Tubing installed into the 2-foot-deep bed carries water heated by 14 solar panels on the roof. McKay said the sand holds heat longer than water tanks.

Heat is radiated through the floors of the home, ensuring virtually even floor-to-ceiling warmth. A computerized system controls 24 temperature points in the house.

Walls of the home are of an insulated material that uses engineered “Lego” blocks comprised of 85 percent recycled polystyrene (coffee cups, packaging peanuts) and concrete.

McKay said he continues to tweak things as he goes along to make the house even more energy efficient.

He figures the system will pay for itself in saved electricity costs in eight to 10 years.

McKay has also embarked upon a project with potential business applications — he wants to engineer space-efficient solar power units whereby homeowners would be charged a nominal installation fee to rent the system.

Solar power’s time has clearly arrived for the couple, but McKay is unsure of when it will become the norm in American homes.

“People usually stay in their normal ‘path’ until something makes them change.”

And when the cost of conventional home energy becomes prohibitive for the masses, change will follow, he said.