With Thermography of buildings there are many parameters that need to be taken into account. The building also needs to be dry, with no rain, snow, direct sun or wind present. We will also need a temperature differential of at least 10 degrees c between inside and outside so your heating needs to be on a good few hours before we arrive to carry out the survey.
So to summarise we ideally need a cloudy / overcast and dry day to catch thermal images in order to give a true representation of energy loss.