The global energy demand is increasing as a result of population growth and increased wealth standards. The share of local renewable energy supply is also increasing, driven by the urge to mitigate climate problems. Residential energy demand and renewable energy supply are both intermittent; the demand profile depends on several aspects like the inhabitants, the physical properties of a building and the outdoor climate. Renewable energy supply is intermittent because it can only occur when the intermittent renewable energy source, e.g. the sun, is present. So, the intermittencies of supply and demand depend on different aspects, hence cause a mismatch. This mismatch must be solved. Energy-flat buildings are a potential solution to this problem. To diminish the problem of energy mismatch on a residential level, dwellings will have to be able to adapt the demand to supply and vice versa. The research presented in this thesis explores the potential of architectural design in eliminating the on-site energy mismatch. In other words, the potential of energy-flat buildings. First, three key-performance indicators for energy-flatness are defined and a dynamic energy simulation model is set-up using Grasshopper Honeybee software. With this tool, the energy-flat performance of several designs can be quantified and analysed. Then, the current mismatch of residential energy in a reference design is determined. Thereafter, the effect of building parameters on the energy-flat performance of a design is researched. The results of this parameter study are then used to design an energy-flat building. The knowledge gained by this design-by-research approach is bundled in a toolbox, which serves as a guide for architectural designers. It is found that the heat balance should be considered first when aiming for energy-flatness, rather than the electricity balance. The nine building parameters researched, all significantly influence the energy-flatness by affecting different elements of the heat balance. An adaptive approach in terms of daily and seasonal differences is required for almost all parameters to achieve the best energy-flat performance. The largest challenges for energy-flatness are the lack of supply potential at night, lower solar power in winter combined with lower outdoor temperatures and the unpredictability of both energy demand and energy supply in short time intervals. The toolbox that is created provides effective energy-flat design principles. Moreover, it is concluded that architectural design can significantly contribute, but not completely solve the mismatch of residential energy demand and supply. The performance of building installations is essential for achieving energy-flatness, but it is only partly researched in this thesis because these building installations lie beyond its scope. Lastly, it is concluded that energy-flat buildings theoretically can be the solution to the (inter)national energy balancing challenge, but it is preferable to distribute the challenge over multiple levels of the system. The relevance of energy-flatness will change in the future, depending on the development of energy storage technologies and the share of renewable energy production. Altogether, the architecture of a building can significantly influence its energy-flatness and the concept of energy-flatness will contribute to effective use of local renewable energy.