Elforbruget falder ved at slukke elapparatet.

Here ved at + infinitive means by doing something.

So:

• ved at slukke elapparatet = by turning off the electrical appliance

This is a very common Danish pattern for expressing means, method, or how something happens.

Examples:

• Man lærer dansk ved at øve sig. = You learn Danish by practicing.
• Hun sparer penge ved at cykle. = She saves money by cycling.

So in your sentence, it tells you how the electricity consumption falls.

Because Danish normally writes compound nouns as a single word.

So:

• el + forbrug → elforbrug = electricity consumption
• el + apparat → elapparat = electrical appliance / electric device

This is very typical in Danish and Germanic languages. English often writes similar ideas as two words or with an adjective:

• electricity consumption
• electrical appliance

But Danish usually combines them into one noun.

The ending -et shows that these nouns are definite singular and neuter.

Here are the base forms:

• et elforbrug = an electricity consumption / electricity use
• et elapparat = an electrical appliance

Definite singular:

• elforbruget = the electricity consumption
• elapparatet = the electrical appliance

So Danish often puts the equivalent of the at the end of the noun instead of using a separate word.

That is why you do not see a separate word for the before these nouns.

Because in Danish, the definite article is often attached to the noun as an ending.

Compare:

• et apparat = an appliance

• apparatet = the appliance

• et forbrug = a consumption / usage
• forbruget = the consumption / the usage

In this sentence, elforbruget and elapparatet already include the idea of the.

Falder is the present tense of falde, which literally means fall.

In Danish, falde is often used where English would say:

• fall
• decrease
• go down
• drop

So:

• Elforbruget falder = The electricity consumption falls / decreases

This is very natural Danish. English often prefers decreases in more formal contexts, but Danish is perfectly happy with falder here.

The present tense in Danish is often used for general truths, typical results, and instructions/explanations.

So this sentence is not necessarily describing one single event happening right now. It can mean something more general, like:

• Electricity consumption goes down when you turn off the appliance
• Electricity consumption decreases by turning off the appliance

This is a normal use of the present tense in both Danish and English.

Here at is the infinitive marker, like English to.

So:

• slukke = turn off
• at slukke = to turn off

After ved, Danish uses at + infinitive:

• ved at slukke
• ved at spare
• ved at bruge

So you should think of ved at as a set pattern.

Yes. Slukke commonly means:

• turn off
• switch off
• sometimes extinguish (for lights, fire, etc.)

In this sentence:

• slukke elapparatet = turn off the appliance

So it is the natural verb for shutting off a device, light, or something powered.

Examples:

• slukke lyset = turn off the light
• slukke fjernsynet = turn off the TV

In this sentence, slukke elapparatet is fine and understandable: turn off the appliance.

Danish can also use slukke for in many contexts, especially in everyday speech:

• slukke for lyset
• slukke for fjernsynet

But direct-object use is also common, especially in more formal or instructional language:

• slukke apparatet
• slukke motoren

So slukke elapparatet is not strange. It can sound a bit like instruction-manual language, which fits this kind of sentence.

Yes, it is understandable and possible Danish, but it sounds a bit general or formal.

It means something like:

• electrical appliance
• electric device

In everyday Danish, people often use a more specific word if they know what the device is, for example:

• fjernsynet = the TV
• computeren = the computer
• ovnen = the oven
• apparatet = the appliance/device

So elapparatet is fine, especially in technical, safety, or informational language, but it is not always the most conversational choice.

El- is a very common Danish first element meaning electric or electricity-related.

Examples:

• elbil = electric car
• elregning = electricity bill
• elværk = power plant / electricity works
• elforbrug = electricity consumption

So in compounds, el- is often the short Danish way of saying something connected with electricity.