Last week in this series we covered the evolution of heating and cooling technology in the US. This week we’ll wrap up by looking at ventilation, and the concept of the building envelope. Ventilation In the 19th century, one of the primary concerns about the indoor environment was getting sufficient ventilation. Scientific theory at the time held that without proper ventilation, carbon dioxide and other pollutants would build up in indoor air and cause it to become ‘vitiated’, in turn causing a variety of negative health effects. In 1836, the British doctor Richard Baron Howard wrote
In a sense they were right that “vitiated air” was responsible for tuberculosis, given that we now know that tuberculosis (like flu and COVID) is an airborne disease, and one of the best ways to prevent airborne disease is through constant replacement of the air! They were wrong about the mechanism, but right about the things to do to prevent tuberculosis.
Modern buildings use carbon dioxide sensors to monitor indoor air quality, with some studies showing negative cognitive effects at even 1000 ppm. There is disagreement on this subject, and 1000 ppm would probably require more ventilation (and energy) than the current configuration of most office buildings. https://dash.harvard.edu/handle/1/27662232
In a sense they were right that “vitiated air” was responsible for tuberculosis, given that we now know that tuberculosis (like flu and COVID) is an airborne disease, and one of the best ways to prevent airborne disease is through constant replacement of the air! They were wrong about the mechanism, but right about the things to do to prevent tuberculosis.
Great articles!
If houses are increasingly sealed envelops, what are the strategies for ventilating them in an energy efficient way?
Thanks for writing these two in depth posts on the indoor climate of buildings.
One thing I’d like to dispute is that ‘building a home to extremely high energy efficiency standards has at best an extremely long payback period’.
In this study, the cost uplift from building to Passivhaus standards (generally considered to be the hallmark extremely high energy efficiency standard) is only 0.9%: https://aecom.com/without-limits/article/debunking-the-myth-that-passivhaus-is-costly-to-achieve/
In this other one, they show how costs used to be substantially higher, but learning by designers and contractors means they expect the cost uplift to stabilise around 4%: https://passivhaustrust.org.uk/UserFiles/File/research%20papers/Costs/2019.10_Passivhaus%20Costs(1).pdf
Would you recommend reading *The Home Comfort Book?*
Modern buildings use carbon dioxide sensors to monitor indoor air quality, with some studies showing negative cognitive effects at even 1000 ppm. There is disagreement on this subject, and 1000 ppm would probably require more ventilation (and energy) than the current configuration of most office buildings. https://dash.harvard.edu/handle/1/27662232
https://doi.org/10.3357/AMHP.5010.2018