Keep garage 'cooler' during summer

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Thorsbane
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Keep garage 'cooler' during summer

Post by Thorsbane » Tue Jul 02, 2019 10:03 am

Does anyone have personal recommendations on how to release all this summer heat from our garage during the summer? It faces west and surely transfers substantial heat to our interior since there is little to no ventilation. Do people install fans in their garage to mitigate?

adamthesmythe
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Re: Keep garage 'cooler' during summer

Post by adamthesmythe » Tue Jul 02, 2019 10:19 am

A garage fan running continuously will tend to make the garage temperature equal to that outside. If it is very hot outside it will be hot in the garage most of the day.

Apart from actually air-conditioning the garage- you can insulate the garage door and put a garage fan on a timer so it only works at night.

Maybe have a look at the Phoenix forum on city-data.com to see if there are any better ideas.

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Just sayin...
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Re: Keep garage 'cooler' during summer

Post by Just sayin... » Tue Jul 02, 2019 10:20 am

I have a south-west facing garage door and it gets HOT inside during summer afternoons - especially when bringing hot vehicles in. I put a locking security screen door on the opposite side of the garage (the cooler side), and am installing a thermostatically-controlled fan in the ceiling. When it gets hotter inside than outside, the plan is to have the fan suck the heat out of the top of the garage - pulling cooler air inside from the outside via the security screen. Project is 50% complete right now, but my neighbor has this system installed (my inspiration for this project), and it works pretty well.

quantAndHold
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Re: Keep garage 'cooler' during summer

Post by quantAndHold » Tue Jul 02, 2019 10:23 am

It’s hard to tell without more information. Is this a freestanding garage, or built into the house? Is there any insulation?

In general, the same stuff that works for a house would work for a garage. The two most cost effective things would be to improve the insulation, and add a ventilation system. There are active ventilation systems that are controlled with a thermostat, so the fan comes on when it gets hot.

If the problem is that the garage is basically inside the house and when it gets hot the house gets hot, better insulation in the walls between the garage and the house would help.

livesoft
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Re: Keep garage 'cooler' during summer

Post by livesoft » Tue Jul 02, 2019 11:47 am

Plant trees that will eventually create a shaded garage. If a garage wall is getting direct sunlight, then put a fence or hedge there to shade the wall.
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bryanm
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Re: Keep garage 'cooler' during summer

Post by bryanm » Tue Jul 02, 2019 12:05 pm

Long shot, but here's an out-of-the box answer: Do you have an older electric water heater in the garage? If so, replace it with a heat pump-based water heater (which acts as an A/C for the garage while heating your water). You'll save electricity vs. a traditional heater. In addition, many locales have (or at least used to have) rebates that reduce or eliminate the cost of the heater and installation.

HomeStretch
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Re: Keep garage 'cooler' during summer

Post by HomeStretch » Tue Jul 02, 2019 12:10 pm

In addition to suggestions from other posters...
apply heat reflecting film on windows in the west-facing walls or garage doors.

chambers136
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Re: Keep garage 'cooler' during summer

Post by chambers136 » Tue Jul 02, 2019 12:13 pm

I put a screen in the attic access hatch and open the garage windows (blocked to only allow about 6" of opening). This cooled the garage significantly. I don't think it's generally recommended due to the possibility of carbon monoxide entering the area above the living space in case a vehicle is left running. I take that risk though- we have numerous CO detectors throughout the house.

adamthesmythe
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Re: Keep garage 'cooler' during summer

Post by adamthesmythe » Tue Jul 02, 2019 12:35 pm

bryanm wrote:
Tue Jul 02, 2019 12:05 pm
Long shot, but here's an out-of-the box answer: Do you have an older electric water heater in the garage? If so, replace it with a heat pump-based water heater (which acts as an A/C for the garage while heating your water). You'll save electricity vs. a traditional heater. In addition, many locales have (or at least used to have) rebates that reduce or eliminate the cost of the heater and installation.
This wouldn't make any difference, unless the new water heater has better insulation than the old. (Possible, I suppose).

