Limits of acceptable change in energy efficiency transformations: with Albert-Schweitzerplaats Knikflat in Ommoord as case study

Currently, the majority of the post-war building stock is in need of profound building transformations. Not only for the improvement of their energy efficiency, but also for the improvement of the technical, social and financial conditions of the building environment (Priemus, 1986). As the topic of post-war building transformation arises, the need for “balancing the conservation or preservation and transformation innovation” does so as well (Blom, Jansen, & van der Heiden, 2004); (Blom, Het verhaal van Nederland tussen 1940 en 1965, 2011). In order to find a balance the research is conducted by the use of the limits of acceptable change. The limits of acceptable change were firstly introduced by Frissell in 1963 and are developed to manage a degree or range of steps in which change is accepted and gradually scales to unacceptance (Frissell, Recreational use of campsites in the Quetico-Superior canoe country., 1963). From this perspective, the research addresses the issue of “To what limits can the post-war building stock be transformed? What is ‘acceptable’ and what is thought to be as ‘not acceptable’?”
A fundamental part in energy efficient refurbishment measures is controlled by the structure of the building envelope and the configuration of the building systems. The building envelope consists of the external walls, windows, roof, and floor, and forms the boundary of the building with its surroundings. Next to this, the key factors of orientation, location and construction define the potential in refurbishment to improve the energy efficiency of post-war multi-family dwellings (Konstantinou & Knaack, 2013).
This research aims to increase and stimulate the application of energy efficiency improvements within the field of the built environment by the use of a case study multi-family dwelling the Albert-Schweitzerplaats Knikflat at the neighbourhood of Ommoord within the city of Rotterdam. Furthermore, it aims to apply the limits of acceptable change framework to the topic of refurbishments in energy efficiency improvement.
The research is divided into three main parts. First the sub-question, ‘How to optimize the energy efficiency of the building envelope of a post-war multi-family residential flat?’ is solved by the use of a theoretical framework of retrofitting and renewable energy sources building envelope measures which define the scale of impact of the building measures on the heating demand. The second sub-question, ‘What are the limits of acceptable change in energy efficiency transformations of a post-war multi-family residential flat?’ is solved by conducting semi-structured interviews with key actors in the decision making of building designs which result in the rate of transformation of the case study building. Subsequently, the third part consists of a combination and synthetization of the first two parts, in which design recommendations for transforming the building envelope within the limits of acceptable change in energy efficiency transformations are developed and evaluated by VABIEPA-W to solve the main question of, ‘How to optimize the energy efficiency of the building envelope of a post-war multi-family residential flat, with respect to the buildings’ limits of acceptable change in energy efficiency transformations?”.
In general the results show that the second façade retrofitting measures have the largest impact, and the roof and ground floor measures the lowest. Moreover the limitation conditions of the actors are found to be merely focused on their own field of view. As for the aesthetical qualities the building is not designated as monumental heritage, these values were not mentioned as conditions for the limitations of the building transformations by the actors.
Finally, a brief summary of the acceptable and recommended transformation measures consist of: external wall insulation, adjustable shading, window replacement with triple LoE ARGON, under slab ground floor insulation, roof insulation and a flat PV-roofing system on 100% roofing area. Applying the recommended transformation measures to the case study results in a total Energy Index reduction of 44%. As the original building characteristics are classified as an energy label F according to the NEN 7120+NV, the building can be transformed to an energy label B within the limits of acceptable change in energy efficiency transformations.