Barcelona as a city has an enormous potential for Optoppen. Much of the city is laid out like the Eixample district, with a strict grid pattern of equally sized blocks of 113.3 metres on each side, with varied building heights often between 4-8 storeys. Where buildings are lower than the datum height for each block, there is an opportunity to “top up” and add storeys.

A study was done on the Eixample district of Barcelona assessing the capacity for these blocks to accommodate vertical extensions (Artés et al., 2017). These findings have been extrapolated to the city’s other districts to calculate an approximate capacity for Optoppen in each location. The building opportunity tool was also used to assess opportunities to add more than one storey.

It is estimated, through this method, that over 195,000 dwelling units could be added to Barcelona’s rooftops.