I have just purchased a two year old Hermann tortoise for my eight year old son, and we are a little unsure how to maintain the temperature in his "cool" shaded area around 20-25 degrees as recommended? We prepared well for his arrival with the construction of a tortoise table taking into cosideration and purchasing the correct uv and basking lighting/substrate/bathing/drinking pool/food dish/limestone flour and Nutrobol vitamins-mineral supplements/thermometers guide books etc, and have also secured an outside planted area with "hot house" and shaded areas for him when the weather brightens a little, but after reading negative comments about heat mats do not know what would be the best/safest way to raise the evening/ambient temperature in his cool/shaded area from 12-15 degrees average approx? We have a fine hemp and shredded newspaper bedding area in there for him which he burrows under and into the substrate, is this enough? He is located in a secure, water and wind proof brick built shed.
Would appreciate greatly any advice, as we obviously want to take the best care possible of him.