The marriage of Control Data Corp. and Electronic Realty Associates (ERA) portends a major shift in the way housing is financed in this country.

ERA, the second-largest real estate franchising company, now will have access to the huge financial resources of Commercial Credit Corp., a Control Data subsidiary. If the merger of Control Data and ERA goes through, Commercial Credit will make "home counseling centers" out of 600 its 680 offices, says Paul Kaus, ERA zone manager.

"We already have $100 million from Commercial Credit to finance mortgages," Kaus said, referring to an agreement reached before the merger was announced. "Control Data has a tremendous amount of capital because its computer business has been so good, and Commercial Credit has been financing those computer purchases. Now, the company wants to move into mortgages."

When it does, Commercial Credit will bring both ideas based on its consumer loan programs and $5.1 billion in assets. The company has revenues of about $1 billion a year and wants to shift its portfolio emphasis to first mortgages.

The new source of mortgage funds will help ERA to into an expansion program with a goal of making 51 percent of the residential sales in the United States by June, 1983. ERA hopes to boost its offices in this country to 8,000 from the present 3,500 and to continue its penetration into markets in Japan, Australia and New Zealand.

"Chicago is the market where we will concentrate first," Kaus said. "We now have 70 offices here, and expect to add another 180. That is one office for each 30,000 citizens."

ERA expects to achieve the growth by adopting new financing tools to help buyers of homes both to obtain a mortgage and to come up with the down payment. One such program would tap individual investors and pools of investors who would provide financing for home buyers and share both in the tax shelter and the appreciation in value at resale.

The plan would resemble the syndicates that control much commercial property, in which tax advantages pass through to the investors along with any gain realized when the property is sold.

"Interest rates of 14 percent to 15 percent shut out 40 percent of the market," Faus said. "We can find investors who will help the home buyer afford these rates by sharing the financing costs in return for tax shelter and profit on resale."

Under the plan, the homeowner would realize nothing from any appreciation in his property over a period of time. The investor would gain that advantage as well as shelter from interest and property tax deductions.

Faus says the return has been calculated at 18 percent to 30 percent in some cases, with a relatively risk-free investment.

The homeowner unable to produce a down payment or to meet high interest payments thus would be able to obtain a home and, at a later date, could buy out the investor or refinance.

"We will introduce the plan in seminars around the country," Faus said. "Right now, we are applying to get approval in Illinois and hope to receive an okay this summer." We're spending a million dollars in legal fees to be sure this meets Internal Revenue Service and SEC requirements."

The company says its surveys show that 10 percent of the investors contacted would consider participating in the program, 20 percent of the homeowners surveyed would use it to move up in housing quality, and 50 percent of the renters responding would consider using it.

The expansion plans of ERA come at a time when most franchise companies have been losing offices due to the slow pace of real estate activity, Faus admitted.