There’s a new trend among homeowners. Many are choosing to replace their long-term mortgages with short-term loans. More than one in three borrowers who refinanced opted for 15-year or 20-year mortgages at very low rates, said Frank Nothaft, chief economist for Freddie Mac in the company’s most recent quarterly survey.

Some banks are offering fixed rates for shorter-term loans at under 3 percent. Jeff Lipes, president of the Connecticut Mortgage Bankers Association and senior vice president of Family Choice Mortgage near Hartford, Conn., says that financing a home for 7 or 15 years makes sense for those who meet two criteria — they want to own their house faster, and they have the cash to support the bigger monthly payments. But save they will.

Consider a loan of $15,000 on a 15-year fixed at 5.5 percent with 13 years to go. Monthly principal and interest equal $1,225. In total, you will play $197,476. Refinanced over 7 years at 3 percent, monthly principal and interest come to $1,982, and the total note will be paid at $166,488. You save over $27,000 in interest fees.

Two metropolitan cities in the Pacific Northwest are leading the nation in green construction with plans to put up living buildings. The Cascadia Center for Sustainable Design and Construction, a six-story complex with a basement, will be constructed in the heart of Seattle. The Oregon Sustainability Center, a seven-story, $64 million project, will go up in the eco-district of Portland State University’s downtown campus.

Both buildings hope to attain the Living Building Challenge certification from the Living Future Institute and will, no doubt, provide critical data for the future construction of sustainable buildings elsewhere. The lead architect on the Seattle Project is Brian Court, who says that building a multi-story green building presents a huge challenge. The Cascadia Center will draw solar energy from the roof, while the Oregon Sustainability Center plans to utilize both solar and geothermal technology.

The two projects are striving to meet a triple net-zero status, where energy, water, and waste are generated, utilized, or recycled on site. Here’s how they plan to manage waste. Rainwater will be collected and treated for consumption. Greywater (wastewater from hand washing, for example) will be recycled for toilets and to cool mechanical equipment. Blackwater (you can guess what that is) will be funneled to onsite natural biological treatment systems and returned to the building as greywater. All environmental eyes are on the Pacific Northwest. If the buildings meet their triple net-zero goals, you can bet that other cities will follow suit.