By Mehran Gharleghi

How did people keep cool indoors before the invention of air-conditioning? Architect Mehran Gharleghi, director of Studio INTEGRATE and curator of the Evolution exhibition on Iranian art and architecture, explains how Iran's extraordinary architects developed clever strategies to beat the heat.

What is the architecture in Iran like?

Iran has one of the most sophisticated architectural traditions in the world. Over thousands of years, its architects have developed a style that combines aesthetic design and function to help people stay cool and comfortable in a hot and arid climate.

Beautiful and practical

In Iranian architecture, function, form and ornamentation are not in contrast or competition. Rather, they come together in buildings and infrastructure that are both works of art and structural wonders. For example, the famously lovely 17th-century Khaju Bridge in Isfahan acts as a crossing and weir over the Zayandeh river, but also serves as a viewing platform, resting place and café where people can meet. The bridge's design regulates water for the irrigation of nearby crops, and even controls wind speed in the area.

Another example is the poetic design of the Persian Gardens, which make up a UNESCO World Heritage site. These are beautiful formal gardens across Iran, dating back to the sixth century BC, which influenced horticultural design as far away as India and Spain. Tucked away behind walls, the gardens create their own micro-climates through subterranean canal systems, shady greenery and porous structures like pavilions, which help circulate fresh air and provide relief from the outside environment. In fact, the word 'paradise' to describe the Garden of Eden was adopted from the old Iranian pairidaeza, from the words pairi meaning 'around', and daeza, meaning 'enclosed wall'.

Understanding the processes of Iranian architects centuries ago can teach today's architects lessons on sustainability, how buildings and their environment can work in harmony, and how good design can improve the quality of people's lives.

Homes in Iran are designed to keep people cool in the heat

In Iran, houses co-evolved with their surroundings over time. Each house and its environment are indivisible: the orientation of houses is determined by the available shade, the direction of the sun, and the flow of wind, so that they provide the most comfort at all times of the year.

Historically, Iran's most prominent building type is the central courtyard house, which was designed to keep its inhabitants cool. Aesthetically stunning, these buildings are among the highest achievements of structural, climatic and cultural engineering. They respond to their location and available resources with a high level of architectural sophistication.

A gorgeous example is the Boroujerdi House in Kashan, which took 150 craftsmen nearly two decades to build during the 19th century. The house has an interior temperature that is 12 degrees lower than the outside at any time, thanks to wind towers and a shady courtyard.

What does Tehran look like?

After the Qajar period, which lasted from 1785 to 1925, Iran went through a period of modernisation, and its cities and the style in which its houses were built changed. Nowadays, the lifespan of each building in Tehran is roughly only 20 years, because people want newer and more contemporary designs. This leads to lots of innovation, but it can also mean that cultural heritage is lost. Iranian architects today try to combine new technology and the need to cater for modern lifestyles, with the traditional design knowledge that is culturally rooted in Iran's environment.

How is art and design incorporated in Iranian architecture?

In Iran, craftsmanship is utterly intertwined with architecture. You can clearly see this in the exquisite, intricate designs of Iranian domes, and in tessellations, which are kaleidoscopic mathematical divisions of patterns and tiles.

Mathematics is an integral part of Iranian art and architecture. During the Islamic Golden Age of the Middle Ages, Iranians excelled in calligraphy and geometric art, due to religious prohibitions on imagery such as portraits, and later, on photography. Because of this, geometric art is very highly developed.

One extraordinary example of this is the use of Penrose tiling in certain high-profile Iranian architecture. This tiling reflects a mathematical equation by the British mathematical physicist Roger Penrose in the 1970s, which corresponded to an equation found throughout the natural world, including in atom formation. These complex equations have been found to have been used in Iran 500 years ago.

The Evolution exhibition is open until 24 April 2015 at Asia House, 63 New Cavendish Street, London W1G 7LP.

***UPDATE*** The exhibition has been extended to 1 May 2015.