noun, noun which may take the genitive case particle 'no'
light and heat; energy (for lighting and heating)
Often used in the context of household utilities, especially in the compound 光熱費 (こうねつひ, utility expenses for electricity and gas).
今月の光熱費は先月より高かった。
This month's utility bill was higher than last month's.
光熱費を節約するために、エアコンの設定温度を上げた
To save on energy costs, I raised the air conditioner's set temperature.