The A/C on a hot day

[Anonymous]

Anonymous wrote:76 is. perfectly reasonable temperature indoors when it's 100 degrees outdoor. Are there really people out there who keep their house at 70 degrees in the summer? Who are you and why do you do this? How terrible for the environment.

Unless you’re not using your AC at all you’re hypocritical knocking others.

[Anonymous]

Anonymous wrote:76 is. perfectly reasonable temperature indoors when it's 100 degrees outdoor. Are there really people out there who keep their house at 70 degrees in the summer? Who are you and why do you do this? How terrible for the environment.

F ck off. The difference between 76 and 70 is negligible, especially if the 70F house has better insulation and a heat pump.

[Anonymous]

Anonymous wrote:

Anonymous wrote:

Anonymous wrote:

Anonymous wrote:

Anonymous wrote:

Anonymous wrote:

Here is the thing though, we try to keep our house cool also -
- all blinds are shut in the day time

This doesn't really help keep the house cool. Once the sunlight is through the glass, it is converted to heat. It hits the inside of the blinds, heats the blinds, and the heat is distributed into the room. It does make it more comfortable for someone who would otherwise sit in the sunshine.

Anonymous wrote:
- we have ceiling fans in all bedrooms

This doesn't cool the house either, but does make it feel cooler under the fan and help distribute the cooling.

Anonymous wrote:
- we got great insulation added in our attic

This is probably the biggest thing you can do to improve comfort and efficiency.

Anonymous wrote:
- we have a whole house fan

This can help in cooling the house down in the evening. But you have to be careful. First, the fan itself has to be thoughtfully installed so it doesn't leak when it's not running. Second, you have to keep an eye on the dew point as well as the temperature. If the dew point outside is higher than inside you will be pulling in humidity which lowers your comfort.

Anonymous wrote:
- we have attic fans not only on the roof of our house, but also we got one installed on the roof of our attached garage. The difference that the attic fans and the extra-extra insulation made is phenomenal.

Attic fans are a terrible idea. They depressurize the attic and end up drawing air from inside the house into the attic. This ends up making your air conditioning work harder. Also, the purpose of attic venting isn't to cool the attic, it's to prevent humidity from accumulating in the attic. The humidity that gets into the attic is coming from inside the house. Pulling more interior air into the attic is actually defeating the purpose of the attic venting.

Anonymous wrote:

Finally, keep your AC unit clean outdoors. Watch YouTube videos to see the DIY.

Indoors too! Change the filters regularly.

Keeping blinds and drapes closed helps keep the house cooler for the same reason insulation keeps the house cooler. It reduces heat loss so the air conditioner doesn’t have to work as hard for the same benefit. Windows the are the biggest heat loss in any house.

Agree that windows are the biggest heat loss in any house. They're also the biggest heat gain in the summer. Blinds don't act like insulation because they have no insulation value. They also allow air to circulate freely so they don't prevent air leaking in, which is a major loss at windows.

But the biggest heat gain from windows in the summer is solar gain, and blinds do nothing to prevent that. The light is already through the glass by the time it hits the blinds and there's no place for the heat it brings to go but into the room. If you're sitting in the room it's more comfortable to not have the light shine directly on you, but the air conditioner doesn't work any less hard. Shutters on the outside, blocking the sunlight from going through the glass at all, are effective. So are awings and even trees.

Cellular shades act as insulation though.

+1 There was a noticeable difference in our heating and cooling bills after installing cellular shades. And ours were just from Home Depot, they weren't anything fancy.

Agree -- at our house adding basic cellular shades reduced the electric bill.

[Anonymous]

Our a/c keeps up, but they're are definitely zones in the house that are warmer or cooler than where the thermostat is located. Upstairs is warmer, basement is cooler, front room with big southwest-facing windows is warmer than the back rooms with lots of shade from backyard trees. The differences are more exaggerated on days when the a/c is running hard. So some rooms might be noticeably warmer on the really hot days, but other rooms will be even cooler than normal.

[Anonymous]

Anonymous wrote:

Anonymous wrote:76 is. perfectly reasonable temperature indoors when it's 100 degrees outdoor. Are there really people out there who keep their house at 70 degrees in the summer? Who are you and why do you do this? How terrible for the environment.

F ck off. The difference between 76 and 70 is negligible, especially if the 70F house has better insulation and a heat pump.

+1. And sorry PP, I can’t sleep if it’s more than 72.

[Anonymous]

Ours seems to be running all the time on these 99 degree days and we just bought this new unit. We prefer 73 or 74 degrees.

[Anonymous]

Anonymous wrote:

Anonymous wrote:You don’t want to let it warm up. If you have the temp set on the tstat to fluctuate a lot, it will run forever to cool the house back down on hot days. Better to set it at a consistent temperature +/- 2 degrees rather than +/- 6 degrees

During hot summer days, do not let the indoor temperature rise very much, because keeping it at a comfortable temperature is less work (also less electricity and less $$$) than letting it warm up and then try to cool it significantly.

