Author Topic: What did you do to keep your house cool?  (Read 4770 times)

Duchess of Stratosphear

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What did you do to keep your house cool?
« on: March 31, 2019, 08:09:34 AM »
My house gets hot in the summer, and I have this sneaking feeling that the summers are only going to get hotter, so how do you keep your house cool? I'm especially interested in what to do for the windows on the west side of my house--awnings? shutters? solar screens? interior shades? I'm also curious about how feasible it is to install an attic fan.

The summers aren't super hot here but when the sun pours in those western windows, it sucks. What have you done to your house to keep the heat out? The cheaper and simpler the better, but I do think this is worth spending a little money on (maybe a few hundred bucks).

Dee18

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Re: What did you do to keep your house cool?
« Reply #1 on: March 31, 2019, 08:19:39 AM »
I bought high quality room darkening curtains from Pottery Barn Kids. (The curtains are sold on the regular PB site, but they were cheaper on the kids site.) They have regular sales and coupons so you can get them at a discount.  Iíve had one set for about 8 years and bought another set this year when I moved to a home with more south and west facing windows.  They make a tremendous difference in how warm my place gets. I just use inexpensive tension rods to hold them up.

Abe

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Re: What did you do to keep your house cool?
« Reply #2 on: March 31, 2019, 09:54:29 AM »
Consider awnings in addition to curtains as they prevent the energy that dissipates as heat inside the house from actually reaching inside during the hottest parts of summer, while letting them in during the evening if needed and during the winter. Curtains alone with white backing can reduce heat gain but a lot of the energy gets dissipated as heat within the house since windows prevent infrared from escaping back out.

Duchess of Stratosphear

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Re: What did you do to keep your house cool?
« Reply #3 on: March 31, 2019, 10:04:23 AM »
I'm really interested in awnings, but it's seriously windy where I live, so I'm a bit afraid of fabric ones. Are wood awnings a thing? I am not seeing many on the Google.

lhamo

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Re: What did you do to keep your house cool?
« Reply #4 on: March 31, 2019, 11:32:48 AM »
We do not have AC.  We are FIREd so have someone at home most days - this is our strategy:

Open all windows at night as long as the temperature outside is cooler than inside.

Keep all shades pulled on the E and S sides of the house in the morning

Open windows on the N and W sides of the house. 

Turn on fans (ceiling fans are worth considering if you don't have them) to circulate cooler air throughout the house as long as outside air temp is cooler than inside.

Close windows as outdoor temp crosses indoor temp.

Pull shades on W side of house.

Sibley

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Re: What did you do to keep your house cool?
« Reply #5 on: March 31, 2019, 04:43:30 PM »
Dependent on many things, but outdoor landscaping can help a lot. Concrete is hot. Plants will help cool things down. And the big trees that shade the whole house make a HUGE impact. Yes, it takes decades to grow them. The later you plant them, the longer it'll be.

Abe

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Re: What did you do to keep your house cool?
« Reply #6 on: March 31, 2019, 05:16:06 PM »
You can purchase durable metal awnings from Costco.

Also, if you donít want to wait for large trees to grow, consider making a trellis and having vines. They will actually function similar to awnings and can withstand high winds

bacchi

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Re: What did you do to keep your house cool?
« Reply #7 on: March 31, 2019, 09:41:24 PM »
Solar screens make a dramatic difference. You can buy supplies and make them yourself easily.

lthenderson

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Re: What did you do to keep your house cool?
« Reply #8 on: April 01, 2019, 06:51:33 AM »
I always plant fast growing native trees on the west and north sides of the house. There is nothing you can do inside that works better than having a house in the shade.

Duchess of Stratosphear

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Re: What did you do to keep your house cool?
« Reply #9 on: April 01, 2019, 07:03:36 AM »
Thanks for the ideas! These windows are high up enough that I would need to plant container plants on the deck to shade them rather than trees, so I'm looking into what kinds of vines I can grow that will get big enough to quickly shade the windows. I am really interested in solar screens, and that seems relatively cheap, so I will do some more googling on that.

Abe, do you have a link to the Costco awnings? All I see are fabric ones.

Does anybody have experience with shutters? They seem expensive....


GuitarStv

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Re: What did you do to keep your house cool?
« Reply #10 on: April 01, 2019, 08:33:37 AM »
Cellular shades coupled with heavy curtains work marvels to keep both light and heat out of the house during the day on the very sunny south side of our home.  Turning off all electronic devices and switching off the power bars that have the wall-wart type charging adapters also makes a big difference (all those suckers put out heat!).

