This is a very good question and I’ll try to shed some light on the subject.
The temperature rating method doesn’t care if a target has been approved by the SBTi or not. It currently treats all targets equally. Even if there indications that this is the case, we currently don’t have enough data to suggest that SBTi approved targets are better at achieving real world emissions reductions. Hence, we can’t make any special allowance for SBTi approved targets.
Also, the temperature rating is a quantitative measure, whilst an SBTi approved target is a more in-depth qualitative and quantitative assessment of a company’s emissions reduction target, as is described in this FAQ “What is the difference between a temperature rating and a science-based target (SBT)?”
The SBTi Finance Tool identifies SBTi approved targets, as it is not only calculating temperature scores, but also portfolio coverage. In the portfolio coverage methodology (see Guidance p 81), only SBTi approved targets are considered. Therefore, the tool needs to know which target have been approved by SBTi.