In Cleveland's green-building scene, all eyes are on two new homes -- ironically called passive homes -- that take energy efficiency to jaw-dropping extremes. The PNC SmartHome began life as an interactive exhibit for the Museum of Natural History. The other was the architectural dream of a well-known Cleveland couple, photographer Linda Butler and Cleveland Clinic doctor Steven Nissen.

Butler and Nissen built their home in the Ambler Heights Historic District of Cleveland Heights, on the site of a cavernous and antiquated mansion that they demolished. Jocelyn and Martin Schaffer, meanwhile, snatched up the PNC SmartHome after thousands toured it, moving it to its new permanent address on Wade Park Avenue.

Passive homes adhere to stringent energy efficiency requirements, using a fraction of the energy of a traditional home. Neither home has a furnace -- nor even a natural gas line. The average monthly utility costs for the Schaffer's home is $20, while the Butler-Nissens shell out about $40.

We'll spare you the in-depth tutorial on air-tight construction, solar gain, and heat loads and instead focus on what it's like to live in Cleveland's greenest homes.

Terminating stereotypes

"With these new tight homes, until people walk into them and sort of kick the tires and see what it's like, it’s really hard to convey on paper the sensation of being in an environment that's different than any they've been in before," says PNC SmartHome's principal designer Chuck Miller of Doty & Miller Architects.

First and foremost, both homes are beautiful, welcoming, and incredibly comfortable. The systems that purr behind the scenes are successful due to their staggering efficiency and near invisibility. Triple-pane windows and stalwart doors secure enough for a bank vault also serve as beautiful portals to nature and the surrounding community. The meticulously insulated walls, floors and ceilings form clean lines that envelop airy, light-filled spaces. Those same elements display a built-to-last quality that suggests a century home in the making.

"This is a much more comfortable house than a standard house because there are no drafts, and the energy system is so quiet, and the house is so quiet," says Linda Butler. "It's also great for people who have allergies because it's a very clean house."

Environmental efficiency also has unexpected benefits: The pure air allows Butler to exhibit her award-winning photography in a lower-level gallery without the need for protective glass.

"It's sort of like seeing them nude," she says. "You don't have the reflections. It's much more intense. You can really see the blacks and whites."

Her collections literally are displayed in a whole new light thanks to LED bulbs, which cast the same light as a standard 60- or 70-watt bulb while sipping just 8 watts or so. "They give beautiful light," adds Butler.

A full-time love affair

While the Schaffers live in their SmartHome only part-time, they have a full-time love affair with it.

"The house was designed to fit into the neighborhood and we think it does that very well," says Martin. "It's very comfortable for us on the inside. It's easy to save energy and there's nothing in this house that causes us inconvenience."

"I love the whole concept," adds Jocelyn. "I love that the house uses very, very little energy to function and that it functions very, very well."

A beautiful irony blooms throughout both homes. Form and figure dazzle while function barely announces its presence. A silk and bamboo kite that Butler first saw flying above the Yangtze River floats in a two-story vestibule. The fresh air beneath its wings now comes courtesy of a complex air exchanger known as an energy recovery ventilator (ERV), which is hidden away in a basement closet.

"I think of it as a little magic machine," says Butler.

In the Schaffer home, cove lighting, built-in shelving and a decorative arch delineate the living room from the entry foyer, evoking arts and crafts styling. Meanwhile, in the Butler-Nissen home, sweeping lines and minimalism conjure a Japanese aesthetic. Instead of traditional furnace systems with vents and bulky ductwork disrupting the homes' delicate designs, discrete heat pumps regulate temperature while just sipping energy.

The vintage-style bathroom in the Schaffer home, with its sleek marble tiling and floors, is economically heated by radiant elements in the floor and towel racks. In both homes, steaming showers and baths in oversized tubs, whirlpools and stalls come courtesy of the sun via solar thermal panels and super-insulated water tanks.

"We wait for sunny days," says Butler. "We love sunny days. When it's sunny out, we feel like we're getting jellybeans or something -- free energy from the sun."

The approach has paid off in more than jellybeans: When the solar panels generate more energy than the house requires, it goes backwards into the electrical grid, earning the homeowners a billing credit. To date, the home has produced more power than it has consumed and the couple is running a $200 surplus with the Illuminating Company.

A greener future?

As for the future of passive home technology, it's likely up to the consumer.

"We can all go to a government building or another building where somebody else pays the bills and it doesn't resonate," says Joe Ferut, architect of the Butler-Nissen home. "But when it starts at home and it comes out of your pocketbook, it really changes your thought process. If everyone was doing this and thought about this, it could be a social cultural change. It's always the small steps that make the big change, the paradigm shift."

Considering how they've opened up their homes to the community thus far, it's a good bet these homeowners will continue doing their part to shape the future of home efficiency.

That said, these homes and homeowners already have established a quiet tether to the past -- and to each other. The venerable but horribly inefficient 1917 structure that was built by famed Cleveland architects Walker and Weeks (Severance Hall, Hope Memorial Bridge) and razed to make room for the new Butler and Nissen passive home is gone but not forgotten. Wood from the meaty old joists was repurposed into a massive table by furniture maker Freddy Hill, while the 95-year-old flooring found new footing in the PNC SmartHome.