If you have a programmable thermostat (e.g., with different settings for sleep, wake, morning, and away), then double-check how all of those various settings, including the time of day for each, are configured.

In winter, we let our indoor temperature rise naturally with sunlight through the windows during the day, because we know it will cool naturally after dark. In summer, by contrast, we keep the inside no warmer than 72F, which is our personal comfort level.

Air conditioners work best when they run continuously. This is true of any electric motor, it's the stopping and starting that's hardest on them. So letting the house heat up, and then having the AC run continuously, uses less electricity and is better for the longevity of the equipment.

But the reason you have AC is for comfort, it's the only reason, you can live without it, people did for hundreds of thousands of years. And letting the house heat up isn't good for comfort. Houses have heat capacity, it takes the AC a long time to wring that heat out of the house, and until it does you're uncomfortable.

[Anonymous]

Anonymous wrote:Ours seems to be running all the time on these 99 degree days and we just bought this new unit. We prefer 73 or 74 degrees.

The AC running continuously in weather like we've had the past few days is a sign that it is appropriately sized. It works best when it's sized so that on the hottest days it runs 100% of the time.

[Anonymous]

What's wrong with 76?

[Anonymous]

If you are concerned about your AC working, stick an instant-read thermometer in a vent to get the temperature of the air coming out. Usually the air coming out is 55-62 degrees.

[Anonymous]

Anonymous wrote:

Anonymous wrote:

Anonymous wrote:

Anonymous wrote:

Here is the thing though, we try to keep our house cool also -
- all blinds are shut in the day time

This doesn't really help keep the house cool. Once the sunlight is through the glass, it is converted to heat. It hits the inside of the blinds, heats the blinds, and the heat is distributed into the room. It does make it more comfortable for someone who would otherwise sit in the sunshine.

Anonymous wrote:
- we have ceiling fans in all bedrooms

This doesn't cool the house either, but does make it feel cooler under the fan and help distribute the cooling.

Anonymous wrote:
- we got great insulation added in our attic

This is probably the biggest thing you can do to improve comfort and efficiency.

Anonymous wrote:
- we have a whole house fan

This can help in cooling the house down in the evening. But you have to be careful. First, the fan itself has to be thoughtfully installed so it doesn't leak when it's not running. Second, you have to keep an eye on the dew point as well as the temperature. If the dew point outside is higher than inside you will be pulling in humidity which lowers your comfort.

Anonymous wrote:
- we have attic fans not only on the roof of our house, but also we got one installed on the roof of our attached garage. The difference that the attic fans and the extra-extra insulation made is phenomenal.

Attic fans are a terrible idea. They depressurize the attic and end up drawing air from inside the house into the attic. This ends up making your air conditioning work harder. Also, the purpose of attic venting isn't to cool the attic, it's to prevent humidity from accumulating in the attic. The humidity that gets into the attic is coming from inside the house. Pulling more interior air into the attic is actually defeating the purpose of the attic venting.

Anonymous wrote:

Finally, keep your AC unit clean outdoors. Watch YouTube videos to see the DIY.

Indoors too! Change the filters regularly.

Keeping blinds and drapes closed helps keep the house cooler for the same reason insulation keeps the house cooler. It reduces heat loss so the air conditioner doesn’t have to work as hard for the same benefit. Windows the are the biggest heat loss in any house.

Agree that windows are the biggest heat loss in any house. They're also the biggest heat gain in the summer. Blinds don't act like insulation because they have no insulation value. They also allow air to circulate freely so they don't prevent air leaking in, which is a major loss at windows.

But the biggest heat gain from windows in the summer is solar gain, and blinds do nothing to prevent that. The light is already through the glass by the time it hits the blinds and there's no place for the heat it brings to go but into the room. If you're sitting in the room it's more comfortable to not have the light shine directly on you, but the air conditioner doesn't work any less hard. Shutters on the outside, blocking the sunlight from going through the glass at all, are effective. So are awings and even trees.

+1
House with many windows with little shade part of the day. No, the AC does not cool it down well when it's 96+ degrees outside.

[Anonymous]

Anonymous wrote:

Anonymous wrote:

Anonymous wrote:76 is. perfectly reasonable temperature indoors when it's 100 degrees outdoor. Are there really people out there who keep their house at 70 degrees in the summer? Who are you and why do you do this? How terrible for the environment.

F ck off. The difference between 76 and 70 is negligible, especially if the 70F house has better insulation and a heat pump.

+1. And sorry PP, I can’t sleep if it’s more than 72.

Don’t be sorry. These people decreeing that 76 is the only acceptable temperature for everybody inspire eyerolls.