Generally, during the day things are tolerable heat wise . . . where it really impacts us is at night.  We put ceiling fans in all of our bedrooms to make things more comfortable.  I try to spend a lot of time outdoors in the heat so that my body gets more used to it.  That, plus taking a cool shower before bed seems to help me get through the night.  We do try to open windows up when it cools off in the evening, but when humidity gets up into 85 - 100% this strategy doesn't really work very well - slightly cooler but extremely sticky air is still uncomfy to sleep in.  It it's really miserable, I'll go sleep in the basement where it's always a few degrees cooler and more comfortable than in the upper floor bedrooms.


GreenToTheCore

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Re: What did you do to keep your house cool?
« Reply #11 on: April 01, 2019, 11:59:27 AM »
Dependent on many things, but outdoor landscaping can help a lot. Concrete is hot. Plants will help cool things down. And the big trees that shade the whole house make a HUGE impact. Yes, it takes decades to grow them. The later you plant them, the longer it'll be.

I second the mention of concrete.
https://www.apnews.com/fe99da5da0d4455eaf2d96842b83b577

Also relevant:
ďThe best time to plant a tree was 20 years ago. The second best time is now."  - Someone Sometime

Duchess of Stratosphear

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Re: What did you do to keep your house cool?
« Reply #12 on: April 01, 2019, 01:51:03 PM »
I am definitely looking at cellular shades! Luckily, I don't have any concrete around me, which makes me very happy. My gravel road has grass growing up the middle of it, which is fine by me. It's cooler here than in the rest of the state, so I am probably just a big old wimp to be complaining. But the summers are getting hotter, so even here it's not as pleasant as back in the day. I think there are some easy things I can do to cool it down a bit.

Lucky Penny Acres

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Re: What did you do to keep your house cool?
« Reply #13 on: April 02, 2019, 01:33:45 PM »
For a cheap and quick solution - standard aluminum foil - put it on the outside of the windows if you can - it will reflect the heat and stop it from entering your house.

If putting it on the outside won't work well (too high / too much outdoor weather exposure will tear the foil, etc.), then you can put it inside the windows.  Or cover a exact size piece of cardboard with aluminum foil and stick it in the window - then you can take it down whenever you want.

It doesn't look the best, but it really keeps things cool and costs very, very little.

J Boogie

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Re: What did you do to keep your house cool?
« Reply #14 on: April 02, 2019, 02:57:02 PM »
I have a multiprong approach and I enjoy using it quite a bit, up until it reaches time to turn on the minisplit.

1890 Victorian converted to duplex, I live on the bottom floor.

I will be building a screen for the transom window above a really big picture window, which will greatly increase cross ventilation as there is otherwise no operable window in that half of the house. Prior to this, opening my front door would be the only way to allow the cool morning air in. Takeaway for everyone here - identify any chokepoints you have like this and if need be, add a window or build/commission a screen window.

I have a mix of solar and blackout shades on my western windows and a few solar shades on my eastern windows.

I have a very quiet and attractive chrome fan that I use in the morning to coax all the cool air in.

I have really tall double hung windows which can be utilized to let hot air out the tops of them. But I have fixed storm windows on top and screens on the bottom so not sure how much hot air is able to really escape.

On humid days over 85 or so, we close up windows, drawn down blinds, and turn on the minisplit - closing closet doors and doors to rooms deemed unworthy of AC, and ensuring our bedroom door is wide open so we have a nice cool evening for sleeping.

Since the temp drops at night, I do my best to convince my wife we don't need AC at night so I get the ceiling fan to draw air up and the double hungs in their up/down position. I sleep far better knowing I'm not drawing crazy amp hours all night... until it reaches a certain dew point :)


SunnyDays

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Re: What did you do to keep your house cool?
« Reply #15 on: April 02, 2019, 06:06:51 PM »
Is it humid where you live?  That makes a big difference in how tolerable the heat is.  A second hand dehumidifier, even if just in the bedroom will help a lot.  That's mainly what I use the AC for, then shut it off once the humidity is reduced.  If you're going to plant a vine, try pole beans - might as well get something edible for your efforts!  My house faces west, and luckily there are 2 big trees just 20 feet away, which REALLY helps.  You can purchase larger trees rather than waiting for a stripling to grow, or plant a poplar closer to the house, with a slower growing tree further away, then once the poplar gets too big, cut it down and the other tree will be large enough to help cool the house.  If you're planning to stay a while, that is.

tyler.close

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Re: What did you do to keep your house cool?
« Reply #16 on: April 02, 2019, 07:59:33 PM »
For the west facing windows, you want an exterior roller shade like this one:

https://www.amazon.com/Coolaroo-436612-Cordless-Southern-Protection/dp/B005X634VS

It is best to intercept the sunlight before it gets into your house. Once the sunlight comes in, it will heat up whatever it lands on which will radiate heat into the rest of your house. So interior curtains or shades don't really help. They are just another thing inside your house that absorb sunlight and radiate heat. You want this process to happen outside your house.

