row of white ventilation chimneys and exhausting machine in hvac system on rooftop of factory building against blue sky

row white ventilation chimneys exhausting machine hvac system rooftop factory building blue sky background vertical chimney boilers factory roof building hvac top exhaust rooftop vertical ventilation cooling system industrial machine industry corrugated iron high machinery conditioning aluminum architecture aluminium blue construction row engineering white copy space manufacture sky plant curve steel perspective outside temperature pipe metal modern ladder pipeline stairs structure tube vent