3 questions to Julien Hans, Energy-Environment Director of CSTB


Public establishment serving innovation, the « Centre Scientifique et Technique du Bâtiment » is fully committed to meeting the challenges of energy and digital transitions in the construction world. Research and expertise, evaluation, testing, certification and even the dissemination of knowledge: its field of expertise covers construction products, buildings and their integration into the heart of the territories.
With more than 900 employees, its subsidiaries and its networks of national, European and international partners, the CSTB group is at the service of all construction players to improve the quality and the safety of buildings.
Member of PEP ecopassport, CSTB carries out in-depth work on eco-construction through projects designed as a whole. Meeting with Julien Hans, Energy-Environment Director of CSTB.

CSTB is a pioneer in terms of environmental declaration: what does the PEP Ecopassport program represent for your establishment and what are your expectations?

Indeed, we participated in the creation of the INIES base, “big sister” of the PEP ecopassport program more than 15 years ago. We registered the first environmental product declaration form there. We therefore know the challenge of mobilizing all manufacturers to make this type of data available. Of course, it is important to carry out qualitative works but also to engage in an environmental policy that makes sense, with increasingly successful technological solutions. Our participation in PEP ecopassort aims to support them in the production and use of this data to carry out building life cycle analyzes. Equipment is more than a stakeholder in the equation of good environmental performance of structures.
The objective is therefore to have as much, as precise and reliable data as possible, from all the manufacturers in the sector. Each manufacturer will thus be able to provide increasingly virtuous solutions. We are on the right path. The challenge is to support them in the stage of declaring this data. This is the evidence of tomorrow: no one would consider constructing a building without knowing its technical properties: acoustic, thermal, mechanical of envelope elements or equipment ... Today, environmental properties have the same level of importance. Construction stakeholders, users, all want to know how products are made and what impact their construction has on the environment. This is an essential factor in the design of a structure.

Can you tell us about your Environmental Performance Laboratory?

The CSTB Environmental Performance Laboratory brings together 4 experts authorized to verify EPD’s of construction materials and products. Concretely, we support manufacturers in preparing their environmental declaration sheets and checking their EPD’s. In some cases, we also make configurators which can be useful for manufacturers to establish their EPD’s more quickly. Instead of producing 1 or 2 EPD’s for a given range, they can carry out specific EPD’s for each product in a range at a controlled cost. They can also change ranges or upgrade their systems without having to start from scratch. There are obviously also configurators for customers of these systems: when you need to provide a complete electrical system for a building, it is more useful to provide, for example, the “dynamic” environmental declaration sheet which can be adapted by example to the lengths of ducts installed and used in the said building. These configurators allow the user to say, "For my project, I can go faster. I was able to configure the solution I was deploying right away and my calculations were done automatically ". This laboratory is housed in our environment division and that directly serves manufacturers to help them in their procedures.

What are your ambitions for the sector in this area over the next 5 years?

A first subject would be based the energy performance warranty of buildings. They are very efficient today, of course, but the challenge is to ensure that these performances are really provided by the building in use. We know that buildings do not behave exactly as imagined when they were designed. In the future, one of the objectives would be therefore to make buildings whose real performance is measured and guaranteed.
Building energy efficient buildings also means contributing to the district, neighbourhoods and territories. For example, better management of collective energy self-consumption or flexibility: these are trends that seem obvious to us and need to be developed.
Thanks to RE 2020, we will be able to have real visibility on greenhouse gas emissions and the impact of our buildings on global warming. Today, the stakeholders still have little order of magnitude to guide them: around one ton per square meter for a building, for the construction phase part and for the emission due to in use phase. How can we move forward and join the carbon neutral trajectory? How to create buildings that strongly reduce greenhouse gases emissions? This is a major challenge for 2025 given the trajectories we want to achieve in order to limit global warming!
Another point concerns the circular economy. We are convinced that with the advent of lifecycle analysis used for carbon calculations, we are getting a lot of very useful data. Buildings will use available renewable materials much better, integrate reuse and recycled products, etc. They will manage recycling better and will also make it possible to design structures which, in the future, will themselves be easier to reuse. This will ultimately limit waste generation and the use of raw materials!
The last angle of attack is obviously to do all this while continuing to progress on buildings that provide good indoor environment quality, quality of air, lighting, acoustics and well-being, quite simply. We will also have to limit our impact on biodiversity, the ambition is ultimately to succeed in environmental issues by succeeding in societal issues.
To get there, we will have to work collectively and united, whether European or national, begins around methods that are shared, accepted, recognized by all as being the right ones. This also implies flexibility so that everyone can make them their own, for example a territory can do things differently from another, by promoting a particular sector according to the ressources available to it. It is the same for comfort in summer, very often specific to a geographical situation. Local and international initiatives should be convergent to allow the evaluation of  progress. It may sometimes annoying that everyone has their own calculator.
The success of most of these topics will be done by keeping in mind that many gains and levers can be operated on a greater scale than building. Take for example the mutualization of surfaces: many urban objects are used very partially. Residential car parks are often empty during the day. At the same time, those of the offices are full. Building parking place in infrastructure is a huge issue in terms of greenhouse gases.
Let’s not neglect all of the things that will need to be addressed on an urban scale. Realizing good buildings will be a prerequisite, but it will not be enough. It’s not just by adding together good products that we make good buildings. It is the same at urban scale: we must not ignore the analysis on global integration.