## 1 Introduction  
### Description of PUH-Environments-Web Search and Literature Survey  
Pop-up housings (PUH) and temporary housing solutions (THS), respectively, can be characterized based on multiple aspects in terms of technical, architectural, infrastructural, economic, ecological, temporal and socio-cultural considerations as well as local conditions and contextual circumstances. The following introductory statements are based on the general analysis of over 85 PUH/THS structures (see list 'Collection of PUH-examples' in Supplementary Materials)that have been researched and recorded/documented for later classification of PUH, which is the main aim of this paper. Moreover, the principal methodology of clustering, applicable to numerous similarly structured problems, is presented. On the one hand, a rising need for affordable and sustainable THS, mainly in urban regions of developed countries, can be observed. This refers to a trend in the housing demand of young people, such as singles, students, workers and professionals, artists as well as young families. Rising requirements in the working environment concerning flexibility and mobility/stand-by duty, potentially lower-income situations and changing social developments/living conditions, among others, are triggering the subtle change in housing needs, particularly of younger generations. Such THS might play a role in the decarbonization of the building sector as well. [PERSON] et al. [1] showed through LCA- and energy consumption simulations that for a high energy efficiency prefabricated building module for temporary housing, mainly consisting of fiber-reinforced plastic (FRP), the pre-use phase causes the most (72%) total environmental impacts compared to the use-phase (23%). Generally speaking, it is vital to use LCA methods to assess the overall energy and environmental performances of such temporary housing units [1]. Apart from housing units of solely architectural experiments and design studies, or artists' visualization projects, there is also a market for (fairly extravagant) micro or tiny homes, ashore and afloat. These units are often single and provide (temporary) housing solutions for users who are seeking exclusive, often self-sustaining housing conditions, frequently being rather highly priced. On the other hand, there are THS for people and user groups with a more 'urgent or critical' housing demand, such as socially underprivileged (local) people, lowest-income households, asylum seekers, refugees and homeless people, to name a few. These THS aim to provide more 'basic' housing/shelter options with high affordability and ease of build possibilities in mind. In general, the global need for temporary housing is rising through the increasing severity of natural disasters, increase in number of climate refugees due to climate change and rapid urban population growth in developing countries [2]. THS for post-disaster situations seem to be analyzed most in the scientific literature [3; 4; 5; 6]. Concerning a post-disaster temporary housing settlement, several contextual factors have to be considered, such as physical characteristics of the settlement, availability of vital services such as education, health and work, infrastructure services, accessibility to the temporary houses within the settlement, economic prospect of the temporary settlement as well as socio-cultural, educational and financial standards of the occupants, as pointed out by [PERSON] [3]. Temporary accommodation in post-disaster situations is an issue that goes beyond the simple provisioning of housings since the whole space for the temporary settlement is important [4]. A considerable part of the provided THS is not produced in the affected region but in a different country, often neglecting local resources, such as building materials and labor workforce. Therefore, social problems and environmental degradation are often the consequence of false planning strategies (i.e., not considering the option of prolonged usage) and commonly require transition to permanent housing [4].