Rates on 30-year and 15-year mortgages fell this week, according to a Freddie Mac survey released Thursday.

Rates on 30-year fixed-rate mortgages averaged 5.70 percent, down from 5.75 percent last week, Freddie Mac said in its weekly survey. The rate was the lowest on 30-year mortgages in five months.

Rates on 30-year mortgages hit a high this year of 6.34 percent the week of May 13. Rates have slowly drifted downward as economic activity cooled in the late spring and early summer and inflation fears receded.

For 15-year fixed-rate mortgages, a popular option for refinancing, rates decreased this week to 5.10 percent, from 5.13 percent last week.

EVENTS . . . The National Association of Home Builders headquarters has on exhibit the PATH Concept Home through Oct. 1. The Partnership for Advancing Technology in Housing's architectural model demonstrates advanced technologies, innovative building practices and a flexibility of systems to meet homeowner needs. The concept home's design includes flexible interior walls, customizable designs offering the quality and curb appeal of a custom-built house without the high cost, and improved production methods to speed construction and improve durability. The display is at the National Housing Center, 1201 15th St. NW, Washington, weekdays from 8:30 a.m. to 5 p.m., and 8:30 a.m. to noon on Oct. 1. . . . The National Building Museum at 401 F St. NW, Washington, plans a discussion at 12:30 p.m. Tuesday on the "Cost and Financial Benefits of Green Buildings." Topics include how cost-effective green buildings can be. Greg Kats, principal of Capital E Group, shares research indicating advantages from a cost-benefits perspective, beyond the environmental and health benefits. Admission is free. For information, call 202-272-2448; Web site: www.nbm.org. . . . Architect Jack Diamond of Diamond+Schmitt Architects is to speak on Oct. 6 at the National Building Museum from 7 to 8:30 p.m. Topics include the Toronto-based firm's work, including the newly commissioned Sidney Harman Theatre in the District, and such projects as Jerusalem's Israeli Foreign Ministry, Toronto's Four Seasons Center for the Performing Arts, and the Life Sciences Center at the University of British Columbia. Admission is $17, $12 for students. Registration is required.

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