When I was younger, I wanted one day to have a Bat Cave just like Bruce Wayne. Then, Batman Begins came out a few years ago and I wanted a cave to call my own all over again. There are some obvious problems with finding such a perfect geological feature to compliment any home — so I’ve lately downgraded my dreams to building the perfect eco hideout instead; the type of place I can wander through backyard woods or across a field in the middle of nowhere to get to. The type of place where you can hunker down for a few weeks at a time and not worry about looking like Tom Hanks halfway through Castaway. Modern, earth-friendly, and cozy — with all the high-tech renewable energy systems and gizmos I can cram into it. Think Thoreau’s cabin at Walden Pond but with an Xbox360, skylights, and solar panels.

Below are four “Eco Spaces” that are unique and perfectly designed to give you the privacy you need without losing any of the comforts. Some are easier — and less expensive — than others, but the end results for all are striking.

Choice One: The EcoHab

Quite possible the ugliest of the our choices here, the EcoHab makes up for looks with beautiful internal lighting, creative use of space, and nice features like underfloor heating, shower, rainwater collection, toilet, and efficient washer/dryer. Besides having kids believe you live inside a spaceship, you can also wow (or bore) them with your Hab’s eco characteristics. The home is composted of cement mixed with fly ash which is then covered with thick polyurethane for superior insulation. Additionally, the outside can be covered in tiles made from from recycled tires. Solar and all the other fixings can be incorporated as well. Prices currently suck for the average consumer at about $90,000 US.

Choice Two: The miniHome

This particular eco space is more suited for a second home than a small retreat. Still, if you’ve got deep pockets and need a place to unwind this may be the perfect “out there” option. Their Micro-Gable and Micro-Shed models are a perfect in-between. According to the site, within 350sq ft. “there is everything you need for comfortable, year-round, sustainable living”. The different models can even be adapted to varying climates; including arctic temperatures. Treehugger ticks off the environmental attributes quite nicely: “SIP’s, low VOC wheatstock particle board, solvent free adhesives, portable green roof, rainwater collection, photovoltaics, LED lighting, composting toilets, stack-effect-based heat recovery ventilator, grey water storage, Stirling multifuel biodiesel system providing heating, hot water and electricity from one unit and, get this, siding made from hemp.” Yup, this one is made to impress. Costs currently start at $107 for the SOLO model, but we’re thinking they’re a bit lower for the smaller designs on the site. If you can afford it, this one impresses in features and construction.

Choice Three : The EcoSpace Studio

This company features meerkats in much of the marketing literature accompanying their structure; so the’re points ahead from the get-go. We’re also entering the realm of ‘affordable’ with this green studio composed of roughly 120 sq feet. I dig the large windows and such features as a green roof, heated water-resistant rubber flooring, sustainable red cedar insulated walls, and the small footprint. A standard model costs about $37K.

Choice Four: The Mini-Jot

The Mini-Jot may be your best bet for aligning price with function. At roughly $100 per square foot, this 120sq ft. studio can fit perfectly as a home office, guest house, etc. The structure is designed with passive solar in mind to reduce heating and cooling costs; as well as insulated lightweight structural panels, super-efficient windows, and optional concrete flooring to act as a heat sink. With the money you save on building costs, you could also add on solar, a wood stove, or other cool green features.

Choice Five: The Hobbit House

I’ve saved the best for last — because seriously, if you can pull these structures off you’ll have a natural hideaway to rival all others. First, let’s take a look at the famed “Woodland Home”; which gives the impression that Gandalf The Wizard may visit at any moment. Half-snuggled into the side of a hill, this home is made from all-natural materials, incorporates a green rood, passive solar design, and some incredible artistic touches. The pictures from the inside of this structure all lit up make it look like something out of a fairytale. Costs for this home came in under $6K, but the time and effort are certainly not included. Another cool project coming in at the same price is the “Low Impact RoundHouse”. Having Celtic origins, this roundhouse is made from sustainable materials and incorporates strawbale and timberframe design. It took only four months to design and build and blends in beautifully with its surroundings. Showers, woodstove, and other modern comforts are all easily integrated. Sure, these two designs are bit too “wild” for some people, but just like the Bat Cave, beauty is in the eye of the beholder.