[Anonymous]

Anonymous wrote:Our inside temp is 72. At night it goes down to 69.

Here is the thing though, we try to keep our house cool also -
- all blinds are shut in the day time
- we have ceiling fans in all bedrooms
- we got great insulation added in our attic
- we have a whole house fan
- we have attic fans not only on the roof of our house, but also we got one installed on the roof of our attached garage. The difference that the attic fans and the extra-extra insulation made is phenomenal.

Finally, keep your AC unit clean outdoors. Watch YouTube videos to see the DIY.

Thanks to the poster for the science behind what works and does not work in our house. There are three more things that we have that I think helps us
- newer energy efficient windows and doors
- window darkening tint on our west and south facing french windows and storm doors. the tint film is outside and so it does not trap heat inside.
- solar panels on the roof that not only provides free electricity but it also insulates our roof to a degree.

Before we made all these improvements, we used portable room ACs in bedrooms to make it cooler than what our whole house AC was capable of. Unfortunately we do not have a dual AC system and this was our way to make summers better.

[Anonymous]

Anonymous wrote:

Anonymous wrote:

Anonymous wrote:

Anonymous wrote:

Here is the thing though, we try to keep our house cool also -
- all blinds are shut in the day time

This doesn't really help keep the house cool. Once the sunlight is through the glass, it is converted to heat. It hits the inside of the blinds, heats the blinds, and the heat is distributed into the room. It does make it more comfortable for someone who would otherwise sit in the sunshine.

Anonymous wrote:
- we have ceiling fans in all bedrooms

This doesn't cool the house either, but does make it feel cooler under the fan and help distribute the cooling.

Anonymous wrote:
- we got great insulation added in our attic

This is probably the biggest thing you can do to improve comfort and efficiency.

Anonymous wrote:
- we have a whole house fan

This can help in cooling the house down in the evening. But you have to be careful. First, the fan itself has to be thoughtfully installed so it doesn't leak when it's not running. Second, you have to keep an eye on the dew point as well as the temperature. If the dew point outside is higher than inside you will be pulling in humidity which lowers your comfort.

Anonymous wrote:
- we have attic fans not only on the roof of our house, but also we got one installed on the roof of our attached garage. The difference that the attic fans and the extra-extra insulation made is phenomenal.

Attic fans are a terrible idea. They depressurize the attic and end up drawing air from inside the house into the attic. This ends up making your air conditioning work harder. Also, the purpose of attic venting isn't to cool the attic, it's to prevent humidity from accumulating in the attic. The humidity that gets into the attic is coming from inside the house. Pulling more interior air into the attic is actually defeating the purpose of the attic venting.

Anonymous wrote:

Finally, keep your AC unit clean outdoors. Watch YouTube videos to see the DIY.

Indoors too! Change the filters regularly.

Keeping blinds and drapes closed helps keep the house cooler for the same reason insulation keeps the house cooler. It reduces heat loss so the air conditioner doesn’t have to work as hard for the same benefit. Windows the are the biggest heat loss in any house.

Agree that windows are the biggest heat loss in any house. They're also the biggest heat gain in the summer. Blinds don't act like insulation because they have no insulation value. They also allow air to circulate freely so they don't prevent air leaking in, which is a major loss at windows.

But the biggest heat gain from windows in the summer is solar gain, and blinds do nothing to prevent that. The light is already through the glass by the time it hits the blinds and there's no place for the heat it brings to go but into the room. If you're sitting in the room it's more comfortable to not have the light shine directly on you, but the air conditioner doesn't work any less hard. Shutters on the outside, blocking the sunlight from going through the glass at all, are effective. So are awings and even trees.

Heat loss and heat gain are the same thing.

Sure, drapes have an insulation value. All material has some R value, even glass.

Closing drapes and shades in the summer helps keep your house cool. There’s absolutely no doubt about it. Windows are a very low r-value, anything you put in front of the window increases the R value of that space. It’s still far less than even an uninsulated wall, but it’s a logarithmic scale, so the most helpful is going from no r-value (for example, an open window) to positive r value (closing the window). After that, the biggest gain will be increasing the r value of the window… the best way to do this is with drapes which will raise the r value above whatever the best glass windows would provide.

[Anonymous]

Anonymous wrote:

Anonymous wrote:76 is. perfectly reasonable temperature indoors when it's 100 degrees outdoor. Are there really people out there who keep their house at 70 degrees in the summer? Who are you and why do you do this? How terrible for the environment.

F ck off. The difference between 76 and 70 is negligible, especially if the 70F house has better insulation and a heat pump.

76 is still a hotter temperature no matter how much insulation you have or what hvac equipment you have. Believing 76 and 70 don’t feel any different is an opinion but the fact is 76 is actually higher than 70 by a considerable amount… you knew that, right?