Der heruntergelassene Rollladen hält die Hitze draußen, aber die Türklinke an der Balkontür bleibt noch warm von der Sonne.

heruntergelassene is the adjective form of the verb herunterlassen, which means to lower / let down.

• herunterlassen → heruntergelassen = lowered
• In this sentence, it describes Rollladen:
  • der heruntergelassene Rollladen = the lowered roller shutter

So this is basically a past participle used like an adjective, very common in German.

Because the participle is being used as an adjective, it has to take an adjective ending.

Here:

• der = masculine nominative singular definite article
• Rollladen is masculine
• after der, an attributive adjective usually takes -e in nominative singular masculine

So:

• der Rollladen
• der heruntergelassene Rollladen

This is the same pattern as:

• der warme Tee
• der geschlossene Laden

A Rollladen is a roller shutter or rolling blind on the outside of a window or door. It is usually more solid than a curtain or blind and can help block:

• sunlight
• heat
• noise
• sometimes even improve security

It is not quite the same as:

• Vorhang = curtain
• Jalousie = blind
• Rollo = roller blind

So in this sentence, Rollladen suggests something substantial enough to keep the heat out.

This means keeps the heat outside / keeps the heat out.

The structure is:

• halten = to hold / keep
• etwas draußen halten = to keep something outside / out

So:

• Der Rollladen hält die Hitze draußen = The shutter keeps the heat out

Here:

• die Hitze is the thing being kept out, so it is in the accusative
• draußen tells you where it stays: outside

This is a very natural German pattern:

• den Lärm draußen halten = keep the noise out
• die Kälte draußen halten = keep the cold out

Because die Hitze is the direct object of hält.

Ask: What does the shutter keep out?
Answer: die Hitze

That makes it accusative.

Also, Hitze is a feminine noun:

• nominative: die Hitze
• accusative: die Hitze

So the form looks the same in both cases, but its role here is accusative.

draußen means outside.

In this sentence:

• die Hitze draußen halten = to keep the heat outside / out

draußen is the idiomatic word here.
außen usually means more like on the outside / outer and is less natural in this kind of sentence.

Compare:

• Die Schuhe bleiben draußen. = The shoes stay outside.
• Die Hitze draußen halten. = Keep the heat out.

So draußen is the normal adverb for physical outside space.

Türklinke means door handle, especially the kind you press down.

It is a compound noun:

• Tür = door
• Klinke = handle / latch handle

German uses compound nouns constantly, so it is normal to combine words like this into one noun.

A related word is:

• Türgriff = door handle/grip

In many contexts, Türklinke sounds very natural for the handle you press with your hand.

an der Balkontür means on the balcony door.

This uses:

• an = on / at
• der Balkontür = dative singular feminine

Why dative? Because this is a location, not movement.

Compare:

• an der Balkontür = on/at the balcony door → location
• an die Balkontür = to the balcony door → movement toward it

So here:

• die Türklinke an der Balkontür = the door handle on the balcony door

Because after an in a location meaning, German uses the dative.

The base noun is:

• die Balkontür = the balcony door

But after an with location:

• an der Balkontür

So:

• nominative: die Balkontür
• dative: der Balkontür

This is a very common pattern with two-way prepositions like an, auf, in, unter, etc.

Balkontür is a compound noun made from:

• Balkon = balcony
• Tür = door

So it literally means balcony door.

In German compounds, the last part determines the basic meaning and gender:

• die Tür is feminine
• so die Balkontür is also feminine

This is a key rule for German compounds:

• Haustür = house door / front door
• Autotür = car door
• Küchentür = kitchen door

bleibt warm means remains warm / stays warm, while ist warm just means is warm.

So:

• ist warm = it is warm
• bleibt noch warm = it is still warm / it remains warm

Here, bleibt noch warm suggests contrast:

• the shutter keeps the heat out,
• but the handle is still warm from the sun

That idea of continuing state is why bleibt works well.

Here noch means still.

So:

• bleibt noch warm = stays warm / is still warm

It shows that the warmth has not disappeared yet.

Common uses of noch include:

• Ich warte noch. = I’m still waiting.
• Ist es noch offen? = Is it still open?
• Es ist noch warm. = It’s still warm.

von der Sonne means from the sun.

So:

• warm von der Sonne = warm from the sun

It explains the source/cause of the warmth.

You could also think of it as:

• the handle has become warm because sunlight hit it

German often uses von in this simple, natural way to indicate what caused a physical effect.

Yes, but the nuance is a bit different.

• von der Sonne = warm from the sun
  This is the most natural everyday phrasing here.
• durch die Sonne = through/because of the sun
  This sounds a bit more like explaining the mechanism or cause.

In this sentence, von der Sonne is smoother and more idiomatic.

Because aber does not change normal main-clause word order.

In German main clauses, the finite verb stays in second position.

So the second clause is:

• die Türklinke an der Balkontür = element 1
• bleibt = finite verb in position 2
• noch warm von der Sonne = rest of the clause

This is different from conjunctions like weil, which send the verb to the end.

Compare:

• ..., aber die Türklinke bleibt warm.
• ..., weil die Türklinke warm bleibt.

Because in German, all nouns are capitalized.

In this sentence, that includes:

• Rollladen
• Hitze
• Türklinke
• Balkontür
• Sonne

This is one of the most visible differences from English and helps you spot nouns quickly when reading.

Yes. It is a very natural way to describe a shutter that is already down.

German often uses participles as adjectives in exactly this way:

• das geöffnete Fenster = the opened/open window
• die geschlossene Tür = the closed door
• der heruntergelassene Rollladen = the lowered roller shutter

So this phrase is completely normal and idiomatic.