I put these exterior shades on my western windows and it made a noticeable difference. I added one little tweak to the installation, mounting the roller on wood blocks to create a bigger gap between the shade and my house. I was thinking this would help the breeze blow the heat off the shade so there's less of it to radiate off the shade through the window. 
« Last Edit: April 02, 2019, 11:08:29 PM by tyler.close »

MrSal

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Re: What did you do to keep your house cool?
« Reply #17 on: April 03, 2019, 07:29:18 AM »
My house gets hot in the summer, and I have this sneaking feeling that the summers are only going to get hotter, so how do you keep your house cool? I'm especially interested in what to do for the windows on the west side of my house--awnings? shutters? solar screens? interior shades? I'm also curious about how feasible it is to install an attic fan.

The summers aren't super hot here but when the sun pours in those western windows, it sucks. What have you done to your house to keep the heat out? The cheaper and simpler the better, but I do think this is worth spending a little money on (maybe a few hundred bucks).

Outside shutters and close them during the day. The shutters with angled slats are best because it still allows light in.

Is your attic insulated? You should put some cellulose in the attic. It makes a big difference. I hear, besides shutters, there is a brand of bug screening, where the tiny little holes are angled and can block 90% of direct sunlight. It might be worth it as well

I see some recs of curtains and cellular shades. These do not work because the heat is already inside the house and it will radiate and mix with the air inside.

Insulation, fans, solar screen for insects (also called privacy screens), awnings ... outside shutters, whole house fan (at night or morning once its cooler than inside, you can bring outdoor air inside and make the house cooler and reset the inside temp for the day - very advantageous during a long spell of hot day temperatures).
« Last Edit: April 03, 2019, 07:34:22 AM by MrSal »

J Boogie

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Re: What did you do to keep your house cool?
« Reply #18 on: April 03, 2019, 07:44:04 AM »
So interior curtains or shades don't really help. They are just another thing inside your house that absorb sunlight and radiate heat.

Not so.

Yes, they absorb some sunlight. But their thermal mass is negligent, thus the amount of heat they will radiate is a tiny fraction of the heat that would be absorbed and radiated by flooring or furniture or what have you.

Anecdotes here and official data bear out this truth.

https://www.energy.gov/energysaver/energy-efficient-window-attachments

Agreed that exterior window treatments are more effective, but the difference is nowhere near as dramatic as you suggest.

tyler.close

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Re: What did you do to keep your house cool?
« Reply #19 on: April 03, 2019, 08:53:14 PM »
So interior curtains or shades don't really help. They are just another thing inside your house that absorb sunlight and radiate heat.

Not so.

Yes, they absorb some sunlight. But their thermal mass is negligent, thus the amount of heat they will radiate is a tiny fraction of the heat that would be absorbed and radiated by flooring or furniture or what have you.

Anecdotes here and official data bear out this truth.

https://www.energy.gov/energysaver/energy-efficient-window-attachments

Agreed that exterior window treatments are more effective, but the difference is nowhere near as dramatic as you suggest.

I get a different conclusion from reading that page. The only interior window treatments claimed to be very effective are tight fitting, insulated ones that attempt to turn the window into a wall. About exterior shades, the page says: "They are most effective at reducing solar heat gain."

Once the sunlight enters the house, that energy must become heat, regardless of the thermal mass of what the sunlight falls on. You can try to trap that heat against the window, but that's hard. Most interior window coverings don't have much R value and also allow air flow through and around them. That's not going to be effective. An exterior shade doesn't need to be tight fitting or have R value. That practical difference makes a dramatically better result.

Duchess of Stratosphear

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Re: What did you do to keep your house cool?
« Reply #20 on: April 04, 2019, 07:15:32 AM »
Good stuff! Thanks y'all.

I think one issue with cooling my house is that I have casement windows. From some comments and things I've read, double hung windows are better at letting you control air flow. If I have to replace windows at some point, I'll likely go with double hung, but that's a far future thing.

tyler.close, I like the idea of something on the outside of the house, but a roller shade would likely just get beaten to death by the wind and keep me awake at night unless there is a good way to really secure it. Shutters would probably be better, but damn, they are expensive, and, one window is super high and another window is in a door and shutters would seem awkward there. Still, it could be worth it; cheaper than a minisplit...

J. Boogie, I am curious about your minisplit. What kind of climate do you live in? Where I live can be humid, so even though it's not as hot as other parts of the state, the humidity is often what keeps me from sleeping well in the summer. I'd really like to avoid installing a minisplit, but as I get older, I have less tolerance for clammy sleeping. Do you use it for heat as well?

MrSal, my attic (or attic-like space) is insulated with fiberglass bats (R-30 is what code requires, I think), but I wonder how those hold up over time if critters get up in there and make nests. It's not a large space and I can't get into it, so investigating this would be a major thing that probably won't happen unless the house starts getting super cold in winter.

