The miniHome, designed by Andy Thompson of Sustain Design Studio in Toronto, is a completely self-sufficient, mobile dwelling, featuring solar and wind energy and recycled and/or nontoxic materials. You can even grow a garden on the roof.
When you think of mobile homes, any number of thoughts comes to mind, but “eco-home” isn’t usually one of them. Yet plenty of folks who walk their green talk aren’t in a position to bankroll a brand-new eco-home. If you want to own your house (maybe even mortgage free), eco-retrofitting a used mobile home just might be the ticket.
“You could go to a used mobile-home lot and buy a 14-by-70 foot home for $1,000 to $2,000, then invest maybe $10,000 in it, and you’d have yourself a pretty dang nice house,” says residential energy-efficiency expert John Krigger, author of Your Mobile Home: Energy and Repair Guide for Manufactured Housing (Saturn Resource Management, 1998). “I have a lot of respect for the way mobile homes use natural resources,” he adds. “They’re very lightweight, and they don’t require much in the way of materials. The average site-built house probably uses three times as much material for a given floor area.”
Another advantage is that, unless you’re in a park with narrow lots, you can orient your mobile home so the long dimension runs east-west. That exposes the greatest wall area to warming winter sun and cuts down on the amount of wall area facing the cold westerly winds and hot summer-afternoon sun.
Canadian mobile-dwelling innovator Andy Thomson has observed that people living in mobile homes can use from 10 to 100 times less energy and resources (propane, water, materials, and electricity) than people who live in site-built houses. “Mobile home codes don’t spell out minimum room sizes,” he says, “so you can be really space efficient, which automatically cuts down on material use, energy consumption, and impact on the land. They also use less water because fixtures are ultra-low flush, with low-volume delivery. Furthermore, mobile-home codes allow for more creativity in how you heat, cool, handle waste, and filter graywater.”
The catch is you’ll have to do some work. Even brand-new mobile homes aren’t very energy efficient and are notorious for outgasing formaldehyde and other toxic substances, so your best bet all around is to buy a used mobile and upgrade it. Before undertaking any projects, however, be sure to consult a good book or a qualified professional—and be very wary of existing mold and mildew.
High and dry
Dealing with moisture is the first step in improving almost any mobile home. Mobile homes can leak at roof vents, window perimeters, screw holes, and roof edges without overhangs. Water that collects under the home because of poor site drainage can also cause damage, and plumbing leaks and stray landscape watering can wreak their own havoc. To prevent this, site a mobile home well, making sure you:
• provide good drainage;
• add gutters or overhangs to the roof;
• fix plumbing leaks;
• install a ground-moisture barrier under the home;
• seal leaks in the roof and walls.
In many mobile homes, what appears to be water leaking in from outside is actually condensation from internal moisture buildup. Most mobile homes need some mechanical help:
• Use vent fans in bathrooms and in the kitchen, with backdraft dampers to avoid air leakage.
• Consider adding a whole-house fan.
• Install a heat-recovery ventilator to keep interior air fresh and pressure balanced without wasting heat.
Energy specialist Cal Steiner, who gives workshops in weatherizing mobile homes points out that a furnace blower can drive moisture into wall, attic, or floor cavities, where it’s likely to condense and cause structural damage. The solution is to create an air barrier around the indoor space by sealing cracks and penetrations in the home’s interior membrane:
• around heating ducts and registers;
• at air conditioners;
• in the underbelly or floor/chassis;
• around plumbing;
• at building joints;
• around electrical penetrations;
• behind cabinets;
• at loose siding, paneling, and trim.
In addition, seal all penetrations in the furnace closet and provide adequate room under the furnace closet door to let air return to the furnace without building up pressure. These measures will also conserve heating and cooling energy.
And finally, a few simple lifestyle changes can reduce indoor air humidity.
• Cook with lids on pots.
• Open a window when cooking or taking showers.
• Don’t keep too many of those water-loving houseplants.
• Leave wet clothing and boots in a mudroom.
• Vent the clothes dryer to the outdoors.
• Don’t use a humidifier unless it has been medically prescribed.
Use energy well
Even when mobile homes have some insulation, it’s often poorly installed with gaps that reduce its effectiveness. You can pull back a portion of the cladding to blow or foam in additional insulation. In some cases—especially if you’re removing the interior or exterior surface—it may be practical to add fiberglass batts. The right way to approach an insulation project will depend on the mobile home, your climate, how handy you are, and whether you can find good contractors. Adding insulation may also facilitate the installation of a new air/vapor barrier.
Chances are, you’ll want to increase the insulation level of your mobile home no matter when it was built. Even the most recent codes only require R-14 to R-22 insulation in the roof, depending on the thermal zone it’s built for. So the most important thing to look at is the structural condition of the home; it’s much easier to reinsulate than to repair kinks in the framing. And research performed at the National Renewable Energy Laboratory indicates that mobile-home dwellers can save up to 40 percent on their energy bills through good weatherization. To take it up a notch, add solar panels.
Park that thing
Krigger sees rural areas as the best location for eco-mobiles; not only are mobile homes outlawed on many city lots, but paying site rent at a mobile-home park can negate the real joys of mortgage-free ownership. A big yard also allows you to correctly orient your home and landscape to enhance its appearance and energy efficiency. “In fact,” says Krigger, “landscaping may be your best long-term investment for reducing heating and cooling costs.”
Properly selected and placed, trees can reduce summer cooling bills by creating shade, and winter heating bills by acting as windbreaks. Deciduous trees provide shade in summer and admit warming sunlight in winter. A lattice or trellis with a climbing vine can block sun while allowing cooling breezes—and if you don’t like the appearance of mobile homes, it can help a lot there, too! If summers are hot, provide shade plantings around patios and pavement to reduce reflection of solar heat from their surfaces.
What if you do want to live in town? As Thomson sees it, trailer parks have a lot of potential for eco-community: rent is cheap; hooking up to utilities is optional; lots are small (requiring less land and infrastructure); you’re not digging foundations (therefore not disturbing the earth or reducing its capacity to take in water); and there are often shared facilities such as park space, swimming pools, and laundry facilities. The sense of community in a trailer park is often much greater than in suburbs—partly because of park rules that define appropriate behavior, including quiet hours.
Is there an eco-mobile in your future?
Ecology-minded people should think twice before dismissing mobile homes, suggests Thomson. “I realized the people who are most passionate about green building often have little money, and the people with the most money often have no passion for green living,”he says. How do we reconcile that? Find ways to make housing cheaper. Eco-mobile homes are a good start.”