We breathe in air that is approximately 21.95% oxygen, 78.09% nitrogen, 0.93% argon, 0.04% (400ppm) of carbon dioxide (CO2). Like CO2 oxygen dissolves in the lungs and is transported to the blood via diﬀusion across the lung tissue (alveoli). The lungs act as a filter to ensure what our body needs from the air is delivered to the bloodstream appropriately so it can oﬀer its life-giving energy to take its course. We can’t see air. But it’s nature and composition provides us with life. No air in our lungs = no life, thus our understanding and respect for it must be held in high regard. We often hear the phrase ‘you are what you eat’ which is very much true regards to nutrition and the additional energy our body requires to thrive.
When we breathe our bodies exhale (purge) the byproduct of what is not serving us. Carbon Dioxide (CO2) is given oﬀ as a by-product of cell metabolism and is carried by the blood through the venous system (veins) to the lungs. Here it is exhaled. The concentration of CO2 in each breath is ~ 3.8% and the ‘average’ person produces approximately two pounds of carbon dioxide each day. More CO2 is given oﬀ by strenuous activity from sedentary (eating) to exercise and dancing.
Now, what happens when the lungs of the body are not aligned with the ‘lungs’ of a building space? To allow us to relate this thought let’s think of our time when sitting in a classroom. Did you ever get sleepy? Lethargic? Feel completely drained of energy? This may have more to do with poor air quality than with overworking your brain. A classroom of 30 students producing 2 pounds of CO2 each day averaged over 8 hours will provide 21 pounds of CO2 in an hour. Each student’s lungs would be responding to this high level of CO2. The average CO2 level the body seeks to align with is 400ppm. If a building’s mechanical ventilation system is not set up properly and insuﬃcient ‘fresh new’ air is not introduced the CO2 levels will only escalate thus creating an environment with ‘poor, unhealthy air quality’.
When CO2 levels become excessive the body moves into an acidosis state. Thus feeling of sleepiness and lethargy set in. The biology of the human body is seeking to work harder to counter these eﬀects thus draining your natural energy stores to allow you to focus and learn in the classroom setting.
Building Regulations and standards around the world all oﬀer similar requirements with regards to occupied buildings and air quality. In Australia, we have AS1668 which oﬀers requirements on ventilation in buildings. There are references to occupant allowances and minimum ‘fresh’ air which must be introduced into space to allow for improved air quality and to counter the eﬀects of human’s natural emission of CO2 from the lungs. You can google HVAC and gather much information on the fundamentals of such systems. The fundamentals are very much quite a basis. For a nominal volume of airflow introduced into a space for “air conditioning” purposes about 10% of that air is delivered “fresh” from outside. Thus you have 90% of the air recirculated back into the same space while 10% is replaced with ‘fresh air’. CO2 concentrations for an occupied space shall seek to fall within an acceptable range of 400-800ppm. If you have ever been in a meeting and have fallen asleep within 30 minutes you can be soured that a mechanical HVAC system with a higher concentration of ‘fresh’ are was likely not provided or installed… or turned on
It’s common sense to suggest here that ‘more fresh air is better’ for the human body. And you would be CORRECT! As mechanical engineers, we are required to balance this regulated fresh air requirement with a desire to provide ‘thermal comfort’. Thermal comfort and air conditioning will be discussed in a separate blog to demystify. However, the more fresh air we introduce to a space the larger the ‘air conditioning’ systems and thus more expensive to purchase, install, operate, and maintain. We will delve into how healthier buildings are possible without large $$ implications in future blogs.
For now, take a deep breath and appreciate the life-giving power of air. Also, have a deep respect and gratitude for the power of the lungs in your body to filter the air and allow this air to be delivered where needed in the body. We are a firm believer in Froster Engineering that when we look to nature we can find many hidden gems that drive greater solutions for our health and wellness. For now, let’s start here. If you have a specific topic of interest and want to know more please e-mail me at jeﬀ@frosterengineering.com.au and we will provide either in a blog, podcast or direct response
We see the light and love inside you. Let’s Inspire Positive Change in the Places We Live Together.