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Article | Energies | Smart building

Breakthrough technologies for enhanced energy performance

Building energy systems

Published on 7 May 2019

When it comes to making smarter use of energy, the construction industry is on the front lines. Buildings are by far the leading consumer of energy in France (44%), coming in ahead of transportation (32%), manufacturing (21%), and farming (3%).* And heating is at the top of the list, accounting for 65% of total energy consumption for primary residences.

The French government’s environmental agenda includes a number of heat-related regulations for buildings that are now coming into force. For new buildings, the bar has been set high: all will have to be energy-positive—producing more energy than they use—by 2020. And for existing buildings, there are new regulations governing heat- and energy-related upgrades to reduce overall energy consumption and curb greenhouse gas emissions.

At Liten, we are tackling these issues holistically, looking at insulation, air quality, heating, hot water production, air conditioning, ventilation, and—of course—occupant comfort. The latest models used at Liten go beyond simulations, privileging a probabilistic approach that factors in both external (fluctuations in weather) and internal forces (occupant behavior). Our researchers are investigating which technologies are most likely to achieve the desired energy performance in a complex, highly fluctuating environment.

Liten is at the forefront of several high-potential technologies, from PV solar to innovative building-envelope materials and the processes used to manufacture them. When combined, they are capable of achieving the energy performance levels set forth in the new regulations. Several of these technologies are already being tested in partnership with manufacturers. In addition, we collaborate with CSTB, a Grenoble-based technology and development center for the construction industry, to assess all new building-related technologies coming out of the Liten institute.

* Source: Chiffres clés de l’énergie 2014, Commissariat général au développement durable.


Aligning with the new regulations before they come into force for future-ready buildings today

  • We develop aesthetic technologies that are realistic in terms of cost and appeal to construction companies, architects, and designers.

  • We take into account occupant comfort and ease-of-installation.

  • We combine a palette of solutions to achieve optimal energy performance despite fluctuating weather and user behaviors.

  • We test and evaluate energy performance on site, with the ultimate goal of obtaining the relevant approvals and certifications for the innovations we develop.


COMEPOS, a project to make the positive-energy-home design and build process more efficient.

As project coordinator, we are working with 22 partners to develop a new energy-positive single-family home concept that aligns with the new heat regulations. Energy-positive test buildings (including 25 in France with very different weather conditions and uses) will be used to assess component performance in each region and to determine which solutions are truly effective depending on climate, construction techniques, and occupant lifestyles. The project will also help get positive-energy homes and innovative building components and systems to market faster. The goal is to encourage all home builders in France to leverage the results of this five-year project (2013–2018).

​We are working with concrete manufacturer Vicat on an EU project to develop multifunctional building facade materials.

The goal is to develop building-integrated PV panels that produce electricity and insulate concrete-slab building facade modules. Installing the solution on east- and west-facing building facades appears to achieve the best balance between production and consumption.

We are working with Crosslux to develop semi-transparent PV-enabled double-glazed windows.

The solution, intended for office and other commercial buildings, will enhance occupant comfort by reducing glare from the sun while producing solar energy to power building systems like HVAC and lighting. This type of solution can make a very direct contribution to energy-positive buildings and, when used in tandem with battery packs installed at each window, can also store energy for use during peak demand/low sunlight hours.

​​Our researchers are developing a silica aerogel that would serve as an insulating stucco for building facades. 

They have tested hydraulic mortars containing a silica aerogel for use as an insulating stucco to save energy. According to numerical models, the mortars could cut heat loss by 25% on new building facades; this figure rises to up to 50% for existing-building upgrades. The stucco was applied to a Liten test house as part of the Parex-It R&D project. One patent application was filed for the technology.

Multifunctional window research.

We are currently studying PV modules outfitted with sensors and a storage battery. Windows equipped with the modules could be used to air buildings when the outside temperature allows and to run shutters and lighting.

Heat storage using phase-change materials.

Phase-change materials (like certain types of paraffin) can be used to store heat—such as the heat that builds up behind a building facade exposed to the sun during the day—to heat the building at night, or at any other time heat is needed. These materials can also be used to store the “cool” that builds up in building materials at night for use as air conditioning during the day. Likewise, the cooler temperatures in the ground can be channeled to building facades or interiors. Ines, the French national solar energy institute, has patented several systems of this type.

  • Around 50 researchers

  • 25 patents

  • Publications: 

Ibrahim M, Biwole PH, Wurtz E.  June 2014. Limiting windows offset thermal bridge losses using a new insulating coating. Applied Energy 123: 220–231.

Ibrahim M, Wurtz E, Biwole PH, Achard P. December 2014. Transferring the south solar energy to the north facade through embedded water pipes. Energy 78: 834–845.

Brun A, Wurtz E, Hollmuller P, Quenard D. December 2013. Summer comfort in a low-inertia building with a new free-cooling system. Applied Energy 112: 338–349.

Foucquier A, Robert S, Suard F, Stéphan L, Jay A. July 2013. State of the art in building modelling and energy performances prediction: A review. Renewable and Sustainable Energy Reviews 23: 272–288.
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  About a home cooling system developped at Liten (click here).

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