Common Thread #5: Coping with summer without the cold sweats

With a heatwave that has set in for the second time this year throughout metropolitan France, the population is facing a new critical moment. Indeed, faced with increasingly frequent heat waves, many French people are enduring a new form of fuel poverty: suffering from soaring temperatures in their homes without any response or respite. What can be done?


Flashback to 2003. Remembered for its record-breaking temperatures, the extreme heat wave that year caused the death of 19,000 people, most of them elderly. This dramatic sequence revealed a number of weaknesses in our system :

 Inability to absorb health services,

 Isolation and lack of consideration for our elderly,

 Lack of air conditioning equipment (residential, tertiary pre-2003),

 Unsuitability of the insulating building envelope,

 Insufficient regulatory framework (labour law, construction, etc.)


The shock to public opinion was such that the authorities took a number of measures :

 Creation of the heatwave plan,

 Census of the public affected and identification of public freshening places in the municipalities,

 Implementation of the Solidarity Day,

 Strengthening measures at work.


The following years saw an increase in the widespread use of air conditioning. One of the consequences of the increased use of air conditioning in urban areas (urban heat islands in summer) is to release waste heat into the atmosphere by cooling the interior of buildings... Depending on the number of room air conditioners, the outdoor temperature can increase by up to two degrees. This also has an impact in terms of energy: "According to the UN, by 2050 there will be almost 10 billion people on earth, two thirds of whom will live in cities. With global warming, air conditioning could account for 45% of the world's electricity consumption, compared to 10% today.



In the long term, if cold waves have a significant impact on electricity consumption in France, summer energy consumption also becomes a strategic issue.  It is in this context of foreseeable tensions that the State wished to carry out a new environmental regulation of new buildings (RE2020) provided for by the law "Evolution of Housing, Development and Numerical" (known as the ELAN law).


The notion of "summer comfort" refers to the ability of a building to maintain a pleasant maximum indoor temperature during the summer, without having to resort to an air conditioning system (which can be very energy-consuming, as seen above). Designing buildings that are resilient and adapted to hot weather has therefore become a necessity, bearing in mind that in 2020, one out of two French people said that they had suffered from heat in their homes for at least 24 hours (survey by the National Energy Mediator).


Feedback from RT 2012 indicated that the TIC (Conventional Indoor Temperature) indicator was not sufficiently correlated with the summer discomfort perceived by the occupants and that the indoor summer comfort temperature calculated by all certified software was not always in line with reality (often higher). If this requirement had been a real advantage, we would have observed a control of overheating situations in the new buildings delivered (even though they comply with the indicator). However, this was not the case, and in fact the opposite happened.

The ER 2020 presents an important evolution on the theme of summer comfort, the TIC indicator (Conventional Indoor Temperature) introduces a new requirement on discomfort degree-hours (DH) through a new calculation method that takes into account the effects of climate change on buildings: temperature evolution, more frequent, more intense and longer heat waves. Thus, the update of the meteorological scenarios of the regulation integrates the insertion of a heat wave sequence.


The RE2020 reinforces the threshold of the Bbio coefficient (-30%), it also aims at reducing the RWH energy consumption (-20%). (1)


What is an uncomfortable summer comfort level ? The RE2020 defines 2 thresholds that the temperature inside the building must not exceed to avoid discomfort :

 At night, the temperature threshold is 26°C. 

 During the day, an adaptive temperature threshold between 26° and 28°C.


Regulations are moving forward for new buildings. The renovation project is just as important. The objective set by the Executive for the next 5 years is to renovate at least 700,000 homes per year.


With the climate and pandemic context, our activities have changed considerably. We no longer work as we used to, we no longer teach as we used to, we no longer trade as we used to. We live in a hybrid society, and all our activities take place in buildings and now also in homes. It is clear that buildings have not kept pace with the changes in human activity on a large scale.

It is strange that our buildings and homes, the heart of our daily activities, do not follow the same mutation as our vehicles which, being more and more connected, exchange information and data with their users for more comfort. At the very least, can we imagine making a long journey without air conditioning?


At OGGA, we promote the idea that buildings and homes can be instrumented at a controlled cost. In summer, the connected building can update its own configuration in real time and autonomously.


In the summer, a network of connected sensors can draw a dynamic map of the building that evolves over the course of the energy day and the needs, before resorting to air conditioning.

Depending on the orientation of the building, direct measurements from sensors (thermometer, anemometer, etc.) or weather data flows, the building can activate common or individual equipment according to the best scenario :

 Free-cooling: a system of automatic activation of windows or air handling units to increase the volume of incoming air, facilitating the circulation of outside air to the inside 

 Brise-soleil: automated management of the angle of incidence of the slats in the event of overheating 

 Blinds, awnings, shutters: improving thermal insulation


(1) Bbio: The conventional bioclimatic energy requirement of a building for heating, cooling and artificial lighting

PEC : The Primary Energy Coefficient (PEC) is the total primary energy consumption of a building over a year.  This is one of the key points of the RE2020