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Currently, energy renovation operations mainly focus on the thermal insulation of the building. But in most cases, the implementation of effective ventilating systsems adapted to the project remains a neglected element.
However, this element plays a key role in maintaining the sanitary and environmental quality of a construction. Between IAQ, thermal comfort and energy consumption, it is an essential factor in the design of a healthy and sustainable building.
I Note: According to the ADEME, a French public agency responsible for implementing energy and ecological transition policies, Ventilation can represent up to 20% of energy consumption in large office buildings.
Some tools now allow to anticipate the issues related to the ventilation strategy from the design phase. So how to determine which ventilating systems to choose as part of an energy renovation? We tell you everything!
If the priority today is thermal insulation of buildings, it must be accompanied by adequate ventilating systems.
And for good reason: a more significant airtightness has the effect of reducing outdoor air infiltration within the building. However, when air exchange is less important, the quality of indoor air is deteriorated.
In this context, it is common to observe an increase in the concentrations of pollutants emitted indoors as well as a rise in humidity. These parameters can, not only have an impact on the health of the occupants, but also on the durability of the structure!
If natural ventilation improves air renewal, it is generally insufficient to guarantee healthy air. It also has a double disadvantage: the opening of windows causes external pollutants to enter the building and at the same time leads to temperature variations.
The implementation of adequate ventilating systems is therefore crucial and particular attention must be paid to its size. An oversized device will create unnecessary investment costs as well as a situation of overconsumption. On the contrary, an insufficient system will not be able to guarantee a healthy and comfortable environment.
Any energy renovation operation must therefore be accompanied by a reflection on the ventilation strategy in order to find the right compromise between health parameters, comfort, and energy savings.
It is estimated that indoor air is up to 8 times more polluted than outdoor air. The reason is that, when the air renewal is insufficient in a building, the atmospheric pollutants present remain trapped inside.
This situation is even more problematic as the building materials chosen for renovation can be non-negligible sources of VOC emissions.
| Note: certain construction materials (coatings, partitions, insulation products…) are subject to a labeling indicating their level of VOC emissions. This allows materials to be classified into four classes (A+, A, B and C) ranging from ‘very low emissions’ to ‘high emissions’. Attention, even if this score is useful for orienting oneself towards less emissive products, it nevertheless has its limits.
Significant airtightness can also lead to increased humidity and, consequently, the development of mold.
In a context of inadequate ventilation, building occupants are then exposed to various harmful substances that can have serious consequences on their health.
High humidity can cause major problems for the building. Indeed, the development of fungi (mold, dry rot…) risks causing the decomposition of certain materials and therefore, severely damaging the building.
From an energy point of view, air charged with humidity will be more difficult to heat than dry air. This situation can lead to an increase in heating needs and therefore, an increase in energy consumption: very unfortunate in the context of an energy renovation project!
More generally, a good ventilation strategy is essential to limit heat loss. Indeed, it ensures sufficient air renewal without having to go through natural ventilation, which can cause significant temperature variations depending on the season.
Surface, occupancy or even materials are all criteria to take into account in your choice of ventilation! Also, determining the most suitable strategy for your project can quickly be complex.
Two options are available in terms of CMV typology:
Airflow rate refers to the quantity of air exchanged in a given space over a defined period, typically expressed in cubic meters per hour (m³/h).
Airflow rates are calculated and determined based on several factors, including the room size, expected occupancy, and the intended use of the space.
Standards exist to define minimum airflow rates depending on the type of room. Spaces with high occupancy, such as meeting rooms or cafeterias, generally require higher minimum values.
A piloting profile defines how ventilating systems are programmed and/or reacts to occupancy variations and the ambient environment.
The ventilation can be constant or modulated, either according to a time schedule, or depending on parameters measured in real-time such as CO2 concentration, humidity or temperature.
With a well-designed control profile, ventilation can be optimized for each space in the building and based on actual use. For example, a meeting room does not need to be constantly 100% ventilated.
Thanks to intelligent piloting, it is therefore possible to significantly reduce the use of ventilating systems, and thus reduce the energy consumption related to its use. Excessive operation of the system is avoided, which extends its life while improving comfort and indoor air quality for occupants.
INDALO® helps you determine the best ventilating systems for your project.
As part of an energy renovation, the use of GTB software is the best way to optimize the design of your project.
INDALO® allows testing several precise ventilation strategy scenarios in your building.
Our solution will take into account a wide range of parameters such as material and furniture emissions, outdoor pollution or even the activities of future occupants. These data feed into its indoor air chemistry calculation engine in order to precisely simulate the building’s IAQ for each tested scenario.
INDALO® will assist you and help you choose the most relevant strategy for your project.
|Note: INDALO® simulations help you meet the IAQ criteria of numerous environmental certifications such as BREEAM, WELL or LEED.
The objective was to assist the Master Builder in determining whether or not it was necessary to set up a AHU within the City Hall and to define the way of ventilating.
The materials, furniture, occupancy and use have been provided. Several different ventilation scenarios were proposed during the study in two distinct areas: the Ground Floor and 1st Floor.
The operation of the ventilation is as follows: 100% of the airflow when occupied, 10% of the airflow when unoccupied. In addition, an F7 supply air filter is applied to the blowing as part of Scenario 1.
Scenario 1: DF ventilation (Master Builder’s recommendations) on the 1st floor and SF on the ground floor
The results in terms of IAQ are excellent but the air renewal seems too important. Such flows are not necessary, especially for the Council Room.
With this scenario, the premises are overventilated: IAQ is very good but energy consumption is excessive.
Scenario 2: SF ventilation by extraction + air entries on the ground floor and 1st floor
The results in terms of IAQ are satisfactory, but fine particle concentrations may exceed the threshold of 10 µg/m³ due to the lack of air filtration at the air entries.
Scenario 3: Natural ventilation through window openings on the ground floor and 1st floor
The results are satisfactory in terms of IAQ. Fine particle concentrations remain below the thresholds. Since the air intake is limited, fewer outdoor pollutants enter compared to Scenario 2. CO₂ levels are also acceptable, except in the Council Room, where occupancy can be high.
Natural ventilation alone is not sufficient to ensure occupant comfort in the Council Room.
Scenarios 4 & 5: DF Ventilation (30 m³h/occupant) in the Council Room on the 1st floor / SF ventilation by air supply in the Council Room on the 1st floor
Both scenarios yield very satisfactory IAQ results. Pollutant concentrations are slightly higher than in Scenario 1.
However, Scenarios 4 and 5 have the advantage of operating with lower airflow rates than Scenario 1, helping to optimize energy consumption.
Scenario 2 offers controlled single-flow air renewal in the Council Room, with filtered air inlets to reduce fine particles. However, it requires regular filter maintenance. This scenario could also be suitable for other areas.
Scenario 3, based on periodically opening windows, is optimal for offices but unsuitable for the Council Room due to potentially high CO₂ concentrations during periods of heavy occupancy.
Finally, Scenarios 4 and 5 optimize IAQ in the Council Room by adjusting airflow rates to limit over-ventilation and, in Scenario 5, integrating a heat diffusion system. Both scenarios enable energy optimization while maintaining very good air quality for occupants.
Suitable for both design and renovation projects, INDALO® therefore helps you determine which ventilating systems to choose, but also in your choice of materials.
Our solution evaluates the concentration of pollutants but also the risks of mold and viral infections.
With INDALO®, you make better choices to limit investment costs, protect the health of occupants and design a more sustainable building.
