Introduction
The concept of being able to hitch up and explore a variety of environments and climates is thrilling. Picture this: A family sets out for a summer adventure with a travel trailer. Parents in the front seat, windows down, a warm breeze blows through the vehicle with kids playing car games and watching a new world go by in the back seat. Imagine the many exciting adventures that lie ahead for this family.
Now, consider these mental images: What will the weather be like? Is the family traveling somewhere warm? Perhaps a lake or mountains where the outdoors will be explored? Nice warm days, cool nights. It will be a comfortable vacation. After all -- that's what vacations are for.
There's a reason this is a rather iconic and ideal image. This is exactly what most of today's travel trailers are designed and built to do. This is what I call a 3-season trailer design. The typical travel season for most travel trailer users is summer. A warm summer, but not too hot, with mild temperatures, light breezes, and always comfortable in shorts. The reason we call this 3-season is that the trip may extend into both Spring and Fall. Travel trailers are built to handle this type of moderate climate condition.
Now imagine this scenario: It's April, and that same family is on that first camping trip of the season. Well prepared in the 3-season travel trailer, they notice large clouds forming on the peaks of the mountains ahead. As they gain elevation, it starts to rain, then sleet, and finally, as they arrive at the campsite, there are a couple of inches of snow on the ground. They will only discover that the 3-season trailer is not one of the many four-season travel trailers designed to perform well in extreme hot or cold weather.
This is when the issue of the 3rd and 4th seasons comes into play. Extreme weather is the enemy of travel trailers. Even with a strong furnace and a couple of full bottles of propane, the trailer will not be able to handle winter camping trips, and things will start to fail. There is simply a limit to how well the system is designed to resist hot and cold temperatures. And it's not even the heating system's fault -- it was working as designed. The issue is more fundamental. The problem is that most weren't designed or engineered as four-season trailers, specifically designed for extreme weather protection.
A rational definition of a 4-season camper to most observers would be one that could be used all year long regardless of the weather or the temperature. The problem is the RV industry doesn’t have a true definition for a 4-season camper, and RV marketers are free to call them whatever they want. It reminds me how the term green has been misused to describe earth-friendly or sustainable products.
Personal experience has been my best teacher. Joanna and I have camped and lived full-time in countless travel trailers for years, and I've discovered that no two travel trailers are the same. While one trailer's design may be fully functional and comfortable down to 20º, another seemingly identical travel trailer may start failing at the point of freezing. A standard package trailer is not a luxury. A luxury travel trailer, by definition, is created to take you farther, do more, and provide the best living experience in extreme living conditions.
For the purposes of this article, we're focused primarily on how to keep cold air out and the water systems from freezing. I aim to help clarify what makes a luxury travel trailer 4-season capable and what affects the performance in all climates.
What is a 4-Season Travel Trailer?
A 4-Season Travel Trailer, also known as an all-season travel trailer, is specifically designed to provide comfort throughout the year, even in extreme winter or summer conditions. These trailers are built to withstand harsh weather and ensure a comfortable experience for travelers. The main advantage of a 4-Season Travel Trailer is its enhanced ability to handle cold winter conditions, thanks to superior insulation, advanced heating systems, and specialized tires.
An ordinary travel trailer is not designed to respond to many environmental conditions. However, our amazing world has countless places and experiences far from sunny and 75.
This awareness is especially important for people who call their trailer home year-round, known as full-timers. The major difference between full-timers and recreational campers is simple: one has a traditional home they can return to after their trip, and the other is living in a travel trailer full-time. This is the key difference between a recreational vehicle (RV) and a Living Vehicle (LV). One is designed for recreation, spanning a short period, and the other is designed for full-time living as a primary residence.
When winter comes, or hot weather makes trailer living impossible, the family puts their trailer in storage and returns to the comfort of their bricks and sticks home. When winter arrives for the full-timers, the trailer must continue to perform to suit the very real requirements of the environment. At this point, the full-timer has two options: follow 75º by moving to a more temperate locale or upgrade their HVAC system and cold-weather camping capabilities.
