Ключевые слова: bill, bills, cash, cheapness, coin, coins, cost of light, costs, dark, ecology, economy, ecosustainability, ecosustainable, electricity, electricity costs, energy, energy classes, environment, environmental protection, eur, expenses, fair, household budget, light, light bulb, light bulbs, lighting, low consumption, low consumption light bulbs, money, ordinary costs, ordinary expenses, savings, sustainability, sustainable,