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Compilation of the most frequently asked questions about WindBox and its implementation. Enjoy reading the FAQ!
Who is your solution designed for?
What are the installation criteria?
I'm a private individual. Can I install WindBoxes?
Unfortunately, not today!
Installation complexity: WindBoxes come in batches of 5, for better energy yields. This requires a roof at least 12.50 m long, strong enough to support them: this is rarely the case on single-family homes.
Low energy yields: Installation conditions are often not conducive to home installations. Located in dense urban areas, houses are often of the same height, preventing the wind from accelerating and taking off.
Industrialization to come: Today, we're in the early stages of marketing the WindBox. It's not yet available off the shelf.
Which buildings are targeted?
In principle, all flat-roofed buildings are eligible. However, the output of a WindBox varies considerably depending on the building and the site's meteorological and urban data.
There are four criteria for maximizing production:
- Location in a windy area (refer to Global Wind Atlas to compare locations),
- A minimum height of 8 m (the higher the building, the better the results),
- Moderate urban density (in the path of prevailing winds),
- Good orientation in relation to prevailing wind corridors.
Once a building has been identified, we carry out production potential studies (solar and wind), to assess the suitability of an installation and its feasibility (including the selection of one of the facades).
Where are WindBoxes installed on a building?
The WindBox is positioned over the acroterion, at the edge of the best-exposed façade(s). The best orientation on the building is determined by an analysis of the prevailing wind corridors.
What happens if the wind changes direction?
The WindBox captures winds at 160°. If the main axis changes, depending on the season for example, kWh are lost.
In the majority of studies carried out (200+), the winds foregone by choosing the best-exposed façade are between 0 and 5 m/s. This represents less than 30kWh per year, a small amount of energy.
WIND my ROOF has chosen to do without this small energy gain, which is more than compensated for by simpler design and installation than a model that recovers all the wind.
Some areas, with highly disparate wind conditions, will be less suitable for our turbines. This is the case of Bordeaux, France, for example. Once again, targeting is key: the WindBox is not suitable for every building or every region.
This is the principle of decentralized renewable energies: harnessing the best sources locally with simple, effective means.
Do I need a building permit?
A prior declaration is required before any work is carried out.
What type of roofing is best suited to WindBoxes?
Roofs must be flat and at least 12 m long. Roofs can be made of concrete or steel. A structural study is required prior to installation.
Can I buy just one WindBox?
No! WindBoxes come in packs of 5 for energy efficiency reasons.
How are WindBoxes installed?
WindBoxes are supplied "ready to use". They come complete with mounting brackets and inverters. They can be weighted down if the structure allows, or attached directly to the structure and soon to be waterproofed.
What are the project stages?
Projects begin with a series of studies, firstly of the production potential, and secondly of the building (structural studies, electrical connections, etc.).
Once relevance and technical feasibility have been validated, design and assembly are launched. Installation involves lifting and electrical connection. A control office validates the installation.
Find out more about WindBox
Are there different WindBox sizes?
No, today there's only one version of WindBox.
What materials are used in the design?
The WindBox is made of galvanized steel and aluminum.
I'm worried about the nuisance...
Is WindBox noisy?
There is no emergence (0 decibel) at 2 m from the module. Wind turbines rotate at a maximum of two revolutions per second, much slower than in the automotive sector, which uses the same type of parts. The wind will therefore be noisier than the WindBox.
Acoustic studies can be carried out on a project-by-project basis.
Does the WindBox stand up to strong winds? or extreme temperatures?
Tests at the CSTB in Nantes in 2021 tested the WindBox in continuous winds of up to 180 km/h, and down to -15°C. In mainland France, this means that there will be no problems with the WindBox being blown off by storms.
In the French overseas departments and territories, further development is required, particularly on mounting brackets, before any installations can be envisaged.
Is biodiversity in danger?
The WindBox features a visible, permanent fairing, enabling birds to anticipate the obstacle. The blades rotate from 3 m/s (10.8 km/h), i.e. over 60% of the time on average.
As a preventive measure, WindBoxes can be fitted with safety nets to prevent birds from entering the turbine.
It's big and ugly, isn't it?
Tastes and colors...
A WindBox occupies 4m² and is 1m60 high, weighing 350kg (87.5kg/m²). On an 8 m high building, they will be barely visible, and may be confused with other traditional roof-mounted installations (air conditioning, for example).
Architectural integration can be carried out on new projects, prior to their construction. For existing buildings, the colors and spacing between WindBoxes can be adjusted to better integrate the installation with the building.
Architects, we want to work with you!
What does your stuff produce?
How much energy does a WindBox produce?
Energy production depends on the area's wind and sun potential, building height, facade orientation and urban density. It can range from 0 kWh to 2,500 kWh per year and per unit. To be multiplied by the number of units installed.
The challenge is to find the most suitable buildings!
Why pair the turbine with solar panels?
Coupling the two sources helps to offset the seasonal nature of wind and solar power, smoothing out the year-round production curve. In most cases, wind power is more powerful in winter, solar power in summer.
A few exceptions: in Bouches-du-Rhône, wind power varies very little with the seasons! The addition of solar power simply means that more can be produced in the same space.
It's useless compared to nuclear power plants!
It's true that to build a nuclear reactor you need 500,000 WindBoxes in a tropical zone... But we never said we were going to replace nuclear power plants.