As has been done for decades, the trailer may be moved to warmer climates, which is the most common solution. A mobile lifestyle lexicon has even been created, with such terms as snowbirds, those who fly south for the winter to continue living in their full-time and traveling home safely. Relocating the travel trailer out of the cold is one way to live year-round, and frankly seems most enjoyable to me! After all, I too enjoy sunny and 75º most of the time.
But what happens if you cannot relocate or want to be in a frigid environment? For example, I love skiing. Being first on the mountain is important, after all -- fresh tracks. Being able to park overnight at a winter resort parking lot in December means I will always be first on the chair lift. It is simply awesome.
What happens if work demands require you to be in a cold location? Or, a sudden Arctic cold front arrives in early September, and you're suddenly trapped in a wind chill of -10º, with the threat of frozen water tanks? Every one of these examples isn't only possible but has happened to me. And more importantly, these dramatic weather conditions are no longer the exception -- they are becoming ever more common with our ever-changing world climate.
Often, simple design fixes such as heated holding tanks are not enough for winter RVing. A luxury 4-season travel trailer should be designed to survive and thrive in all weather conditions and climates. Knowing you have options is the key to owning a true 4-season capable trailer. This is what I call freedom of choice. Understanding exactly what makes your trailer able to withstand very hot and very cold environments means you have better options to choose where and when you travel -- and how long you stay there.
A 4 season travel trailer is a travel trailer is designed to stay comfortable year-round through the harshest winter and summer conditions.
Young, or young at heart, a quality life is about the pursuit of freedom. More than ever, luxury travel trailer owners are taking their units off-grid and challenging the limits of what climates they may travel.
The 4-season capability question must be answered: How easily does the trailer perform in very hot or cold climates? The answer is more complex and involves several variables.
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When considering a trailer that's four seasons capable, there are ten very important concepts to consider:
Comfort
I love camping. I have a sleeping bag designed for sleeping in subfreezing temperatures. Camping in very cold weather is not a good time, but I love being over-prepared. That sleeping bag is rated down to 20˚F. So, I bought it thinking I'd planned for plenty of buffers should temperatures get below freezing when camping. Only after buying it did I realize that this fancy 20˚ rating was, in truth, a survival rating, not a comfort rating. The comfort rating wasn't even below freezing. I felt duped.
It's not enough for a travel trailer to have a 4-season survival rating. A proper 4-season travel trailer should be designed to thrive in all conditions and the most comfortable manner possible. They must be designed to withstand the demands of critical, life-giving systems. A luxurious design considers heat resistance, insulation, thermal breaks, heat/cooling loss, and freeze protection, all working together to create the simple condition: comfort.
Outside of the actual design and function of the travel trailer's well-appointed interior, the bottom line of 4-season comfort is answered by the trailer's ability to maintain the interior temperature comfortably in either hot or cold environments. The challenge for most trailers is they are often woefully insulated, and the installed systems are under-equipped. This can be a real challenge with walls just 1-½” to 2” thick!
A typical bricks-and-sticks home has walls 6” to 8” thick and is built on concrete slabs or conditioned crawl spaces. A trailer floating in space with cold or hot air circulating at all times is not an easy problem to solve.
Each of these components is critically important when choosing the proper 4-season trailer. We'll start with the most important factor in maintaining year-round comfort: insulation.
How effective are the walls, floor, and ceiling barriers in protecting the inside temperatures from outside temperatures? Or another way to ask is, "How well does the trailer resist heat transfer from outside to inside?" The more resistance, the less the heating or cooling systems must work to keep that inside at a comfortable temperature. This concept of resistance is the key here.
Insulation is measured in the R-value, with the R being resistance. R-value measures resistance to heat flow through a given thickness of the space or material.
There are several types of insulation, and inch-for-inch, the best is closed-cell rigid foam. I even prefer rigid insulation over triple-layered roof insulation because it offers the best R-values, is lightweight, and is completely waterproof.