Think about the thermodynamics. The water heater works by depositing thermal energy into the water. Some heat leaks out through the insulation.

If there is a compressor outdoors then the effect is equal to any other heat source. If the compressor is in the garage (do they do this??) then it is worse.

The most likely heat inputs are through the garage door (not always insulated, and even if insulated probably not that well) and periodic heat inputs (opening the garage door, driving a car with hot engine in).
Last edited by adamthesmythe on Tue Jul 02, 2019 12:38 pm, edited 1 time in total.

RetiredAL
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Re: Keep garage 'cooler' during summer

Post by RetiredAL » Tue Jul 02, 2019 12:37 pm

Thorsbane wrote:
Tue Jul 02, 2019 10:03 am
Does anyone have personal recommendations on how to release all this summer heat from our garage during the summer? It faces west and surely transfers substantial heat to our interior since there is little to no ventilation. Do people install fans in their garage to mitigate?
In modern ( less than 40 years old ) homes, the wall(s) between the house and garage are insulated to the same standards as any other exterior wall in the home. Thus having a hot garage will have minimal or no impact to inside temperature ( or A/C load ) of the home when compared to any other exterior wall.

IMO, a south or west facing un-shaded wall with its windows will have much more impact to interior heat gain than a garage to interior wall will.

Hockey10
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Re: Keep garage 'cooler' during summer

Post by Hockey10 » Tue Jul 02, 2019 12:38 pm

When you arrive home on a hot day, park the car on the driveway for several hours until the car cools off. Parking a car with a hot engine in an already hot garage will only make the heat worse.

anon_investor
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Re: Keep garage 'cooler' during summer

Post by anon_investor » Tue Jul 02, 2019 12:44 pm

It probably depends how safe your neighborhood is and the garage configuration, but most houses here have detached garages that are behind the houses and people just leave their garage doors open...

littlebird
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Re: Keep garage 'cooler' during summer

Post by littlebird » Tue Jul 02, 2019 12:50 pm

Hockey10 wrote:
Tue Jul 02, 2019 12:38 pm
When you arrive home on a hot day, park the car on the driveway for several hours until the car cools off. Parking a car with a hot engine in an already hot garage will only make the heat worse.
This is a good idea that I’m going to try. I believe an uninsulated door is better in hot places, to alleviate this problem, but my current home has an insulated door.

Winston19
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Re: Keep garage 'cooler' during summer

Post by Winston19 » Tue Jul 02, 2019 12:50 pm

Is the roof properly ventilated? When we re-roofed our detached garage we added roof vents. It doesn't heat up nearly as much now.

bryanm
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Re: Keep garage 'cooler' during summer

Post by bryanm » Tue Jul 02, 2019 12:51 pm

adamthesmythe wrote:
Tue Jul 02, 2019 12:35 pm
bryanm wrote:
Tue Jul 02, 2019 12:05 pm
Long shot, but here's an out-of-the box answer: Do you have an older electric water heater in the garage? If so, replace it with a heat pump-based water heater (which acts as an A/C for the garage while heating your water). You'll save electricity vs. a traditional heater. In addition, many locales have (or at least used to have) rebates that reduce or eliminate the cost of the heater and installation.
This wouldn't make any difference, unless the new water heater has better insulation than the old. (Possible, I suppose).

Think about the thermodynamics. The water heater works by depositing thermal energy into the water. Some heat leaks out through the insulation.

If there is a compressor outdoors then the effect is equal to any other heat source. If the compressor is in the garage (do they do this??) then it is worse.

The most likely heat inputs are through the garage door (not always insulated, and even if insulated probably not that well) and periodic heat inputs (opening the garage door, driving a car with hot engine in).
I may not have been clear--I'm suggesting replacing a traditional electric water heater, which converts electricity into water heat, with a heat pump water heater, which converts heat pulled from the air insight the garage into water heat. The more ambient heat input into the garage, the more efficiently the heat pump pulls that heat from the air into the tank. (Yes, there is heat loss back into the garage, but most of the heat goes into the pipes.)

