Learn Hardcore Indonesian: Rumah terasa sejuk ketika tirai dibuka dan kipas menyala. - The house feels cool when the curtain is opened and the fan turns on.

Terasa means “to feel/be felt (by the senses)” with the thing being felt as the subject. Example: Rumah terasa sejuk = “The house feels cool.”
Merasa means “to feel” with a person as the subject. Example: Saya merasa sejuk = “I feel cool.”
Don’t say “Rumah merasa sejuk” (ungrammatical).

Why use sejuk instead of dingin or adem?

Sejuk = pleasantly cool, refreshing (neutral/positive).
Dingin = cold, possibly uncomfortably cold.
Adem = colloquial for “cool,” very common in speech (from Javanese). So this sentence highlights a comfortable coolness, not coldness.

Does rumah mean “the house” or “a house”? How do I make it definite?

Indonesian has no articles. Rumah can be “the house” or “a house,” depending on context. To mark it clearly definite, use:

Rumah itu = that/the house (specific).
Rumahnya = the house (contextually “its/their house,” or “the house” known in context).

Is this sentence in the past or present? How do tenses work here?

Indonesian doesn’t mark tense on verbs. The clause with ketika (“when”) sets a time frame, but it can describe past, present, or habitual situations depending on context. You can add time words if needed:

Past: Kemarin rumah terasa sejuk ketika…
Habitual: Biasanya rumah terasa sejuk ketika…
Future: Nanti rumah akan terasa sejuk ketika…

Why is tirai dibuka in the passive voice? Could I use the active?

Tirai dibuka (passive) focuses on the curtain and leaves the agent unspecified: “the curtain(s) is/are opened.”
Active alternative: ketika (kami/saya) membuka tirai = “when (we/I) open the curtains.” Use active if you want to mention the doer.

What’s the difference between dibuka and terbuka?

Dibuka = “is opened/gets opened” (an action by someone).
Terbuka = “is open” (state/result). In a time clause, both can work:
ketika tirai dibuka (when the curtains are being opened/got opened)
ketika tirai terbuka (when the curtains are open)

Do I need yang: “ketika tirai yang dibuka”?

No. Yang introduces a relative clause (the curtain that is opened). Your sentence is a normal verb clause: tirai dibuka. Use yang only if you mean “the curtain that is opened,” e.g., tirai yang dibuka membuat ruangan terang.

What does menyala mean, and how is it different from dinyalakan or menyalakan?

Menyala = “to be on/to be lit” (intransitive state). Kipas menyala = “the fan is on.”
Dinyalakan = “is turned on (by someone)” (passive).
Menyalakan (kipas) = “to turn on (the fan)” (active). Choose based on whether you want to emphasize the state or the action/agent.

Should it be kipas angin instead of just kipas?

Kipas can mean any fan (handheld or electric).
Kipas angin specifically means an electric fan. Because of menyala (“is on/lit”), it’s clear we mean an electric fan, so kipas is fine. For clarity, you can say kipas angin.

Does dan here mean “and” or “and then”? Are the two actions simultaneous?

Dan means simple “and.” Both things are understood to hold at the same time within the “when”-clause: “when the curtains are opened and the fan is on.” For sequence (“and then”), use lalu/kemudian.

Is a comma needed anywhere? What if I front the time clause?

Your word order is fine without a comma:

Rumah terasa sejuk ketika … If you front the time clause, use a comma:
Ketika tirai dibuka dan kipas menyala, rumah terasa sejuk.

Can I use karena (“because”) instead of ketika if I want to show cause, not just time?

Yes. For explicit causation:

Rumah terasa sejuk karena tirai dibuka dan kipas menyala. = “The house feels cool because the curtains are opened and the fan is on.”

What’s the difference among ketika, saat, waktu, and kalau?

Ketika = when (neutral/formal).
Saat = when/at the moment (very common, neutral).
Waktu = when (colloquial; also “time” as a noun).
Kalau = if/when(ever) (conditional/habitual, conversational). All can fit with nuance shifts:
Rumah terasa sejuk saat/ketika… (neutral)
Rumah terasa sejuk kalau… (if/whenever; more casual)

How do I negate this sentence correctly?

Use tidak before adjectives/verbs:

Rumah tidak terasa sejuk ketika… = “The house doesn’t feel cool when…”
Don’t use bukan here; bukan negates nouns/pronouns.

Is there any implied agent for dibuka? Can I add one?

Yes, dibuka implies “opened (by someone)” without naming them. You can add an agent, but it’s more natural to switch to active:

Less natural: ketika tirai dibuka oleh saya
More natural: ketika saya membuka tirai

Could I say Di rumah terasa sejuk or Rasanya sejuk di rumah?

Yes:

Di rumah terasa sejuk… = “It feels cool at home/inside the house…”
Rasanya sejuk di rumah… = “It feels cool in the house…” Both focus on the location/feeling rather than the house as the grammatical subject.

Is tirai singular or plural here? How do I mark plurality?

Indonesian doesn’t require plural marking. Tirai can mean “curtain(s).” If needed, you can clarify:

Beberapa tirai = some curtains
Reduplication (tirai-tirai) can mark plural but is often unnecessary or stylistically marked.

What about terbuka vs dibuka for nuance? Which is more natural here?

Use dibuka if you want to highlight the action of opening (someone opens them at that time).
Use terbuka if you just care that they are in the open state. Both are natural; pick the nuance you want.

Is there a more colloquial way to say the whole sentence?

Yes, for everyday speech:

Rumahnya adem kalau gordennya dibuka sama kipasnya nyala.
Notes: adem (colloquial “cool”), gorden (common word for curtains), -nya marks definite/possessive, sama (“and/with” in casual speech), nyala is often used without the prefix in casual speech, though menyala is standard.

Why does menyala have the prefix meN- and change to meny-?

The root is nyala (“flame/glow”). With the meN- prefix, assimilation produces menyala (meN- + ny- → meny-). It’s an intransitive verb meaning “to be on/to glow/to burn (light).”