Window Insulation for Campers

Those big picture windows in our RVs let us enjoy the great outdoors from the comfort of our coaches, but they also allow heat transfer that makes our units hotter in summer and colder in winter. But there is a cure.  Actually there are several to choose from.

Luxury units sometimes have double-pane windows like newer homes to reduce heat transfer but many RVs, especially older or entry level models, will have only single pane windows.   Single pane glass is fairly good at conducting heat.  Just touch a single pane window on a cold day!   Double pane windows have two sheets of glass separated by a sealed section of inert gas, creating a "dead air space" inside.  They conduct far less heat, keeping your RV cooler in summer and warmer in winter. Upgrading your windows to dual-pane would be an expensive proposition -- IF you could even match up the size of your windows.  What can you do about that?  There are several feasible options you can explore.

The simplest and least expensive option is to make sure you take advantage of whatever window coverings you already have.  Keep drapes, curtains, shades or blinds closed to retain heat in winter and keep it outside in summer. I n summer take advantage of natural shade to keep your RV cooler.  In winter, park in full sun to absorb as much heat as possible, basking the the light of a hydrogen fusion furnace 93 million miles away (the Sun). Y ou might be surprised how much just using your curtains or shades will help maintain a comfortable temperature inside your RV.   If your window treatments are in need of repair, consider replacing them with versions with better insulating qualities, such as replacing thin curtains with heavy, insulated drapes or sturdy day-night shades.

A semi-permanent winter fix is to add a plastic "storm window" covering to the outside (or possibly inside) of your windows, partially simulating double pane windows.  The plastic won't be as thick as glass and and the "dead air space" between it and the window won't be as well sealed (there are "weep" holes in the bottom frame of most RV windows) or as effective as the inert gas chamber in a double pane window so it won't work quite as well, but it will help.  Dual pane windows are completely sealed and contain an inert gas to enhance their insulating qualities.   Plastic film storm window insulation kits can be purchased at hardware stores and home centers.  You cut the plastic film to fit your window, install the included sticky strips to hold it in place, stretch it over the outside frame, then warm it with a heat gun or hair dryer to shrink it so it fits tightly and securely.   I have not yet tried this option myself but I have heard is is quite effective and the science behind it is sound.  I have concerns about how fragile the tightly stretched plastic might be to flying debris and whether it would stand up to freeway speeds without coming off.   This is primarily an option for cold weather since it interferes with opening the windows for fresh air in warm weather.  I recently purchased several plastic storm window kits so I can try them out, but haven't gotten around to it yet, but, as I said before, the science is sound, so it is worth a try.

A simple and convenient solution to excessive summer heat is "solar" film.   It also adds a measure of privacy as long as it is brighter outside than inside.  Having it professionally installed can be quite expensive but you get crystal clear tinted windows.  You can install it yourself if you have the patience. tools, and skill.  You must clean the windows very thoroughly, including the tracks around them to avoid getting any dust or dirt under the film.   Cut the film slightly larger than the glass area of the window.  The film sticks to itself very well so you need take care to apply it directly to the glass  Start at the top and then slowly peel the backing away as you work your way to the bottom.  Spray the film with water and use a small squeegee to carefully smooth the film.  Work from the center toward the edges to avoid getting bubbles in the film.  If you end up with small bubbles you can't squeegee out, carefully prick each one with a pin to allow the air to escape as you squeegee them flat.  Then trim the edges with a razor knife or single edge razor blade.  Solar film, either reflective or "limo tint" will block a lot of the sunlight entering your vehicle, reducing heat and protecting interior surfaces from sun damage.   The film also functions as partial privacy panels as long as it is darker inside your RV than it is outside.  Some states have restrictions on how dark window tinting can be on front side windows and it should never be added to windshields, except perhaps a strip a few inches tall along the very top as a sun shade.

