Temperature & HVAC
Tropical plants need a sustained environment of 60 to 90 degrees Fahrenheit. Only a few plants can tolerate dips below 50 degrees without major systematic damage. Even a few seconds of cold air (from an open door for example) can damage a tropical plant. For example, Peace Lilies, Ficus, and Dracaena leaves turn black even with brief exposure. Dips below 60 degrees will cause Ficus to lose leaves, and other plants turn yellow. Exposure to cold air can reduce water usage, allow fungus to spread and rot the roots, or cause foliage spots. Exposure to very hot temperatures causes some plants to wilt, others to lose leaves. Water usage is also dramatically increased in high temperatures. Wilting a plant can cause systematic damage, with symptoms similar to cold damage.
Heating and cooling systems should provide a constant temperature of 60-80 degrees Fahrenheit. Large skylights and southern-facing window walls can naturally warm the space (the “greenhouse effect”) to high temperatures even during winter. (Consider the heat burden during the air-conditioning season.) Heat rises and will accumulate dramatically at the top of atriums if not circulated (e.g. ceiling fans.)
Continual air movement is important to simulate a natural environment. The ideal humidity range is 40-80%, but keep in mind that foliage plants add 10-30% to the humidity level, depending on their rate of transpiration and the temperature. If system does not remove moisture, condensation could accumulate on glass and plant leaves.