Improving energy efficiency in your coach

Topic: Improving energy efficiency in your coach (Read 3144 times) previous topic - next topic

Improving energy efficiency in your coach

June 24, 2011, 07:41:46 am

Greetings all,

Having spent a number of years researching and improving the energy efficiency of my home, I can't help but see numerous areas of the coach where heat loss/gain is a serious issue. Referring to my 91 U225 in this case. Would like to share my thoughts and observations and learn what, if anything, you may have done to your coach in this regard. I've always found investing in efficiency to be worthwhile.

The three worst places for energy efficiency appear to be - the skylight, bathroom fan, and ventilation fan.

Skylight - Standing in the tub while cleaning things up on a sunny day left me soaking wet. It was like sitting under a heat lamp. All I see here is a layer of plastic between the inside and the outside. Have done some preliminary searching - I see shades, to be mounted on the inside (too late - the heat has already got in), and at least one company making a cover which fits on the outside around the frame with an elastic and blocks most of the heat gain, but do not see where anyone makes an energy efficient type, like a double pane with low e-material or something similar. While I do like having the light in there when taking a shower, and the headroom the skylight affords, at this point I'm inclined to cover the skylight to kill the heating and heat loss aspects.

Fans - can't see doing away with these, and yet again - nothing there in terms of energy efficiency. With the bathroom fan, again, nothing but a layer of plastic, and with the vent fan - a metal louvered cover between the inside and outside, which isn't anywhere near air tight. I do see vent pillows/plugs at Camping World, and bought a couple for the fans, though they don't fit all that well into the existing openings.

Then there is the glass. I know newer coaches have been improved in this regard, but with my 91 it's all single pane glass. All I can think to do with this is to apply a tint material to cut down on heat gain, and use the curtains when it's cold.

A windshield solar cover is in the plans. Being a newbie I'd really like to hear your thoughts on this topic. Thanks.

Steve

Re: Improving energy efficiency in your coach

Reply #1 – June 24, 2011, 08:27:36 am

Steve, it sounds like you have already investigated the alternatives pretty thoroughly.

We have multiple layers in the skylight. It came from the factory that way. There is a milky plastic flat sheet across the bottom, and a double layer of plastic in the dome. The cuts down quite a bit on the heat transfer however an insulation "pillow" or make an aluminized insulated cover out of a windshield heat reflector will help more. We use the aluminized cover velcroed to the bathroom vent.

We also put 1/2" styrofoam inside the plastic cover to the kitchen vent. We used 1/2" X 1/4" self adhesive insulation strip around the edges to get a positive air seal when the cover is in place.

The coach had Penninsula, double pain windows installed everywhere except the front drivers and passenger windows. The cost according to the receipts in the coach when we bought it was around $5,000. They are remarkably better than the original single pain windows in our 93, U225. Much quieter and cooler. Regrettably the front drape was removed and electric MCD shades were installed. We plan to re install the front drapes for insulation purposes and better privacy.

We also had bright white paint installed on the roof for better heat reflection and to make the coach easier to keep clean.

With all of that said, in our recent heat wave the coach still gets incredibly hot. There is not enough insulation in the roof for all of these improvements to make a lot of difference in 100 degree heat. The heat transfer still overwhelms the A/C in the late afternoon. The best answer is to FIND SHADE.

Re: Improving energy efficiency in your coach

Reply #2 – June 24, 2011, 08:41:53 am

Have you ever seen a bus that was setup for Saudi or the middle east. THey have added a shield layer / metal plate above the roof with about a 3" air gap, just to reduce the direct effect of the sun cooking everything and everyone. General opinion is it halps a lot. Have seen one of these that came back to the states.
Maybe if you added enough solar panels it would have the same effect ? ANyting to keep sun directly from roof / paint ?

