Ecotropy, urban sensors

Vue 3D du bâtiment South Express, un des premiers pilotes réalisés par Ecotropy

Helping the designers of buildings to produce buildings that are more energy efficient

Buildings are the greatest potential source of energy savings. To face up to the challenges posed by the energy transition, the building construction sector is undergoing two fundamental transformations. The first is the increasing use of digital devices and the second is the development of performance-based approaches that lay the emphasis on achieving results rather than the obligation to apply certain techniques. Digital devices such as communicating sensors and software that performs modelling or data processing make it possible to more accurately predict, monitor and control the energy consumption of a building, in order to reduce its consumption without impinging on the comfort of its occupants.

A team of researchers from two IFSTTAR laboratories ─ SII (Structures and Integrated Instrumentation, in Nantes) and LISIS (Laboratory for Instrumentation, Simulation and Scientific Computing, in Marne-la-Vallée) ─ has been working on this topic for a number of years. One area covered by their research is digital monitoring of the energy performance of a building. The aim of this research is to develop software tools that provide the basis for simulation models that reproduce this energy performance as accurately as possible. A reliable simulation model improves our understanding of how the building works from the thermal point of view in order, for example, to more effectively target renovation works or rapidly detect malfunctions in its systems. A good thermal model can produce enormous reductions in energy wastage: a recent study of a number of cases showed that simulation paid for itself after only a few months.

However, simulation encounters major difficulties with the tools that are currently on the market. Obtaining an accurate simulation is a long and costly process. Simulation software requires a large amount of input data combined with a large number of hypotheses which introduce uncertainties into the predictions provided by the computation process. In order for it to be possible to use simulation on an existing building to validate and monitor its performance, it is essential to remove the errors generated by these uncertainties from the model. This is done by adjusting a number of parameters on the basis of the real performance of the building. This process, which is similar to the calibration of the sensor for a physical measurement, is known as “model calibration”.

The IFSTTAR team has written computer code that facilitates and automates this process. It combines a thermal modelling engine, measurement data from sensors in the building and powerful computing algorithms that are based on optimisation theory. This success was achieved after six years of R&D work that saw 10 or so publications and a large number of scientific collaborations, for example the ANR/MEMOIRE project on instrumented energy audit techniques, the ANR/PRECCISION project, and the ADEME/FBE research workshop on methods for guaranteeing energy performance.

In order to respond to the strong demand from the building sector for this type of tool, IFSTTAR researcher Alexandre Nassiopoulos set up a firm ─ Ecotropy ─ in 2006 to market an industrial version of the software. Ecotropy is intended for firms offering energy efficiency services (consultancies or firms operating and maintaining heating, ventilation and air conditioning systems) and enables them to deliver buildings that genuinely achieve the levels of comfort and consumption that were promised during the design phase.



Ecotropy received the active support of IFSTTAR from the outset and very soon afterwards that of the Atlanpole business incubator which is supported by the Pays de la Loire region. For its start-up, Ecotropy also raised initial capital of €120,000 from the European business accelerator KIC Inno Energy.

In 2016 the company clarified its focus, deciding to concentrate on tertiary office buildings, particularly those built or managed with guaranteed performance contracts. This first year also saw the development of an industrial version of the computer code, whose first version will be brought to market in mid-2017. In addition the firm has carried through a number of pilot projects to refine technological aspects and provide proof of concept.

After a turnover of €30,000 in 2016, Ecotropy is targeting a turnover of €100,000 in 2017 and €900,000 in 2018.

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