Sustainable Architecture in Coahuila's Desert, What Actually Works

Sustainable architecture in a desert climate is built first with passive decisions —thermal mass, orientation, ventilation— and only then with machines. Since December 7, 2011, Mexico's NOM-020-ENER-2011 building code has required limiting heat gain in every new home through its walls, roof and windows [1]. In the Paredón desert, Coahuila, that matters more than in a temperate climate: annual potential evaporation (1,856 mm) is more than seven times the rainfall (256.8 mm) —our own calculation from CONAGUA's (2024) figures [5].

Key facts

• NOM-020-ENER-2011 has limited heat gain through the envelope of every new home since December 7, 2011 [1].
• In the Paredón aquifer, annual evaporation is more than seven times the rainfall (1,856 mm vs. 256.8 mm), according to CONAGUA (2024) [5].
• A study by Felipe Sotta Benaprés (Construcción con Tierra 3, FADU-UBA) eliminated simulated cooling demand in 300 mm and 500 mm adobe walls in a Mediterranean climate; the 100 mm wall did show demand [3].
• In northern Mexico's hot-dry climate, air conditioning is a household's second-largest energy use, according to researchers at the Universidad Juárez Autónoma de Tabasco who cite CONAFOVI (2006) [4].
• Ramos Arizpe, home to Paredón, has a very dry, semi-warm climate across 50% of its territory, according to INEGI [6].

Why does Coahuila's desert demand a different kind of architecture?

Because the climate does not forgive design mistakes. CONAGUA describes the Paredón aquifer with an arid, semi-warm climate (BWhw), an average annual temperature of 18 to 22 °C, and rain concentrated in summer (5-10% in winter) [5]. Ramos Arizpe, which includes Paredón, gets 100 to 600 mm of rain a year, according to INEGI [6]. Ignoring that combination means having to compensate later with electricity.

What is thermal mass, and how does it delay heat?

It is a heavy material's —earth, stone, adobe— capacity to absorb heat during the day and release it hours later, once the outside temperature has dropped. A study by architect Felipe Sotta Benaprés (Construcción con Tierra 3, FADU-UBA), based on a paper presented in 2007 at the Pontifical Catholic University of Chile, simulated adobe walls of three thicknesses using the climate of Los Angeles, California, and concluded that "by regulating wall thickness, adobe's thermal behavior can be used to reduce heating demand and eliminate cooling demand entirely for dwellings in a Mediterranean climate over the year" (translation) [3].

What does Mexican law require of a sustainable building?

NOM-020-ENER-2011, "Envelope of buildings for residential use," was published in the Federal Official Gazette (DOF) on August 9, 2011, and took effect 120 calendar days later, on December 7 of that year [1]. According to CONUEE, Mexico's energy-efficiency agency, "heat gain from solar radiation is the most important source to control, which is achieved through proper envelope design" (translation) [2].

How do orientation, overhangs and cross ventilation work?

A west-facing window catches the most intense afternoon sun, right when the building has already absorbed heat all day; that is why the code promotes shading elements to cut that gain [2]. In northern Mexico's homes, "energy used for climate control ranks second in household consumption" (translation), according to researchers at the Universidad Juárez Autónoma de Tabasco who cite CONAFOVI (2006); their induced-ventilation simulation, using a solar chimney, is for a hot-humid climate, not the desert [4].

More in the Ex-Hacienda Amargos project and desert water management.

What role does water play in sustainable desert building?

One of scarcity. CONAGUA concluded in 2024 that in the Paredón aquifer there "is no volume available to grant new concessions" (translation): a deficit of 39,033,049 m³ a year against recharge of 23.6 hm³ [5]. Any new well requires a concession, under the free-extraction suspension agreement of April 5, 2013 [5].

What does the Ex-Hacienda San Juan de Amargos teach about building in this climate?

According to Jesús Antonio Saro Llaguno, owner of Bodegas Capellanía, quoted by El Diario de Coahuila in October 2021, the Ex-Hacienda San Juan de Amargos, in Paredón, Coahuila, "dates from 1750" (translation) [8]. According to the fact box published by Vanguardia in 2017, the hacienda "was rebuilt in 1870-1910" (translation), and according to Jesús Saro, director of Bodegas Capellanía quoted in that same story, the casco "has cellars and even tunnels" (translation) [7]. That a 19th-century earth-and-stone building is still standing proves no specific technique, but it matches what the code and the materials studies measure. More in the hacienda's history and Coahuila desert biodiversity.