Re: Improving energy efficiency in your coach

Reply #3 – June 24, 2011, 08:51:26 am

We use a quilted Mylar type sun shield behind the drapes on our U280. Every attempt is also made to park with rear to setting sun. This keeps afternoon sun off WS and by time sun sets and it starts to cool Bedroom temp is OK. And shade is your friend.
Gary B

Re: Improving energy efficiency in your coach

Reply #4 – June 24, 2011, 09:02:15 am

Quote from: Kent Speers – June 24, 2011, 08:27:36 am

Regrettably the front drape was removed and electric MCD shades were installed. We plan to re install the front drapes for insulation purposes and better privacy.

Just in case, Kent, you might want to save the MCD shades in case you change your mind.

Re: Improving energy efficiency in your coach

Reply #5 – June 24, 2011, 09:46:03 am

I have a set of solar screens from MCD for the cockpit. They really help and you can see out, but no one can see in during the daytime. These screens help to prevent the heat from entering the coach. The factory curtain does the privacy thing, but the heat still gets inside. MCD says black is best.

Re: Improving energy efficiency in your coach

Reply #6 – June 24, 2011, 10:10:30 am

Quote from: Dave M – June 24, 2011, 08:41:53 am

Have you ever seen a bus that was setup for Saudi or the middle east. THey have added a shield layer / metal plate above the roof with about a 3" air gap, just to reduce the direct effect of the sun cooking everything and everyone. General opinion is it halps a lot. Have seen one of these that came back to the states.
Maybe if you added enough solar panels it would have the same effect ? ANyting to keep sun directly from roof / paint ?

It's funny that you mention that Dave. I had considered doing this just on principle. Did not know it was actually in practice. A thin layer of aluminum mounted off the roof would do it, taking into account the effects of airflow at speed (ie so it doesn't blow off going down the highway). Powder coat it white to minimize heating of the shield. Would make a great platform for adding solar panels. Hmmm... need about 280 sq ft of material, plus mounting brackets... going to look into this more. If you could make it tilt in two directions with panels on it that would really be something.

Wouldn't it be nice if we had flexible solar panels? All of our awnings could be power generators, as well as the entire roof. Some day, maybe.

Parking in the shade was also my first thought

But I'll assume this isn't always possible, and regardless, at some point sunlight will be upon you.

I'm confused by MCD saying black is best. In my experience, it is best at absorbing and radiating heat (which is why most all electrical heat sinks are semi gloss or flat black), but for a window shade I would think white would be best, as it stays coolest in sunlight. I must be missing something here.

Steve

Re: Improving energy efficiency in your coach

Reply #7 – June 24, 2011, 10:17:43 am

Quote from: Merle Hench – June 24, 2011, 07:41:46 am

Skylight - Standing in the tub while cleaning things up on a sunny day left me soaking wet. It was like sitting under a heat lamp. All I see here is a layer of plastic between the inside and the outside. Have done some preliminary searching - I see shades, to be mounted on the inside (too late - the heat has already got in), and at least one company making a cover which fits on the outside around the frame with an elastic and blocks most of the heat gain, but do not see where anyone makes an energy efficient type, like a double pane with low e-material or something similar. While I do like having the light in there when taking a shower, and the headroom the skylight affords, at this point I'm inclined to cover the skylight to kill the heating and heat loss aspects.

I bought some sunscreen material & cut it to size of skylight.
Added some snaps on the material & glued the other side of snaps onto the skylight.
I still get the light but heat dramatically reduced.

Re: Improving energy efficiency in your coach

Reply #8 – June 24, 2011, 10:22:56 am

Was wondering what a window upgrade was worth. $5K huh? Gulp...

Was looking at the coach windows just now; they already have a pretty dark tint. Seems that a reflective film on the outside of the glass might have some benefit. I remember seeing a product like this when researching things for my home; I also remember most all glass mfrs saying that applying any such film would void any warranty.

Was at Home Depot yesterday; saw a big chart next to stack of air conditioners for sale. According to the chart, 13000 BTUs is enough to cool an 800 sq ft space. My coach is only about 280 sq ft, and yet I have two of these A/Cs? Really got me thinking about reducing heating/cooling requirements.

Am going to make a go at improving my girl. Primarily focusing on reflecting or blocking the heat from the outside, rather than blocking it once it got inside. Lots to think about here. Thanks.