My personal favorite is another easy, inexpensive, easy, and effective solution:  double reflective bubble/foam insulation.  You can buy Reflectix and other brands at hardware stores and home centers in rolls from 10' to 100' and widths of 2' or 4'.  You can then cut panels to fit each window and insert them behind the existing window coverings.  A 48" x 10' roll is usually under $25. A 25' roll, if you can find them, is between $40 and $50.  Cut the panels just slightly larger than the opening so they will fit tightly.  This helps them stay in place and mostly seals the opening to limit the circulation of air from between the insulation and the glass.  In addition to controlling heat transfer they are also very effective at blocking unwanted light.  The reflective quality combined with the insulation value will help you maintain the desired temperature in your RV year round.  In the summer it will keep things cooler, reducing the load on your air conditioner and generator and making you more comfortable.  In winter, it will retain heat, conserving propane and keeping you cozy.  I have used this option in my RVs for many years with very satisfactory results.  In fact, when I get new RV, it is one of the very first additions I make.   I even use it in windows at home for room darkening and, in winter, to conserve heat.  At first I just used auto windshield covers in my RV but now I buy Reflectix in bulk rolls.  Auto windshield covers are good option, especially if can get them at good price.   I sometimes find them at my local dollar store!   Reflectix is heavier so it provides more insulation and being stiffer it stays in place better.   It can be easily cut to fit any window. It rolls up for easy storage or you can lay the panels flat on a bed or slide them down behind the sofa.  When I had a Class A with a pull-down bunk over the front seats, I found that was an excellent place to store the window panels during travel.   When putting Reflectix in windows, for maximum benefit, don't push it up tight against the glass. You want to leave a little air space between the insulation and the glass.  If the Reflectix is in contact with the glass heat could be conducted directly between the Reflectix and the glass.   The insulation itself has an R-value just slightly greater than R1.  Leaving some air space between the insulation and the glass can significantly boost the R-value.  For comparison, the R-value of the 3" fiberglass insulation in your residence is R-13.   Much of that insulating value comes from "dead air space" created by the insulation.  So why not just leave the walls empty?  Insulation almost eliminates convection that would draw heat from he inside of the walls as well as reducing heat transfer.  Foam panels help keep heat out in summer and in in winter -- and function as privacy panels.  I use foam inserts in all my windows year round, removing them only when I want to see out or open the window for ventilation.  The reflective quality reflects heat (from the outside in summer and back into the living space in winter) beyond the insulation value.  Reflectix can be used on RV windshields that are too big for auto sun shades or you can buy special RV windhshield sun screens that will cover that huge expanse.  Since windshields are single thickness glass, even in new luxury motorhomes, blocking sunlight beating down through that huge expanse will make an immediate and significant difference in solar heating of your motorhome.  You can often feel the difference as you put the shade in place.

Interior insulation panels.   A reader of this blog suggested window insulation panels from Advanced Energy Panels.  This is certainly an option worth looking into.   They are custom made panels that essentially are internal storm windows, turning ordinary windows into something close to dual pane windows.  Unlike Reflectix, they are clear so they don't block the view.  Since they don't block sunlight, the won't be as helpful at keeping the interior cool in summer as Reflectix and won't control light intrusion or add privacy but might do a better job of keeping the heat in when you want it and out when you don't.

Most RV window frames are pretty well sealed but over time they may begin to get loose and develop drafts.   Make sure all the mounting screws are tight and the butyl sealing tape around the frame is in good condition.   The best solution to damaged sealing tape is to remove the window and re-seal it with fresh butyl tape but in a pinch you can seal windows with DAP or even silicone.  Besides drafts, loose windows can allow rain or snow melt in too, so you want to always keep them tightly sealed.  If you look closely, you'll find "weep holes" in the lower channel of RV windows. These are designed to allow condensation that drips from the windows to escape to the outside instead of overflowing and running down the inside walls.  You might get a tiny draft through these openings, but well-placed Reflectix inserts will mitigate air flow.  Even though it may be tempting to seal those weep holes to prevent dust and drafts from entering your RV, it really isn't a good idea. Without them condensation will drip into the channels and overflow down inside walls if it doesn't have anyplace else to go.  Not only will this cause unsightly marks on the wall, it can create a damp environment that fosters dry rot, mold, and mildew.

OK, what about tent windows?   Not sure that tent windows lose any more heat than tent walls since both are pretty thin.  That being said, what can you do to reduce heat loss in your tent?  First, if it has rain fly, make sure it is in good condition and properly installed.  Some folks sew an additional "skirt" onto the rain fly so it comes almost all the way to the ground to help keep snow and cold air from blowing up under the fly in winter weather.  If it doesn't have a rain fly, covering it with a tarp may help.   Protecting the tent itself from direct exposure to the elements will minimize unwanted heat transfer.   You might use Reflectix or a similar foam/bubble foil insulation inside your tent or between the tent and the rain fly to keep you warmer in winter and cooler in summer.  It can be bulky to carry around so it isn't an option for back packing but you might find it useful when car camping. Using it under your sleeping bags can help keep you up off snow or frozen ground and having it all around you will reflect a lot of your body heat back instead of letting it leak out through the thin tent walls.   Even though it is only a fraction of an inch thick, it is still many times thicker and provides many times more insulation than even the heaviest tent fabric.   And, of course, make sure your windows and zippers are in good repair so they seal properly to keep out rain, snow, and drafts.

Stay comfortable!