A fascination with solar energy and a keen interest in economy led John E. Eckland to design and build a house in Great Falls that acts as its own collector of solar energy.

He believes it will provide up to 90 percent of the heating and hot water his family requires and save up to $1,500 a year in fuel bills.

The redwood frame house is being completed on a five - acre site. It is crammed with solar energy features.

I've been watching the construction of houses in this area for the past 10 years and paying particular attention since the energy crisis in 1973," Eckland said. "In that time, I noticed very little change in the way the houses were being built."

Eckland thought he ought improve on the energy - saving features of his own house by using some of the new tecnology and advanced ideas. "I wanted to build a house would not be an energy guzzler during the years the house will be standing, he said.

The most distinctive feature of the house and the key to its solar energy system are 14 floor to ceiling windows, all of which face south and permit sunlight to flood the house during the winter. The sunlight heats the dark brown Italian tile floors and brick walls on the first floor, and brick walls on the first floor, stones the heat, and then releases it , Eckland said.

On a bright, sunny day, I can raise the temperature of the house eight degrees," he said. It could take nine gallons of furl oil to raise the temperature by that much, he said.

During the summer, the sunlight does not heat the floors and walls because of a series of overhanging eaves and balconies, according to Eckland

In its passive aspects, the combination of the southern exposure, the placement of the windows and overhangs as well as the construction material allow the house to gather and store solar energy.

"The active part of the solar system utilizes collectors to heat large amounts of water, which is used on cloudy days and at night," Eckland said.

An economist with the Central Intelligence Agency, Eckland designed the house around the needs of his family, which includes three children. He and his wife Susan have done much of the work on the house themselves. Because of the time they have put into the construction, it's hard to tell how much it would have cost to have the house built by a contractor, he said.

An estimate would be $200,000, he said: "I've had contractors tell me that a house like this could be built for $30 to $40 a square foot" The cost of the Eckland house, not counting their own labor will probably total $125,000 to $130,000 he said.

The couple started the house a year ago and plan to finish it in a few weeks.

In addition to five bedrooms, the 5,000-square-foot house has a large living and dining room, game room, family room, laundry room, office and garage.

Like most solar houses, the Eckland house is heavily insulated. It has R-19 fiber glass insulation in the exterior walls and is framed so that it can hold six inches of insulation. The insulation in the ceiling is R 40 and 12 inches thick, Eckland said.

The entire house built on a six inch - thick slab of concrete. Under the concrete is two inches of stytofoam and imbeded inthe concrete is a quarter of a mile oc coiled copper pipe,which carries hot water throught the ground floor of the house.

THe floor slab as well as the 900 square feet of interior brick walls are used to increase the thermal mass of the house, Eckland said. Without this mass. the passive solar system will not work, he noted.

On a sunny December day, about 1 million BTUs of solar energy will enter the house through the south - facing windows and be stored in the concrete and brick," he said.

This much energy - equal to 10 gallons of fuel oil - can be stored by raising the temperature of the house only about eight degrees, say from 67 degrees to 75 degrees," he added.

Even when night temperature drop to30 degrees, Eckland anticipates that no backup heat or heat from the active solar system should be necessary to keep the house comfortably warm when winter days are sunny.

Eckland has not yet installed the active part of his solar system, which will consist of 600 square feet of thermal siphoning collectors mounted on the dirt bank along the south side of house.

Tonce installed, two large water tanks on inside and one outside will hold 3,000 gallons of water, will store about 1 1/2 million BTUs of heat, or enought to heat the house for two consecutive cloudy winter days.

"The hot water from the collectors will heat the house by being pumped through the quarter of a mile of copper tubing that snakes through the concrete slab on the first floor," he said.

In addition, water hot enought for washing dishes will be pre - heated in the solar tanks outside and further heated by the backup system. It will use less energy to heat the water once it has been pre - heated in the solar system, he said.

According to Eckland , the active solar system will not require elaborate electronic controls because of the location of the outside collectors.

Because the outside tank is located above the collectors, the fluid in the collectors will flow by itself into the outside storage tank." he said. "From there, hot water will periodically be exchanged for water int he inside storage tank." Distribution of the heat will be controlled by a normal household thermostat which will, at about 67 degrees, start pumping hot water through the concrete slab in the floor. A second thermostat set slightly lower will turn on the backup oil heating system if the house starts to get cloder, he said.

In addition to the backup oil system, the house also has two airtight woodburning stoves and a circulating heat fireplace.

"All in all, I expect that solar energy will provide about 85 percent to 90 percent of the total heating and hot water required by his family," Eckland said. "Because it is well insulated and tightly built, this house could be heated for a normal winter with about 1,300 gallons of fuel oil."

The active solar system should further reduce oil use to about 150 gallons or less if the wood stoves are used," he added.

Eckland, who said he read 20 to 30 books on solar energy before building his own house, said his house is no more expensive to build than dozens of others of its size in this area.