The Wall Street Journal nailed an important point about housing demand during a recession - even low interest rates can't overcome the inertia of the downturn:

As mortgage rates fall to near historic lows, some home builders are offering even lower interest rates, in an effort to lure buyers amid the slow spring selling season.

The latest sales promotion: Lennar Corp. is offering a fixed 3.625% rate over the life of a 30-year fixed rate mortgage. The deal is besting average rates that have fallen below 5% nationwide, but it comes as other builders are reporting mixed results from similar incentives.

Hovanian Enterprises Inc.’s recent offer of a 3.99% rate sparked “underwhelming” interest from home buyers, says Dan Klinger, president of the builder’s mortgage operation. “It wasn’t like we needed crowd control,” says Mr. Klinger.

Bargain mortgage rates are the latest sales strategy from builders struggling to sell homes. Mounting unemployment continues dogging the sector, because people without jobs, or those afraid of losing one, are unlikely to purchase, no matter how low the rate.

The builders’ low rates may help first-time home buyers, “but it’s not going to goose the trade-up market,” says Thomas Lawler, a housing economist. “That’s because most trade-up buyers use the equity from their previous home for a down payment, and that equity often doesn’t exist any more.”

We'll say it again: To power up a housing market, there's no substitute for population and income growth. Cheap money via the Federal Reserve won't last.