Learn Hardcore Italian: Un computer a basso consumo è utile in ufficio. - A low-consumption computer is useful in the office.

It literally means low-consumption (i.e. energy-saving). In English you’d typically say low-power or energy-efficient when referring to electronic devices.

Why is a basso consumo placed after computer instead of before, like in English?

In Italian multi-word adjectival phrases normally follow the noun they modify. So you say computer a basso consumo, not basso-consumo computer.

Why is computer treated as masculine and why do we use un computer?

Although borrowed from English, computer is a masculine noun in Italian. Therefore the singular indefinite article is un (masculine), giving un computer.

Why is it in ufficio and not al ufficio or nell'ufficio?

With certain common places (like ufficio, scuola, banca), Italian drops the article after in or a for the generic sense: in ufficio, a scuola, in banca. Using al ufficio isn’t idiomatic here; nell'ufficio would imply a specific office (e.g. nell'ufficio di Carla).

Could I say computer di basso consumo instead of computer a basso consumo?

You could say computer di basso consumo energetico, but the most idiomatic pattern for devices is a + adjective + noun (e.g. lampadina a basso consumo, auto a basso impatto). Hence computer a basso consumo is preferred.

What is the function of utile here, and does it require another preposition?

utile is a predicate adjective meaning useful and links directly with the verb essere: è utile. To specify location you simply add in: utile in ufficio. No extra preposition is needed after utile in this context.

Can I say un computer è utile per l'ufficio instead of utile in ufficio, and is there a difference?

Yes, utile per l'ufficio is also correct. The nuance is subtle: utile in ufficio highlights usefulness within an office environment, while utile per l'ufficio focuses on usefulness from or for the office’s needs.