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Journal · Climate & method

Borrowed climates — Hassan Fathy, read for Ibiza

Maximiliano Arrocet — 27 June 2026 · 9 min read

Architects fall in love with the romantic image of great vernacular architecture — a wind tower against a desert sky, a whitewashed dome, a cool dark room in the heat. But carrying a solution from one region to another is an exercise in rigour, and it asks for a neutral eye: which part of the answer is universal, and which belonged only to the place it came from. A warming climate makes the question urgent, and sends us to look at the regions that have wrestled with heat the longest. Hassan Fathy — a genius, and one of our references — is the perfect test. So let us ask it plainly: what of Fathy would actually work in Ibiza?

This is the companion to our first piece on Fathy, and a more critical one. There we admired the house that breathes. Here we take it apart, device by device, and weigh each against the real climate of these islands — keeping what transfers, naming what does not, and saying why.

What Fathy was solving for

Fathy built in Upper Egypt: a hot arid climate, where the summer air is fierce but dry, and the nights fall away cold. His genius was to read the old houses of Cairo and Nubia and distil their answer into a few devices — the malqaf (a wind catcher facing the prevailing breeze), the courtyard that holds a pool of night-cool, the dome whose crown lets the day’s heat climb away, and — crucially — the salsabil, a wetted surface that the incoming air passes over so that evaporation drops its temperature.1 That last move, evaporative cooling, is the heart of the desert answer. It is also the one that does not survive the journey to a humid island.

Hassan Fathy's house section judged for Ibiza: air movement, the dome's stack effect and thermal mass transfer (tick); direct evaporative cooling does not (cross)
What transfers, and what does not
Fathy’s section, weighed against Ibiza’s climate. The air movement, the stack effect of the dome and the thermal mass all transfer. Direct evaporative cooling — the desert’s master stroke — does not: Ibiza’s summer air is already too humid for it to work.

What transfers to Ibiza — and what doesn’t

The decisive fact about Ibiza is not its heat but its humidity. August days average around 29 °C with nights near 22 °C, and the air is muggy for most of the month, the sea breeze — the Embat — arriving warm and damp from the east.2 That single difference sorts Fathy’s devices into two piles.

✓Moving airThe malqaf catches a breeze and stirs the rooms. Ibiza’s summer winds are light (~4 m/s) but real; air movement still helps the body shed heat.3
✗EvaporationDirect evaporative cooling only works when the wet-bulb temperature is below ~22 °C. In humid Ibiza it sits near 23–24 °C — so the cooling is small and the air leaves nearly saturated. The desert’s best trick backfires here.4,5
✓Stack effectThe dome’s lantern lets hot air climb out and pulls fresh air in. The same physics drives a solar chimney — a reliable, humidity-proof engine for ventilation.6
✓Thermal massHeavy earth walls hold the night’s cool against the day. This is universal — and, as it happens, exactly what the local houses already do.7

So the romantic centrepiece — the evaporative cooling tower — is the one thing we should not copy. It was measured at its best in Ahmedabad, at the Torrent Research Centre, where a passive downdraught evaporative system kept interiors roughly 10 °C below the outside and cut cooling energy by around two-thirds.8 But Ahmedabad is hot and dry; that is why it worked. Drop the same tower into a humid Mediterranean August and it would add damp to air that is already heavy, cooling little and comforting less. The lesson is not the tower. It is the reasoning behind it.

Don’t import the image. Import the reasoning.

The intelligence already on the island

And the reasoning, it turns out, is already built into the ground here. The casa payesa, the traditional Ibizan farmhouse, answers the heat with the opposite move to evaporation: mass and shade. Thick lime-washed walls of rubble and marés stone soak up the day’s heat and release it slowly hours later; rooms gather around a courtyard; openings are small and deep; the flat roof is insulated with dried posidonia seagrass and ash; cisterns store the winter rain.7 Where Fathy’s desert house evaporates and draws air, the island house remembers and shades. For Ibiza’s climate, the island had already reasoned its way to the right family of answers — centuries ago.

This is the discipline of transfer. Fathy and the casa payesa are not rivals; they are two intelligent replies to two different questions. The error would be to airlift the Egyptian image whole. The craft is to take what is universal in it — moving air, the stack effect, the honesty of earth — and graft it onto the local logic of mass and shade, while leaving the evaporation in the desert where it belongs. Fathy knew this himself: he illustrated his own book with Paul Rudolph's Yale School of Architecture, where the malqaf's form re-appears in a wholly modern building — proof that what travels well is the principle, not the postcard.

