3 ms·

If it's still being built then it likely won't start being used until sometime next year and at that point we're back to optimizing for energy usage. It's best

by Sargos 5y ago

If it's still being built then it likely won't start being used until sometime next year and at that point we're back to optimizing for energy usage. It's best to pick a long term metric over a short term win when dealing with a building that will last for decades.

dredmorbius 5y ago
This presumes no further epidemics / pandemics, and discounts benefits to "normal" cold and flu season.
- mlyle 5y ago
  Do you think in normal years we'll still keep classroom windows open in the middle of flu season? Even in temperate California, the costs to classroom comfort and running HVAC to try and overcome outdoor temperatures is ridiculous. Good modern buildings are being built with more ventilation and heat recovery built in. Taking this over windows that open can be a reasonable trade. Yes, on the pandemic axis, many of these buildings may be a little worse than a classroom with a whole long wall of opening windows.
  - deleted 5y ago
    [deleted]
  - dredmorbius 5y ago
    I don't know, though I'd suspect that plans for increased air exchange are being considered. For much of the state, through much of the year, open windows are a reasonably minor consideration. Heat-recovery air-exchange would be more efficient, and again, though I don't know what's being considered, I'd suspect that this is part of current discussions. The chief challenge is that of retrofits vs. new construction. Much of California's school infrastructure is 50--100 years old.
    - mlyle 5y ago
      > I don't know, though I'd suspect that plans for increased air exchange are being considered. In general, newer buildings with sealed windows have pretty good air exchange (with heat recovery) and filtration. > For much of the state, through much of the year, open windows are a reasonably minor consideration. Yah, tell that to me languishing masked a 95 degree classroom between building heat gain and a temperature in the 90s, and now ending up with a 60 degree room. It's workable, but it sucks, and we're wasting a lot of energy just to maintain a few degree delta T from outside with open windows. We've had a few weeks where the open windows have been great, but a lot more crummy weeks. I'm a little jealous of those upstairs in the high school building that don't need to open windows.... and have nice temperatures in their classrooms... and have also had 0 secondary COVID cases. It's also really hard to conduct class when there's music, PE, etc, activities outside. > The chief challenge is that of retrofits vs. new construction. I thought we were talking in the context of a new school building being built without windows that open. That said, windows are nice. If you have a class full of kids that are restless, sometimes opening windows and getting some outside noise or a breeze through the room changes the entire mood. It would be sad to lose that.
      - dredmorbius 5y ago
        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. 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. (Keep in mind that mixing air also mixes infectious particles.) 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. I mention older construction as replacing building stock is a long-term and expensive process. New construction will account for an exceedingly small percentage of all utilised buildings. New construction currently planned or in process should if at all possible incorporate lessons from the COVID-19 pandemic, but that's a drop in the bucket. Retrofits are highly likely. If you want to read further, I'm finding numerous results for a search on school ventilation in new construction and retrofits: https://duckduckgo.com/?q=+school+retrofit+construction+ventilation+covid&ia=web https://duckduckgo.com/?q=+school+retrofit+construction+vent... Among the first of those, from the CDC: Reoccupying a building during the COVID-19 pandemic should not, in most cases, require new building ventilation systems. However, ventilation system upgrades or improvements can increase the delivery of clean air and dilute potential contaminants. Consult experienced heating, ventilation, and air conditioning (HVAC) professionals when considering changes to HVAC systems and equipment. Buildings that provided healthy, code-compliant indoor air quality prior to the pandemic can be improved for pandemic occupancy using less costly interventions. Below is a list of ventilation interventions that can help reduce the concentration of virus particles in the air. They represent a list of “tools in the mitigation toolbox,” each of which can contribute towards a reduction in risk. Implementing multiple tools at the same time is consistent with CDC’s layered approach and will increase overall effectiveness of ventilation interventions. These ventilation interventions can reduce the risk of exposure to the virus and reduce the spread of disease, but they will not eliminate risk completely. ... Open windows and doors, when weather conditions allow, to increase outdoor air flow. Do not open windows and doors if doing so poses a safety or health risk (e.g., risk of falling, triggering asthma symptoms) to occupants in the building. Even a slightly open window can introduce beneficial outdoor air. https://www.cdc.gov/coronavirus/2019-ncov/community/ventilation.html https://www.cdc.gov/coronavirus/2019-ncov/community/ventilat... That cites an industry study by ASHRAE (professional association): https://www.ashrae.org/file%20library/technical%20resources/ashrae%20journal/2020journaldocuments/72-74_ieq_schoen.pdf https://www.ashrae.org/file%20library/technical%20resources/... 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.

