Sustainability share on edges differs slightly from share on nodes

[mabijkerk]

When querying the final energetic demand of steam hot water and useable heat on de final demand edge group, this the result for a blank nl2019 scenario:

SUM(
      V(
        FILTER(
          FILTER(
              EG(final_demand),
            energetic?
          ),
          "steam_hot_water? || useable_heat?"
        ),
        "value"
      )
    ) / BILLIONS

186.62196078108914

When querying the same but then using the supply of steam hot water on the final demand node group, this is the result:

SUM(
  V(
    INTERSECTION(
      G(final_demand_group),
      USE(energetic)
    ), 
    "supply_of_steam_hot_water")
) / BILLIONS

186.62196078108914

They produce the same results. However, when I add the fossil share (1 - sustainability share) I get this:

SUM(
      V(
        FILTER(
          FILTER(
              EG(final_demand),
            energetic?
          ),
          "steam_hot_water? || useable_heat?"
        ),
        "(1.0 - sustainability_share) * value"
      )
    ) / BILLIONS

163.94219983930302

And this:

SUM(
  V(
    INTERSECTION(
      G(final_demand_group),
      USE(energetic)
    ), 
    "(1.0 - sustainability_share) * supply_of_steam_hot_water")
) / BILLIONS

163.8581434181152

Once the sustainability share is included, there is a slight difference in what counts as 'fossil' or 'sustainable' heat. I would expect both queries to produce the same results, or at least would like to be able to explain why they don't. This issue is opened mainly as documentation of this issue: because the difference is marginal and the total heat queries do align it is not urgent.

Notifying @marliekeverweij