Lighting is only part of the issue. In order to get a consistently reproducible product, growers also try to maintain a consistent temperature, humidity, and airflow. All of which quickly adds up to massive energy consumption. Weed grows best in mild humidity and pretty high temperatures. Which means that in the winter, they end up heating and humidifying the entire house to what would essentially be tropical levels. And in the summer, they’re worried about consistent airflow and dehumidifying. And dehumidifiers eat a lot of energy.
There’s a reason cops use thermal imaging to find grow houses. Under infrared, they light up like a beacon. Cops can just fly a helicopter around town, and flag any houses that look abnormal:
