The built environment consumes almost 40% of the overall energy consumption. Energy is often produced from the conversion of fossil fuels, which result in CO2 emissions, which in turn cause global warming. Therefore, adaptation of buildings towards less energy use is required to mitigate the effects of global warming. Since the adaptation of existing buildings could play a large role in achieving the climate goals, policies are made in order to stimulate these adaptations. The ‘Energy Performance of Building Directive’ promotes the adaptation of all existing buildings towards nearly zero-energy buildings (NZEB). Currently, offices need to have at least an energy label C by 2023. It is expected that this will increase to label A in 2030 and finally NZEB in 2050. However, the current adaptation rates are too low to achieve NZEB buildings in 2050. Besides, the step-by-step approach from label C to A to NZEB leads to even more pressure to the adaptation sector. If these multiple steps could be skipped, adaptations could be executed more efficient, which reduces costs and time. It could be questioned whether the current policy approach is sufficient to achieve nearly zero-energy offices on time. Therefore, this research will test an alternative policy of going directly towards NZEB, starting from existing offices with a current energy label G. The research question is as follows: What are the technical, financial, environmental and social implications of the proposed policy requirement of NZEB adaptation of office buildings with a current energy label G?
To answer the main research question, the following four themes are explored: office stock, energy policies, building adaptation and office owners. To explore the four themes, different methods and techniques are used. The different methods and techniques are framed within an experimental research design.
The results suggest that technically, the adaptation from label G to NZEB is possible. Financially, the adaptation results in the need for big investment ranging from €353/m2 to €414/m2 and payback period of more than 20 years. Environmentally, the NZEB adaptation results in 3.1 PJ energy savings and 0.6 - 0.7 CO2 emission reductions. Socially, the adaptation results in nuisance for the office owners, since they have to demolish, sell or leave their building vacant.
It can be concluded that the proposed adaptation policy will not lead to the desired effect of nearly zero-energy office buildings because the office owners do not choose to adapt their building but prefer to leave the building vacant or even demolish it. The direct NZEB adaptation requires temporary accommodation and major investments. A large part of the offices will become vacant or demolished, since the adaptation costs are too high compared to the rent values. However, for offices located on locations with high rent levels, the direct NZEB adaptation is more likely to be feasible. Especially, when technical opportunities arise, such as a nearby data center, which can be used for heat waste. Nevertheless, these findings suggest that lots of office owners will not be able to adapt their offices directly towards NZEB. Therefore, it is not possible to generalize such a regulative policy for all offices. However, some recommendations for policy makers are made. First of all, involve stakeholders when evaluating policies. Also, focus on the continuation of rent income during policy evaluations. Moreover, municipalities can already start creating visions for the future of office locations and to achieve NZEB office buildings it is recommended to make use of other policy tools at a differentiated approach.