RT 2012: A new step forward for Building
RT 2012, promulgated on October 26, 2010, sets a new hurdle to be cleared by the Construction sector. To achieve this new energy performance, regulations set requirements for results in order to render the players liable.
Derived from the Environment Forum known as la Grenelle de l’Environnement, RT 2012 sets a mean level of primary energy consumption at below 50 kWhep/m².year for all new constructions.
> This energy efficiency requirement is based on three principles: bioclimatic design (link "requirements for results"), favoring renewable energies (link to "means requirements") and optimizing equipment used throughout the product's lifecycle (link to installer part). The objective is to discover how to obtain the best energy quality level possible, independently of the choice of energy system.
A new working mode
Unlike prior regulations, RT 2012 defines overall performance requirements to be achieved (link to "requirements for results").
> Therefore, prime contractors are given greater freedom in making their technical solution choices. They have to better take into consideration the energy impact of a construction, right from the design stage.
> It also becomes essential for designers and companies to bring their skills together throughout the project generation process to achieve the required level of performance.
Application and testing of RT 2012
> The Grenelle 2 Law requires the production of a certificate acknowledging that the owner has taken the RT into consideration when requesting a building permit, and on completion of the work.
> Checks will be performed every year on a sample range of new constructions.
RT 2012 is a mandatory point of passage towards demands that are going to become increasingly drastic. By the year 2020, the positive energy house will be the standard!
RT 2012 application dates
RT 2012 application dates
I. Results requirements: global indicators
RT 2012 includes three requirements for results designed to obtain good global performance: a climatic requirement (Bbio), a primary energy consumption requirement (Cep) and a summer comfort requirement.
- Bioclimatic requirement (Bbio)
This indicator limits the energy requirements for central heating, cooling and lighting of the building, apart from the systems subsequently implemented. Expressed in points, the Bbio project must be lower than a Bbiomax level , modulated according to the geographical zone, altitude, type of use and inhabitable surface area. To achieve this requirement, the designer is expected to favor insulation, envelope watertightness, structural inertness, adjacent housing, orientation, compactness, solar contributions and the suitable distribution of the rooms.
- Primary energy consumption (Cep)
This requirement concerns consumption in terms of central heating, cooling, lighting, domestic hot water production and auxiliary systems (pumps and fans) estimated at approximately 50 kWhEP/ m2.year (Cmax). Cmax varies according to the geographical location, the altitude, the use of the building, the average surface area of the housing and its greenhouse effect gas emissions.
- Summer comfort (Tic)
The buildings must guarantee a suitable interior temperature (Ticref), not to be exceeded even after a consecutive period of five very hot days. The designer is encouraged to think about innovation solutions for the walls, solar protection and nocturnal ventilation.
II. Means requirements: a few safeguard measures
RT 2012 includes a few safeguard measures designed to direct the designer toward global optimization solutions.
- Envelope airtightness
RT 2012 makes it mandatory to process the envelope airtightness of individual, adjacent housing or collective housing. This airtightness must be justified by an airtightness test (or a blowing door test).
- Renewable energies
In particular, the regulations call for recourse to renewable energies in private houses (individual solar water heaters, thermodynamic water heaters, micro-cogeneration boiler, etc.).
Low and very low temperature radiant systems are compatible with every type of energy, especially renewable energies and are suitable for houses where the heating requirements are low. ACOME has thus decided to launch Acosense, a reversible very low temperature hydraulic transmitter which is attached to the metal (or wooden) framework of the ceilings or walls.
- Other obligations
It becomes mandatory to deal with thermal bridges. Many of them are generally located in the lower floors over a sanitary void or basement. To avoid them, one interesting submission is the low temperature heated floor. In addition to having a heating capacity, it efficiently processes this type of thermal bridge because it serves as an insulator under the floating screed.
Glazed surfaces must total at least one sixth of the inhabitable surface area to favor natural lighting. Solar protections must also be included.
The installation of heating, cooling and lighting systems for the common parts, shall be equipped with automatic management devices in order to minimize wasteful consumption.
The building must include a tool for measuring or estimating the energy consumed in order to keep the user informed.
Liable prime contractor
Based on the concept of overall performance, RT gives the designer greater freedom and responsibility than the previous regulations for the construction of a building. However, henceforward, he has to take into consideration, upstream, the energy component and the bioclimatic design of this project.
No longer focused on results requirements only, the RT requests that the designer achieve overall performance and allows him to choose the materials, shapes and systems. The latter is encouraged to make the most of existing techniques and apply good practices to achieve 50 kWhEP/m²/year.
For instance, with RT 2005, when the architect decided to construct a very "cutaway" building which was not particularly compact, the reference coefficients allowed this. With RT 2012, the energy demand, expressed as an absolute value, no longer depends on the shape of the building. If the architect chooses a cutout shape which is disadvantageous from an energy standpoint, he must compensate for it to reestablish a state of balance. This means that his thinking must be global and more focused, both in terms of the design of the structure and the choice of the systems.
A new working method
To achieve 50 kWhEP/m²/year, it becomes necessary to incorporate the "energy performance" upstream component of the project, into constructive dialogue between the owner, the prime contractor and the design office. Henceforward responsible for the conformity of its project with construction rules, the prime contractor must also ensure that the site is stringently monitored. He must also justify compliance with thermal regulations in his DPE.
What changes for you
Energy concerns are essentially focused on subcontractors who are responsible for implementation quality. Henceforward, each company must guarantee the overall final results and not just the service.
Taking care of operations
The performance level to be achieved requires greater rigor for every trade involved.
> Participants must install the plant materials. If anything else is installed, it will be necessary to prove equal performance with respect to that initially provided for.
> All of the services provided must comply with the engineering plans and the equipment to be installed in conformity with the prescriptions of the manufacturer (for instance, for heated flooring, the layout of the pipes and the indicated flow rates will be mandatory).
> Good air tightness presupposes careful implementation, compliance with state-of-the-art tools and real rigor concerning the usual air passage points. Openings must be designed upstream to avoid unnecessary drilling during engineering.
This stage consists in setting up and testing the equipment installed on the site in order to guarantee its performance. Its operation, maintenance and servicing must also be organized. The installer must provide users with the documentation and user instructions and even train them to use the equipment correctly.
For the first time in the history of thermal regulations, occupant behavior is taken into consideration. The aim is to optimize energy consumption throughout the life of the building.
Energy consumption of the equipment is equivalent to most of the greenhouse gas emissions generated throughout the building's life cycle. The daily acts of each user have a major impact on global consumption. On the basis of this finding, RT 2012 players have thought about the means of ensuring the optimum possible use of the equipment.
- Involving the occupants
The occupants must be aware of the energy operation of their home and their place of work. To encourage them to adopt virtuous and eco-responsible behavior, regulations require setting up a means of measurement or estimation of building consumption, item by item.
> This obligation concerns central heating, cooling, domestic hot water production and the network of electric outlets (domestic appliances, IT networks …).
> Information must be supplied to the occupants every month within their home.
> If the home is connected to a collective energy production system, the distribution of consumption per inhabitant will be established according to a ratio defined by the owner.