Vertical Extension of Buildings

Many policy targets have been developed with the aim of reaching a more sustainable development; more specifically, thestudied policies target energy use and urban growth. For example, by 2050 the aim is that the European Union will havereduced its greenhouse emissions by 90%. Examples of policy targets regarding urban growth can be found in many ofthe larger cities, as they have developed plans for densification so that the population can continue to grow withoutexpanding the city borders. Reaching these targets might be challenging as the human population is predicted to grow andmore people are moving to cities.Even though, there are benefits such as reducing energy use and extending the lifespan of existing buildings, many claimthat energy-efficient renovations are complicated and expensive. Moreover, the densification process is lengthy andfinding the right balance is challenging when many stakeholders are involved. Many citizens are negative towardsdensification projects, as such developments often occupy recreational space. Since both energy-efficient renovation anddensification projects are challenging to implement, other solutions have to be found. The vertical extension of buildingscan be considered a mix of both energy-efficient renovation and densification and therefore has similar benefits andchallenges; however, there are differences. By extending a building vertically no recreational space is occupied and, byselling the added apartments, an extension can pay for the refurbishment of the existing building.In this research, the impacts on sustainability of extending buildings vertically and success factors for the implementationof vertical extension of buildings have been studied. Three studies were undertaken, the aim of each study was tohighlight different perspectives of the vertical extension of buildings. The results of the first study show that the verticalextension of buildings can act as an enabler for energy-efficient renovation and that a low-energy plus the verticalextension renovation concept can reduce energy use by as much as 60%. In the second study the authors claim thatstakeholder participation can lead to more sustainable densification projects; however, currently, it is up to the individualproponents of participation to implement such a process. The results from the third study show that extending a buildingvertically is a complicated process. A development process was proposed in order to simplify implementation