The specification on power consumption of a digital system is extremely important due to the growing relevance of the market of portable devices and must be taken into account since the early phases of a complex System-on-Chip design. In this paper some guidelines are provided for the integration of the information on power consumption in the executable model of parameterized cores, with particular attention to the AMBA AHB bus. This will give important information for the analysis and choice between different design architectures driven by functional, timing and power constraints of the System-on-Chip.