4 min

Thermal Comfort

Family reading

Multi-comfort buildings maintain an optimal temperature using very little energy. On the inside they are neither too hot nor too cold - we feel comfortable all the time, no matter what we do.

What is thermal comfort

The commonly used definition of "Thermal Comfort" is from the American Society for Heating, Refrigerating and Air Conditioning. It is: "That state of mind that expresses satisfaction with the thermal environment and is determined by subjective evaluation". Thermal sensitivity varies from person to person depending on age (the very young and the very old are particularly sensitive), gender, clothing, activity, cultural habits, etc. However, the basic principles behind thermal comfort are largely universal.

How do you experience thermal comfort

Thermal comfort is experienced through conscious interactions between personal factors and environmental factors.

Physiological aspect

Physiological: the way our body works and interacts with our environment

The regulatory systems in our body are constantly striving to balance our heat exchange with the environment. This is done by speeding up or slowing down our heart rate to change our blood flow and regulate heat distribution. When it's too cold, we start shivering to increase heat production. When it is too hot, we sweat to lower the skin temperature thanks to evaporation.

A comfortable indoor environment limits the effort our organs make to regulate body temperature, creating a good energy balance.

The physical aspect

Physical: the main parameters of the environment around us (air temperature, air humidity, air movement, temperature of the surfaces surrounding the room). In the physical environment, thermal energy (heat or cold) is transferred by conduction, radiation, and convection.

Conduction is energy transfer through a solid body, such as a floor or wall. Convection is the transfer of energy from a solid to an adjacent gas or liquid (air or water). And radiation is the radiant energy emitted by a surface such as a radiator.

Socio-psychological aspect

Socio-psychological: the way we feel in general (if we are tired, stressed or happy) and the type of social environment in which we live.

Individuals' current emotional state, mood, level of fatigue, etc. will influence their experience of the environment. Expectations play an important role in how one experiences the physical world. One might expect the beach to be hot and the mountain lodge to be cool, but more generally, perceptions are likely to be based on their own thermal history. Other environmental factors, such as noise or glare, can affect thermal perception, resulting in an increased feeling of overheating.

What factors affect our thermal comfort

A balanced thermal environment is essential for a sense of comfort.

Concentration, dexterity, and the occurrence of accidents are affected by excessively hot or cold temperatures.

The temperature at the time when we are working and the relative humidity in the space determine the general conditions of comfort. Our bodies are also sensitive to small variations in factors such as air speed and temperature gradient. The impact of local elements of discomfort should be minimized. So, we will be able to fully enjoy the space and make it comfortable for us all the time, regardless of what we are doing.

Thermal comfort is determined by the air temperature, the surface temperatures of the structural elements surrounding the room, the humidity, and the lack of air currents.

Multi-comfort buildings must maintain the ideal indoor temperature throughout the year using very little energy, have walls that are pleasant to touch or lean on regardless of the weather outside, and lack drafts even on the floor.

How to design thermal comfort

Key considerations for thermal comfort include:

Air and ventilation: an airtight space, together with natural or mechanical ventilation, can control the internal thermal environment by managing air exchange with the external environment.

Thermal inertia: the materials used to construct the building (the choice of brick, stone or wood for example) have an impact on how quickly changes in atmospheric conditions are felt.

Using the sun: through its overall shape, orientation, number and size of windows, and the ability of surfaces to reflect heat, the building envelope can control how much heat from the sun (solar energy) is allowed to enter the building.

Isolation: insulating the structural envelope of the building and using thermally efficient windows reduces heat loss in winter and heat gain in summer.

Products and solutions for thermal comfort

Isover and Saint-Gobain offers several product categories that have a direct impact on thermal comfort.
Glazing to let the sun in or block it out depending on the climate
Insulation to reduce heat loss or excessive heat in the summer
Plasters and plasterboards to improve thermal comfort
Smart membranes to improve tightness and moisture management
Plasters that insulate and provide weather protection