Re:Why don’t we just open the windows? Covid-19 prevention l...
by mlyle on Tuesday November 30, 2021 @01:53PM
(#29395904)
> Much depends on just how open those windows are. "All windows wide open in every classroom" during very warm or very cold weather is excessive
During a pandemic, it makes a lot of sense-- at least for the "extremes" of weather faced here.
> A window cracked open for ventilation, and either at the top of the classroom (warm weather w/ cooling active) or bottom (with heating), and a fan within the room for vertical mixing ... might help.
Might, but who knows how much? How does one weight the ordinary risk of sickness and infection (outside of a pandemic) with energy costs? (Especially when there are less energy-intensive ways to get the ventilation).
> A slight improvement is to have a single exit point (vented with a fan) and rely on structure permiability to introduce fresh air. That's effectively a negative-pressure system.
> From there, exhaust and intake with heat recovery is the next obvious step.
Yes, and pretty quickly from here you're ending up designing a structure without windows that open, so you can ensure that your fancy ventilation system does the right thing, filters don't get fouled, and you're not wasting heat.
> I mention older construction as replacing building stock is a long-term and expensive process.
Well, sure. But we were talking about it in the context of someone complaining a new building doesn't have windows. Older, smaller, poorly sealed buildings are a lot less likely to be retrofitted with no windows than new construction.
> It also recommends on exhaust fans rather than interior circulation fans to minimise strong internal air currents, with intake provide as I've indicated above.
Well, duh.
An otherwise well-sealed building, with a porous wall structure held at a small negative prssure, is effectively a very simple heat recovery ventilation system, too.
During a pandemic, it makes a lot of sense-- at least for the "extremes" of weather faced here.
> A window cracked open for ventilation, and either at the top of the classroom (warm weather w/ cooling active) or bottom (with heating), and a fan within the room for vertical mixing ... might help.
Might, but who knows how much? How does one weight the ordinary risk of sickness and infection (outside of a pandemic) with energy costs? (Especially when there are less energy-intensive ways to get the ventilation).
> A slight improvement is to have a single exit point (vented with a fan) and rely on structure permiability to introduce fresh air. That's effectively a negative-pressure system.
> From there, exhaust and intake with heat recovery is the next obvious step.
Yes, and pretty quickly from here you're ending up designing a structure without windows that open, so you can ensure that your fancy ventilation system does the right thing, filters don't get fouled, and you're not wasting heat.
> I mention older construction as replacing building stock is a long-term and expensive process.
Well, sure. But we were talking about it in the context of someone complaining a new building doesn't have windows. Older, smaller, poorly sealed buildings are a lot less likely to be retrofitted with no windows than new construction.
> It also recommends on exhaust fans rather than interior circulation fans to minimise strong internal air currents, with intake provide as I've indicated above.
Well, duh.
An otherwise well-sealed building, with a porous wall structure held at a small negative prssure, is effectively a very simple heat recovery ventilation system, too.