The building features many Chinese characteristics throughout its wooden structure, such as the interior bamboo roof panels.
Su said the design concept is loosely based on I Ching, also known as The Classic of Changes or Book of Changes. Originally from the Western Zhou Dynasty (11th century-771 BC), it has been transformed into a cosmological text of ancient Chinese philosophies.
The building specifically follows the trigrams of I Ching: parallels and the close relationships between heaven, Earth and humans.
"In our building, the roof represents heaven, the wheat field is Earth and the exhibition that shows China's civilization is a reflection of human activity," Su said.
The close relationship of heaven, Earth and humans and how they live together in a harmonious way is what made Tsinghua's design proposal stand out from the other 13 submissions, Su said.
The design was completed in late 2013, taking nearly half a year for the Tsinghua University team to complete it.
"Building a project outside China is an unprecedented challenge for us. You need to guarantee smooth communication between design team and overseas construction teams. But no matter how hard you try, unexpected incidents happen from time to time," Su said.
He admitted he has not had a good night's sleep in months.
"There were delays in the construction of the pavilion," Su said.
Feed back on the pavilion have been "so far so good" but that was before the expo opened on May 1, when 20 million visitors from around the world are expected. Su is confident that visitors will have a new impression of China from the building.
"We've already taken all the elements, such as the temperature in summer and Italy's Mediterranean climate, into account to achieve the best results with what we have," he said.
"Imagine Italy's summer light through the bamboo roof of the pavilion, shining upon the golden wheat field. The view can be breathtaking."
FACTS
Milan Expo 2015
Theme: "Feeding the Planet, Energy for Life"
Duration: May 1 to Oct 31
Total area for exhibition: 1.1 million square meters
Participating countries: 140
Estimated number of visitors: 20 million