Without AC: To Insulate or Not?

[featherliteCT1]

If you were going to be living in your trailer, in a hot climate, without a 120 volt air conditioner, would you rather have the trailer insulated or uninsulated? If insulated, I am thinking about 2 3/4 inches of polyiso insulation in the walls and ceiling, yielding an insulation value of about R15, and with the roof painted with Henry’s 587.

1. With Insulation. I am wondering if, with insulation, maybe the trailer would heat up during the day, equal to the outside ambient temperature of, say 95F, with the insulation absorbing and holding that heat at 95F. Once the trailer was heated to 95F, the insulation would then hold that heat until well after bedtime and maybe also would prevent the trailer from cooling down much during the night.

2. Without Insulation. On the other hand, without insulation, maybe the trailer would cool off quickly and equalize to the ambient nighttime temperature. 12 volt fans would be used to cool the inside of the trailer at night.

I currently own a 800 sq ft. house out in the country, with no shade trees, without air conditioning. However, the house is insulated (probably about R18 in the gabled attic and R12 in the stud walls). In the summertime, when it is 95F outside during the daytime, the inside of the windows are covered with blinds to block sunlight. At night, I open all the windows, run a few 120 volt ceiling fans, and the house cools down to about 74F by 6am, when the outside temperature is about 66F. Then, first thing in the morning, I close all the windows. The inside of the house will slowly increase in temperature to about 80F by 8pm.

As an aside, even though the outside temperature starts falling at about 6pm, the temperature inside the house will continue to rise until about 8pm. The house usually equalizes to the outside temperature of, say 80F, by about 10pm.

So, it takes my house about 14 hours during the daytime (from 6am to 8pm) to gain 6 degrees but only 8 hours during the night (from 10pm to 6am) to fall 6 degrees. It would appear that the house cools down almost twice as fast as it heats up.

I would appreciate it if you guys would share your thoughts with me.

Thank you,

Ron

[Padilen]

Insulation helps deaden noises too. For that reason many insulate. If your thinking a cargo trailer, they can be noisy.


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[tony.latham]

I'm a teardrop guy, not a cargo guy, so keep that in mind.

My first teardrop was commercially built and wasn't insulated. When the weather was chilly, dew would form on the inside of the trailer. I built our current 'drop and insulated it. It doesn't sweat. When it's 80-85ºF and we want to take a break, our ceiling fan sucks the breeze in across our bodies, out the roof, and keeps us nice and cool.

I think insulation is a big deal.

Tony

[featherliteCT1]

[quote="Padilen"]Insulation helps deaden noises too. For that reason many insulate. If your thinking a cargo trailer, they can be noisy.

Good point.

[featherliteCT1]

[quote="tony.latham"]I'm a teardrop guy, not a cargo guy, so keep that in mind.

My first teardrop was commercially built and wasn't insulated. When the weather was chilly, dew would form on the inside of the trailer. I built our current 'drop and insulated it. It doesn't sweat. When it's 80-85ºF and we want to take a break, our ceiling fan sucks the breeze in across our bodies, out the roof, and keeps us nice and cool.

I think insulation is a big deal.

Thanks for sharing,

I presume that, in cold weather, when the condensation formed on the inside of your trailer, it was because you were inside generating heat with your bodies and moisture with your breathe. In which case, when the warm, moist, interior air came into contact with the cool skin, the water condensated onto the inside of the skin. Just like what happens on the interior side of a glass window in a house in the wintertime.

So yes, I would absolutely, without question, want insulation in a cold climate because I would not need 120 volts to heat the inside. A propane heater would do the inside heating job.

[John61CT]

Yes it would be nuts to run A/C without lots of as good insulation as possible, floor especially.

Lots of ventilation as well, high-volume intakes at the bottom, exhaust(s) up top, with high CFM fans and variable speed controls.

Cold weather needs more insulation up top, and precision control on the venting.

[featherliteCT1]

Yes it would be nuts to run A/C without lots of as good insulation as possible, floor especially.

Lots of ventilation as well, high-volume intakes at the bottom, exhaust(s) up top, with high CFM fans and variable speed controls.

Cold weather needs more insulation up top, and precision control on the venting.

Well said ... I agree. However, going back to the original post, we are asking about hot weather conditions, rather than cold weather conditions.

[working on it]

Yes it would be nuts to run A/C without lots of as good insulation as possible, floor especially.

Lots of ventilation as well, high-volume intakes at the bottom, exhaust(s) up top, with high CFM fans and variable speed controls.

Cold weather needs more insulation up top, and precision control on the venting.

• I run A/C in my trailer, without any insulation, and the only condensation is on the outside. Any good A/C unit acts as a dehumidifier; that's why condensation drips from most, on the exhaust side of the chassis. From Wikipedia

  Air conditioning (often referred to as AC, A.C., or A/C) is the process of removing heat from a confined space, thus cooling the air, and removing humidity.