We can suss out the thermodynamics if you like, but I can tell you empirically that a heat pump water heater acts as an air conditioner for the space in which it sits, while acting more efficiently than traditional electric heaters (so long as ambient heat is moderately above freezing).

Coburn
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Re: Keep garage 'cooler' during summer

Post by Coburn » Tue Jul 02, 2019 12:58 pm

Ridge venting.

When I had my roof redone some years ago, the ridge venting they put in as part of that process helped tremendously.

Installing active cooling (fans) or planting shade tree will also help of course. The latter will take some years before any benefit. :)

p14175
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Re: Keep garage 'cooler' during summer

Post by p14175 » Tue Jul 02, 2019 1:02 pm

When we lived in the Phoenix AZ metro area we had a vent in the ceiling of the garage and turbines on the roof. It helped a bit in reducing temperature. Big trees shading the garage in the afternoon helped the most.

Where we are at now, in southern AZ, our two garages are detached. One garage has a swamp cooler, the other has a window air conditioning unit. Both work well, but southern AZ is about 10F-20F cooler than the PHX area at peak times and the humidity is much lower during the monsoon season.

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dm200
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Re: Keep garage 'cooler' during summer

Post by dm200 » Tue Jul 02, 2019 1:07 pm

Perhaps a temperature activated ventilating fan - pulling in air from where it likely to be the lowest temperature. Power the fan using solar.

Might a very light color roof help?

wootwoot
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Re: Keep garage 'cooler' during summer

Post by wootwoot » Tue Jul 02, 2019 1:47 pm

Swamp cooler

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dm200
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Re: Keep garage 'cooler' during summer

Post by dm200 » Tue Jul 02, 2019 2:10 pm

I will also second the idea of planting tree(s) to shade the garage. Even slow growing trees can start to help in just a few years. Vegetation on the ground next to and near the garage might also help to absorb the heat and reduce heat bouncing off the ground and heating the garage.

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Sandtrap
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Re: Keep garage 'cooler' during summer

Post by Sandtrap » Tue Jul 02, 2019 2:21 pm

1. Swamp cooler if in the Southwest, or dry climates. Split system A/C Unit.
2. Attic Gable Vent fan. Can be on thermostat auto and/or secondary switch in garage for as needed.
3. Insulate the garage attic.
4. Ensure adequate frieze board venting or other inlet venting in the attic besides the gable vents.
4b. Ridge venting.
5. Insulate the exterior wall that heats up. It can be a hassle but rigid silver back insulation panels can be installed on the interior of a wall like that and it makes a huge difference.
6. Be sure the garage door has a seal so no excess hot air blows in.
7. If no windows, install at least 2 to get cross flow.
8. Shade trees.
Last edited by Sandtrap on Tue Jul 02, 2019 2:30 pm, edited 1 time in total.
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iamlucky13
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Re: Keep garage 'cooler' during summer

Post by iamlucky13 » Tue Jul 02, 2019 2:28 pm

Is the garage insulated?

Are there soffit vents and either a gable or ridge vent?

If not, these options should be considered. A gable vent with a fan that runs only at night could help significantly.

A combination of soffit vents, ridge vents, and a baffle above any insulation to ensure a good air gap between the soffit and the ridge vents not only help keep the interior cooler, but also extend the life of most roofing materials.
adamthesmythe wrote:
Tue Jul 02, 2019 12:35 pm
bryanm wrote:
Tue Jul 02, 2019 12:05 pm
Long shot, but here's an out-of-the box answer: Do you have an older electric water heater in the garage? If so, replace it with a heat pump-based water heater (which acts as an A/C for the garage while heating your water). You'll save electricity vs. a traditional heater. In addition, many locales have (or at least used to have) rebates that reduce or eliminate the cost of the heater and installation.
This wouldn't make any difference, unless the new water heater has better insulation than the old. (Possible, I suppose).

Think about the thermodynamics. The water heater works by depositing thermal energy into the water. Some heat leaks out through the insulation.

