“The Dutch built environment - both residential properties of private owners, corporations and investors, as well as offices, schools, shops and commercial real estate – is largely outdated and not energy efficient” (Platform 31, n.d.). 
This research is about making the built environment more sustainable by refurbishing the building envelope in a smart energy efficient way. A focus is placed on post-war walk-up apartments of which 635.000 were constructed in the Netherlands. Renovation (zero-energy) methods for this specific building type are still missing. In this described context the ‘2ndSKIN’ project already conducted research for a new renovation method that integrated building services in the building’s envelope and was therefore used as a starting point. However, in the end the 2ndSKIN project was not efficient enough in terms of costs and space. Therefore, the goal of this research is the design of a new zero-energy renovation method that improves the current method. The approach they used is still promising and it is often seen in other renovation projects. Therefore, it will be used as the base for the new renovation method in this thesis. In addition to the research on the 2ndSKIN project, other renovations methods that involve upgrading the envelope were investigated together with building services and the post-war walk-up apartment typology, forming the first part of this research: the literature review. From the review, different conclusions were found that formed parameters for the design process. There are fixed parameters like, building layout, structure type, size and orientation but also variables such as ventilation systems and heating systems. The parameters form the base for different concepts, that are introduced in the design phase and that lead to the conclusion of this thesis: the design of a new prefabricated zero-energy renovation concept for post-war walk-up apartments, that integrates the building-services in a space and cost-efficient way.