Ключевые слова: air, background, banknote, battery, calculator, central, climate, closeup, cold, color, comfort, control, convector, dollar, domestic, economy, efficiency, electric, energy, expense, finance, heat, heater, heating, home, hot, house, modern, money, object, optimize, pay, plumbing, radiator, room, save, system, temperature, thermal, utility, wall, warm, winter,