New Zealand's traditional processes of construction, cemented the minimum standards and acceptable solutions of our building code, have resulted in the continued implementation of substandard envelope details that are thermally underperforming. Achieving high thermal performance in the exterior envelope is crucial for occupant health and reducing large heating requirements. Thermal performance is especially important for homes within Climate Zone 3, which has a higher requirement for thermal performance due to its colder climate. The construction industry has developed a range of proven methods to increase thermal performance, although these strategies are often not implemented in practice due to a variety of factors – including budget, availability of materials or products, and design constraints imposed by a project brief. In response to these issues, this thesis will ask: How can architects design ‘beyond the minimum’ and increase the performance of New Zealand homes by critically reconsidering New Zealand’s traditional detailing? Windows are the weakest link in the thermal envelope, and the structural requirements of their openings significantly reduce the thermal performance of their surrounding wall systems. Fenestrations are also crucial in defining New Zealand’s architectural language, due to the importance placed on our architecture’s relationship with the natural landscape. For these reasons, the window can be seen as a fundamental intersection between beauty and performance in architecture, and is therefore used as the central vehicle to investigate the research question. The thesis begins by comparing a selection of recent NZIA award-winning homes in the Canterbury region. Selected details from these projects will be analysed through THERM simulations, that will allow for visualisation of heat loss through thermal bridging, as well as simulation of achieved R-Values. Three full scale architectural projects will then be undertaken. Each will build off the tectonic and formal language of the award winning designs, to create beautiful architectural details with increased thermal performance. These designs will explore the thermal performance challenges present in three distinct building typologies in the Canterbury region. An agile design workflow which utilises thermal simulation of design details in the conceptual and developed design phases will be tested, where real-time feedback on thermal performance is used to inform architectural design decisions. Findings aim to assist architects in making design decisions around the detailing of the thermal envelope, and highlight specific areas where beauty and performance considerations could be resolved more effectively. The design outcomes will reinforce the ability of architects to reconcile architectural form and performance in contemporary practice, and demonstrate opportunities to create higher quality buildings that respond to, and reflect, New Zealand’s unique context.