R-value is important and is where the travel trailer industry puts most of its attention -- after all, it's easy to understand and is backed up by the R-value number stamped on the insulation used. But it's just one of the key factors determining the insulation material's effectiveness.
Insulation is a great resistor for thermal transfer, but weak spots exist throughout the outside wall design. Areas, where insulation cannot be installed create a tremendous weak point. Areas such as structural studs, window frames, and hatch compartments allow heat to move easily from out to in. Each of these examples represents a direct heat transfer mechanism where the temperature outside easily goes inside.
To resist that heat transfer, a thermal break is needed to stop heat flow.
A thermal break is an energy dam (think resisting flow) and an element of low thermal conductivity in a travel trailer wall, such as insulation discussed above (good at resisting). It's anything placed between the wall's support structure and the interior to prevent the flow of heat or cold.
Another way to think of a thermal break is it is why you'd use potholders to pick up a hot plate from the oven. It's a material or space that resists heat. A double-pane window is an example of air space being a thermal break. In technical terms, space inhibits heat or cold from two closely aligned materials from transferring energy to one another. But too often in travel-trailer design, the idea of thermal break becomes an afterthought, a mere foot-save.
I recommend paying particular attention to the concept of the thermal break. For this reason, published R-values for travel trailers mean next to nothing. If wood or metal studs are used, what protects the interior from that very susceptible stud location without insulation? It doesn't matter how much insulation you put in a wall if a metal stud is a thermal highway from inside to outside every 12” or so.
A travel trailer with single-pane windows is another deficiency. This is precisely why a four-season travel trailer should have double-pane windows.
Many RV manufacturers tout high R-values as a sales tool with little real-world consideration for allowing the occupants to stay warm or cool, allowing for true year-round RV living. Unfortunately, manufacturers tout their four-season RV as having a four seasons package simply because it has thermal pane windows or extra space heater appliances.
Those I've studied include Northwood Arctic Fox North, Arctic Fox North Fork, and Oliver travel trailers; even these units with a so-called Arctic package fall short. Although they may have a double-hulled fiberglass shell and tank heaters, they fall short on several important design principles. That includes insulated hatch covers, block foam insulation, and thermal barriers.
An ideal scenario would be completely separating the structural system from the insulation system -- like a Russian Doll. The structural system is on the outside, and the insulation is on the inside. This is extremely difficult to accomplish when only a few inches of wall space exists.
As you can see, the devil of luxurious design is in the details. Using as many tools and techniques to break the interior environment from the outside is what it's all about.
The success of experiencing very hot or cold climates in a travel trailer is measured by comfort, which is the ultimate goal. In extreme temperatures, the functionality of those comfort-driven appliances is absolutely necessary. The failure of one critical system would require immediate attention and a change of plans.
It's obvious why the inside of a travel trailer should be protected from freezing. One would think that most traditional travel trailers are freeze-protected, but most camping trailers' water tanks, piping, faucets, and other sensitive equipment systems are not.
Most trailers on the road have many fresh and waste water valves exposed below the chassis. This doesn't work for sub-freezing climates. Water expands when frozen; a pipe or tank holding liquids will undoubtedly freeze. A ruptured waste water tank with frozen solids is as bad as you imagine.
Industry engineers concoct solutions that prevent travel trailers from freezing. These semi-solutions include heated tanks (very limited energy hogs), extra fiberglass insulation (not solving the real problem), dual pane windows, and complex heating systems with tons of capacity (overcompensating for a poorly designed frame.)
The issue is these are all just putting Band-aids on the problem. Unfortunately, the designer paid little or no attention to thermal insulation design and was required by a marketing or sales team to pump out a list of features for a low cost.
A beautiful design feels right and works for the user even when cold weather camping. It's easy. Great engineering is simple and works intrinsically. Great engineering combines several layers of the earth's natural forces to create a magical result. The best solution I've discovered protects critical systems, it's called a conditioned basement.
