The main technical risks involving Smart Buildings with IoT are: market's devices incompatibility with the system, network vulnerability, and the system's inability to scale and meet new requirements. This paperwork proposes a technological architecture for intelligent buildings with IoT, which guarantees a scalable, compatible and secure system. The architecture is decentralized, has four main layers, a control panel that works on critical situations and monitoring processes. A benchmark of the proposed architecture and other six shows that the proposal is superior in scalability and security. Expert judgment shows that the design has high acceptance.