This research is conducted in the context of current efforts for net zero delivery in Scotland. Such a target is widely acknowledged as challenging by the industry necessitating some aspects of building design to change for higher performance. This study looks at ‘what is optimal’ in terms of carbon, both in operation and embodied in materials for dwellings by using the Pareto Optimal solution in a simulated case study in Edinburgh. At first, the potential of available glazing systems to find an optimum in operational and embodied carbon is investigated. The study then calculated the embodied carbon and operational carbon for added insulation and compared them against each other to find the most energy and environmentally-efficient option. An analysis to investigate the LCA of the 52 HVAC systems for the second phase of the building's life span is then conducted and finally a parametric analysis of using shading devices to observe if they can offer operational savings for the case study concludes the paper. This study demonstrates some recommended design solutions by globally used standards e.g. Passivhaus and common practices may not lead to carbon emissions minimisation in the refurbishment process.