by Sargos 5y ago

dredmorbius 5y ago

This presumes no further epidemics / pandemics, and discounts benefits to "normal" cold and flu season.

mlyle 5y ago
Do you think in normal years we'll still keep classroom windows open in the middle of flu season? Even in temperate California, the costs to classroom comfort and running HVAC to try and overcome outdoor temperatures is ridiculous. Good modern buildings are being built with more ventilation and heat recovery built in. Taking this over windows that open can be a reasonable trade. Yes, on the pandemic axis, many of these buildings may be a little worse than a classroom with a whole long wall of opening windows.
- deleted 5y ago
  [deleted]
- dredmorbius 5y ago
  I don't know, though I'd suspect that plans for increased air exchange are being considered. For much of the state, through much of the year, open windows are a reasonably minor consideration. Heat-recovery air-exchange would be more efficient, and again, though I don't know what's being considered, I'd suspect that this is part of current discussions. The chief challenge is that of retrofits vs. new construction. Much of California's school infrastructure is 50--100 years old.
  - mlyle 5y ago
    > I don't know, though I'd suspect that plans for increased air exchange are being considered. In general, newer buildings with sealed windows have pretty good air exchange (with heat recovery) and filtration. > For much of the state, through much of the year, open windows are a reasonably minor consideration. Yah, tell that to me languishing masked a 95 degree classroom between building heat gain and a temperature in the 90s, and now ending up with a 60 degree room. It's workable, but it sucks, and we're wasting a lot of energy just to maintain a few degree delta T from outside with open windows. We've had a few weeks where the open windows have been great, but a lot more crummy weeks. I'm a little jealous of those upstairs in the high school building that don't need to open windows.... and have nice temperatures in their classrooms... and have also had 0 secondary COVID cases. It's also really hard to conduct class when there's music, PE, etc, activities outside. > The chief challenge is that of retrofits vs. new construction. I thought we were talking in the context of a new school building being built without windows that open. That said, windows are nice. If you have a class full of kids that are restless, sometimes opening windows and getting some outside noise or a breeze through the room changes the entire mood. It would be sad to lose that.
    - dredmorbius 5y ago
      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. 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. (Keep in mind that mixing air also mixes infectious particles.) 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. I mention older construction as replacing building stock is a long-term and expensive process. New construction will account for an exceedingly small percentage of all utilised buildings. New construction currently planned or in process should if at all possible incorporate lessons from the COVID-19 pandemic, but that's a drop in the bucket. Retrofits are highly likely. If you want to read further, I'm finding numerous results for a search on school ventilation in new construction and retrofits: https://duckduckgo.com/?q=+school+retrofit+construction+ventilation+covid&ia=web https://duckduckgo.com/?q=+school+retrofit+construction+vent... Among the first of those, from the CDC: Reoccupying a building during the COVID-19 pandemic should not, in most cases, require new building ventilation systems. However, ventilation system upgrades or improvements can increase the delivery of clean air and dilute potential contaminants. Consult experienced heating, ventilation, and air conditioning (HVAC) professionals when considering changes to HVAC systems and equipment. Buildings that provided healthy, code-compliant indoor air quality prior to the pandemic can be improved for pandemic occupancy using less costly interventions. Below is a list of ventilation interventions that can help reduce the concentration of virus particles in the air. They represent a list of “tools in the mitigation toolbox,” each of which can contribute towards a reduction in risk. Implementing multiple tools at the same time is consistent with CDC’s layered approach and will increase overall effectiveness of ventilation interventions. These ventilation interventions can reduce the risk of exposure to the virus and reduce the spread of disease, but they will not eliminate risk completely. ... Open windows and doors, when weather conditions allow, to increase outdoor air flow. Do not open windows and doors if doing so poses a safety or health risk (e.g., risk of falling, triggering asthma symptoms) to occupants in the building. Even a slightly open window can introduce beneficial outdoor air. https://www.cdc.gov/coronavirus/2019-ncov/community/ventilation.html https://www.cdc.gov/coronavirus/2019-ncov/community/ventilat... That cites an industry study by ASHRAE (professional association): https://www.ashrae.org/file%20library/technical%20resources/ashrae%20journal/2020journaldocuments/72-74_ieq_schoen.pdf https://www.ashrae.org/file%20library/technical%20resources/... 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.