With the increasing adaptation of Internet of Things (IoT) platforms in decentralized cloud environments, more focus given towards facilitating the privacy awareness building upon goals set by current European Union (EU) General Data Protection Regulation (GDPR) regulations. Therefore, it is necessary to empower the end users (both private and corporate) of IoT platforms with the capability of deciding which combination of self-hosted or cloud-oriented IoT systems are most suitable to handle the personal data they generate and own as well as with the ability to change the existing (or pre-set) configurations at any time. Furthermore, adaptation of GDPR regulations in IoT platforms is challenging as there are needs for significant efforts to integrate privacy policies in a programmatic way to: (i) increase awareness of users about which data is collected, where it is transmitted, by whom, etc.; (ii) provide controls to enable users to notify such aspects, being at the same time aware of how such a decision affects the quality of the IoT services provided in that IoT platform. BRAIN-IoT project focuses on complex scenarios where actuation and control are cooperatively supported by populations of IoT systems. The breakthrough targeted by BRAIN-IoT is to provide solutions to embed privacy-awareness and privacy control features in IoT solutions. In this work, the authors explore the following key areas: (a) privacy awareness in IoT systems using GDPR regulations and BRAIN-IoT platform, and (b) propose a conceptual framework for Privacy Impact Assessment (PIA) using privacy principles presented in GDPR regulations. The proposed privacy awareness framework is cross-platform, so it is suitable to support a wide number of heterogeneous IoT systems, deployed by corporate and private users.