[CoastalCoder]

From some (personal) research I did several years ago, I think good ventilation is by far the biggest concern.

A well-sealed, occupied room can build up significant CO2 levels pretty quickly. In my particular case, one person, not exercising, could bring CO2 above 800ppm (reported) in just a few hours.

So I think lack of ventilation causes way, way more excess CO2 than is caused by recent increases in atmospheric CO2. At least in my suburban neighborhood; maybe it's a lot worse in a dense city.

[kadoban]

My issue with that is that in the summer, ventilation is ~impossible. It's 110 degrees out there, reasonable ventilation would mean either burning out my A/C or living with temps that are far too high.

[christiangenco]

I had this problem living in Dallas: it'll hit 108°F just about every day this week.

I also couldn't spend thousands on an energy recovery ventilator (ERV) installation because I've been living in rental properties.

My solution was to buy an ERV for ~$500 and rig it up to an open window: https://gen.co/air

I've since moved into a condo with a bedroom with no windows and french glass doors so I installed a cat door and mounted the ERV vents to that.

I think there's a lot of money here for someone to build an ERV designed to be window mounted.

[Retric]

Simplest solution is a high efficiency air to air heat exchanger to let you circulate a lot of outside air. They are less efficient when dealing with high humidity, but you can have this as part of your HVAC system and never really think about it.

https://en.wikipedia.org/wiki/Heat_recovery_ventilation

[kadoban]

Interesting, I don't think I knew that was an option. I'll look into it, thanks.

I rent right now, which means I doubt I can, but hoping to buy soonish.

[danans]

If you do this (install an HRV), expect it to cost many thousands, and make sure all your duct-work is running through very well insulated spaces, or you will obviate the heat recovery part, and you will just have a very expensive ventilator.

[kadoban]

Yeah, I'd assume it'd have to wait until I'm going to replace an hvac system anyway. But in my price-range of homes, that's fairly likely to be ~required anyway.

Sounds like something that would be worth it, I spend almost all of my time indoors and we have pets pumping out co2 as well.

[danans]

> But in my price-range of homes, that's fairly likely to be ~required anyway.

TTBOMK, there is nowhere in the US that an HRV or ERV is required by code [1], regardless of the price range. There are a lot of very expensive homes built with no thought to indoor air quality.

In many places in the US, due to higher air-tightness requirements, mechanical ventilation is required, but that can be as minimal as having bath fans and a kitchen extractor fan.

1. Ontario CA requires them on new builds https://www.huskyair.com/blog/newsflash-ontario-is-making-hr.... Maybe Germany also?

[CoastalCoder]

Interesting problem. Mind sharing roughly where that is?

[jasonpeacock]

Due to climate change, that's could be pretty much anywhere it's summer. E.g. check out the UK:

https://www.metoffice.gov.uk/about-us/press-office/news/weat...

[kadoban]

Ah, yeah, Phoenix summers. I believe parts of Texas and some other places are somewhat similar.

In the winter the situation is _much_ better, but probably 4 months out of the year, the outdoors are unlivable.