Replicable urban densification
Basic information
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Project Description
Urban redensification is no longer something new. Existing building projects, however, are characterized by its unique planning process. In contrast, the aim of this work is to combine roof extension in lightweight timber construction with the potential of reproducibility on typified residential buildings from the 1950s to the 1960s in Hamburg. A fundamental modular system solution responds not only to the lack of affordable housing, but also to the massive consumption of resources and land.
Project Region
EU Programme or fund
Description of the project
Summary
Urban redensification has long been the talk of the town, but the uniqueness of each individual building project leads to increased planning effort and therefore offers no real competition to the standard approach of demolition and new construction.
The idea is to develop a fundamental modular system solution in lightweight timber construction, applicable to the similar building typology of residential buildings from the 1950s to the 1960s using the City of Hamburg as a transferable case study.
The advantages are obvious: reduction in consumption of resources and land, use of renewable raw materials, creation of affordable housing, counteracting serious gentrification processes, desirable mixing of residents and preservation and enhancement of the architectural identity.
The aim is to renovate the existing buildings in a way that is friendly to the occupants and that comforts the users as well as the architectural effect.
Many existing buildings of post-war architecture are endangered or have already been demolished. It is urgently necessary to find a sustainable solution for post-war architecture, otherwise Hamburg will exchange an important part of its architectural identity to faceless investor buildings.
Currently, every roof extension is a one-off solution. The research aims to develop a fundamental ´system building set´ out of wood, which is applicable to a common building typology.
Continuing to build on the existing stock by means of a systematic solution is not only a preservation model of cultural heritage with a low CO2 footprint and a high social purpose for the City of Hamburg, but should also be considered for the entire European region within the framework of the New European Bauhaus.
Key objectives for sustainability
The idea provides various components of sustainability:
Ecological sustainability - Roof extension counteracts the increasing consumption of resources and the growing environmental degradation that accompanies it, since no additional land is consumed and no soil is sealed. Existing infrastructure can be used. The building sector is responsible for around 40% of Germany's total energy and material consumption, as well as 53% of the country's annual waste. By preserving the existing building stock, the loss of resources and energy due to conventional demolition and inadequate recycling of non-separable building materials is prevented. Energy retrofitting of the existing building reduces the environmental impact of high energy consumption during operation. The extension of the existing building by roof extension using a lightweight timber construction that can be separated by type contributes to the conservation of resources. Increased use of renewable resources such as wood can contribute significantly to reducing the building sector's emissions of carbon dioxide in the long term.
Economic sustainability - Material values can be secured through a maintenance-friendly recyclable construction method of the roof extension, which promotes potential reusability and deconstructability. The building does not represent hazardous waste at the end of its use, but ideally an urban raw material repository.
Social sustainability - By protecting and preserving existing structures, as well as upgrading existing buildings that create identity, a society worth living in can be achieved in the long run. Demolition and new construction often lead to the displacement of lower-income segments of the population.
To sum it up a modular system solution for roof extensions in lightweight timber construction, has the aim to minimize the environmental impact on the climate and soil as well as the impact on people, while at the same time optimizing the follow-up costs.
Key objectives for aesthetics and quality
The built environment is a contemporary witness of the development of society and creates a spatial identity. Post-war residential architecture was characterized by overcoming material hardship, so that the social necessity of creating housing was the first priority. Nevertheless, functional residential buildings were created in an autonomous formal language. In Hamburg, the red brick, which was frequently used, was a decisive factor. In professional circles, post-war modernism is referred to as an underestimated era.
In the meantime, many residential buildings from this period are in need of renovation and the question arises whether the existing buildings should be preserved or replaced by new buildings.
In Hamburg, there is a tendency to want to preserve the typical aesthetics of Hamburg's red-brick neighborhoods and to develop them further in terms of quality. For neighborhoods in the east of Hamburg there is already an urban preservation ordinance with design specifications, the so-called "brick ordinance".
Within the scope of the work, the potential of a a ´system building set´ is being investigated and proposed as a solution. The aim is to achieve a high degree of flexibility in façade and floor plan design. The individual components are to be designed in such a way that, despite series production and standardization, an individualized configuration is possible.
The modular system can be adapted to the individual requirements of the site and counteracts the monotony of mass housing. In the newly created apartments new and modern forms of living can be tested, which enrich the housing market.
From a building culture perspective, there is the potential to add a modern period layer to the existing neighborhood. This can lead to new attention and acceptance in neighborhoods with a backlog of redevelopment.
All in all, the ´system building set´ enables an aesthetic upgrading of the existing, taking into account the changing needs of growing cities.
Key objectives for inclusion
Inclusion is addressed in the work by upgrading the stock without pushing out the existing residents.
In Hamburg, as in many other large cities, there is the problem of gentrification, the displacement of lower-income groups and the shortage of housing affordable to them, which leads to social inequality in the housing market. Under current housing market conditions, housing choice is often a privilege of those who can financially afford it.
Roof extensions are expensive and do not, in and of themselves, contribute to affordable housing. However, lower-income groups benefit via trickle-down effects.
In the course of the increase, the existing residents can remain in their familiar environment and do not have to leave the apartment against their will.
The fact that the addition of more floors will create more living space with additional rental income will make it possible to partially finance the refurbishment.
It is assumed that roof extensions contribute to a balanced social mix. This is based on the assumption that in the case of a roof extension with refurbishment of the existing building, the profitability calculation is extended to the entire property. The often higher rents of the new attic apartments are used to cross-subsidize the now renovated existing apartments on the lower floors. Following the construction work, existing residents can remain in their traditional, less expensive existing apartments.
Thus, the preservation of the existing buildings and the cross-financed refurbishment through the roof extension counteracts the exchange of lower-income residents for higher-income residents and promotes a social mix.
Innovative character
In practice, the construction of roof extension is a frequent occurrence. However, these are always individual solutions and there are many legal and technical standards that create obstacles for the building owners. Since the city of Hamburg is interested in vertical densification, changes have been made in recent years to the federal building regulation, making it easier to add storeys from a building law perspective.
One of the biggest obstacles is the load-bearing reserves of the existing buildings, since in the early post-war period a lot of living space had to be created in a short time with limited materials and the cross-sections of the supporting structure had to be reduced to a minimum.
Therefore, a detailed knowledge of the existing building typologies, structural systems and used materials is necessary.
The task is to move away from a single solution to a systematic solution. The innovation of the work is to find a fundamental ´system building set´ solution with wood, which is tailored by its adaptability for the majority of typical residential buildings from the 1950s to the 1960s. The ´system building set´ provides the creation of quickly available housing in large numbers at a reasonable price.
The ´system building set´ consists of a fixed set of building blocks with standardized properties, which can be combined with each other according to the specific application. The building task can be assembled from them without the need to adjust the shape of individual building blocks.
Continuing to build on the existing stock through a systematic solution is a model to preserve the cultural heritage with a low carbon footprint. Therefore, it should be considered within the framework of the New European Bauhaus for whole Europe.
In this context, Hamburg can serve as a role model by advancing vertical redensification through adaptation of the federal building regulation and the brick ordinance as an incentive to preserve existing buildings of cultural&a
