Learn Swedish: Så länge som du inte rör termostaten är det varmt på övervåningen. - As long as you do not touch the thermostat, it is warm on the upper floor.

In Swedish, så länge can mean 'for now' or 'as long as'. When it acts as a subordinating conjunction meaning 'as long as' (or 'provided that'), you can add som. It is completely optional, so Så länge du inte rör... is also perfectly correct and very common in everyday speech.

Why does inte come before the verb rör in the first part of the sentence?

Because Så länge som du inte rör termostaten is a subordinate clause. In Swedish subordinate clauses, sentence adverbs like inte must come before the conjugated verb. This is often called the BIFF rule (Bisatser, Inte Före Finita verbet).

Why does the second half of the sentence start with är det instead of det är?

Swedish uses the V2 rule, meaning the verb is always the second block of information in a main clause. The entire subordinate clause (Så länge som du inte rör termostaten) counts as the first block. Therefore, the main clause must start immediately with the verb är to keep it in the second position.

Why do we use the preposition på instead of i for the upper floor (övervåningen)?