Validation discussion

2.7.1 Research methods

As mentioned earlier, there are a few flaws which are unavoidable when using simulations. First, simulations are a simplified representation of reality and can therefore never provide exact output. Second, input for the simulation is usually based on historical data and not what will happen in the future. Moreover, input can also be based on assumptions which might be incorrect. Finally, any inaccuracies in either the simulation or the input data might cause further error.

When these flaws are combined, the output of the simulation can be quite

uncertain. In their study of lifecycle embodied energy, Rauf and Crawford (2015) identified an error range in their results of ±42%, a number which clearly shows the complexity of making long-term prognoses. Burke et al. (2017) showed that varying 16 parameters within realistic distributions in 1000 energy use simulations resulted in total annual energy use in the range of 40kWh/m² to 80kWh/m². This complexity is also highlighted in Chapter 4.4.2 other findings not reported in attached publications, where it is noted that just a small change in the inputs can have significant consequences for the results. One could therefore argue that long-term prognoses are limited and should not be used as the sole basis for decision-making. However, the purpose of lifecycle analyses is to provide depth and understanding of the available options. The outputs are not meant to be regarded as facts: one has to understand that reality is different from a prognosis. Moreover, understanding the effect of changes in key inputs on the results, as a form of sensitivity analysis, can provide valuable insights into the performance of different concepts. The alternative would simply be to guess what renovation concept would be best and that would not do. Thorough analyses are necessary because they increase knowledge and understanding of the available decisions; thus, even if the results of the simulation are flawed and are unlikely to realise, the

knowledge and insights gained are valuable.

2.7.2 Case studies Case study 1

One of the difficulties with case study 1 is that it could be argued that even a minimalistic renovation concept should offer some sort of energy reduction. For example, new windows, even with low U-values, could probably reduce energy use compared to the 50-year-old windows in the building. Additionally, concepts focused more on minor improvements, such as improved windows and the

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installation of a heat pump, would be interesting to study and compare to the other concepts presented in case study 1.

The rent for both the minimalist and the code-compliant renovation concepts were based on best estimates; however, it could be argued that the user value is the same for all concepts and so there should be similar rent changes for all concepts.

In their description of user value, Hyresnämnden (2017) does not highlight any effects of energy-efficient renovation, such as thermal comfort, as noteworthy when determining user value.

Case study 2

The purpose of case study 2 was to use innovation theory as a means to establish vertical extension of buildings as an innovation and contribute to the diffusion of this innovation. Vertical extension of buildings is an innovation in its early stages, with some early adopters. For example, in a national report of 31 studied

renovation concepts, only one of the concepts included a vertical extension (Högdal, 2013). Even though vertical extension of buildings does have a niche to fill, “take-off” in the market has yet to occur. According to Rogers (1995) diffusion of innovation is the process by which an innovation is communicated through certain channels over time among the members of a social system. Case study 2 contributed to the diffusion of vertical extension of buildings by focusing on the innovation-decision process. This is accomplished by sharing the

knowledge gained from studying the four cases and creating a development process so that the decisions regarding the implementation of vertical extensions can be simplified. This would enable more developers to determine if the vertical extension of buildings can be implemented.

As highlighted by Davidson (2013), case studies can sometimes fail to capture the subtleties of the innovations, especially if the cases are researched from outside.

The development process is based on all identified success factors from the four cases and literature on the topic; in other words, the process could likely contribute to further implementation of vertical extensions. Even so, the development process is probably not optimal and will need further development.

Case study 3

The simulations undertaken in case study 3 pose significant validation concerns since no realised renovation concepts were assessed. The study was thus considered theoretical. However, the data used to create and simulate these theoretical concepts were gathered from the industry. Several interesting approaches were assessed. Different insulation materials, methods for

prefabrication and ventilation methods were compared and eliminated in reference group discussions, forming the six renovation concepts examined in the case study. The inputs for the lifecycle profit analysis were then gathered from energy

simulations, construction cost simulations and companies in the industry. Yet, while the energy simulation software used in the study has been certified, the construction cost software had not; therefore, there was no way of knowing if the construction costs were realistic or not. As a result, the outputs from the analysis are rather uncertain. Since it was a pre-study, some uncertainty was expected.