A conditioned basement is a compartment below the main floor of the trailer. It's a large space to house all the electrical equipment, water tanks, and critical systems. In a traditional home, this would be considered a crawl space -- a conditioned basement with insulation on all exposed sides.
When the heat source is located in a conditioned basement, it draws air from the main space into the basement. The warm air in your unit is the same as the air in the basement. This naturally keeps all critical systems and equipment at the proper temperatures.
Poorly constructed trailers are built from wood, fiberglass, and plastic compounds. Well-built trailers, including the floor, ceiling, and floors, are made from metal. A metal floor is a wonderful addition to the conditioned basement design. The floor and joists act as radiator fins and retain heat. After all, metal is a wonderful conductor of heat. This results in a passive warm floor system. As a bonus, the floor is only as warm as the air inside the unit. It's in perfect sync. This basement design keeps the floor warm, and the conditioned space below the raised floor maintains a climate-controlled area for all the water systems, tanks, and temperature-sensitive electronics.
When it comes to freezing protection, the value of a conditioned basement cannot be understated and becomes the basis for all other design decisions. An all-season travel trailer is the best way to experience a wonderful warm floor, walls, and space for the occupants. For this reason, I recommend going with an all-aluminum trailer that circulates the air from the living space into a conditioned basement.
Now we get to the part of 4-season design where the current travel trailer industry excels. Manufacturers have seemingly accepted the travel trailer shell's poor performance standards- the same way it has been built for generations. With this acceptance comes the push for more powerful heating and cooling, with robust HVAC systems, to accommodate 4 season living.
Suppliers of this vital equipment have been competing for years on bigger air-conditioners, more powerful furnace systems, and highly complex heat exchangers. These supporting HVAC components add heat to the unit when the shell cannot resist heat loss. Unfortunately, this naturally becomes extremely inefficient because each one of those appliances takes a ton of power -- electricity or fuel.
Look closely at an air-conditioner or heater, you'll see a sticker that measures BTUs. This rates the power of the appliances. The higher the BTUs, the more electricity or gas it will consume. But what is a BTU? What does it stand for? And what does it mean?
BTUs measure thermal energy. A BTU is the energy needed to heat or cool a pound of water at 1 degree Fahrenheit at sea level. The shell design can also be measured in terms of BTU heat loss. The more BTUs, the more capable an appliance is in raising or lowering a temperature. In this case, more BTUs are better.
Nevertheless, a higher BTU-rated travel trailer does nothing with an inefficient shell design without any thermal break. I've lived in spaces where it didn't matter how powerful the furnace was or the additional space heaters I had because a poorly designed shell destroyed any cooling or heating.
There isn't any one factor that makes or breaks a well-designed year-round outdoors RV shell. It's hundreds of tiny critical design decisions, all working in tandem.
Windows, doors, and hatches are typically the greatest source of heat loss. Uninterrupted insulation is the most successful method of protecting a travel trailer from the outside elements. When that insulation is interrupted by a window or door, there is an opportunity for heat loss. Because of this, trailer companies for 4-season units often minimize the number of windows and doors to the exterior. Unfortunately, this is counterproductive to appreciating the great outdoors and passively managing warmer or cooler weather conditions.
It is difficult to enjoy nature when you're in a submarine with tiny portholes. So extra care must be taken to ensure the windows and doors offer outstanding protection from the elements. Dual pane windows and insulated doors are a must-have.
Doors and windows are also where water intrusion is most common in the shell design. Techniques to increase resistant hatches include automotive quality double D-seal doors, drip rails, and weep holes and channels for water to escape. These details are no small feat to create a 4-season capable shell.
The same goes for doors as hatches. They should be weather-resistant materials and, of course, water-tight. Hatches should be insulated with at least 2” rigid closed-cell insulation being the most desirable. The latches must be designed to work in cold weather, too. I've been traveling many miles in trailers not designed for freezing temperatures, and I couldn't open an exterior compartment due to a frozen latch. Simple stuff, but it all has to work.
