The Torre Windsor was designed in the 1970s at a time when fire engineering was not so well advanced and sprinklers were not compulsory in office buildings.
Spanish re codes were redrafted in 1996 and demand that sprinklers be installed in all new office buildings.
But in 2003 the city of Madrid deemed that sprinklers were unnecessary in a building under 100m.
The Windsor building is 97m tall.
It is understood that city politicians are now trying to bring Madrid in line with the national regulations.
Extensive furbishment work was under way at the time of the fire and it is understood that some of this was intended to bring the building's fire standards up to date.
An additional emergency staircase was added to the south side of the building, alongside replacement of the façade and the addition of two more storeys.
There are unconfirmed media reports that sprinkler systems were being fitted as part of the refurbishment.