In his "Here Comes the Sun Shower" opinion piece in Tuesday's New York Times, Larry Hunter, a professor of physics at Amherst College, urged the Obama administration to support the use of residential solar water heaters. Hunter suggested that a $10,000 solar water heater could pay for itself in as few as six years if the government were to raise the federal tax credits from 30 percent to 40 or 50 percent.

Essential information: Read our report on tankless water heaters, another way to potentially save energy when heating water.

• Sweeping will get you off the couch. Sweeping burns only a few calories a minute, but you could probably use the activity that comes from bending and stretching when using a broom and dustpan.

• The environment will benefit. While the amount of electricity you'll save by not using a vacuum is negligible, think of the collective savings if everyone skipped the vacuum. What's more, improper disposal of NiCd batteries, found in many cordless models we tested, is hazardous, and it can be a hassle to dispose of them safely.

• The battery might not last. If a cleanup job will take more than 10 minutes or so, you might need to get out the broom and dustpan since the battery in most hand and stick vacs runs down after that little time.

• Cordless models lack smart-charge capability. None of the three cordless sweepers we tested has a smart-charge capability, which switches a charged unit to trickle charge to avoid overheating, a potential fire hazard. What's more, the battery on some cordless vacs isn't replaceable, so once the power pack no longer takes a charge, the vacuum is useless.—Ed Perratore

Essential information: Visit our vacuum product page for more information on all types of vacuums. If you suffer from allergies or asthma, Use our Ratings of small vacuums (available to subscribers) to find models that scored best at trapping small particles. And if you have any breathing problems, always wear a dust mask before emptying the dustbins of any of the tested models.

I thought the story was a spoof until I saw the CEO of iRobot Corporation being interviewed. I'm familiar with the company because we've reported on its robotic home appliances.

At the next commercial break, we decided to check out the iRobot site. Right there next to a link to Roomba vacuums and Scooba floor cleaners was a link to "Government & Industrial Robots," including the iRobot's Packbot, Warrior, and a squadron of other military-grade robots. (The SUGV model is shown.)

My son asked whether he could buy one. Why? Perhaps he figured the iRobot Negotiator might persuade my husband and me to give him his own credit card or extend his curfew. It was a moot point, since these devices are sold only to governments. You can buy the company's home robots, though based on our past tests of these appliances, you might not want to.

As part of our October 2008 review of vacuums, we found that the Roomba 560, $350, was among the worst performers at cleaning edges and corners and sometimes ventured beyond its electronic borders. And in a May 2006 story, we reported that a mop was faster and more thorough than the Scooba, $399. Both easily wiped up coffee, grape juice, and tea stains, but the mop was better on stubborn stains like crayon and shoe polish.—Celia Kuperszmid Lehrman

Essential information: If you're in the market for a new vacuum, read our latest report (available to subscribers) and visit our vacuum product page. 

The number of U.S. mortgages that could be in foreclosure by 2012, depending on how bad the recession gets, according to a late-2008 report by Credit Suisse. In April 2008, the bank had forecast 6.5 million foreclosures.

Essential information: If you're struggling financially and are concerned about losing your home, read "Financial Traps Are Flourishing," from the March 2009 issue of Consumer Reports. And if you're considering buying a property in financial distress, check out the advice in "How to Buy a Foreclosed Home."

One of those profiled in the Times' article stores her food in a compact refrigerator instead of a full-size model. While that might sound like a good energy-saving move, it's not necessarily a smart decision because compact refrigerators are not particularly efficient for their size.

In our latest report, we found that while tall compact refrigerators got higher energy-efficiency scores than shorter ones, these appliances typically use a lot of energy for the storage space they provide.

We also noted that some compact refrigerators consume almost as much electricity as a full-size refrigerator. The Frigidaire FRC05L5D[B] (shown) has a claimed capacity of only 4.6 cubic feet and will cost about $38 on average to run each year; its EnergyGuide label says it will use 348 kilowatt hours annually. But for about $6 and 59 kWh more per year, you could run the Kenmore 7787[2] top-freezer we've tested, which has a claimed capacity of 18 cubic feet. The up-front cost of a full-size refrigerator will be higher, of course.—Kimberly Janeway

Essential information: Check out our Energy-Saving Guide for more advice.

I've read that oils in coffee can raise cholesterol. Do some brewing methods produce more of these oils? Are paper filters better than metal ones?

Studies have linked two oils produced when coffee is brewed to increases in both total and low-density-lipoprotein (LDL, or bad) cholesterol levels. Researchers believe the amount of the cafestol and kahweol oils that ends up in the coffee you drink depends on the brewing method you use and how the water comes in contact with the ground coffee.

Drip coffeemakers, like those we tested in our latest report on these appliances, distribute water to the grounds gently enough so that the cafestol and kahweol pass through only in negligible amounts whether you use a paper or a metal filter. The same goes for instant coffee and coffee brewed in a traditional percolator.

But the studies have found that other brewing methods might boost both total cholesterol and LDL cholesterol. The Scandinavian boiled, Turkish/Greek/Mediterranean (shown), and French-press brewing methods addressed in these studies produced coffee with relatively high levels of cafestol and kahweol. Espresso contains more of the oils, and even boiling water poured onto ground coffee can result in the release of the oils.

If you're watching your cholesterol, you might be better off not using one these brewing methods on a regular basis.—Ed Perratore

Essential information: Read our March 2009 report on caffeinated and decaffeinated coffees (available to subscribers). Learn more about cholesterol and how to maintain healthy levels.