Sweden passed legislation to achieve a target of net zero greenhouse gas emissions by the end of 2045. The Energy Performance of Building Directive further obliged European countries to ensure zero-energy building codes and improve the quality of indoor environments when buildings are renovated, as approximately 40% of total greenhouse gas emissions in Sweden are produced while heating buildings. Windows currently play a significant role in improving the quality of indoor environments and cutting total energy consumption, thereby reducing greenhouse gas emissions and mitigating environmental impact. Selecting a suitable window design is a complicated task compounded by two main difficulties: i) the availability of multiple window designs, each with a different glazing system, size, form and position; and ii) conflict between visual comfort, thermal comfort and energy consumption. Previous studies have primarily analysed a limited selection of window designs; however, analysing a wide variety of glazing systems, sizes, forms and positions will help resolve the abovementioned difficulties, thereby ensuring zero-energy building codes while improving the quality of an indoor environment. A multi-objective optimization was therefore completed to analyse the performance of a wide variety of window design variables and select suitable designs for an office room in Sweden. The results show the potential of multi-objective optimisation to resolve the difficulties of selecting suitable window designs.