Why Am I Getting So Much Condensation On My Double Glazing.?

i recently had two new double glazed windows put at the the front of my house upstairs, since ive had them put in i seem to have had a lot of condensation at the bottom of the windows,yet the downstairs windows ,which were put in about 5 years ago don't seem to have as much and it quickly goes on the downstairs windows. the heat in my rooms is the same downstairs and upstairs. is there something wrong with the units. i need some advice before i call the company back.