Learn Hardcore Croatian: Prije spavanja ugasimo svjetlo i klima-uređaj da štedimo struju. - Before going to sleep we turn off the light and the air conditioner to save electricity.

The verb is spavati (“to sleep”).
Its verbal noun (a noun made from the verb) is spavanje (“sleeping” as a thing).
The genitive singular of spavanje is spavanja.

So:

prije spavanja = “before sleeping”
Structures like *prije spavanje (nominative) or *prije spavati (infinitive) are ungrammatical.

If you want to use a full clause with a verb instead of a noun, you say:

Prije nego što spavamo – “Before we sleep”
Prije nego što odemo spavati – “Before we go to sleep”

What exactly is spavanja – a verb or a noun, and how does it decline?

Spavanja is a noun form, not a verb form.

Base verb: spavati (“to sleep”)
Verbal noun (like English “sleeping” as a thing): spavanje (neuter noun)
In the sentence, spavanja is genitive singular of spavanje.

Singular forms of spavanje are:

Nominative: spavanje (sleeping – as a noun)
Genitive: spavanja (of sleeping / before sleeping)
Dative: spavanju
Accusative: spavanje
Locative: spavanju
Instrumental: spavanjem

You see spavanja after prije because prije always takes the genitive.

What is the grammatical form and aspect of ugasimo, and why use that form here?

Ugasimo is:

Person/number: 1st person plural (“we”)
Tense: present tense
Verb: ugasiti (perfective) – “to turn off, to switch off completely”
Aspect: perfective

So ugasimo literally means “we (will) turn off (completely)”.

In Croatian, the present tense of a perfective verb often refers to a single, completed event, and in patterns like this it’s often used for repeated, regular actions:

Svaki dan odem na posao. – Every day I go (and arrive) at work.
Prije spavanja ugasimo svjetlo. – Before sleeping, we (each time) turn off the light.

Using the perfective ugasiti highlights the result (“it ends up off” each time), which is natural when talking about one complete action done each night.

Could I also say Prije spavanja gasimo svjetlo? What’s the difference between ugasimo and gasimo?

Yes, Prije spavanja gasimo svjetlo is grammatically correct and understandable.

The difference is aspect:

ugasiti – ugasimo = perfective
Focus on the completed action (“we switch it off, and it’s off”).
gasiti – gasimo = imperfective
Focus on the process or repeated activity (“we are in the process of turning it off / we turn it off in general”).

In this kind of routine-sentence, both are possible, but:

Prije spavanja ugasimo svjetlo – common and very natural; each time we perform that single action.
Prije spavanja gasimo svjetlo – also okay, a bit more neutral/process-like.

For everyday speech, you’ll hear ugasimo svjetlo / ugasi svjetlo a lot when giving instructions or describing habits.

Where is the word we in this sentence? Why don’t we say Mi ugasimo…?

Croatian is a “pro-drop” language, meaning that subject pronouns are usually omitted because the verb ending already shows person and number.

ugasimo has the -mo ending → this automatically tells you the subject is “we”.

You only add mi when you want to emphasize or contrast:

Ugasimo svjetlo. – We turn off the light. (neutral)
Mi ugasimo svjetlo, a oni ga ostave upaljeno. – We turn off the light, but they leave it on. (contrast)

Why is it svjetlo and not svjetla?

Svjetlo is a neuter noun meaning “light” (as in a lamp/light in a room).

Its basic forms:

Nominative singular: svjetlo
Accusative singular: svjetlo (neuter accusative = nominative)
Nominative/accusative plural: svjetla

In this sentence, svjetlo is the direct object of ugasimo, so it’s in the accusative singular, which for neuter is the same as the nominative: svjetlo.

Croatian typically talks about “turning off the light” in the singular, even if several bulbs go off:

Ugasiti svjetlo – to turn off the light
Upaliti svjetlo – to turn on the light

So svjetlo here is the normal, idiomatic choice.

What case are svjetlo, klima-uređaj, and struju in, and why?

All three are direct objects of verbs, so they are in the accusative case:

ugasimo svjetlo
- Verb: ugasiti (“to turn off”)
- Direct object: svjetlo (neuter, inanimate)
- Neuter inanimate → accusative singular = nominative singular → svjetlo.
(ugasimo) klima-uređaj
- Noun: klima-uređaj (masculine, inanimate)
- For inanimate masculine nouns, accusative singular = nominative singular → klima-uređaj.
štedimo struju
- Verb: štedjeti (“to save”)
- Direct object: struju, from struja (feminine)
- Feminine accusative singular typically ends in -u → struju.

