In Toulouse, the Public Housing Office has equipped a sample of its social housing with sensors connected to a long-distance network (LoRa) to measure the real gain in thermal performance, after renovation. Actility, M2M start-up, and the CSTB Carnot Institute provide the technology. A first in France.
Like all social landlords, Habitat Toulouse has the obligation (Grenelle 1 law) to renovate its most energy-intensive housing stock by 2020. To facilitate its task, the legislator authorizes it to recover up to 50% of the economy on the resulting energy bill by increasing rents. But on one condition: that it proves to its tenants that the real gain corresponds to the estimate a priori. The Toulouse lessor has decided to go beyond the obligation, as explained by its heritage director, Gérald Lepain: “Following our discussions with tenants’ associations, we decided to collect real energy performance data on three years. This allows us to bring more transparency to the tenants.
For the two technical service providers, Actility and the CSTB research center, it is also an opportunity to test the LoRa transport network, as well as their modeling algorithms. In a context of buzz around connected objects and unlicensed transport networks (ISM frequency bands) for the M2M, use in real conditions could give them a head start.
Four years after the agreement in principle between the tenants and the lessor, in Toulouse, most of the 160 social housing units chosen for the operation were equipped with sensors in November 2014. They are representative of the 1,250 housing units of a housing program. heavy renovation, “closed and covered”, on eight residences. While this program is almost complete, the first data collection campaign could begin with the arrival of the cold season. First results expected for June 2015.
For energy performance after construction, Habitat Toulouse has called on the Center Scientifique et Technique du Bâtiment (CSTB). This public research institute covers all the issues related to the building. “Like all Carnot institutes, we have targeted R & D offers. But we are also able to support developments with operational deliverables, “says Lionel Bertrand, head of the Innovation Development Division at CSTB’s Energy and Environment Division.
This is the work of his team, carried out on behalf of the Breton start-up Actility, which are used: they consisted of developing “smart EPC”, the algorithmic module that serves as an engine for analyzing the data sent by the sensors , which will restore the intrinsic performance gain and the thermal signature of the dwellings. It is also the CSTB that manages the project for the installation of some thousand sensors and five antennas needed. “For a T3, 4 or 5 sensors are necessary”, illustrates Lionel Bertrand. Each main room houses a triple temperature-humidity-brightness sensor, to which are added impulse sensors placed on the central electricity meter, or even on the gas meter for the equipped dwellings.
With some 40 employees, Actility is at the crossroads of machine to machine (M2M) – that is, the connection and exchange of data between objects – and energy. Its founder, Olivier Hersent, is a “serial entrepreneur” from Orange’s labs.
“We are on an extreme case of low speed network, with a problem that is to collect data for three years with some measurements every ten seconds,” he says. The sensors, supplied by a Breton company, NKE Electronics, operate without batteries and without power supply, by “energy harvesting”, by collecting diffuse light energy. As for data transport, it uses differential compression techniques and the ThingPark Wireless low-speed and long-distance network, which is based on the French LoRa technology and the ISM free frequency band (Industrial Scientific and Medical).
This type of network is not the only one to see itself as the future of M2M for professional applications. But LoRa would have serious advantages over its competitors, according to Olivier Hersent: in addition to a range of 15 km (3 km in town), it is distinguished by a variable bit rate that allows it to go from a few hundred bits / sec to 50 kbits / dry when the sensor is close to the antenna. With shorter transmissions, life expectancy and average energy consumption would be optimized, says Olivier Hersent. In Toulouse, five antennas will have been enough to cover the eight residences. While the budget is 5,000 euros per unit, an envelope of 800,000 euros, the three partners already see further. Actility defends the idea of a national LoRa network at lower cost, in support of M2M. “We have plenty of ideas for new services,” slips Lionel Bertrand of CSTB. Fire detection, distribution of heating costs according to use, home automation applications …, the tracks go far beyond energy efficiency.