Hace una hora que estamos registrando la sala.

In this pattern, hace una hora que means for an hour now or it’s been an hour since the action started.

So:

Hace una hora que estamos registrando la sala
= We’ve been searching/inspecting the room for an hour

A very useful pattern is:

Hace + time period + que + present tense

It describes something that started in the past and is still happening now.

Because Spanish uses hace literally as it makes / it has been in this kind of time expression.

So Hace una hora que... is like saying:

It has been an hour that...

Even though the action began in the past, the sentence is measuring the time up to the present moment, so hace stays in the present.

Compare:

• Hace una hora = an hour ago
• Hace una hora que estamos registrando la sala = we’ve been searching the room for an hour

The presence of que plus a present-tense verb changes the meaning.

Here, que links the time expression to the clause that follows.

It is part of the structure:

Hace + time + que + verb

You usually should learn this as a fixed pattern, rather than translating que word by word.

So:

• Hace una hora = an hour ago
• Hace una hora que + verb = have/has been ... for an hour

Without que, the sentence would not have this same for an hour now meaning.

Estamos registrando is the present progressive: we are searching / we are in the middle of searching.

It emphasizes that the action is currently ongoing.

• Estamos registrando la sala = We are searching the room
• Registramos la sala usually means we search the room or we searched the room, depending on context, but it does not highlight the ongoing process in the same way.

In this sentence, the speaker wants to stress that the action has been continuing for the last hour, so estamos registrando fits very naturally.

Not if you want the same meaning.

Hace una hora que registramos la sala would sound wrong or at least very unnatural for we have been searching the room for an hour.

If the action is still in progress, Spanish normally uses:

• Hace una hora que estamos registrando la sala
• Llevamos una hora registrando la sala

If you want to say the action happened and finished an hour ago, you would say something like:

• Registramos la sala hace una hora = We searched the room an hour ago

So the difference is:

• ongoing action → Hace una hora que estamos registrando...
• finished action in the past → ...hace una hora

Usually, no.

This is a classic false friend.
In many contexts, registrar means things like:

• to search
• to inspect
• to examine
• to check thoroughly

So registrando la sala often means something like searching the room or inspecting the room.

Spanish registrar can sometimes relate to recording or registering in certain contexts, but with la sala, the most natural meaning is usually searching/inspecting the room.

Because Spanish uses the definite article much more often than English.

So where English might say:

• searching the room

Spanish naturally says:

• registrando la sala

Dropping the article here would usually sound incomplete or unnatural. In Spanish, talking about a specific room normally requires la.

Yes. A very similar sentence would be:

Estamos registrando la sala desde hace una hora.

This also means:

We have been searching the room for an hour.

So these are both natural:

• Hace una hora que estamos registrando la sala
• Estamos registrando la sala desde hace una hora

They are very close in meaning. The first starts with the time expression; the second starts with the action.

Yes, absolutely. This is one of the most common alternatives.

Llevamos una hora registrando la sala
= We’ve been searching the room for an hour

This structure is extremely common in Spanish:

Llevar + time + gerund

Examples:

• Llevo dos días estudiando = I’ve been studying for two days
• Llevan meses trabajando aquí = They’ve been working here for months

Many learners find this easier to use than the hace... que... structure.

Because Spanish and English organize time differently.

English often says:

We have been searching the room for an hour.

Spanish usually expresses that idea with:

• present tense in a time structure: Hace una hora que...
• present progressive if the action is visibly ongoing: estamos registrando
• or llevar + time + gerund

Spanish does have compound tenses like hemos estado registrando, but they are not the normal choice here. In everyday Spanish, especially in Spain, the simpler structures above are more natural.

Yes, the structure itself is completely normal in Spain.

Also, sala is a standard Peninsular Spanish word for room/hall/lounge, depending on context, and registrar meaning to search or inspect is also very natural in Spain, especially in police, security, or formal contexts.

A more conversational everyday sentence in some situations might use another verb depending on the exact meaning, but grammatically this sentence is perfectly standard for Spain.