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This super-efficient house cost less than $200 to operate all summer long By Jim Harger

CASCADE TOWNSHIP, MI - Architect Evan Mathison can go on for hours about all of the features he has packed into the sustainable house he designed for his family. Some are esoteric details that only architects will comprehend.

Here's one that everyone who pays the bills can understand: Mathison's utility bills totaled only $193 in the four months between May and September this year. That includes air conditioning, cooking, laundry and hot water for a family of five.

LEED-platinum certification - the highest rating possible -- is pending for the house, says Mathison, a principal with Mathison | Mathison Architects, a firm he founded with his father, Tom Mathison.

It could cost even less in the future, says Mathison, who completed the house last year. They are still learning how to take advantage of its green roof, solar electrical panels, geo-thermal heating and cooling system and triple-paned European windows.

"The house is performing well," says Mathison, who estimates he built the 3,100 square-foot house with four bedrooms and three bathrooms for about $750,000. That added cost up-front will pay for itself over the years as they reap the benefits of the investments they made in building the house, he says.

Set on a 1-acre wooded lot, Mathison oriented the two-story house to scoop up as much sunlight as possible through the big windows he put on the southwest side of the house.

To keep the house airtight, he used triple-paned insulated windows imported from Europe that tilt or turn for ventilation. The 13-foot triple-paned sliding glass door drops into an insulated channel that seals out any drafts when closed.

To keep the sunlight out during the summer months, Mathison designed a sun trellis that blocks 90 percent of the direct light in the summer while allowing the light to flow into the house during the winter, when the sun is lower in the sky.

The house was designed with a narrow floor plan designed to let the sunlight flow into every room. The rooms are connected by a two-story hallway that acts as an air stack that ventilates the house by opening windows on the ground and second floor.

While the south side of the house has more than 500 square feet of windows, the north side has only 120 square feet - most in clerestory windows designed to provide soft lighting and open up the rooms.

To keep down the costs of operating the house and eliminate the threat of carbon monoxide poisoning, the "flame free" house has no gas service. The modern fireplace is fueled by a canister of bio-fuel.

About half of the house is on a concrete slab designed to soak up the sunlight in the winter. The remainder of the house has wide walnut floor planks. The ceilings have cedar panels that hide the air conditioning vents.

The cedar ceiling panels along the hallway also are embedded with 60 single-watt LEDs that add sparkle to the house.

The home's walls are made of 6.5-inch-thick structural insulated panels (SIPs). The house also was wrapped with 2-inch polystyrene panels. A 0.75-inch gap was built between the olive-green fiber cement siding to prevent the build-up of moisture in the walls.

The green roof over part of the house helps cool the house in the summer, retain heat in the winter and absorbs rainwater that would otherwise run on the ground. Mathison said he had to water the fledgling plants during the recent drought conditions.

While the materials behind the walls and ceilings are unusual, the house itself is typical of a modern design. The cabinetry was built by Woodways Industries, in some cases replacing the need for furniture purchases.

The kitchen includes a butler pantry to hide countertop appliances, quartz counter tops and a large family dining table made from a tree trunk by an Amish sawmill in Indiana.

On the second floor, reading lofts were built in the children's bedrooms to take advantage of the tall ceiling heights and clerestory windows.

Mathison built an office loft accessible by a ship's ladder after his children created a homework room out of the space he had intended for his home office.

Outside, they created a rain garden to absorb the runoff from the blacktop driveway. Mathison says he had intended to install a permeable driveway but ran into budget constraints.

Looking back on the project, Mathison says they had the same budget decisions most homeowners face when they decide how much money to spend on materials and design versus long-term operating costs.

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