I also recommend UV tinting to reduce the radiant heat from the sun. The trailer's entire envelope, which includes the walls, ceiling, and frame, is where the game of temperature control is won or lost.
The chassis and frame design components are the most susceptible components to heat loss throughout a travel trailer's interior. These collective components are called the trailer envelope. Think back to thermal breaks, which are the direct metal-to-metal connections. These are the points of greatest energy transfer from in to out and out to in. A poorly designed and constructed shell envelope wastes the most energy. Radiating heat from outside and heat transfer from points where studs meet inside and outside walls. A thermal break is necessary.
The exterior color of the travel trailer also has a great deal to do with radiating heat away from the interior space. A dark-colored exterior will absorb and hold radiant heat from the sun, whereas a lighter color or silver will reflect it. Unlike solar panels, where absorbing the sun is highly advantageous, the exterior surface of the travel trailer should do the exact opposite. Light, reflective exterior colors will ensure the skin does not get unreasonably hot in direct sun.
If you can find a trailer that uses air as an insulation tool, all the better. In our discussions about insulation and heat transfer, one material is not widely discussed, and for a good reason: air.
One of the best ways to ensure a hot exterior wall does not radiate heat or cold into the interior wall is to separate it physically, so it does not touch it. Ever heard how a vacuum is the best insulator? Well, the air is a very close second. As you can imagine, this is no simple engineering exercise. A travel trailer wall has limited space to offset the wall to create an air gap, let alone the structural components needed to support that wall standing vertically. Air gaps prevent heat from transferring to the inside walls, ceilings, and floors.
Whatever the case, particular attention must be given to the outermost envelope of the travel trailer. After all, this point is where the trailer meets the environment and is most susceptible to hot and cold weather.
The difference between on- and off-grid use is fairly simple. On-grid means you're connected to and reliant on the city's electrical, water, and waste services. Off-grid means you are not connected to nor reliant on a utility grid and may manage your resources no matter where or when you travel.
There are many benefits to on-grid living, the most obvious being you'd be connected to an inexhaustible supply of electricity for heat and air conditioning. If you spend a lot of time in subfreezing temperatures, using electricity to heat your home will be much simpler, and life doesn't get much easier than plugging into a 110v power outlet. But as always, there are tradeoffs: neighbors, noise, and interruptions. Or what about feeling the pull of that electrical chord -- ever feel like a ball and chain keeping you from traveling to off-grid locations?
When plugged into the grid, your trailer should operate all its electrical systems without concern. You can run unlimited electrical systems while charging the onboard batteries… until the power grid darkens. While seemingly luxurious, it's a tremendous limitation.
Off-grid is for those who want to experience freedom. Along with this comes the unbridled adventures of the Great Outdoors, wherever their heart leads. In this case, the travel trailer must first be self-contained and capable of storing enough supply for vital resources like fuel, energy, and water. Self-contained means that you use what you take with you. Once those resources are gone, your travels must end. The key is extending those onboard resources as much as possible.
To go off-grid for a longer period, you'll need a robust renewable power source, such as solar or other power generation sources, which leads us to our next topic.
I believe a luxury 4-season travel trailer was created out of a desire for ultimate freedom. Off-grid travel is not just about traveling in remote environments. The concept provides the freedom to travel when and where you want, with as few limitations as possible.
A 4-season travel trailer is intended to be used year-round and should not be limited by summer or winter when temperatures venture outside ideal comfort. So naturally, 4-season travel trailers should be designed for summer and winter environments. Of course, these two seasons have very different requirements of what is possible to travel successfully. For example, the available sun during winter is significantly less than in summer. There may be very little to no sun, depending on where and when you travel.
In the summer, we are blessed with a wonderful natural resource from the sun to generate a seemingly endless supply of natural energy. This is particularly useful for high-power demand equipment that helps keep the inside cool such as air conditioners. We believe 4-season travel trailers should be designed to leverage this resource and run the air conditioning system from solar power.