So for the high upstairs window, I'm thinking something interior works best. For the downstairs window, lots of things could work. For the door, maybe a screen door with the solar screen in it? Plus lots of beans :)


SunshineAZ

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Re: What did you do to keep your house cool?
« Reply #21 on: April 04, 2019, 08:52:44 AM »
You did not say where you are at, but I live in the high desert of SE AZ and we have very large south facing windows.  We had all the windows in the house tinted with ceramic tint and have cellular shades on them.  We also open the windows at night to let in the cool air and then close them in the morning. 

Also, when I was looking for similar advice I searched for "passive solar design" and there are several government sites with good information on ways to reduce your energy usage with small changes, such as plants, shades etc.

J Boogie

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Re: What did you do to keep your house cool?
« Reply #22 on: April 04, 2019, 08:58:29 AM »
Once the sunlight enters the house, that energy must become heat, regardless of the thermal mass of what the sunlight falls on. You can try to trap that heat against the window, but that's hard. Most interior window coverings don't have much R value and also allow air flow through and around them. That's not going to be effective. An exterior shade doesn't need to be tight fitting or have R value. That practical difference makes a dramatically better result.

No argument that the sunlight is going to warm up anything it hits. But if it's making a 2lb shade 80 degrees instead of 70 degrees, that's not going to be very effective at heating the rest of the room. The window jambs and stool will be exposed to the sun (as well as the reflected rays if the shade is bouncing radiation back) and heat up, that's true. They probably weigh 8 lbs or so depending on window size. So, to your point, the jambs and stool will heat the air between the shade and window and that heated air will diffuse. But the average home interior weighs maybe 50,000 pounds so the 10 lbs exposed to the sun represents ~ .0002 percent of the interior being heated by the sun.

So yeah, I'd rather have 0% of my interior being heated by the sun. But I'm just fine with .0002% if it means I can operate it manually from inside, have the aesthetic exterior I want, and not have to worry about wind and rain beating down on it.

Just my take. Obviously my numbers are kind of guesstimated but if there are any fundamental errors feel free to correct them.





J Boogie

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Re: What did you do to keep your house cool?
« Reply #23 on: April 04, 2019, 09:16:50 AM »
J. Boogie, I am curious about your minisplit. What kind of climate do you live in? Where I live can be humid, so even though it's not as hot as other parts of the state, the humidity is often what keeps me from sleeping well in the summer. I'd really like to avoid installing a minisplit, but as I get older, I have less tolerance for clammy sleeping. Do you use it for heat as well?

I live in St. Paul, MN.

Some days get really humid - we used a window unit before we put in the minisplit. It's AC only, which is fine - we've got a great boiler system that provides plenty of heat.

It hasn't yet been figured out how to minimize humidity in a passive way. Maybe we can develop this technology, but until then we've got AC and dehumidifiers. I'd use AC, as dehumidifiers still use plenty of energy and they also create heat.


jps

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Re: What did you do to keep your house cool?
« Reply #24 on: April 04, 2019, 09:51:39 AM »
Do you know how much insulation you have in your attic?

Not only does it keep heat in in the winter, it can help keep the cool in in the summer.

Prairie Stash

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Re: What did you do to keep your house cool?
« Reply #25 on: April 04, 2019, 11:07:57 AM »
Do you know how much insulation you have in your attic?

Not only does it keep heat in in the winter, it can help keep the cool in in the summer.
Dang, beat me to it.

People often forget that insulation works both ways; keeps heat in or out! Insulation cost about 15% of windows and has more impact. That giant solar heater above peoples head lets in more heat than a window.

If you want to spend a lot of money, redo windows. If you want it to be effective, more insulation. R-30 isn't much, the code is a minimum standard, just like getting a D- means you passed.

tyler.close

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Re: What did you do to keep your house cool?
« Reply #26 on: April 04, 2019, 09:05:14 PM »
Just my take. Obviously my numbers are kind of guesstimated but if there are any fundamental errors feel free to correct them.

Again, the mass of various objects is not relevant. The sunlight has the same amount of energy regardless of the mass of the object it shines on. All that sunlight energy becomes heat.

J Boogie

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Re: What did you do to keep your house cool?
« Reply #27 on: April 05, 2019, 08:36:28 AM »
Just my take. Obviously my numbers are kind of guesstimated but if there are any fundamental errors feel free to correct them.

Again, the mass of various objects is not relevant. The sunlight has the same amount of energy regardless of the mass of the object it shines on. All that sunlight energy becomes heat.

To the contrary, the thermal mass of various objects (as well as their efficacy in absorbing the sun's radiation) is the most relevant factor in the entire equation.

