That would make it completely green and legal. But I didn't see any vent, not sure if they use one though. The roof was interesting.

It is EPDM rubber roofing(I use quite a bit of that, it allows innovative design in building). That seems like a poor choice. First, it's hot! A real solar collector. Next, it's heavy. And with such ample roof pitch, it's overkill. I think a cedar shingle roof would be lighter, cooler, and the rain water might have a better taste. Wood shingle would be a nice visual element for the house boat.

Any roofing though would be a good spot for some solar panels. They had a small pressure pump to run the on demand hot water (propane fired) to the outdoor shower.

You could easily put enough panels on the roof to even run refrigeration(off the grid so to speak). But it's easy to critique when you don't know what budget was used. The float(s) looked to be salvaged and cobbled together with some new components. But it's perfectly adequate for protected water.

I'm wondering more about the use of a houseboat like this in Maine waters. It (and all houseboats) is a seasonal dwelling due to our winters(there are no harbors I'm aware of that have year round dockside facilities for houseboats in Maine).

They'll need to be hauled seasonally. That could be difficult if they're big. However,... if they fit on a hydraulic trailer, they could be quite easy to haul, economical to do so, and simply and cheaply stored inland on blocks.

They are not easily navigable as a tow away from sheltered waters or up our rivers from the coast. So where they originate or launch is likely they're cruising ground.

And I see them as a perfect platform to mount a winch which could allow them to haul a large mushroom mooring which makes them able to "anchor" legally for the season. This is an affordable option for a summer home in some amazing neighborhoods(they're shoal draft, very shoal draft).

If you're not in a Maine harbor that has local mooring ordinances, I don't think a houseboat has any regulations(assuming you're not using a head) beyond maybe a light at night(this has patio solar lights).

But that's a good thing as it's more or less the same for us on our boats. We have the right to navigate, anchor in our federal waters. I don't want that to change.

I might build one myself and use it as a dock and summer home for my sailboat.