• I also leave open one, or both, vents on my sidewalls, to eliminate CO2 build-up, and I think this helps, also. In cooler weather, the vents or windows are slightly cracked, and the small electric heater(s) keep condensation away.
• There are times, when neither A/C or heat are used, just my main 11" house-type fan, even on humid nights; I've seen no condensation, as the increased airflow sends much of the moisture out thru windows or vents.
• Once, I had a lot of water leak into my trailer thru a semi-unsealed door, leaving 1+ inches of standing water on the floor. I dried it out as well as I could, with towels and tilting the trailer, but I slept on top of my (thankfully) dry mattress, with vents open, main fan on, both heaters running, and the A/C on, as well. Even though it was still raining and super-humid outside, my trailer was drier inside the next morning, than when I went to sleep. I left the devices running thru the next day, and my carpet was almost dry by that night.

[John61CT]

asking about hot weather conditions, rather than cold weather conditions.

Just a side note for others' benefit reading later

[John61CT]

I run A/C in my trailer, without any insulation, and the only condensation is on the outside.

Just to clarify, none of my post had anything to do with condensation, but thanks for the info.

[tony.latham]

I presume that, in cold weather, when the condensation formed on the inside of your trailer, it was because you were inside generating heat with your bodies and moisture with your breathe. In which case, when the warm, moist, interior air came into contact with the cool skin, the water condensated onto the inside of the skin. Just like what happens on the interior side of a glass window in a house in the wintertime.

Tony

[working on it]

I'm a teardrop guy, not a cargo guy, so keep that in mind.

My first teardrop was commercially built and wasn't insulated. When the weather was chilly, dew would form on the inside of the trailer. I built our current 'drop and insulated it. It doesn't sweat. When it's 80-85ºF and we want to take a break, our ceiling fan sucks the breeze in across our bodies, out the roof, and keeps us nice and cool.

I think insulation is a big deal.

Thanks for sharing,

I presume that, in cold weather, when the condensation formed on the inside of your trailer, it was because you were inside generating heat with your bodies and moisture with your breathe. In which case, when the warm, moist, interior air came into contact with the cool skin, the water condensated onto the inside of the skin. Just like what happens on the interior side of a glass window in a house in the wintertime.

So yes, I would absolutely, without question, want insulation in a cold climate because I would not need 120 volts to heat the inside. A propane heater would do the inside heating job.

I was mainly responding to featherliteCT1 about the benefits of having A/C and heat both available in an uninsulated space, and that airflow is also a necessary component in the equation. And to tony.latham, who brought up dew and condensation, where A/C, heaters, and airflow each contribute to solving problems in an uninsulated trailer. But, I referenced John61CT, because I took exception to your statement "it would be nuts to run A/C without lots of as good insulation as possible". It was a conscious choice on my part, since I thought that in the climate I camp in, insulation could be dispensed with, as an unneccessary complication to a plywood-only structure. In my post, I've shown methods proven to work (for me) to bypass insulation problems, and nuts as I may be for not insulating, I felt that it was the best choice, for me, at the time. My input might broaden the scope of featherliteCT1's investigation, so I added my experiences to the thread. Thanks for your input on this matter.

[McDave]

A big part of the Thermal cycling equation is MASS. Houses have Tons of mass, and mass cycles at it own pace. Trailers on the other hand have relatively little mass, hopefully. In general we try to keep the weight as low as possible, due to trailer GVWR and in the interest of the tow vehicle. Trailers, with or without insulation thermal cycle quickly. The insulation adds almost zero mass, but will slow the thermal cycle, either gain or loss. However, since there is little mass, exchanging air will have a rapid effect.
In your case if the interior is warmer than ideal, and the O.A.T. (Outside Air Temp) is cooler, you can easily "dump" the heat via the gigantic vent opening in rear, A.K.A the ramp door. Open that and turn on a vent fan and the temp will drop immediately. Even a simple chimney effect will exchange air at a slower but constant rate, keeping the interior closer to the O.A.T. An open vent at ceiling and floor will allow for "heat rises, cold falls" and as the less dense hot air rises and leaves, the cooler more dense air pushes in to replace it.
Insulation in this case will probably only help conserve and retain whatever input you decide to add, be it heat or cooling.
Depending on your local environment and your personal tolerance, you may be able to go "au natural" i.e. no heat or cooling input, but without insulation temp change will be uncontrolled and perhaps extreme. Just consider how hot your truck is inside at midday. Possibly hotter than O.A.T.
If you plan to run refrigerator or even keep ice chest, they will be exposed to that heat, but not any cooling breezes.
The word stifling comes to mind.
Anyways, the difference between a house and a trailer is mass... They are two different animals.

McDave

[John61CT]

I was coming from a POV that energy efficiency is an important value, especially when burning expensive dino juice to keep cool in a hot climate.

Sorry I used an unnecessarily disparaging term for those who may disagree.

[featherliteCT1]

[quote="McDave"]...since there is little mass, exchanging air will have a rapid effect.
... Open that [ramp door] and turn on a vent fan and the temp will drop immediately.

McDave,

As always, I especially appreciate your comments. I think you are saying that you would insulate the trailer even if you NEVER had AC and would ALWAYS be in a hot climate? Correct?

Thanks,

Ron