Calc-U-Load is a WindowsÂ®-based software program designed to calculate residential heating and cooling loads quickly and accurately, the company says. It uses a whole-house approach that is said to make load sizing faster. It will also calculate annual operating costs using different types of fuels. The software can graph and print results incorporating the customer’s name and location. Thermal-Works Software, 4540 Patterson Rd., Caledonia, MI 49316.