Designing so that the sun shines on intentionally heavy materials known to readily absorb solar energy is a major part of passive solar design.

To avoid solar gain, you would do the opposite - ensure the sun does NOT shine on heavy materials that readily absorb solar energy. And you can do that by having the sun shine on a blind instead.

https://www.energy.gov/energysaver/energy-efficient-home-design/passive-solar-home-design

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

https://sciencing.com/materials-absorb-reflect-solar-energy-8878.html

And as long as we're here on this forum...

http://www.mrmoneymustache.com/2011/09/01/what-is-thermal-mass-and-how-can-it-make-you-money/




Duchess of Stratosphear

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Re: What did you do to keep your house cool?
« Reply #28 on: April 05, 2019, 09:20:30 AM »
Do you know how much insulation you have in your attic?

Not only does it keep heat in in the winter, it can help keep the cool in in the summer.
Dang, beat me to it.

People often forget that insulation works both ways; keeps heat in or out! Insulation cost about 15% of windows and has more impact. That giant solar heater above peoples head lets in more heat than a window.

If you want to spend a lot of money, redo windows. If you want it to be effective, more insulation. R-30 isn't much, the code is a minimum standard, just like getting a D- means you passed.

Because of the way my house is built, it would be really hard to redo the "attic" insulation. There isn't away to get in there. I don't know how to explain it, but the upstairs is one big space with a 3 foot hip wall and then the roof starts. There is a flat ceiling in the middle (below the roof peak) where I could cut into the attic space if I had to (and I've thought of doing this to install a whole house fan). I could put more insulation in that part, maybe, but getting somebody to cut into that space sounds expensive. I'm not explaining this well, sorry.

If I had it to do all over again, I would build using passivhaus technology. Oh well.

J Boogie

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Re: What did you do to keep your house cool?
« Reply #29 on: April 05, 2019, 09:36:28 AM »
I don't know how to explain it, but the upstairs is one big space with a 3 foot hip wall and then the roof starts. There is a flat ceiling in the middle (below the roof peak) where I could cut into the attic space if I had to (and I've thought of doing this to install a whole house fan). I could put more insulation in that part, maybe, but getting somebody to cut into that space sounds expensive. I'm not explaining this well, sorry.

It sounds like your the unconditioned spaces are disconnected - like there might be 2-4 sections above the eaves (beyond the knee wall), and then there is one at the peak. Usually they are connected by ventilation chutes which allow air to come up the eaves and out the ridge vent or alternative (as hip roofs don't often lend themselves all that well to ridge venting).

If you live in a snow heavy climate, ice dams and major icicles can potentially be a sign you have inadequate attic insulation - but they can form during a thaw-freeze cycle regardless of insulation too. Widespread ice dams among your neighbors usually means there was a thaw and subsequent freeze and offers little insight to your insulation situation.

TBH, it sounds like you need a minisplit to minimize humidity and sleep comfortably. And a solar array to power it might be a decent idea as well, always a good investment when market valuations are high.

Duchess of Stratosphear

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Re: What did you do to keep your house cool?
« Reply #30 on: April 05, 2019, 11:21:49 AM »
I would love to someday incorporate a PV system, but that is probably out of my budget range right now, which is a shame because I have a good site for it.


tyler.close

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Re: What did you do to keep your house cool?
« Reply #31 on: April 05, 2019, 03:08:35 PM »
Just my take. Obviously my numbers are kind of guesstimated but if there are any fundamental errors feel free to correct them.

Again, the mass of various objects is not relevant. The sunlight has the same amount of energy regardless of the mass of the object it shines on. All that sunlight energy becomes heat.

To the contrary, the thermal mass of various objects (as well as their efficacy in absorbing the sun's radiation) is the most relevant factor in the entire equation.

Designing so that the sun shines on intentionally heavy materials known to readily absorb solar energy is a major part of passive solar design.

To avoid solar gain, you would do the opposite - ensure the sun does NOT shine on heavy materials that readily absorb solar energy. And you can do that by having the sun shine on a blind instead.


That last part is where you've gone wrong. Both high mass and low mass objects turn sunlight into heat. High mass ones just release that heat more slowly, allowing it to be stored for later. So on a sunny winter day, a high mass object can store heat from sunlight into the night. That high mass object will take longer to heat up though. A low mass object will heat up faster in the sunlight, but won't store much heat into the night. It releases its heat right away. Think about sitting on a stone bench first thing in the morning versus a folding camp chair. On a sunny summer day, that low mass object will act the same: heating up fast and releasing the heat fast. If that low mass object is in your house, it is releasing the heat into your house.

Consider also the paradox in your current model of how things work. The sunlight has entered your house. That's energy in your house. You can't make that energy disappear. You can pump the heat out or store it or contain it, but you can't make it disappear. It sounds like you think the blind is making the energy disappear.

