1. Keep it simple and affordable.
A house with bamboo flooring, tankless water heaters etc. is obviously going to cost more than baseline homes with no upgrades, but keep the price close to average. Save the buyer money and energy by cutting down on square feet. Remember, the Prius debuted at around $20,000, which is low/mid-priced.
I think the Cavco "Freedom" solar park model is a good example of simple, good green design, and it is reasonably affordable relative to other park models (400 sq. ft.), but from an energy standpoint (as well as solid construction) R-11 insulation and 2 x 4 walls are disappointing. It would have been nice to see SIPS walls with R-20 or more.
A “green” double-wide around a thousand square feet would be fine. It can be done with making the master bedroom small and the 2nd bedroom even smaller. A home of 700 to 1000 feet would gain a market for small families, retirees, single people, and vacation home buyers.
As a country, we have become a nation encouraged to shop and want more than we can afford. In homes, including manufactured homes, the idea that bigger is always better, is part of the problem. Smaller is going to be back, and energy efficient is going to be "in" for several years ahead. The new home market is faltering at this point. People can buy foreclosures at bargain prices. However, I expect that well designed manufactured homes will have a market in the new homes market, especially for the approaching bulge in baby boomer retirees.
An example of a nifty interior floor plan and an attractive exterior in a smaller doublewide, is the 864 sq. Karsten RC-2, with the dormer option. It is their smallest model. Without the dormers, the interior loses its character (light, aesthetic appeal) and feeling of spaciousness. I've toured one, both ways, with and without dormers. On the web, there isn’t a photo or even a drawing of the exterior of the home. Instead the Karsten website shows a drawing of a generic home when you do the “brochure.” I took many photos of this charming house a few years ago, but lost them when my hard disk got fried in a lightning storm.
One reason I like this particular home, the RC-2, from the standpoint of heat conservation, is the lack of registers and heating ducts. The home is designed to have the central heater, with passive circulation throughout the house. No ducts losing energy, or getting dirty. No sound of fans blowing through ducts. It is both the design and the small size of the home that allows this. It probably never sold well for the lack of a 2nd bathroom. Karsten is now owned by Clayton.
2. How about a model of manufactured home with R-30 to R-50 walls, that are a foot or more thick. The higher thickness would be best suited to areas with winter climates with temps below freezing.
Insulation is the most cost effective way of improving efficiency, and thicker walls, usually necessary to fit in more insulation, give a home a feeling of permanence and quality. For the thicker walls and frame structure, engineered woods, SIPS, or a sandwich of blown-in insulation between two sheets of oriented strand board, such as in Dr. Feist's "passivhaus" See article in THE NEW YORK TIMES.
Feist's passive houses, have R-60 walls, and are heated in the winter by appliances and human occupants, or supplemental heating by a very small heater. They use less than one tenth the energy of an average home of the same size. In the last decade thousands of these passive homes have been built in Europe, and architects like Karin Klingenberg carry on his work in the U.S.
3. Forget water catchment for a while.
While water catchment might be good for some remote locations, people who want it can get put on rain gutters and do it themselves if they need it. Instead, center the design around passive and active solar. So, a roof (shed, gable, or split gable with clerestory windows), oriented from 40 to 60 degrees. Use the same heavy gauge metal as is on the i-house. And silver is a good color.
Passive solar design should include one or two double-door sized windows on the South side, including one in the bedroom on the south side smaller windows on East and West and just a few small windows on the North side.
There’s a problem using a shed roof, for solar panels, in that if you want passive solar orientation, the high wall ends up on the north side. That can be avoided by using a flat ceiling inside. If using a flat ceiling, make it 9 feet high.
4. On option of slotted rolling shades, for the large windows on the south of the house. Insulated shades with a reflective or white exterior (for summer).
5. Use a conventional door for main entry into the house, instead of a sliding door.
6. Stick with the Andersen windows, bamboo flooring, Ikea cabinets, tankless water. All those features are well worth the extra money.
One thing I see that might be right about a flatter roof depends on how many homes are sold to parks, where people don’t have an option of facing the home and its roof for optimal southern exposure.
One other thing I'd like to see a manufactured home company do: A garage with apartment above unit, with the apartment about four hundred to 550 square feet. Again, it would have multiple uses: garage and guest house, vacation home, mother-in-law home, extra rental income, or home for a single person.
Lastly, as via my suggestion in an earlier post. If the design for the i-home ends up undergoing drastic alterations, or being scrapped, consider expanding the 2nd bedroom into a tiny home. I think on its own, or maybe something a little larger, it would make a nice cottage. I would like to see a photo of it head on, and also the inside.
While I saw a Prius at a local dealer when it first came out, and then some driving around, it is very hard for people in some states to see a new model home. Dealers carry only a few models. In New Mexico, I've never seen a "park model" anywhere, although I know they must be somewhere. A few dealers have one model on display. In Phoenix they are all over. How many people can go to a show?
So, please take some videos, or at least comprehensive photos, of all your homes, no matter how fancy or humble. I watch amateur videos that some RV dealers do on youtube or their sites. Even though they don't bother with extra lighting, and they are usually bad quality, I like seeing the tour. Dealers of manufactured homes don't seem to be doing many videos like that. I'd like to see a video tour of the i-house. It would prime people's interest in the green direction of manufactured housing.