock-scored local limestone and it is burrowed into the escarpment midway up a cliff. The ceiling lies several yards beneath a forest and a vineyard. The insulation effect is without equal. Even in winter, the temperature rarely drops below 65. I heat my main living room with a wood stove. There is an electric radiator in the combined kitchen and dining room.

Jérôme, Audrey and Daphné were the first global-warming refugees to be my guests. They stayed in their troglodyte cottage for five days, barely emerging the entire time except for grocery runs.

When I moved into my cave, my focus was less on global warming than on aesthetics. The French, despite their manifold cultural virtues, lack a flair for interior design. The houses available in my price range sported decades worth of striped, toile or floral wallpaper — sometimes all three in a single room — inexpertly mounted, with the most recent update glued over the old one. House after crumbling, 19th-century house presented bathrooms with mold-blackened grout surrounding the brown tile and ocher-toned porcelain fixtures, last updated circa 1960.

The climate-forward nature of my dwelling was a lucky accident.

In France, as in the rest of Europe, fewer than 5 percent of homes have air-conditioning. Cost is a huge factor. Taxes and add-on charges send electricity rates through the roof, even though 75 percent of electric energy generated in France comes from nuclear plants. Surtaxes include contributions to green energy development, pensions for public utility workers and a 20 percent value-added tax. All of these amount to an effective tax of more than 50 percent (the number varies somewhat from place to place). I paid 66 percent in taxes on my electric consumption last year.

Humans have lived in caves in this region since the Middle Ages. Work in and around them dates from when the local limestone was quarried to build the ubiquitous abbeys and chateaus for which the Loire Valley is renowned. Villages sprang up, complete with domed brick and stone ovens. Stonecutters fashioned their own dwellings on site.

Christophe Léotot, a geologist and forensic expert in the area, estimates that the number of cave dwellers in the Indre-et-Loire and Maine-et-Loire regions peaked at around 40,000 during the 1860s, when commercial exploitation of limestone was at its height. At that time, upward of 100,000 metric tons of stone a year were transported by barges on the Loire and its contiguous waterways throughout the region. Of the caves once occupied, 60 percent have since been abandoned and are not habitable.

Calculating the 21st-century occupancy rate proved difficult. In 2002, a team of geologists was put together by the French Geological Survey to assess the number of caves in the Loire Valley. Local mayors were sent questionnaires. In the end, the team selected a group of representative parishes that they surveyed on foot, and extrapolated the total number from their count. Dr. Léotot estimates that there are around 2,000 human-inhabited caves in the Loire Valley today.

Structurally, limestone is stable when its temperature remains between 53 and 68 degrees. It does not tolerate freezing temperatures, because it is so porous. Caves once abandoned are rarely reoccupied; many collapse after the humans leave. When there were working quarries, the continuously inhabited residential caves maintained an even temperature year-round.

French activists, upset by the government’s inaction on global warming, have demanded that elected officials treat the matter for what it actually is: a crisis of epic proportions, equal parts ecological, environmental and humanitarian. On March 14, four nonprofit groups — Oxfam France, Greenpeace France, Notre Affaire à Tous and Fondation pour la Nature et l’Homme — filed a lawsuit against the government for its failure to meet its obligations, under the 2015 Paris agreement, to reduce carbon emissions.

Moving the entire population of France into cave homes is not a practical solution to the next heat wave. Stringent local and regional laws make new development in abandoned caves, and further excavation of existing caves, close to impossible.

If I were a betting woman, though, I would wager that my quirky choice of home becomes a trend.

Erica Rex is a science journalist who is working on a book about the emergence of psychoactive drugs to treat depression and PTSD.

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