Steve

Re: Improving energy efficiency in your coach

Reply #9 – June 24, 2011, 10:28:24 am

Quote from: Barry Beam – June 24, 2011, 10:17:43 am

I bought some sunscreen material & cut it to size of skylight.
Added some snaps on the material & glued the other side of snaps onto the skylight.
I still get the light but heat dramatically reduced.

That looks to be the most practical solution Barry.

I'd still like to keep the heat out altogether though, and that would require something on the outside. More digging and thinking to do on this.

Steve

Re: Improving energy efficiency in your coach

Reply #10 – June 24, 2011, 11:08:52 am

Quote from: Merle Hench – June 24, 2011, 10:10:30 am

Wouldn't it be nice if we had flexible solar panels? All of our awnings could be power generators, as well as the entire roof. Some day, maybe.

Several Companies make them
Uni-Solar 136W PV Module, Amorphous, Laminate, Black, 24V, PVL-136

Re: Improving energy efficiency in your coach

Reply #11 – June 24, 2011, 11:31:41 am

Just for ##its & giggles, I got into goggle, found MCI coach made the double roof buses for Saudi and also some showed up in west TX hauling prisoners, Seems the idea is loved. Can not see a FT with a double roof, but some times creativity and need over rule standard practice.

Re: Improving energy efficiency in your coach

Reply #12 – June 24, 2011, 12:04:18 pm

Anyone have any experience with the high tech, space age roof paint? jc

Re: Improving energy efficiency in your coach

Reply #13 – June 24, 2011, 12:43:17 pm

Maybe someone living near the Space Shuttle storage can make a deal on the heat tiles from under them and glue these on the roof. I think they have pulled them from use (or at least one). It actually would not be hard (just a lot of work) to add a solid foam layer on the roof then fibreglass or !! over the top. A/Cs etc can be raised on the necessary thickness supports to keep them flush with the new top. I would talk to some paint covering experts first to try that angle.
My long time thought has been (and is very easy to do) to make a small track in Alum' that runs down both sides of the coach and about 1" higher than the A?Cs and have a Sunbrella awning that can be motor driven or hand cranked to cover the entire roof area in extreme heat. This will work and fairly inexpensive to do -BUT- big problem if you have solar panels. This is what is keeping me from drawing up plans for our bus right now. At least this method allows air to pass under the awning for vents etc. Just a thought. Am I crazy or what???

Re: Improving energy efficiency in your coach

Reply #14 – June 24, 2011, 02:07:52 pm

Prior to my trip out west last summer I bought several sheets of the thin blue foam at home depot. This is the stuff that is dense and doesn't crumble much went cut. I cut pieces for each window except cab area, to fit behind shades and wide enough so that the shade brackets held it in place along with the blind hold it too. I cut a piece to fit the galley fan cover which also added some strength to it so that it doesn't feel like it will break taking it on or off. I also cut a piece for the skylight. Never did address the cab area but all this foam helped a great deal. I have kept in in place in fact.

Re: Improving energy efficiency in your coach

Reply #15 – June 24, 2011, 03:10:21 pm

Quote from: George Stoltz – June 24, 2011, 09:02:15 am

Quote from: Kent Speers – June 24, 2011, 08:27:36 am

Regrettably the front drape was removed and electric MCD shades were installed. We plan to re install the front drapes for insulation purposes and better privacy.

Just in case, Kent, you might want to save the MCD shades in case you change your mind.

Our plan is to reinstall the drapery rod and keep the shades. I don't know why but that's the plan.

Quote from: hotonthetrail – June 24, 2011, 12:04:18 pm

Anyone have any experience with the high tech, space age roof paint? jc

I used to manufacture Kool Kote pool deck paint. It had a 3M hollow microsphere in the paint that both reflected sun light and added insulation to the paint. It was very effective at keeping the pool deck cool in direct sun light, concrete 140 F - Kool Koted pool deck 95 F but I had no data on the insulative factor beneath the coating. Kool Kote is no longer available but there probably are other similar coatings. The coating was pretty expensive. The 3M microspheres were over $300 per pound back in 2004 but fortunately very little was added per gallon.

