French Perspective: Thermal Regulation for New Residential Buildings

This summer, the Innovation Exchange is thrilled to host Alice H. from Paris, France!  Alice is a project manager on energy retrofit of residential buildings at the research division of an energy utility company in France. She’s volunteering at CEE for a few weeks to discover the nice people of Minneapolis and also learn about energy efficiency in American buildings. So far, she’s really enjoying her stay!

Alice is going to write a few blog posts during her stay about what’s happening in France right now. Here are some previews of future topics:

  • A tricky scheme for energy providers who must help homeowners  achieve energy savings over a three-year period or else pay a financial penalty
  • Which incentives are available in France today? For which technologies?
  • A short scan of the rising natural gas technologies in France (micro combined heat and power boiler, natural gas heat pumps, solar water heaters linked to natural gas boiler...)


A first step leading France towards energy positive homes by 2020

In 2007, France organized the  “Grenelle Environment,” a round table for civilians and public services representatives to discuss environmental concerns. They aimed to define the key points of the government policy on ecological and sustainable development issues for the coming years. Among other things and as the building sector is responsible for consuming 42.5 percent of the total energy consumption of France1, these round tables lead to a law introducing RT2012, a new thermal regulation for new residential buildings.

RT2012: A new thermal regulation for new residential buildings

Today, new residential buildings adhere to the thermal regulation of 2005, called ‘RT 2005’. ‘RT2012’, will take effect January 1, 2013. It’s a first step towards a standard that will require new residential buildings to produce more energy than they consume.

What the difference between ‘RT2005’ and ‘RT2012’?

The idea behind these two thermal regulations remains constant: new buildings must consume less energy than the law’s energy target. New RT2005 residential buildings consume on average 150 kWh/m2-yr (47.5 mBTU/ft2-yr) and new RT2012 residential buildings will consume 50 kWh/m2-yr (15.9 mBTU/ft2-yr). In other words, buildings constructed after January 2013 will have one third of the actual energy consumption of buildings that meet the RT2005 standards.


This target of 50 kWh/m2-yr includes energy consumed (Cep) by the following systems: heating, domestic water heating, lighting, air conditioning and all the pumps required to provide the building energy needs. In addition, this target is adjusted according to the location of the house, its indoor area, and finally a coefficient to increase the usage of wood energy or district heating.

According to EIA and its Residential Energy Consumption Survey, the energy consumption of single family houses in the Midwest is 46.3 mBTU/ft2-yr, the same as the French buildings built under RT2005.

Besides the energy consumption target, RT2012 also requires the building’s design to:

  • Minimize its energy needs linked to the building envelope, which is a new standard compared to RT2005. To check this out, a standard called “Bbio” is defined as the ‘bio-climatic need’ of the building and takes into account factors such as the solar orientation of the building. Each new building has to have its Bbio lower than a Bbiomax. Bbio calculations take into account the building’s space heating, lighting, and air conditioning needs. 

  • Ensure a summer thermal comfort: as in RT2005, the “Tic” (or Indoor Comfort Temperature) standard which expresses the conventional indoor building temperature has to be under a value called “Tic reference”. 

Just to give you an idea: in my experience, the heat in France is less hot and humid than the one you experience here. Even South of France has a different heat, more dry I think!

RT2012: not only a Cep + Bbio + Tic but also renewable, air tightness, and mean (monitoring) requirements

Besides the low energy consumption target, the ‘Bbio’ and the summer comfort standards, another RT2012 innovation compared to RT2005 is its introduction of new requirements. Among them, there are:

  • A renewable energy requirement that each new building must be equipped with either: 

o   solar water heater with at least 21.4 ft2 of solar panel  

o   OR a heat pump water heater
o   OR a micro combined heat and power boiler
o   OR have at least 5 kWh/m2-yr (15.9 mBTU/ft2-yr) produced by a renewable energy  (could be with photovoltaic panels for example)

  • The building ratio between window surfaces and wall surfaces has to be greater than to 17% to enure the building will get enough natural light to minimize its lightning needs

  • An air tightness test has to be performed on each new buildings and the result must match the requirement of an air leak lower than 1.97 ft3/hr-ft2 of cold walls under a differential pressure of 4Pa.

  • The energy consumption of space heater, domestic water heater, and air conditioning systems has to be monitored or estimated accurately to give the occupant access to its energy consumption data at least once a month.

What to keep in mind about RT2012?




Next steps: Energy positive new buildings in 2020

RT2012 will lead to a future thermal regulation expected in 2020 (RT2020) which will require all new buildings to produce more energy than they consume! This coming regulation is yet to be defined, but we’ll see some previews of its details as energy efficiency labels are defined over the next several months.

For further information:

The Grenelle Enviroment
Bâtiments neufs: Réglementation Thermique 2012


Related posts:

Women in Energy: Research and Engineering
A Pattern Language for Residential Energy Efficiency
Bicycling Counts: Interview with Visual Storyteller Arlene Birt

Source:
Reglementation thermique 2012- un saut energetique pour les batimen... 


Photo credit:
Creative Commons Attribution 2.0 Generic License  by  Celso Flores 

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