Comment by jmartrican | Hacker News Reader

Comment by jmartrican | Hacker News Reader

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I have a 3-story house in the US Northeast. The AC that cools the 2nd and 3rd floor broke. instead of paying to replace it, I'm trying to use passive cooling techniques. The house was built in 1870, before ACs. I suspect the original residents had techniques for keeping it cool. For example, I suspect they had awnings on every window. They kept the windows open on the top floor to create cross winds that pushes the accumulated hot air out of the house. And I suspect they had large trees on the property to create shade and cool the air.

I'm slowly replicating these techniques plus some fans to help push hot air out, including a gabel fan in the attic. I started getting awnings, but not yet on every window, they definitely help. Started planting trees around the property and around the house to create shade. I did get two window ACs, one on 2 ND and one on the 3rd floor, to help when it gets to high 80's and above. I want to see how far I can take this. I'm definitely going with the approach of having more air flow vs. other passive techniques that lock in the air, e.g. closed attics.

It depends on a lot of factors. Many older homes today were converted from barns and other structures that were not designed to optimize climate.

But some homes were indeed designed with climate in mind. The broad rear side might face the south to be heated during winter. The whole house may be configured with one long hallway with windows or screen doors at either end to allow cross breeze. Windows on different floors may be designed to open part way to facilitate cross breeze. The fire place may be located deeper in the house near the bedroom, with subsequent rooms getting farther from the fire so in winter you can shut the doors and only heat your own room with the one fireplace.

An attic fan that can switch between blow and suck is essential to keep cool (and prevent mold using air flow). When it's cool in the early mornings, keep windows open to cool the house, then close them when the sun rises and close shutters. As the temps rise throughout the day, you crack a window upstairs and turn on a window fan (blowing inward) and one window downstairs (blowing outward) to create a downward breeze, or the reverse to pump heat up and out.

My ex hasn't owned an AC in 10 years. She just regulates the doors and windows and has window fans. House is 130 years old

> An attic fan that can switch between blow and suck is essential to keep cool

Why would the AC attic need to suck air in? I never thought of that but will consider it now.

It’s more to remove hot air from the top floor, and allow cooler air to fill the bottom of the house.

> The house was built in 1870, before ACs. I suspect the original residents had techniques for keeping it cool

I think it's tempting to ascribe some lost ancestral knowledge to older house, but to be completely honnest a lot of them weren't designed with thermal considerations in mind (or rather, the thermal efficiency was accidently achieved by following some heuristics).

A lot of these older houses were simply badly insulated. They required a lot of wood or coal to keep warm during the winter or had the occupants wearing layers inside at all times but would cool down quite fast in the summer during the night, only to heat up again during the day.

Good, explicit thermal design appeared with mid-century houses. [0]

[0] https://www.youtube.com/watch?v=Qq-3cZ0cbws

It was substantially cooler on average in 1870.

One thing to keep in mind is that in a lot of old houses, the top story was unfinished attic. It wasn’t livable space because it was too hot in the summer. Your 3rd story was probably like that.

My second story in craftsman bungalow wasn’t finished until the 70s. And that is probably when the window AC was put in that makes it usable in summer. The first story has lots of windows for cross breeze and stays nice in summer.

I live in TX and I sometimes wonder about the same- how did anyone lived here 100 years ago (or why they thought it would be a great idea). The best I could come up with - they just dealt with it. High temperatures meant staying in shade and sweating more. You can do only so much structurally but there are weeks when it doesn’t go below 90 in the night.

My grandfather grew up in a rural area that didn't have electricity or running water until he was a teenager. He would occasionally mention little tips and tricks to how they used to deal with not having some amenities. Many were simply less desirable options. He had these hard, flat wooden chairs that were in his house growing up. He said because of them, they tended to just keep working on the farm until they were tired enough to go directly to bed.

Careful with the shade trees. I had to cut down 2 due to them messing with my foundation. Now I have no shade. It’s difficult to find ones that can shade from a proper distance.

For my NE house I’m looking into solar panels to run AC. It’s two birds with one stone - the panels generate electricity exactly when it’s needed the most, and then, the panels shade the roof, preventing heat from reaching it in the first place.

You will also want a battery. You'll see that most of the time your peak in usage doesn't match your peak in production. And selling back electricity for pennies and then having to buy electricity for way more.

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