Assumption of usable floor area or floorspace

We need to define how we deal with floor space and/or usable floor area. We use this value for a couple of reasons:

  1. Buildings are of an average floor space size, we define the amount of buildings in a certain area based on that.
  2. We define the population based on the average dwelling size / dwellings per building / total floor space per building. See for an example, our input files here: dwellings per building in Albania; area per dwelling in Albania.
  3. We define average cost per area for buildings. See for example Commercial values with AREA_PER_BUILDING_SQM / COST_PER_AREA_EUR and Residential values with COST_PER_AREA_EUR

Now, what do they / we define as floor area? If we want to calculate structural costs, it makes sense to take the 100% of the floorspace. If we want to calculate costs of contents, do we use usable floor area? I think the same is true for number of dwellings inside a building.

I asked Marusa (architect) and it seems that 65% of the floor space in commercial buildings is used as a rule of thumb for usable floor area, in the best cases. They don't work with residential buildings, so she didn't really know there, but said it probably is higher. She also said that this can be found in the BKI this is for German buildings but we don't really know where to look. @ds maybe you want to give that a try, as it's a German company?

There is also this (German) master thesis from the TU Wien: https://repositum.tuwien.at/handle/20.500.12708/15291

Update for HeightAndFloorspaceRule v25.01 refactoring

We had a discussion about the different floorspace definitions in collaboration#623, we agreed on using the terms and the factors of calculation: total floor area which equals to covered area x number of stories; gross floor area(total floor area_ x 0.95), and net floor area(total floor area x 0.7). Also, we will only store the latter two in our database.

Now, for the HeightAndFloorspaceRule refactoring, we could consider to apply these definitions in the new changes. Questions that related to how the !26 (closed) goes are:

  1. We replace the current naming of the rule, as well as the floorspace in the rule and attributes dict?
  2. Have two areas stored? We only have floorspace as output now.
  3. We implement the factors for area calculation.

\rfc @ds @pdlmora @laurens @pomodoro

Edited by Chengzhi Rao