Quote from: Jerry & Coleen – June 24, 2011, 09:46:03 am

I have a set of solar screens from MCD for the cockpit. They really help and you can see out, but no one can see in during the daytime. These screens help to prevent the heat from entering the coach. The factory curtain does the privacy thing, but the heat still gets inside. MCD says black is best.

I guess I forgot to mention we too use white sun screens on the front windows and windshield. Ours are velcroed on to the winshield from the inside. They make a tremendous difference reflecting heat but its still hot on the dash.

Re: Improving energy efficiency in your coach

Reply #16 – June 24, 2011, 04:07:24 pm

Hard to see a better way to shade the roof than solar panels, killing several birds with one stone. The pull over sumbrella sounds interesting, will need to be penetrated for air conditioners of course. I suspect that if you consider the final cost of a good stowable and deployable system the solar panels will start to look better.

We just finished a week in the hill country with little nephew and niece running in and out continually. All awnings deployed, door side of coach facing dead West. It was roasting hot with minimal shade but the two ac units were able to keep the coach in mid 70's at all time. These are older units. I think a factor is exterior color, those paint jobs are sweet but hard to beat reflective white. I don't think the thermo windows really make a lot of difference for air conditioning as you are only trying to keep the inside about 25 degrees cooler than outside, not a huge differential. Now if you're in Montana for the winter and trying to deal with a 100 degree inside outside differential, they are a very big deal.

Shading windows and some sort of shading for top is probably going to be the most effective solution. Or bump up the tonnage of AC, the American way. Kent, I wonder if those microspheres were similar to the ones you can obtain from West Marine as lightweight epoxy filler. Sounds like the making of a reflective, insulative paint. Wonder if you could walk on them without crunching the spheres?

Chuck

Re: Improving energy efficiency in your coach

Reply #17 – June 24, 2011, 04:14:59 pm

Quote from: Dwayne – June 24, 2011, 02:07:52 pm

Prior to my trip out west last summer I bought several sheets of the thin blue foam at home depot. This is the stuff that is dense and doesn't crumble much went cut. I cut pieces for each window except cab area, to fit behind shades and wide enough so that the shade brackets held it in place along with the blind hold it too. I cut a piece to fit the galley fan cover which also added some strength to it so that it doesn't feel like it will break taking it on or off. I also cut a piece for the skylight. Never did address the cab area but all this foam helped a great deal. I have kept in in place in fact.

I have been using the car windshield solar covers cut to size & put under the shades.
Really lowers the heat penetration on the windows.
I like being able to fold up & put away when not needed.

Re: Improving energy efficiency in your coach

Reply #18 – June 24, 2011, 04:33:00 pm

Chuck, if your are talking about the non-skid used for marine coatings, it is different. The light weight stuff is usually either pumice or solid glass spheres. The hollow glass spheres are the ones that are so expensive and hard to make. They are also not strong enough for use in a floor or deck coating that gets lots of foot traffic of people wearing shoes. They should however be fine for a motor home roof.

Re: Improving energy efficiency in your coach

Reply #19 – June 24, 2011, 09:55:53 pm

Several of us use a blanket across the inside of the windshield to insulate the front of the coach. We hang a wood closet rod about the full width of the coach behind the valence and drape the blanket over it to form a double layer.

Re: Improving energy efficiency in your coach

Reply #20 – June 25, 2011, 02:31:55 am

We use Reflectix aluminized insulation sheeting for the windshield and the bedroom windows, and sometimes one of the living room windows. It's aluminized on both surfaces and about 3/8" thick. Just cut to size for the window and unroll them and hold in place behind the OEM day-night shades or the MCD shades. They make a really really big difference in either extreme cold or heat. A 4' wide roll is about $35 at Home Depot, and the stuff lasts at least 2 years with daily rolling/unrolling (e.g. for the windshield.)

Re: Improving energy efficiency in your coach

Reply #21 – June 25, 2011, 06:04:34 am

Quote from: Barry Beam – June 24, 2011, 11:08:52 am

Several Companies make them
Uni-Solar 136W PV Module, Amorphous, Laminate, Black, 24V, PVL-136

Did not know that. Progress.