So all three are in the accusative, but their forms look different because they belong to different genders and declension types.

Why is klima-uređaj written with a hyphen? Can I say klima uređaj or just klima?

Standard written Croatian prefers klima-uređaj as a compound noun:

klima (short for klimatizacijski) + uređaj (“device”) → klima-uređaj.

About the variants:

klima-uređaj – standard, recommended in more formal or careful writing (school essays, official texts).
klima uređaj – often seen and understood, but less neat from a prescriptive point of view.
klima – very common in informal speech, used alone and declined as a feminine noun:
- upaliti/ugasiti klimu
- Klima ne radi.

In the sentence you gave, klima-uređaj is a safe, standard choice.

What does da do in da štedimo struju? Is it the same as English “that”?

Here da introduces a purpose clause: it tells you why you turn things off.

da štedimo struju ≈ “so that we save electricity / in order to save electricity”.

Key points:

da + present tense often works like a kind of subjunctive:
- Učim da položim ispit. – I’m studying so that I (can) pass the exam.
You cannot just drop da and say *ugasimo… štedimo struju – that’s ungrammatical.

In other contexts, da can correspond to English “that”:

Želim da dođeš. – I want you to come. (literally “I want that you come.”)

A slightly more formal alternative in your sentence would be:

…kako bismo štedjeli struju. – “…so that we would save electricity.”

Why is štedimo in the present tense, not the future (ćemo štedjeti)?

Štedimo is present tense, 1st person plural of štedjeti (“to save”).

Croatian, like English, uses the simple present to talk about habits and routines:

Svaki dan pijem kavu. – I drink coffee every day.
Prije spavanja ugasimo svjetlo… – Before sleeping we turn off the light…

The phrase Prije spavanja signals that this is a regular action each time you go to sleep, so present tense is perfect.

If you said da ćemo štedjeti struju, it would sound more like a specific future plan (“so that we will save electricity (on that occasion)”).

Why is it štedimo struju, not štedimo struje or some other form?

Štedjeti (“to save”) normally takes a direct object in the accusative: you save something.

štedjeti novac – to save money
štedjeti vrijeme – to save time
štedjeti struju – to save electricity

Here:

Nominative: struja (electricity)
Accusative singular: struju

We use the singular because struja is a mass noun, like English “electricity”. You’re not saving “units” or “types” of electricity.

Štedimo struje (genitive plural) would usually mean something like “we are saving different kinds / quantities of electrical currents”, which is not what you want here.

You may also hear:

Štedimo na struji. – We save on electricity. (locative with na – focus on costs)

Can I change the word order, for example to Prije spavanja ugasimo klima-uređaj i svjetlo da štedimo struju?

Yes. Croatian word order is fairly flexible, especially with coordinated objects.

All of these are natural:

Prije spavanja ugasimo svjetlo i klima-uređaj da štedimo struju. (original)
Prije spavanja ugasimo klima-uređaj i svjetlo da štedimo struju.
Ugasimo svjetlo i klima-uređaj prije spavanja da štedimo struju.

What usually feels less natural is splitting the prepositional phrase awkwardly into the middle:

?*Ugasimo prije spavanja svjetlo i klima-uređaj… – understandable, but stylistically a bit clunky; speakers prefer Prije spavanja ugasimo… or Ugasimo … prije spavanja.

For a learner, it’s safest to keep Prije spavanja either at the very beginning or just before the verb phrase.

How else could I express the same idea in Croatian?

Some common, natural variants:

Using a full clause with prije nego što:
- Prije nego što odemo spavati, ugasimo svjetlo i klima-uređaj da štedimo struju.
  – “Before we go to sleep, we turn off the light and the air conditioner to save electricity.”
Using the imperfective gasiti and a slightly more formal purpose clause:
- Prije spavanja gasimo svjetlo i klimu kako bismo štedjeli struju.
More casual, with klima instead of klima-uređaj:
- Prije spavanja ugasimo svjetlo i klimu da štedimo struju.

All of these are correct; the differences are mostly in formality and style, not in basic meaning.