This is the 10943rd most frequent Polish word.
energooszczędne
Energy-efficient.
The word 'energooszczędne' here is used as an adjective to describe the light bulbs, indicating that they save energy.
Kupiliśmy energooszczędne żarówki do domu.
We bought energy-saving light bulbs for the house.
In this sentence, 'energooszczędne' functions as an adjective modifying 'rozwiązania' (solutions), suggesting that the solutions are designed to conserve energy.
Wybieram energooszczędne rozwiązania do ogrzewania.
I choose energy-efficient solutions for heating.
Here, 'energooszczędnych' is an adjectival form describing devices ('urządzeń'), emphasizing their feature of being energy-efficient.