In light of the climate crisis and conflicting political ambitions in many countries to rapidly increase the number of dwellings, what housing strategies could reduce emissions? Co-living is one strategy sometimes highlighted but rarely implemented in mainstream construction practices. Using two Swedish case studies, the potential embodied carbon savings are explored for co-living designs. When comparing building designs, normalisation of impacts or energy use per floor area is unequivocally the norm. The present comparison between co-living and traditional apartment design indicates an embodied carbon savings at the building level of 10–20% depending on whether embodied carbon is normalised per gross or residential floor area. However, normalisation per capita (inhabitant) shows substantially higher savings of 21–36% depending on the case studied. The effect of different metrics is illustrated to quantify potential embodied carbon savings of non-mainstream building design solutions such as co-living. Even more substantial embodied carbon savings can be achieved by avoiding new construction through the ability of enabling a more efficient use of indoor space. The need for rethinking carbon and space metrics will help the building sector meet emission targets. PRACTICE RELEVANCE Evidence is provided to show that design for co-living could be one way to offer a climate-efficient and qualitative housing alternative for single households in many countries. However, to visualise such potentials, developers are recommended to use additional metrics when evaluating how resource or climate-efficient are alternative designs. Traditional metrics such as kWh or kg CO2 e/m2 of gross or heated floor area ought to be complemented by displaying resource use or embodied carbon per designed number of building user and per accessible floor area for each user. Up-to-date generic values are provided for the embodied carbon of different types of space. These can be used in early planning to display the consequences of the number of kitchens and bathrooms and their space occupation in client decisions and early architectural design.