Looking at those cells, though, I see the only approved substrates are metal and membrane roofs. Not a show stopper, but then I noted these are 18 feet long, but only produce 136 watts? Going to look into what's out there some more. Thanks.

Here's a link to a picture of an MCI with a double roof - Greyhound Bus Museum . I like this idea. I don't know how feasible it might be, but I'm going to play with it.

I too envisioned some sort of awning that could easily be deployed over the coach when parked. Don't see how that could easily be done though.

Lots of good ideas - foam, sun screens, etc. I happen to have a 1/2 roll of Reflectix laying around. Might make for a cheap windshield cover. I'll give it a try.

There are a number of coatings and paints I've read about which are supposed to reflect heat or insulate. One which I'm still looking into is a ceramic coating - Attic Radiant Barrier Paint, Wall Vapor Retarder Coating, and All About Ceramic Insulation . This may well be as good as, or better, than a double roof.

I know our coaches cannot be made as energy efficient as a well built home, but I think there's a lot of room for improvement. I feel that blocking the heat on the outside is more effective than on the inside, but haven't thought through the practical aspects of this. More to explore here.

Steve

Re: Improving energy efficiency in your coach

Reply #22 – June 25, 2011, 09:29:54 am

Quote from: Merle Hench – June 25, 2011, 06:04:34 am

There are a number of coatings and paints I've read about which are supposed to reflect heat or insulate. One which I'm still looking into is a ceramic coating - Attic Radiant Barrier Paint, Wall Vapor Retarder Coating, and All About Ceramic Insulation . This may well be as good as, or better, than a double roof.

Steve

When first reading the web page this coating sounded ideal for a coach roof. I thought they might be using the same hollow glass spheres I mentioned previously but considering the price of the coating, I doubt that it is expensive enough to be the same thing. Still it looked like a good idea until I read the data sheet. This is basically regular acrylic interior wall paint with fillers. It probably works fine for its intended use but I doubt that it will stand up to exterior applications like a coach roof. If there are other exterior coatings with similar fillers, it might be a very good alternative to the white urethane coatings now being used.

Re: Improving energy efficiency in your coach

Reply #23 – August 12, 2011, 11:02:54 am

Greetings,

Just to update with regards to roof coatings - ceramic insulating paint is a no-go. Doesn't seem to be any independent testing with regards to the wild claims being made. The consensus - it's snake oil. I'm going to have to go along with that.

Some years ago I had an old white Chevy repainted by the local Maaco shop (hey - it was an old Chevy

. They did a nice enough job for the money, but the big surprise was the paint they used - and I don't know what it was. A very bright white with a hint of blue to it, you could put your hand on the sheetmetal when it sat in the sun, and it was cool to the touch. The interior stayed much cooler than before. At night, when driving under streetlights with photocells, they switched off - so much light reflected off the paint that the photocells switched the lights off (it was quite a sight driving at night. The lights did come back on after a minute.) At any rate, a very reflective paint will have more benefit.

After more web crawling, I've decided at this point to go with Polycoat's Safe-T-Plex RV elastomeric roof coating. It's not as cheap as some, but they claim I'll have a maintenance-free roof for 20 years if applied properly. It is also 92% reflective. Sounds good to me. I did a find only a couple of user reviews - but they were very positive. The mfr claims no failures with 7000 packages sold, and they guarantee against leakage. They've been around for 20 years --> RV ROOF REPAIR

In my case, I'm not that worried about leaks - more of an issue of putting something on the no-gelcoat-left roof surface. But if it does reduce some the heat gain inside, and seals the roof against leaks, then it's worthwhile.

I'd be very interested to hear if anyone has any experience with this stuff. A search here turned up zero hits.

Steve

Re: Improving energy efficiency in your coach

Reply #24 – August 12, 2011, 02:21:35 pm

Quote from: Merle Hench – August 12, 2011, 11:02:54 am

... A very bright white with a hint of blue to it, ...

How white was your car? It was so shiny bright white that the street lights thought the sun had come up when we drove by!

What a great story!

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