The energy transition is a long, iterative process spanning several decades. WIND my ROOF aims to provide a complementary, local and renewable solution for buildings that need it.
It is by combining renewable and/or low-carbon sources that we can hope to meet the objectives of the Paris agreements and the IPCC recommendations.
By the way, we all subscribe to JMJ and Bon pote in the team, and recommend them to you!
Are there better regions than others for installing WindBox?
Yes, yes, yes!
Some regions are windier than others: Brittany, Normandy, the Hauts de France and the Rhone Valley are more suitable for our installations. Conversely, Alsace and the Basque country are not suitable regions. To carry out projects there, you'll need to aim for very tall buildings.
In Europe, the north of Germany, the UK, the Netherlands, Belgium, southern Italy and the Portuguese coast are all windy zones.
WIND my ROOF is not yet in a position to export outside Europe.
How is the WindBox more efficient than simple rooftop solar panels?
In terms of space occupied on the roof, WindBoxes generally produce more per square metre than solar power alone:
- In a case study in Le Havre, for example, the WindBox's output is equivalent to 12.25m² of solar power for 4m² of occupied space. In this windy, moderately sunny region, 4m² of wind power is equivalent to 8.73m² of solar power (30° inclination).
- In another case study near Marseille, the WindBox's output is equivalent to 8.5m² of solar power for 4m² of occupied space. Solar power is stronger here, and 4m² of wind power is equivalent to 5.2m² of solar power (30° inclination).
Generally speaking, wind power is also better suited to certain regions that lack sunshine: northern France and Europe in general have a low solar yield, whereas these regions benefit from an exceptional wind resource.
Other regions are neither windy nor sunny ("yes, but Strasbourg has a great Christmas market")... We don't have a solution yet, sorry!
Does it pollute?
What is the ecological impact of WindBox?
The WindBox enables the local production of clean electricity, which is less carbon-intensive than the European electricity mix.
For its photovoltaic solar panels, WIND my ROOF uses solar panels manufactured in Europe, whose carbon footprint is estimated at 35 g eq-CO2/kWh. For information, the carbon footprint of solar panels sourced outside the European Union is estimated at 43.9 g eq-CO2/kWh.
For its turbine, an in-house carbon assessment based on data supplied by ADEME revealed an average carbon footprint of 30 g eq-CO2/kWh over 20 years, based on wind turbine production of 1,000 kWh/year. The higher the output, the lower the carbon footprint.
Is WindBox made in France?
WIND my ROOF is a French company committed to local production, as close as possible to its customers. Whenever possible, parts are sourced from French or European manufacturers. The WindBox is assembled in Saint-Nazaire, France. Since January 2022, WIND my ROOF has been producing its units there at the plants of SIMRA, a subsidiary of SEGULA Technologies.
In all, 60% of the WindBox's value is produced in France. The aim is to gradually increase the French share.
And is it cost-effective?
What is your sales model?
Today, we sell directly. Leasing and third-party investment models are being studied for implementation in the medium term.
What to do with the energy produced?
The usual model on our projects is self-consumption with resale of surplus. WindBoxes can also be coupled to a storage system, for recharging appliances or electric vehicles. We are also working on collective self-consumption projects.
What energy savings can be expected?
The savings on your bill will depend on the plant's output (hence the importance of good targeting) and the cost of kWh on site (and its evolution over 20 years). For example, with a unit production of 2,000 kWh per year :
- For a manufacturer paying €0.10/kWh for electricity: €200 savings per year and per unit;
- For a social landlord paying €0.17/kWh for electricity: savings of €340 per year per unit.
Do you use resellers?
For the time being, no. As the solution is new, we'd like to keep a close eye on the projects we put in place. In the medium term, this will be possible.
Why not resell the entire production?
Today in France, total resale is not economically attractive: feed-in tariffs for wind and solar power (less than 6c€/kWh) are lower than the cost of electricity for customers (from 8 to 17c€/kWh depending on the sector).
What is the return on investment for your projects?
This will depend on the project (production and customer kWh cost). The aim is to align the post-industrialization process with that of rooftop solar panels, i.e. a return in 8 to 12 years in France.
Have you thought about...?
... operate WindBoxes using exhaust air from ventilation systems?
On paper, it may sound appealing, but our brilliant engineers have looked into it, and it's just not feasible. To work properly, the WindBox would have to be positioned as close as possible to the exhaust vent, and the overpressure created in the ventilation motors would consume as much or more energy than the turbine would produce at its output.
... stack WindBoxes on top of each other?
This would not allow optimal production.
The last WindBox will be the most efficient, because the wind goes where it's easiest to go. The others would be useless. What's more, town-planning regulations prevent installations that are too high on roofs, so it wouldn't be possible.
... put WindBoxes on the roof of a truck? or in a metro station?
We can, but just to look pretty then.
"Nothing is lost, nothing is created: everything is transformed". Antoine Laurent de Lavoisier (1743-1794) anticipated this question and knew that the aerodynamic drag of a WindBox on the roof of a truck would result in excessive fuel consumption and very poor efficiency.
I'm not a climate skeptic, but...
... I think it sucks!
And you have every right to!
We are, however, working hard (hard) to find solutions for building transition, so we urge you to make constructive comments and be measured in what you say.
How come? We forgot a question ?
We'll try to answer it if the answer exists!