REsponsive, INtegrated , VENTilated - REINVENT - windows.

The research project REINVENT has two goals: to increase knowledge about opportunities and challenges related to dynamic building facades; and develop an advanced dynamic window that reduces energy use for air conditioning buildings and at the same time enhances the indoor climate. This window is based on a double window that makes optimal use of the cavity air flow, with integrated sensors and control technology for automatic control. The product is an extremely flexible and intelligent window that can change properties according to environmental conditions, user needs, and criteria set by the building management system. The design and development of the innovative window/facade system is based on extensive multi-scale modeling and simulation combined with experiments on full-scale prototypes. The project also contributes to expanding scientific knowledge in the following fields: physics related to ventilated double-glazed windows/facades; integration of dynamic windows/facades in buildings; control logic for advanced dynamic systems in a total energy and indoor climate perspective; integration of sensors, control and communication technology in facade systems; and system control through real-time simulation. These topics represent some of the biggest barriers to the development and spread of advanced and dynamic window/facade systems. Both numerical and experimental methods are used in the project. Existing models for the simulation and analysis of double windows/facades have been adjusted and tested. The models were tested under different conditions and with different simulation tools to measure accuracy and sensitivity. The results from the simulations were also compared with already existing measurements. On the basis of these experiments, guidelines were developed for new numerical models for simulation of double windows/facades. Two full-scale mockups of double glazing/facades were built: one for testing in the climate simulator, the other for testing in an outdoor test cell. Experimental measurements have been carried out to assess the performance of the facade and to validate and develop the new numerical model. One of the two full-scale mockups has an embedded system for local control of the façade’s dynamic features. The embedded system was also developed to test different configurations and to record information and measurements from the mockup to support the development of control logic to manage the facade. Experimental activities with the use of the climate simulator have generated data that can be used to validate and/or calibrate detailed simulation models, including numerical fluid dynamics models. Subsequent data analysis has contributed to a better understanding of how the properties of a double window/facade affect the thermal performance of these systems. Sensitivity analyzes were also performed using tailored simulation models. These analyzes allowed us to identify the most important factors and constructional features of double facades and develop the flexible double window/facade. The combination of theory and simulation in this project has provided a better understanding of the possibilities and limitations of a (fully) flexible double window. Important results of REINVENT are: a preliminary framework for the development of robust algorithms for real-time simulation of facades; a control system that ensures optimal regulation of facades by controlling the direction and rate of air flow and heat addition from the sun in a dynamic way; a concept and simple prototypes produced at full scale using 3D printing of an intelligent ventilation valve, to test its functionality and integration of the embedded system. A model of the fully flexible window was developed and tested in two software tools for BPS, and has now been integrated into a BPS with promising results. This model was used in the last part of the project in combination with the management method that was developed. This new control approach targets multi-objective performance and is based on simulation. This approach has been proved to optimize the behaviour of the flexible DSF compared to conventional control approaches (e.g. rule-based controls). After the completion of the REINVENT project, we will continue to use the models and methods developed to see how the performance of the flexible double window/facade can be optimized under different climatic conditions. In the long term, simulation under different climatic conditions will give us a better understanding of the properties of the flexible double window/facade so that we can develop solutions that satisfy different requirements. We will also continue to develop and improve control methods based on simulation with the aim of robust implementation of model predictive control in real time. With the help of simulation studies, we will also try to define simple control rules that can be easier to integrate into embedded control systems.

The project has generated knowledge and know-how in the following areas: • thermophysical behaviour of double skin facades/windows (DSFs/DSWs) in relation to cavity features, shadings, and airflow mechanisms; • optimal operational logic for DSFs/DSWs in a multi-domain perspective; • integration of fully dynamic DSFs/DSWs into the energy concept of buildings; • strategies and challenges for integration of on-board sensing, control and communication technologies in windows and façade systems, as well as use of real-time simulation. Beyond the applications to double skin facade/window systems, the knowledge generated may lead, when suitably applied to more or less advanced dynamic building envelope systems, to improve the design, performance, and control of such technologies. In particular, improved performance can be achieved by employing relatively simple embedded control system and exmploiting simulation-based control approaches as developed in the project.

The research project is aimed at developing a new façade system that reduces energy use in buildings. The system is based on a double-skin façade/window (DSF/DSW) architecture, and integrates innovative ventilation valve, sensing and control technologies. The final product is an extremely flexible and intelligent fenestration component, capable of changing its performance and behaviour according to the boundary conditions of the surrounding environment, as well as to the requirements set by the users/building management system. In comparison to the present-day situation, this system reconfigures the role of the window and demonstrates that advanced windows can greatly improve building performance to become a key component in the building energy concept. It is intended for a large range of applications (new or existing buildings, dwellings or commercial buildings) and control strategies. The advantages that a window system such as this can provide, are so significant that it is possible to enable naturally climatized buildings. The research project is organized into five work packages with sub-tasks. The design and development of the innovative façade component is supported by an extensive multi-scale modelling and simulation task, coupled with experiments in a climate simulator. These activities also contribute to expanding scientific knowledge in the following fields: thermophysics of naturally ventilated DSF/DSW, interaction of dynamic building envelope components within the building as a whole, control logics for advanced dynamic systems from a total energy and indoor environmental perspective, integration of on-board sensing, control and communication technologies into window and façade systems, and system control through real-time simulation. These topics represent the biggest challenges of the research project and are some of today's main barriers to the development and spread of high performance, advanced, and dynamic fenestration systems.