Greystache

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Re: What did you do to keep your house cool?
« Reply #32 on: April 06, 2019, 07:43:05 AM »
I installed solar electric panels on my roof three years ago. One of the unanticipated benefits I experienced is that the panels actually shade the roof. My upstairs has a cathedral ceiling (no attic) with just a thin layer of insulation between the ceiling and roof above. The roof used to get very hot in the summer and it would cause the room below to heat up. Now the solar panels shade the roof and keeps the shingles and the room below slightly cooler. There is a small air gap between the panels and the roof so the heat does not transfer from the panels to the roof.

lilsaver

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Re: What did you do to keep your house cool?
« Reply #33 on: April 06, 2019, 11:38:24 PM »
Whole house fans would be a good option, but best to use later in the day to add cool air to the circulation. Check with your utilities provider, sometimes they offer a rebate. Also, tile flooring feels coolers on my feet than carpets/rug. Dress lightly - look especially for light weight cooling fabrics for shirts and pants. Instead of using central AC, you can put a small air conditioner in a small room.

former player

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Re: What did you do to keep your house cool?
« Reply #34 on: April 07, 2019, 03:38:08 AM »
Just my take. Obviously my numbers are kind of guesstimated but if there are any fundamental errors feel free to correct them.

Again, the mass of various objects is not relevant. The sunlight has the same amount of energy regardless of the mass of the object it shines on. All that sunlight energy becomes heat.

To the contrary, the thermal mass of various objects (as well as their efficacy in absorbing the sun's radiation) is the most relevant factor in the entire equation.

Designing so that the sun shines on intentionally heavy materials known to readily absorb solar energy is a major part of passive solar design.

To avoid solar gain, you would do the opposite - ensure the sun does NOT shine on heavy materials that readily absorb solar energy. And you can do that by having the sun shine on a blind instead.


That last part is where you've gone wrong. Both high mass and low mass objects turn sunlight into heat. High mass ones just release that heat more slowly, allowing it to be stored for later. So on a sunny winter day, a high mass object can store heat from sunlight into the night. That high mass object will take longer to heat up though. A low mass object will heat up faster in the sunlight, but won't store much heat into the night. It releases its heat right away. Think about sitting on a stone bench first thing in the morning versus a folding camp chair. On a sunny summer day, that low mass object will act the same: heating up fast and releasing the heat fast. If that low mass object is in your house, it is releasing the heat into your house.

Consider also the paradox in your current model of how things work. The sunlight has entered your house. That's energy in your house. You can't make that energy disappear. You can pump the heat out or store it or contain it, but you can't make it disappear. It sounds like you think the blind is making the energy disappear.

Isn't the point that the blinds limit the volume of space which is heated by sunlight?  As in, just the few cubic inches between the window and the blind rather than the several cubic feet/metres between the window and the floor/walls/furniture?

tyler.close

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Re: What did you do to keep your house cool?
« Reply #35 on: April 08, 2019, 09:20:24 AM »
Isn't the point that the blinds limit the volume of space which is heated by sunlight?  As in, just the few cubic inches between the window and the blind rather than the several cubic feet/metres between the window and the floor/walls/furniture?

A home's exterior walls are five inches thick, air sealed, stuffed with good insulation and yet still allow some heat to pass through them. Do you really think the blinds are blocking any heat? Air moves freely around them and they are paper thin.

GuitarStv

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Re: What did you do to keep your house cool?
« Reply #36 on: April 08, 2019, 10:10:26 AM »
Isn't the point that the blinds limit the volume of space which is heated by sunlight?  As in, just the few cubic inches between the window and the blind rather than the several cubic feet/metres between the window and the floor/walls/furniture?

A home's exterior walls are five inches thick, air sealed, stuffed with good insulation and yet still allow some heat to pass through them. Do you really think the blinds are blocking any heat? Air moves freely around them and they are paper thin.

I do.  The cellular shades we've got significantly block both heat and cold as well as air movement.

In the summer when you pull the blinds up the air on the window side is 10 - 15 degrees warmer than the air on the bedroom side.  In the winter if you leave the shades down for a couple days significant ice will accumulate on the window . . . if you leave them up no ice will accumulate on the windows.

SheWhoWalksAtLunch

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Re: What did you do to keep your house cool?
« Reply #37 on: April 08, 2019, 10:25:24 AM »
I'm really interested in awnings, but it's seriously windy where I live, so I'm a bit afraid of fabric ones. Are wood awnings a thing? I am not seeing many on the Google.

Yes, wood awnings are a thing.  Search for Bermuda Shutters.  They're slatted wood and I've seen them work well on a home I rented in Florida. 

