Retrofit for continuity! Sustainability and gentrification of tenement apartment blocks in Dutch Cities from inter and post war period

Increasing energy efficiency of the housing stock is one of the largest challenges in the built environment today. In line with the international Paris-Climate-Change-Conference 2015, Dutch cities have great ambitions to reduce CO2 and to transform their cities into smart and climate neutral cities. In accordance with the transition from the use of fossil energy towards renewable energy, Dutch housing association organization Aedes have promised that their average housing stock is going to have Energy Performance Certificate (EPC) B in 2020. The recently published Woonagenda 2017-2021 of Aedes speaks about zero carbon housing stock for all housing associations in 2050. Moreover, refurbishment of the existing housing stock is broadening and including more social and feasible themes: providing affordable and attractive housing for young people in the rapid growing Dutch cities; encouraging local and self-governance; improving quality of life; green space, change of behaviour of tenants before and after the transformation and cultural heritage. However, in current practice the emphasis is on energy efficient renovation approaches for row-housing. Besides that, current design solutions are mainly supply-driven, being developed by contractors for professional clients who have a focus on technological aspects. Parameters like aesthetics, heritage, behaviour and user preferences are not explicitly addressed in current innovative programs. The complex transformation of tenement apartment blocks in city regions are not taken into account. There are some risks with the refurbishment of this housing stock.First, there is a performance gap in the prediction of energy consumption before and after the deep renovation because of changing use of the dwelling by tenants. Second, the consequence of transformation is an inevitable house expense increase. Since the renewed Housing Act of 2015, houses are only being assigned to tenants with appropriate low incomes. According to the new Woningwaarderingstelsel, the rent of refurbished dwellings increase could rise above the so-called ‘Social Housing’ limit (€592,55 and €635,05). Hence, the apartments will become unaffordable for individual tenants since they will no longer be eligible for state income subsidies when residing in more expensive housing. Third, when speaking about refurbishment, there are issues to be considered like whether a building has heritage or narrative value. In addition, according the Dutch Housing Act 70% of the tenants of a block must agree to the refurbishment. For this reason there is a need for a more integral vision and approach to deal with deep renovation of tenement apartment blocks.The research group Beyond the Current of Delft University of Technology is aimed to develop a feasible General Transformation Framework (GTF) for affordable tenement apartment blocks of three to five storeys in Dutch city areas from inter war (1916-1925) and post war period (1946-1965). Characteristics of these tenement blocks are. Each stair well has no lift and between 4 to 8 apartments. The apartments are between 50 and 70 square meter. The different units are always a part of housing block, the housing blocks are always a part of a coherent urban ensemble. All together there is estimated that 480,000 of these apartments are in the city regions of Amsterdam, Rotterdam, Den Haag and Utrecht. A more thorough conceptualization of transformation of these blocks and clearer correlation between and within the parameters energy efficiency, user preferences and cultural heritage is yet to be developed for the coming period. For each time period new goals are established, which means that the transformation of buildings will be adapted to the requirements of that time. Our foremost aim and assumption is that an apartment building stays affordable and can be retrofitted to sustainable housing, instead of being demolished for new building. The present paper describes the first phase and explains the method of the research project.Accepted Author ManuscriptHeritage & DesignTeachers of PracticeDesign of Construtio