What is changing with the RE2020 summer comfort regulations?
The only way to achieve the 2050 carbon neutrality target is by drastically reducing greenhouse gas emissions. For several years, the construction sector has been innovating and finding sustainable, environmentally responsible solutions to build bioclimatic homes that are good to live in all year round, despite increasing temperatures due to global warming. At the same time, the French government is implementing standards that directly affect the design and construction of new buildings.
Summer thermal comfort and the RE2020 environmental regulations
New RE2020 summer comfort regulation
The new RE2020 "summer comfort" regulation fills a gap in the previous regulation. As a reminder, the RT2012 regulations did not consider the cooling requirements of buildings. This means that in some buildings, users cannot cope with the overly high indoor air temperature during periods of exceptionally hot weather, unless an air conditioning system is used. From this point onwards, summer thermal comfort will now be accounted for in RE2020.
In a world that needs to reduce its greenhouse gas emissions, current air conditioning systems have become far too polluting and will not be installed in bioclimatic buildings. Fortunately, we can do without them. Smart solutions for summer comfort are now available, such as using high inertia building materials and installing rainscreen cladding for external insulation, to provide excellent wall insulation.
Cooling requirements and the RE2020 regulations
Air conditioning is criticised when heat waves occur, as it consumes energy to cool the air inside while warming the air outside. In addition, its manufacture and use are responsible for high quantities of greenhouse gases. Climatologists predict that episodes of intense heat will keep happening and average global temperatures will rise.
As a result, the air conditioning used during hot weather will give way to more environmentally friendly and sustainable solutions for cooling the interiors of new buildings. In this respect, summer thermal comfort is now considered in RE2020, as the aim of this Environmental Regulation is to have resilient buildings.
Summer comfort is taken into account when calculating bioclimatic need indicator (Bbio). It is represented by the Degree Hour or DH used to calculate cooling requirements. This new RE2020 indicator assesses the discomfort felt by users of a building, how long it lasts and the intensity of the heat. To avoid reaching the Bbiomax (maximum bioclimatic need) limit, the DH must be considered when designing buildings. This RE2020 summer comfort threshold must be between 26°C and 28°C (max.) between 7.00 am and 10.00 pm and a maximum of 26°C between 10.00 pm and 7.00 am.
Rainscreen cladding to provide comfort in summer
Rainscreen cladding can be fitted to provide summer comfort. Fixed by a façade specialist to the structure of the building, rainscreen cladding provides insulation from the outside. As well as its insulating properties, it has the advantage of not taking up space inside the building and therefore does not reduce its surface area.
Several types of materials are available for rainscreen cladding, such as wood, PVC, stone or even terracotta. Durable, attractive and eco-friendly, clay-based terracotta rainscreen cladding effectively provides the summer comfort required by the RE2020 standards. It's maintenance-free and fully resistant to all kinds of weather, from the very coldest to the very hottest.
Wall insulation for summer comfort
Poorly insulated walls can lead to an increase in indoor temperatures up to levels that users can find very uncomfortable. They can also be vectors of humidity. Good wall insulation provides a pleasant temperature all year round, even when temperatures soar. The RE2020 regulations state that summer comfort cannot be achieved if the insulation is too thin. It therefore recommends a minimum of 300 mm for wall insulation, low floors and roofs. R=1 terracotta bricks, such as the Calibric one from Terreal, meet these performance criteria and guarantee an excellent balance between cost and performance. A proven solution that effectively addresses "critical" points, such as terracotta insulating tiles also contributes to the performance of the building.
In line with the RE2020 regulations for summer comfort, natural and eco-friendly materials are our first choice. Wood fibre, also known as wood wool, is particularly effective and offers excellent thermal resistance and therefore perfect wall insulation.
Managing solar gain for improved summer comfort
In a bioclimatic building, the RE2020 regulations require that as much light as possible comes from natural sunlight. This is why it is preferable to have large, glazed surfaces—particularly south facing ones—to allow the maximum amount of light to penetrate the building. They let in light and also transmit heat. However, what is an advantage in winter becomes a disadvantage in hot weather.
To counter these heat gains and thus ensure high levels of comfort in summer, solar protection should be installed. These systems may be fixed or mobile.
- Fixed sun protection includes sun sails, pergolas, roof overhangs and sunscreen baguettes.
- Mobile sun protection includes roller shutters, gazebos, positionable sunscreen baguettes, shutters and awnings.
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