J Boogie

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Re: What did you do to keep your house cool?
« Reply #38 on: April 08, 2019, 12:46:30 PM »
Just my take. Obviously my numbers are kind of guesstimated but if there are any fundamental errors feel free to correct them.

Again, the mass of various objects is not relevant. The sunlight has the same amount of energy regardless of the mass of the object it shines on. All that sunlight energy becomes heat.

To the contrary, the thermal mass of various objects (as well as their efficacy in absorbing the sun's radiation) is the most relevant factor in the entire equation.

Designing so that the sun shines on intentionally heavy materials known to readily absorb solar energy is a major part of passive solar design.

To avoid solar gain, you would do the opposite - ensure the sun does NOT shine on heavy materials that readily absorb solar energy. And you can do that by having the sun shine on a blind instead.


That last part is where you've gone wrong. Both high mass and low mass objects turn sunlight into heat. High mass ones just release that heat more slowly, allowing it to be stored for later. So on a sunny winter day, a high mass object can store heat from sunlight into the night. That high mass object will take longer to heat up though. A low mass object will heat up faster in the sunlight, but won't store much heat into the night. It releases its heat right away. Think about sitting on a stone bench first thing in the morning versus a folding camp chair. On a sunny summer day, that low mass object will act the same: heating up fast and releasing the heat fast. If that low mass object is in your house, it is releasing the heat into your house.

Consider also the paradox in your current model of how things work. The sunlight has entered your house. That's energy in your house. You can't make that energy disappear. You can pump the heat out or store it or contain it, but you can't make it disappear. It sounds like you think the blind is making the energy disappear.

It sounds like you think a 2lb blind heated to 80 degrees by the sun can significantly affect the temperature of a 100,000 lb 75 degree house.

The sun's rays have far different effects on different materials. Stepping on grass vs stepping on blacktop is a good example of this. Your logic is proved wrong by the existence of the urban heat island effect. These heavy, sun-absorbing materials like concrete and steel make everything around them hotter. Your argument would have the grassy green areas at the same temperatures because they're simply releasing their heat right away.

In fact, this is such a factor here that it overrides whether or not something is inside vs outside of a house.

US Dept of Energy:

"Window awnings can reduce solar heat gain in the summer by up to 65% on south-facing windows and 77% on west-facing windows....

In cooling seasons, cellular shades can reduce unwanted solar heat through windows by up to 80%"

The reason for this is that cellular shades are made of such a light, heat-resistant material compared to an awning which must be durable and able to withstand wind, rain, and other elements. The awning will absorb the sunlight and slowly transfer the heat to your house which it is connected to. It is obviously still extremely effective, especially if is light colored or reflective.





tyler.close

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Re: What did you do to keep your house cool?
« Reply #39 on: April 08, 2019, 02:32:48 PM »
A home's exterior walls are five inches thick, air sealed, stuffed with good insulation and yet still allow some heat to pass through them. Do you really think the blinds are blocking any heat? Air moves freely around them and they are paper thin.

I do.  The cellular shades we've got significantly block both heat and cold as well as air movement.

In the summer when you pull the blinds up the air on the window side is 10 - 15 degrees warmer than the air on the bedroom side.  In the winter if you leave the shades down for a couple days significant ice will accumulate on the window . . . if you leave them up no ice will accumulate on the windows.

Congratulations, it sounds like you have tightly installed, well-insulated window treatment. That makes your window more wall-like than the window with loose, paper-thin blinds that I was addressing.

It's hard to know what to think of the 10-15 degree difference in air temperature during the summer. I assume you're running the A/C, so just setting that to a lower temperature is going to make for a bigger temperature difference. I don't know how much work the A/C is doing to maintain that 10-15 degree difference. You could try leaving the blinds open one day to see how much more energy your A/C consumes.

GuitarStv

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Re: What did you do to keep your house cool?
« Reply #40 on: April 09, 2019, 07:25:33 AM »
A home's exterior walls are five inches thick, air sealed, stuffed with good insulation and yet still allow some heat to pass through them. Do you really think the blinds are blocking any heat? Air moves freely around them and they are paper thin.

I do.  The cellular shades we've got significantly block both heat and cold as well as air movement.

In the summer when you pull the blinds up the air on the window side is 10 - 15 degrees warmer than the air on the bedroom side.  In the winter if you leave the shades down for a couple days significant ice will accumulate on the window . . . if you leave them up no ice will accumulate on the windows.

Congratulations, it sounds like you have tightly installed, well-insulated window treatment. That makes your window more wall-like than the window with loose, paper-thin blinds that I was addressing.

It's hard to know what to think of the 10-15 degree difference in air temperature during the summer. I assume you're running the A/C, so just setting that to a lower temperature is going to make for a bigger temperature difference. I don't know how much work the A/C is doing to maintain that 10-15 degree difference. You could try leaving the blinds open one day to see how much more energy your A/C consumes.

