Temperature controllers - there are various kinds that can be used. One such includes a dehumidifier to raise the temperature and lower humidity, another is a space heater that does the same thing. An air conditioner controls temperature by lowering it and the humidity, there is also an evaporative cooler- it lowers the temperature while raising the humidity, and of course, the humidifier which both increases the temperature and humidity.
Venting creates a place for hot air to leave the space and go outdoors and prevents that air from recirculating. Fans in your grow room do not decrease the heat, they only redistribute the air. Evaporative coolers and ACs bring the temperature down alongside you making sure to funnel the heat outdoors, they work in any climate. Evaporative coolers need air that has a humidity of under 30%.
When looking into temperature controllers, consider the strain of plant that you have, cold or heat will not sit well with some greenery more than others. Depending on your strain there will be a piqued reaction to cold or heat and forming a resistance to these. Choose the correct schedule for your lights, and look at the weather and environment it is in, does it get too cold at night, or is overheated during the daytime? Work with the temperature controllers and timers cycle of on and off ensuring that your grow light will be on during the night while off when it is the daytime in order to equalize temperatures.
When growing in the cold, be sure to use temperature controllers to bring the air back to homeostasis. Try to harness the heat from your grow room naturally and avoid overheating by keeping the grow lights off during the day. Plus this will save you on electricity and raise fewer red flags about suspicious electricity bills. Your grow lights being on at night helps to insulate the plants from the elements when it is coldest. Not to mention some people are charged less on their electricity bill for usage that is at night. Marijuana plants, at each of their stages, will thrive in moderately higher temperatures of about 30 degrees Celcius.