If there is a compressor outdoors then the effect is equal to any other heat source. If the compressor is in the garage (do they do this??) then it is worse.
The compressor is usually mounted on top of the water heater, so inside the garage, which is exactly why it is better. Because it is a heat pump, not a resistance heater, it pulls heat from the air inside the garage, transfers it to the water, then you run the water to your shower and the heat goes down the drain.

For the same reason, owners who locate them indoors often complain about the room they are installed in being cold as a result. My brother has one in his garage, and leaves the door between the garage and kitchen open during the summer to benefit from the cooling effect, since his house does not have AC.

In addition to cooling the room they are in, they can potentially save as much as 2/3 of your water heating cost, and unsurprisingly, work best in warm climates.

quantAndHold
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Re: Keep garage 'cooler' during summer

Post by quantAndHold » Tue Jul 02, 2019 4:39 pm

RetiredAL wrote:
Tue Jul 02, 2019 12:37 pm
In modern ( less than 40 years old ) homes, the wall(s) between the house and garage are insulated to the same standards as any other exterior wall in the home. Thus having a hot garage will have minimal or no impact to inside temperature ( or A/C load ) of the home when compared to any other exterior wall.
This is correct, IF the builder did the insulation correctly. Which isn’t always the case. The problem might be an issue with the workmanship on the insulation when the place was built. It might be worth getting a home energy audit to see what’s going on.

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lthenderson
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Re: Keep garage 'cooler' during summer

Post by lthenderson » Wed Jul 03, 2019 8:27 am

Thorsbane wrote:
Tue Jul 02, 2019 10:03 am
Does anyone have personal recommendations on how to release all this summer heat from our garage during the summer? It faces west and surely transfers substantial heat to our interior since there is little to no ventilation. Do people install fans in their garage to mitigate?
In our west facing garage, I just plumbed a register vent from our house heating and air conditioning system. (There is no return vent for obvious reasons.) It tends to keep our garage around 10 to 15 degrees cooler than the outside temperature during the summer and probably 20 to 30 degrees warmer during the winter. I don't know why the temperature difference is more during the winter other than the solar gain from the west facing garage door windows is contributing versus hurting as they do during the summer.

random_walker_77
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Re: Keep garage 'cooler' during summer

Post by random_walker_77 » Wed Jul 03, 2019 9:24 am

lthenderson wrote:
Wed Jul 03, 2019 8:27 am

In our west facing garage, I just plumbed a register vent from our house heating and air conditioning system. (There is no return vent for obvious reasons.) It tends to keep our garage around 10 to 15 degrees cooler than the outside temperature during the summer and probably 20 to 30 degrees warmer during the winter. I don't know why the temperature difference is more during the winter other than the solar gain from the west facing garage door windows is contributing versus hurting as they do during the summer.
Caution -- your air handler is sucking air out of the house (through the return vents) and pushing some into the garage. That's going to leave your house with negative pressure, and your garage with positive pressure. This is going to tend to push some garage air into the house, but not necessarily depending on how easily air from the outside connects to your garage and to your home's interior.... bottomline, I doubt this meets code, and you should make sure you've got carbon monoxide detectors in your house, including one near the garage.

Regarding why it's hotter in the winter -- is the duty cycle of the furnace in the winter higher than the a/c during the summer?

misterno
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Re: Keep garage 'cooler' during summer

Post by misterno » Wed Jul 03, 2019 9:56 pm

I bought this

It made a huge difference

https://www.lowes.com/pd/Owens-Corning- ... -L/1243805

br0nd
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Re: Keep garage 'cooler' during summer

Post by br0nd » Wed Jul 03, 2019 10:12 pm

Here is my two cents..
I live in the hot Southwest... All my homes prior to this one had uninsulated attached garages and were unbearable in the summer.
My new home has an insulated garage.. Walls, attic, garage door and it was better but still miserable. But I made a few changes and now its as good as a non air-conditioned garage can get..
1) I installed vents at the bottom of my insulated garage door (painted the same color as my door so basically invisible) to let in cooler air
2) installed this vent fan at the top of my garage wall with a smart thermostat that only turns the fan on when it's hotter inside the garage than inside
https://www.homedepot.com/p/iLIVING-175 ... /207174645



My garage is now generally 10 degrees cooler than the outdoors during peak heat of the day.

