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Croatian grammar

"Ne smeta im što je unutra ledeno JER dok ugriješ jednu takvu kuću, potrošio si više energije nego na tri nebodera." - this would be a more correct way to say the whole sentence.

This is quite a complicated matter in Croatian language to explain but I will try to make it as short and concise as possible.

Like Peachey said, the situation here is hypothetical/theoretical.
Usually when you have a situation where an event doesn't necessarily have to happen (it's theoretical) you use present in both parts of the sentence. So you could also say (and you can hear that in common language conversations): "... dok ugriješ jednu takvu kuću, potrošiš više energije nego na tri nebodera."

But because the verb POTROŠITI (to have spent) is a verb that unlike TROŠITI (to spend) describes a finished or completed action, you can use past tense as well. Both sentences are used and are correct.
In fact this only works with such verbs to begin with. For example you cannot say: "...dok ugriješ jednu takvu kuću, trošiš više energije nego na 3 nebodera."

SOME OTHER EXAMPLES:

Dok položiš jedan ispit na tom fakultetu, prođe cijela godina.
Dok položiš jedan ispit na tom fakultetu, prošla je cijela godina.
("By the time one passes a single exam in that college, a whole year has passed." The subtle meaning expressed in this sentence is that passing an exam is quite hard and takes a lot of effort.)

Dok se oni sjete, ja optrčim Zemlju 2 puta.
Dok se oni sjete, ja sam optrčao Zemlju 2 puta.
(By the time they get themselves together/organize themselves, I circle(d) the Earth 2 times/twice.)

In the last example you can see that this form is also used to express an exaggerated hypothetical (but improbable situation) to convey a point: "they're simply taking too long to get themselves ready/organized and I could have finished doing all kinds of things - circle the Earth - in the meantime).

I hope this was helpful. :-D