Zhang Long, an Associate Professor of the School of Architecture at Tianjin University, has been involved in the repair work of the Summer Palace since 2004. Ever since he joined the Summer Palace Conservation Team from Tianjin University, he has spent countless of days and nights in the Summer Palace.

Tianjin University's Summer Palace Conservation Team is led by Professor Wang Qiheng, an architect specializing in ancient Chinese buildings, and consists of a dozen members. The team members believe that cultural relics reflect the social life style, cultural aesthetics and scientific and technological level of an historical period. This information is hidden in the overall layout of the building group, the internal and external space of the buildings, the structural mode, and even the building materials. Zhang Long said, "We do not simply expect visitors to admire the static beauty of Kunming Lake, Longevity Hill and the Tower of Buddhist Incense, we want them have a hear-to-heart communication that travels across time and space with the Summer Palace, listening to the whisper of the buildings with thousands of magnificent tales from the past."

According to Zhang Long, the collaboration between the Summer Palace authority and Tianjin University can be traced back to 1957 when an internship in ancient architectural surveying and mapping was conducted. Relevant results of the internship have been included in the book "The Best Specimens of the Imperial Garden of the Qing Dynasty". In 2004, Professor Wang Qiheng of Tianjin University established Tianjin University's Summer Palace Conservation Team, providing overall work for the Summer Palace including surveying and mapping, research, conservation planning, restoration design, and heritage detection. In 2006, Tianjin University's Summer Palace Conservation Team undertook the planning formulation for the preservation of Summer Palace's cultural relics. The team clarified the changes to the Summer Palace over different times. In 2014, Tianjin University and the Summer Palace authority signed a cooperation agreement on cultural relics preservation.

There are over 3,000 gardens and palaces architectural elements in the Summer Palace. Tianjin University team collected data of the buildings through advanced technologies such as global positioning, three-dimensional laser scanning, low-altitude information collection, and building information modeling. With modern technologies, the team completed over 95% of the digital surveying and mapping of the resort's ancient buildings, rendered over 3,500 drawings, and collected information about hidden places.

The residence of the Ministry of Foreign Affairs of Qing Dynasty at the Eastern Palace Gate was also the office for Foreign Affairs of the government of the Qing Dynasty. Its main building is the combination of the expansive roof of Chinese architectural design with a modern western triangular roof structure. During the surveying, the team found that users then added pillars in the middle for auxiliary support in case of the collapse of the roof frame, which defeated the original load-carrying design of the triangular roof structure. The team came up with a protection solution, maintaining the original components and adding a steel tie rod on the lower chord to link with the original steel tie rods, which restored the original large space and at the same time providing convenience for later reuse. The design was awarded second prize in the 2015 National Project Survey and Design Awards.

With multidisciplinary cooperation, they are turning rescue protection to preventive protection; through scientific monitoring, finding problems and risk factors; and adopting measures in advance to protect the historic architecture from destruction. With that aim, Tianjin University have gradually established a multidisciplinary research team including architectural history, architectural technology, engineering surveying, earthquake engineering, geotechnical, materials, computer graphics, optical fiber sensing, and low altitude remote sensing. The team has made major contributions to promote the protection of the Summer Palace, including the monitoring of deformation of the Great Opera Hall of the Dehe Garden, The Stone Boat, and Residence of the Ministry of Foreign Affairs of the Qing Dynasty, the vibration of the Great Opera Hall of the Dehe Garden, the paintings in the Long Corridor, and the micro environment and erosion of the Summer Palace.

The Dehe Garden, where Empress Dowager Cixi watched opera performances, is one of the most important acoustic architectural heritages in China. In 2011, scientists were confused as to how to guarantee the authenticity of the acoustics. Led by Liu Gang, an Associate Professor of Architecture at Tianjin University, a group of scientists conducted a series of comprehensive acoustic tests and came up with the solution. According to their analysis, the palace conforms to the demands of modern acoustical theory as a performance stage for Opera. Originally, craftsmen used thin wooden doors and windows to absorb sounds and beams, columns, stones and sparrows to evenly spread the sound. They also constructed "resonance" with the help of an aerial stage and the heavy wood floor of the stage. The Tianjin University team through research on historical materials and deduction of acoustic simulation, restored the original appearance of the corridor for watching opera performances.

The East corridor of Dehe Garden has now been fully restored by the team, providing an unprecedented experience for tourists of the very first ancient acoustics museum, where they may experience the scenes of the Empress' daily life in theater through virtual reality technology. Zhang Long said, "Visitors can experience the Empress Cixi and nobles watching the opera performances in the Great Opera Hall, and also the changes to the architectural components and acoustics conditions of the Great Opera Hall through application virtualization."

There is another delightful story about the team, when in 2014 they were surprised to see a mysterious and uneven acceleration of fading of the oil paintings' in Summer Palace's corridor. There are more than 8,000 colorful paintings on the beams of the Summer Palace corridor, which was regarded as the world's largest oil painting gallery.

Led by Professor Liu Gang, an investigation group was set up. They conducted micro-environmental tests on light radiation, and discovered that there had been a slight change in lighting conditions on one side of the corridor. The clearance of a few tree by the Kunming Lake during rationalization of the park was blamed, which caused the lake to reflect the sun light straight onto one side of the corridor. The study group soon proposed a plan for restoring the environment, which solved the problem successfully.

Apart from the restoration of the building, the team managed to add modern elements as an innovation. In 2004, a study focusing on lighting technology in the ancient gardens was jointly set up by Tianjin University and the Summer Palace authority. Professor Ma Jian, the leading scientist of the project, said: "By means of modern landscape lighting, the Summer Palace can be integrated into the scenery of the metropolis - Beijing."

At that time, further studies in that field were put on-hold. The idea that "The artificial lighting will destroy the beauty of ancient structures, as well as endangering the surrounding ecological environment" was shared all over the world. However, the group carried out their experiment with scientific, low-carbon and ecologically sensitive lighting equipment. Using different light sources, the group carried out a series of arduous lighting experiments on oil paintings. In 2008, the Summer Palace was opened for night tours with its bright night scenery. It also became a successful model of ecological lighting protection in the world.

More information is available at http://www.tju.edu.cn/english/news/spotlight/201711/t20171101_300371.htm