4nwestsaylng
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Re: Keep garage 'cooler' during summer

Post by 4nwestsaylng » Wed Jul 03, 2019 11:15 pm

Thorsbane wrote:
Tue Jul 02, 2019 10:03 am
Does anyone have personal recommendations on how to release all this summer heat from our garage during the summer? It faces west and surely transfers substantial heat to our interior since there is little to no ventilation. Do people install fans in their garage to mitigate?
When I lived in Phoenix, I bought an evaporative cooler (aka "swamp cooler"), full size, side mount, and attached it through a side wall of the garage. You can even get a thermostat to turn it on. It does a great job only if you are in a low humidity area such as the desert.Much less expensive to run than air conditioning for a garage. Otherwise as posted above, a thermostat vent fan. I had one in the attic, and kept the attic hatch in the garage open so the heat would flow to the attic and then out.

I finally solved my problem by leaving Phoenix.

THY4373
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Re: Keep garage 'cooler' during summer

Post by THY4373 » Thu Jul 04, 2019 1:22 am

adamthesmythe wrote:
Tue Jul 02, 2019 12:35 pm
bryanm wrote:
Tue Jul 02, 2019 12:05 pm
Long shot, but here's an out-of-the box answer: Do you have an older electric water heater in the garage? If so, replace it with a heat pump-based water heater (which acts as an A/C for the garage while heating your water). You'll save electricity vs. a traditional heater. In addition, many locales have (or at least used to have) rebates that reduce or eliminate the cost of the heater and installation.
This wouldn't make any difference, unless the new water heater has better insulation than the old. (Possible, I suppose).

Think about the thermodynamics. The water heater works by depositing thermal energy into the water. Some heat leaks out through the insulation.

If there is a compressor outdoors then the effect is equal to any other heat source. If the compressor is in the garage (do they do this??) then it is worse.

The most likely heat inputs are through the garage door (not always insulated, and even if insulated probably not that well) and periodic heat inputs (opening the garage door, driving a car with hot engine in).
I had a heat pump hot water heater in my garage at my old house and I can assure you it cooled and even more importantly dehumidified my garage. It was great. Most of the heat removed for the garage was put in the hot water which was used in the house it did not leak back into the garage if it did it wouldn't have been much of a hotwater heater. That said an expensive fix even if the hotwater heater is already in the garage unless you were going to replace it anyway.

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Bammerman
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Re: Keep garage 'cooler' during summer

Post by Bammerman » Thu Jul 04, 2019 8:00 am

If the garage has a dark, flat "membrane" type roof, you could paint it with a white elastomeric roof paint. This is what I did, and it reduced the heat inside/under the roof significantly. A can of this stuff is about $25 at Lowes and is enough to cover a one-car garage.

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dodecahedron
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Re: Keep garage 'cooler' during summer

Post by dodecahedron » Fri Jul 05, 2019 1:35 pm

littlebird wrote:
Tue Jul 02, 2019 12:50 pm
Hockey10 wrote:
Tue Jul 02, 2019 12:38 pm
When you arrive home on a hot day, park the car on the driveway for several hours until the car cools off. Parking a car with a hot engine in an already hot garage will only make the heat worse.
This is a good idea that I’m going to try. I believe an uninsulated door is better in hot places, to alleviate this problem, but my current home has an insulated door.
Great idea to let car cool down before parking it in the garage in hot weather--it also avoids letting a huge amount of cool air flow out of the house while the garage door is open.

(In bitter cold winter, when I am making multiple trips in a short period of time, I don´t put my car into the garage for similar reasons, don´t want all the warm air whooshing out every time I open the garage door.)

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dm200
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Re: Keep garage 'cooler' during summer

Post by dm200 » Fri Jul 05, 2019 1:49 pm

In addition to adding shade trees, etc., perhaps a trellis with vines or climbing rose bushes, etc. might also be worth a try.

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