The "Download Now" link directs you to the iTunes App Store, where you must continue the download process. You must have iTunes installed in order to open the link, and you must have an active iTunes account to download the application. This download may not be available in some countries.
From ISIS IC:
B3E stands for "Building Energy Efficiency Evaluation". This software specifies the energy efficiency of the building automation of an existing building. The type of energy supply and building automation installed or to be installed must be selected in the individual steps. Therefore, the current energy efficiency class of the existing building automation, from the worst value "D" to the best value "A", and the efficiency class of future building automation will be determinated. Based on this classes, the type of the building, current energy prices and consumption rates for energy the software will calculate possible savings.