What to learn

If Fathy’s tower is the wrong import, his section is the right teacher. Keep his diagram of moving air and turn it to Ibiza’s climate. Instead of cooling the incoming air by evaporation, cool it against the ground: draw the Embat down through a buried earth-to-air tunnel, where the soil holds steady near 19 °C through the worst of summer and can shed several degrees from the air without adding a drop of moisture.9 Let thick mass — the casa payesa’s lesson — bank that coolness for the day. And let a dark, sun-facing solar chimney do the work the desert dome once did: warmed by the very sun that is the problem, it pulls the cool air through the house and breathes the hot air out at the top.6 The engine is solar; the cooling is the earth’s; the moisture is left untouched.

None of this is free of difficulty, and rigour means saying so. Buried tunnels can sweat and grow mould if they aren’t drained and detailed with care, and in some ground they must be sealed against radon; mass is slow and unforgiving if the orientation is wrong; and a passive system moderates the peaks rather than abolishing them — it earns its keep by cutting the hours the machine must run, not by replacing the climate.9 But it is honest to the place. It is the casa payesa, re-read with Fathy’s intelligence about air and section — and it is the same line of thought that gave us the Cubo in-finito.

That is what travelling well looks like. Not the borrowed image, beautiful as it is, but the borrowed reasoning — tested against the wet-bulb line, the soil temperature, the prevailing wind, and the houses that were already here. A genius like Fathy does not give us a form to copy. He gives us a way of asking, and the courage to look at the regions that learned heat before we did. The answer for Ibiza will be its own — earth, mass, shade and moving air — but we would not have found it as clearly without him.

Technical bioclimatic section of a hybrid casa payesa: exterior air intake, buried earth-air tunnel (soil ≈19°C), thermal mass, aljibe and a solar tower, with a single continuous air path
A buildable section for Ibiza
The cool Embat (E–SE) is taken in at grade, drawn down a buried earth-air tunnel that holds ≈19 °C through the summer and delivered to the room through a floor grille; thick mass banks the cool, and a sun-warmed solar tower (+6.20 m) pulls the air through and breathes the heat out. One continuous path — every opening drawn, to a one-metre scale.
Wind rose for Ibiza: orient the catch to the cool summer Embat from the E–SE; shade and mass against the sun and the hot Ponent and Llebeig from the S and W–SW
Orienting to the wind — Ibiza
Which way to face: the cool summer sea breeze — the Embat, from the E–SE — is the wind to capture; the sun and the hot afternoon Ponent / Llebeig (S, W–SW) are what to shade and to mass against.
Hand-drawn family of wind towers: the Persian badgir, Hassan Fathy's malqaf with wetted baffles, the Torrent evaporative tower, and the BedZED wind cowl
A family of wind towers
The lineage this essay borrows from: the Persian badgir, Fathy's malqaf with its wetted baffles, the evaporative tower at the Torrent Research Centre, and the rotating wind cowl of BedZED — catching the breeze, breathing the heat out. Blue = cool air in, orange = warm air out.

References & further reading

  1. Hassan Fathy, Natural Energy and Vernacular Architecture, University of Chicago Press, 1986 — esp. the section through the Qa'a of Muhib ad-Din (Fig. 48–49; airflow measured by the Architectural Association, London, 2 April 1973, arrow length ∝ airspeed), the malqaf with wetted baffles and wind-escape (Fig. 56), the badgir (Fig. 66), the sun-and-wind orientation diagram (Fig. 9) and Paul Rudolph's Yale School of Architecture, carrying malqaf forms into modern design (Fig. 52); full scan, Internet Archive. And Architecture for the Poor, 1973.
  2. Ibiza summer climate data (August ≈29 °C high / ≈22 °C low; muggiest month; light easterly winds): Weather Spark — Ibiza; Climates to Travel.
  3. Windcatcher / badgir experimental performance and thermal comfort: Energy & Buildings / Building & Environment (experimental + simulation study).
  4. Direct evaporative cooling — wet-bulb limit (~22 °C) and loss of effectiveness in humid air: Building America Solution Center (PNNL).
  5. Wet-bulb depression and evaporative cooler output in humid conditions: technical note on wet-bulb temperature.
  6. Solar chimney / stack ventilation, induced airflow and sizing: J. Afonso & A. Oliveira, Solar chimneys, Energy & Buildings; and solar chimney + earth-air exchanger study.
  7. Casa payesa — traditional Ibizan construction and thermal behaviour (mass, lime, courtyard, posidonia roof): Anfora Ibiza; ACS Ibiza.
  8. Passive downdraught evaporative cooling, principles and the Torrent Research Centre (Brian Ford): arq: Architectural Research Quarterly, Cambridge Core; post-occupancy evaluation, Torrent Research Centre.
  9. Earth-to-air heat exchangers — performance (summer air ΔT up to ~8 °C), soil temperature at depth, and condensation / radon / maintenance risks: Experimental study, arid environments; holistic review of EAHE applications.
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