We typically do not run the air conditioning during the summer (usually reserving it for the the times in the summer where humidity is at about 90% percent).  10 - 15 degrees difference is the difference between the cool interior (which we cool off by opening windows at night) and the air heated by the sun coming in through the window.

I have occasionally forgotten to close the blinds in the morning in one of the upstairs bedrooms, and temperature will be much warmer in the afternoon in the room.

Aegishjalmur

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Re: What did you do to keep your house cool?
« Reply #41 on: April 16, 2019, 04:44:45 PM »
No AC Brick home in Denver with big windows facing directly E/W so morning and night got alot of glare.

We did a few things:

1. Light blocking curtains with a 2nd set of lighter curtains underneath so when the sun was on the other side we could open the lightblocking curtains and get more light.

2. Ceiling fans.

3. Window fans box fans and cyclone fans. Come evening first we would open up the front(east) windows and side windows and put the fans in pulling the hot air out. Once sun got farther down open the back with fans blowing in creating crossbreeze. We also would have fans in doorways to create more crossbreeze.

4. Get rid of your incandescent/halide bulbs-those get hot.


ender

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Re: What did you do to keep your house cool?
« Reply #42 on: April 16, 2019, 04:50:51 PM »
Air is a very good insulator.

Curtains keeping an air barrier is a decent layer of insulation. The sun puts out a lot of heat too so windows directly facing sun that have curtains can have a significant impact.

Wintergreen78

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Re: What did you do to keep your house cool?
« Reply #43 on: April 18, 2019, 07:13:27 PM »
See if your electricity company has a program to do home energy assessments. In California most of them have free or cheap programs to come out and help identify areas where you can reduce energy usage. They usually offer cheap or free options for things like replacing weather stripping, putting in led bulbs, etc.

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Re: What did you do to keep your house cool?
« Reply #44 on: April 19, 2019, 07:13:30 AM »
So far I've gotten one cellular shade installed, and I'm looking into solar screen that I can put up on the outside of that window as well as growing some plants to shade it.

I do need to do an energy audit! I've looked into it before but haven't taken the leap. I can't afford to do any major insulation upgrades right now, so I sort of just don't want to know how bad it might be.


GuitarStv

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Re: What did you do to keep your house cool?
« Reply #45 on: April 23, 2019, 01:38:49 PM »
My house is the coolest on the block because I live there.

familyandfarming

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Re: What did you do to keep your house cool?
« Reply #46 on: May 20, 2019, 05:02:35 AM »
I donít like the look of heavy drapes and prefer a minimalist look. I have 7 large west facing windows in my living room. The outside wall is stone, while a nice accent to the house, absorbs heat in the summer. My view is nice, but in the summer it gets hot! I cut pieces of white bathroom paneling (teachers also use this material to make white boards for kids to use in math) from 4x8 sheets to fit each window. You can either completely cover the window space or create a panel that allows a bit of space for some light. I store them in a closet in the living room. An added bonus is the panels are great for blocking light when you want to watch TV on a bright day.

I created these panels for my bedroom windows too. There are times you want greater darkness in a bedroom and they do the trick! They are easily stored under the bed. The panels are tons cheaper than drapes and are only out when needed.

expatartist

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Re: What did you do to keep your house cool?
« Reply #47 on: May 20, 2019, 06:12:17 AM »
Our climate is hot and humid much of the year. I use a combination of Japanese sudare which let airflow through even when sun's shining https://www.ebay.com/itm/Japanese-Traditional-Bamboo-Blind-Sudare-Kibune-made-by-Tokiwa-Sudare-/183764474485 (mine are 50-100 years old from a temple and much cheaper), super powerful ceiling fan and bedroom fans, only using AC if things are really bad (like this week) and blackout curtains in the bedroom. The architecture is designed for hot climates before aircon: long, narrow, shaded but well ventilated too like a shotgun house or shophouse design.

brute

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Re: What did you do to keep your house cool?
« Reply #48 on: May 20, 2019, 06:21:24 AM »
My house is the coolest on the block because I live there.


thurston howell iv

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Re: What did you do to keep your house cool?
« Reply #49 on: May 29, 2019, 11:26:23 AM »
We put R49 batts in the attic and then added Gila brand thermal window tint (from Home Depot) to most all of our windows. It made a huge improvement to do the tint. It's not super dark but reflects 73% of the heat and 99% of UV rays.  Made differece of 5-10* in most locations. Also put a light mesh "awning" over the porch and it was a 15* difference... I measured with my thermal laser tool from Harbor freight.

We also have thermal curtains to help cover windows and keep the cool/heat in depending on the weather. Also ceiling fans.

Yesterday it was 96*. A/C set to 76* inside... I only heard it kick on a couple of times to maintain the temp!!