How to renew the "fifth façade" of the city?
As part of the overall urban landscape, the "fifth façade" (the roof or roof of the building) is also a three-dimensional display of urban culture, regional characteristics and spatial planning.
On the eve of the two sessions in Shanghai in 2024, the special research team of the Xuhui District Municipal People's Congress deputies carried out research on the Xujiahui business district and Hengfu style area, and proposed to improve the planning control of Shanghai's "fifth façade".Countermeasures and suggestions。 For example, enhance the economic and social value of the roof space, integrate urban leisure, sports, catering and other functions, and arrange functional formats that can be experienced, promote communication and diversification.
This means making the roof accessible to people. Compared with "green space opening", the technical requirements and renovation costs of "open roof" are much higher. So, what kind of roof structure is suitable for transformation into a roof that can be rebuilt, and what are the difficulties and points that need to be paid attention to in urban roof renewal?
The fifth façade is renewed, with different pursuits in different periods
The "fifth façade" of Chinese cities has been renewed, and relevant policies have appeared more than ten years ago. In terms of purpose, some of them are mainly to increase urban greenery and alleviate the heat island effect (the phenomenon of higher temperatures in one area than surrounding areas), such as in 2012"Guiding Opinions on Promoting the Healthy Development of Urban Landscaping"There are also in pursuit of space beautification and a sense of order, such as in 2017Measures for the Administration of Urban Design。
At the end of 2021, the Ministry of Housing and Urban-Rural Development made a decision on "promoting the beautification of urban building roofs" proposed by the Fourth Session of the 13th National People's Congressreply-- We will continue to optimize the fifth façade of the city and compile national urban design guidelines.
In terms of optimizing the fifth façade of the city, Shanghai is a pioneer. In the fall of 2023, it will be released in Shanghai"Guiding Opinions on Strengthening the Planning and Construction of the Fifth Facade of the City"。 The basic principles include not only the principle of overall aesthetics and the principle of green economy, but also the principle of functional rationality, which encourages the expansion of functions according to local conditions, integrates the ecological landscape of roofs and the functional value of activities, and creates a public space for the public to rest and watch. That is, to encourage the conversion of more roofs into accessible roofs.
The roofs of the Venerable are generally flat roofs, rather than large sloping roofs that are common in ancient Chinese architecture. Liang Sicheng's "big roof" was criticized for wasting building materials, so in order to consider the construction cost, many low-rise or multi-storey public buildings with flat roofs were built from 1949 to the early days of reform and opening up.
However, in use, flat roof buildings, especially residential buildings, dissipate heat too quickly, which is not as thermal insulation as sloping roofs, and the carbon emissions are greater. The nationwide began to last for more than twenty years"Leveling to Slope"。
In the process of "leveling and reforming slopes", public buildings such as office buildings, hospitals, government agencies, schools, shopping malls, stations and performing arts venues are often neglected. At present, the renovation of the "fifth façade" is expected to incorporate more functional ascendable roofs, which is aimed at this kind of public buildings, which is also a manifestation of urban renewal entering the "deep water area" and becoming more refined.
What are the difficulties of roof renovation?
After combing, researchers from the surging research institute found that the main difficulties in transforming the roof that cannot be allowed to move to adults are as follows:
The first is the issue of load. On the one hand, whether the bearing capacity of the roof is sufficient, and on the other hand, if the original foundation is weak, the building as a whole cannot achieve a large load. If the weight of the new material is aggravated by the weight of the whole building, there may be problems such as irregular settlement.
The second is the issue of building structure. When the roof is transformed into an accessible roof, how do people "get on" the roof? Transforming from a manhole or a steel ladder to a stairwell, or with an elevator, will involve changes in the building structure.
Again, it's funding. The cost of building structure renovation is not low, and who pays for it is a question. In the early days, many construction projects were shelved due to financial problems. Even if there are subsidies, it is worth paying attention to whether the subsidies can cover the cost of structural adjustment and realize the complete implementation of the project.
In Shanghai, there are some successful roof renovation projects, such as Bailian Group Headquarters, Boneimen Foreign Company, Yongxing Warehouse, World Skills Museum, etc., all of which have realized the function of meeting the functions of public space on the basis of safety. However, it is worth noting that the building itself is a historical and cultural heritage, so the renovation funds are relatively abundant, which is also one of the reasons why these projects can be successfully renovated.
How to promote the opening of the roof, how to open it more reasonably?
Compared with "green space opening", "roof opening" has much higher technical requirements and renovation costs, so the speed of promotion is slower. How to effectively promote the opening of the roof, the researchers of The Paper Research Institute put forward the following suggestions:
The first is to update in batches. Commercial buildings, schools and other buildings can be used as pilot projects to "test the waters" through financial subsidies. For the most difficult old office buildings, it is recommended to wait until the flow of urban renewal funds is more mature and there is a more feasible profit model.
The second is to strengthen supervision. In the process of "testing the water", relevant departments such as housing and construction need to strengthen supervision and carefully assess whether the building itself is suitable for renovation, so as to avoid the roof that is not suitable for renovation being mistakenly changed to a multi-functional roof, and the building becomes a dangerous building.
The third is to update the version of the existing planning guidance guidance. existingGuidanceThe technical support is mainly for new buildings and new areas, while there is a gap in the renovation of old buildings with the most flat roofs, especially "non-historical" old buildings. It is recommended that technical support be extended to different types of buildings.
The fourth is to balance the public nature with the original function of the building. For the company's private office buildings, the roof can only be used occasionally by the company's personnel after renovation, and the surrounding residents are not allowed, and the public nature is limited. Can the rooftop be as public as the pocket park after the "attached green space" is opened, and can be used by the public without hindering the office?
Internationally, it is like using external direct elevators, or adding gentle slopes from urban public spaces, or introducing overhead walkways from adjacent buildings, so that office workers and citizens can be diverted and go directly to the roof without going through the inside of the building, so as to enjoy the dividends after urban renewal.
