The project draws on the traditional organisation of the old town in terms of density and climate intelligence. In the city plot, like in the winter town, the building is compact to prevent too much heat gain or loss, highly protected on the perimeter, and organised around courtyards that bring light and ventilation. On the oasis plot, lighter, spread constructions draw inspiration on the summer city as these benefit from a milder microclimate, the shade of the palms, and humidity of the citrus trees.

In these latitudes, shelter from the strong sun is primordial (solar exposure can increase felt temperature by some 10ºC) to avoid that temperature increases above the air one: the project provides large canopies, slabs extend for 3m or more (cutting down radiation on glazed surfaces by at least 55%), musharabiyas protect from the horizontal rays, palm trees cover outdoor spaces, and in the roofs, a double layer (with a canopy of PVs or simply rocks) creates an air gap that avoids direct contact with the sun. The spaces in-between cool down the air before it reaches inside, progressively controlling the climate. When the weather allows it, large sliding windows remain open, extending the space, to enjoy outdoors. The structure holds concrete to stabilise peak temperatures: during summer, the main levels have natural temperatures 3-8ºC lower than outdoors, which in its turn reduce the need for air conditioning.

Inside the oasis, measured air temperatures are 2-3ºC lower than in the surroundings. The ground floor is always in the shade: palm trees cover the highest layer, whereas citrus and fruit trees are closer to the human height. Humidity is higher, especially in the afternoon, and radiant temperatures are also much lower due to the low surface temperatures of the leaves, which effectively balances air temperature. Felt temperature is all year long 3-8ºC lower than air temperature. The large shaded parvis is a type of space is unique in these climates. As no surface is ever exposed to the sun, radiant temperatures never surpass air temperature. During hot days, the thermal sensation is some 5ºC lower than air temperature and can be up to 10ºC lower than in the street.

"Al Ula is situated on an ancient Incense Route, and is home to many ruins including Hegra, an old Nabbatean city, Saudi Arabia first UNESCO World Heritage Site. The history and the landscape here are impressive and fascinating, almost overwhelming in their strength and dimension. The old town of Al Ula is divided between a winter city, dense and compact, and a summer city, sprawled out in the oasis, under the palm trees, to take advantage of the oasis’ microclimate and shadow. The site of the project is not the old city nor the great landscape. The project engages with the city, it is part of the modernity of AlUla, reflecting its historical particularity: a fixed stop on a nomadic route. This project should become a link between different experiences of the site: nomadic or sedentary, temporary, or long time, local or touristic, educational or cultural, urban or agricultural. The space must give room to all these experiences and mixes.

The project proposes to let the ground floor almost free of constructions and open. At six meters high, a large platform is built on pilotis, to accommodate the program: the Villa Hegra, a cook school, and a hotel. It forms a second public circulation, above the ground, which serves all the functions and enables to cross the whole plot in the canopy of the trees, offering two possible paths for the pedestrians: on the ground or in the air.
On the urban part of the plot, the platform provides on the ground floor an open and high space, shaded, like a large parvis, used as a free public space. The permanent and pleasant shadow, the gardens in the patios, and the proximity of the oasis brings coolness in this public space.
In the oasis part of the plot, the platform protects the buildings from flooding and allows a very minimal footprint of the constructions on the ground, leaving the soil completely natural and free for agriculture. The agricultural oasis will be regenerated, building a layered farming with dates, citrus, figs, and vegetables.

· Creating a link between the urban and the oasis side of the plot
· Reinterpreting the old town’s organisation in term of density
· Bringing back the garden inside the city
· Taking advantage of the oasis microclimate to limit the energy needs"

Lacaton & Vassal

AlUla has a Dry Arid climate of Low Latitudes (BWh in the Koppen Geiger climate classification, 26ºN). Temperatures are very high, especially during summer as they normally reach above 40ºC due to the intense solar radiation (daily incident radiation of 700-1000 W/m² across the year). However, diurnal ranges are also large - 13-14ºC-, as temperatures cool down quickly at night due to the cloudless night sky. The annual average is 23ºC. Humidity is very low (20-50% on average), wind speeds are low and constant (annual average of 2.7 m/s), and should be carefully controlled, as it normally carries dust. During the hottest period, average temperatures are around 32-33ºC, and reaches 40ºC on average in the afternoon. During the mild period, the average temperatures are around 13ºC, with a low average of 5ºC, and a high average of 18ºC in the afternoon. A small amount of sun can heat up interior spaces very fast.
A study of local conditions revealed that inside a fully developed oasis, temperatures can be 2-3ºC lower than in the weather station, which significantly improves the conditions inside the oasis plot. Local wind studies pointed that during the mornings, the wind comes from the north: the breeze is welcome as temperatures are lower and comes from the oasis bringing freshness. During the afternoon, the wind comes from the west-south-west, charged with the heat of the city. This time, the breeze is not necessarily welcome as during the hot period temperatures are too high, and the wind from the city can be at even higher temperatures.