 one thing is very rarely addressed and this is solar cooling and for heating with solar energy we always have the contradiction that when we need heat most in the northern or very southern latitudes the sun is not very strong and in the very hot climates we often have excessive sunshine and that's why solar cooling is a good choice and it's actually on the market but it's not very visible so far and so have a look at that and one word to air conditioning for air conditioning the key issue is humidity it's not the cooling energy itself but it's to make the air in a range of moisture that is good for the house so dehumification is very important and if anybody of you is very interested in this issue Professor Schmitz here from THH is an expert in this and maybe some of you have followed classes with him