While most trailers will run an air conditioner with a generator, this is a terrible primary power source and consumes a lot of fuel. Conversely, the amount of sun available in the winter is significantly less, with very different impacts. With just a fraction of available solar energy than during the summer, this significantly changes where a trailer may gain energy to power the necessary heating systems during winter.
Due to the lack of solar in the winter, a capable 4-season travel trailer must rely on alternative fuel sources to provide the necessary energy to keep the inside warm. Propane is common and regularly used as a fuel source for travel trailers. The better the insulation and thermal shell design, the less heat that's required, and in turn, the less propane consumed. Combining gas and electric heat is a winning approach adding a bunch of solar panels and minimal sun exposure.
In order to make this a reality, the energy capacity in the battery system must be as large as possible. This allows you to store power from the sun and use it later when that solar power is unavailable. The bigger the battery capacity, the longer you can run these critical components. I recommend a minimum 10 kWh battery bank for short-term travel. If you want to travel in extreme temperatures for weeks, if not months, I recommend a battery system as big as possible.
Additional power generation sources such as propane or gas generators can create redundant power sources when solar is unavailable. These redundant power sources are designed to recharge your batteries without solar power. One additional and often overlooked resource is the engine's power in the tow vehicle. There are high-voltage alternators designed to work with advanced battery equipment in the 4-season travel trailer so that the tow vehicle can recharge the entire trailer energy pack in hours. This allows quick recharge times during winter months and the convenience of charging and running high-demand power systems to keep the interior conditioned at all times.
Astronauts in a space capsule 100,000 miles from the earth are glad there are two sources of oxygen. Check that -- it would be critical to your survival and safe return to earth! If you're traveling in a travel trailer, off-grid, in 20˚ temps, 100 miles from mechanical support services, it might not be an issue of life and death, but I guarantee you'll sleep better knowing you had two sources of heat just in case one ran out of fuel, or electricity, or failed altogether.
While we may not yet be traveling to space soon in our 4-season travel trailers, 4-season use is increasingly more challenging to ensure everything goes according to plan. Murphy's Law is always possible regardless of how thoughtfully a travel trailer is designed. If you travel in freezing temperatures and rely on one heat source, it will inevitably fail when needed.
A backup ready and waiting is one of the most important factors in true 4-season capable design and planning. It's critical to have two sources of power generation, two sources of heat or cooling. Redundancy means we always plan for something to go wrong or run out of fuel. When it does, we get to continue with our backup plan, not because something went wrong but because it was part of the plan initially. Being reliant on one critical system is an incredible risk. When two is one, and one is none, having multiple backup plans in place will allow you to go further and stay longer in extreme environments.
The design of a luxury travel trailer must carefully consider the concept of redundancy. Multiple sources of power, heat, and cooling are vital when pushing the limits of travel.
So, what's the ideal experience for a 4-season, off-grid-capable trailer setup? A successful luxury travel trailer design will include these options built-in and seamlessly integrated:
Shell Design
- Thoughtfully designed & engineered thermal shell
- 100% closed cell rigid foam insulation used
- Thermal breaks in the walls with a true air gap
- Seamless aluminum roof for water protection.
- Large windows, skylights, and ceiling fans for natural ventilation and outdoor connection.
- Dual-pane windows and patio doors
Interior Design
- Conditioned basement and subfloor heating system
- Aluminum flooring and floor joists for passive warm-floor
- All water systems are located in a conditioned basement
- Easy access to all systems for convenient servicing
Energy and Equipment
- Large lithium battery capacity of over 10 kWh
- Solar panels with at least 1200 watts
- Tankless water heater capable of operating in freezing temperatures
- An Air-Conditioning system that is capable of running on solar power
- On-board backup generator, tow vehicle alternator, and other sources of redundant power generation
- Powerful and efficient furnace and air-conditioning units
- Redundant systems for heating and cooling
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