Common sense predicates a building envelope that is not adequately sealed will leak. Air leakage decreases user comfort through moisture, drafts, unwanted noise and may even lower air quality. More importantly, air leakage can account for 25-40% of the energy used for heating and cooling. So insist on a properly sealed building envelope to let your house perform at maximum potential. Consider a product from the Bradford wall wrap range or Pro Clima INTELLO (a certified Passive House component).
We incidentally hold a Level 1 Certificate in Thermography, however, if you are interested in obtaining a professional Airtight Building Assessment including thermal imaging and/or a blower door test, we can highly recommend the team at 3ARK.