Zużycie energii w okresie rozliczeniowym jest wysokie.

Because zużycie usually takes the thing being consumed in the genitive case.

So:

• energia = energy
• energii = of energy

In this sentence, zużycie energii literally means consumption of energy.

This is very common in Polish with nouns like:

• zużycie wody = water consumption
• produkcja prądu = electricity production
• brak czasu = lack of time

So energii is not the subject here; it is the noun connected to zużycie.

It is in the locative case because of the preposition w when it means in.

Breakdown:

• okres = period
• w okresie = in the period
• rozliczeniowym = billing / settlement-related, matching the case, number, and gender of okresie

So:

• okres rozliczeniowy = billing period
• w okresie rozliczeniowym = in the billing period

After w meaning location or time, Polish usually uses the locative:

• w domu = in the house
• w szkole = at school
• w maju = in May
• w okresie rozliczeniowym = in the billing period

Because zużycie is a neuter singular noun, and the adjective must agree with it.

Here are the forms of wysoki in singular:

• wysoki = masculine
• wysoka = feminine
• wysokie = neuter

Since zużycie is neuter, the sentence uses:

• Zużycie ... jest wysokie.

This is just standard adjective agreement in Polish.

Yes, zużycie is a noun. It means consumption, usage, or sometimes amount used, depending on context.

It comes from the verb family:

• zużyć = to use up
• zużywać = to consume / use up repeatedly or over time
• zużycie = consumption / usage

In practical contexts like electricity, gas, or water bills, zużycie is very commonly used for consumption:

• zużycie energii = energy consumption
• zużycie gazu = gas consumption
• zużycie wody = water consumption

In this sentence, wysokie is best understood as high.

Polish often uses wysoki / wysoka / wysokie for things that are not physically tall but are at a high level, such as:

• wysokie ceny = high prices
• wysokie koszty = high costs
• wysokie zużycie energii = high energy consumption

So this is a normal and natural collocation.

Yes. Polish word order is more flexible than English because grammatical endings show the roles of the words.

The neutral version is:

• Zużycie energii w okresie rozliczeniowym jest wysokie.

But you could also say:

• W okresie rozliczeniowym zużycie energii jest wysokie.

This puts more emphasis on during the billing period.

In English, word order is more fixed. In Polish, changing the order often changes focus or emphasis, not the basic meaning.

Because Polish does not have articles like a or the.

So Polish simply says:

• zużycie energii

and depending on context, English may translate that as:

• energy consumption
• the energy consumption
• consumption of energy

The exact English article is supplied by context, not by a separate Polish word.

It means something like billing period, settlement period, or accounting period, depending on context.

In utility bills, okres rozliczeniowy usually means the span of time for which usage is calculated and billed.

So in an electricity or gas context, billing period is usually the most natural English equivalent.

Word by word:

• okres = period
• rozliczeniowy = related to settling accounts, billing, or calculation

In the present tense, Polish usually keeps jest in this kind of sentence.

So:

• Zużycie energii ... jest wysokie. = Energy consumption ... is high.

You normally would not omit jest here in standard Polish.

Polish sometimes drops forms of to be in informal styles or special constructions, but with a sentence like this, jest is the normal and correct form.

Yes. The subject is zużycie energii.

More precisely:

• the main noun of the subject is zużycie
• energii depends on it and means of energy

Then the rest of the sentence says something about that subject:

• jest wysokie = is high

So the structure is basically:

• [Zużycie energii w okresie rozliczeniowym] = subject phrase
• [jest wysokie] = predicate

Yes, but that would not be a complete sentence by itself unless it is being used as a heading or label.

Compare:

• Zużycie energii w okresie rozliczeniowym jest wysokie.
  = The energy consumption in the billing period is high.

• Wysokie zużycie energii w okresie rozliczeniowym
  = High energy consumption in the billing period

The second version is just a noun phrase, not a full statement. You might see it as a title in a report, warning, or chart.

A very useful clue is the ending -e.

Many Polish neuter nouns end in:

• -o
• -e
• -ę
• -um (often borrowed words)

So zużycie is neuter, and that is why the adjective is also neuter:

• zużycie ... wysokie

This is something worth memorizing together:

• to zużycie
• to zużycie jest wysokie

Using to with a noun while learning is a good trick for remembering gender.

Yes, it sounds fairly formal and very natural in technical, administrative, or utility-bill contexts.

You might see it in:

• bills
• energy reports
• customer service messages
• meter summaries

In casual speech, someone might say something simpler depending on context, but this sentence is perfectly normal and idiomatic in written Polish.

You negate jest with nie:

• Zużycie energii w okresie rozliczeniowym nie jest wysokie.

This means:

• The energy consumption in the billing period is not high.

In Polish, nie usually goes directly before the verb:

• jest → nie jest