Fundamental research

Sustainability pioneers Amstelius and Dutch Green Company, in collaboration with Ben Bronsema, obtained an innovation grant from RVO in early 2014 to further develop and realize the world's first concrete(n) zero-energy building with the innovative 'Earth, Wind & Fire' concept (EWF concept). Dutch Green Company has obtained a grant in the amount of approximately €500,000 as the leader in cooperation with several research partners of TKI EnerGO (RvO).

VENTECDAK

In the EWF concept, a Ventecdak (or Powerdak 1.0) was developed with the main function of natural extraction of ventilation air. Wind energy was generated here using wind turbines in the overpressure chamber. The efficiency proved insufficient due to low yields and high costs. Thus, not a cost-effective solution.

Inspired by the Powerdak 1.0, the idea arose between Bert Blocken of Eindhoven University of Technology (TU/e) and Ben Bronsema of Delft University of Technology to modify the Powerdak 1.0 by using vertical axis wind turbines, taking advantage of the increased wind speeds in the venturi roof, among other things. This was called the Powerdak 2.0.

THE POWER ROOF 2.0

The objective of the additional fundamental research was to optimize the power coefficient of the turbines in order to achieve cost-effective generation of wind energy in the built environment. For this purpose, the wind turbines in the venturi roof wind farm had to meet specific aerodynamic and electromechanical requirements, viz:

• The morphology of the roof;
• The blade shape of the turbines;
• Expected energy production.

At the time, the standard turbines on the market performed inadequately so a custom solution had to be sought for the BREEZE project. An additional grant application for the development of a prototype wind turbine by TU/e was unfortunately rejected. The theoretical models showed very high energy yields of 200,000 kWh based on preliminary simulations with 40 turbines in the Powerdak 2.0. Unfortunately, in practice, the production of wind energy by the intended turbines turned out to average ≈ 62,000 kWh per year. This definitively did not provide a profitable business case.

THE POWER ROOF 3.0

It was then decided to develop a Powerdak 3.0 in which the vertical axis turbines were arranged on the roof on a multiple curved plane, making use of acceleration effects of the wind as in the Powerdak 2.0. Simulations were used to optimize the morphology of the roof shape. In collaboration with Luc Heijnen of Troades, a vertical axis turbine was purchased from Windspire in the United States for further testing in a wind turbine at The Von Karman Institute for Fluid Dynamics (VKI) in Leuven. Based on this field test, the effectiveness of the blade profile and blade angle could be investigated using the simulation model developed by TU/e. Global calculation with the manufacturer's data indicated that this could provide a profitable business case. Unfortunately, the test of the vertical axis turbine in the VKI wind tunnel again showed mediocre results. Subsequently, some alternatives with 28 and 20 vertical axis turbines of about 3m height, respectively, were studied but their estimated annual yield was ≈ 100,000 kWh. This was still insufficient for the realization of the Powerdak 3.0 on the BREEZE project to achieve an energy-neutral building.

POWER FACADE & ROOF

The alternative we then explored was to generate solar energy using custom BIPV on the façade, in the solar chimneys, on the canopy and roof. This resulted in the Power Façade & Roof of the current BREEZE project. Its total energy output is ≈ 200,000 kWh per year.

During basic research in the period 2014-2015, Ben Bronsema led the further development of the EWF concept for Hotel Breeze. To develop the technical components of this concept, we collaborated with the world's most advanced companies and the technical universities Technical University Delft, Technical University Eindhoven and the renowned Von Karman Institute for Fluid Dynamics.