Developing heating and cooling load calculations for buildings requires experience and care. While the heat transfer for building enclosure assemblies can be calculated using well developed techniques, all it takes is poor construction quality to negate the thermal performance of an enclosure system. Building envelope commissioning is now gaining more attention, which can include both blower door testing, as well as thermal imaging. In 2006, the lowest cost thermal imager cost approximately $7,500. The Fluke TiS hits a $2,000 price threshold, while still being acceptable for commercial use.