It’s lunchtime, time to get your Lean Cuisine queued up. You unwrap it, then zap it. When you take it out of the microwave, it’s boiling hot on the edges and freezing cold in the middle. You know what I’m talking about.

And you wonder: why doesn’t it heat my food like a regular oven?

This is a question beyond the interest of science. It carries important quality-of-life-and-lunch consequences.

To answer it, let’s think about what it means to heat something. Heat is really just molecules moving around. When you get something hot, you get the molecules agitated.

Microwaves and regular ovens have somewhat different ways of agitating food molecules (though the way they agitate cooks may be similar). A regular oven, once you’ve preheated it, is full of hot air. When you put your tasty treat inside, the heated air interacts with the cooler surface of your food and moves some of the molecules around. Over time, the molecules exposed to the surface transfer their heat energy to the molecules next to them through a process called conduction. Eventually, the heat gets conducted all the way to the center of your meal, but it takes a while, which is why you have to leave your tasty treat in the oven for what seems like forever when you’re hungry.

In this conventional oven, the baking bread is surrounded by hot air, which lends it its crispy crust.

In contrast, a microwave tickles your treat molecules with radio waves. There’s no hot air in the microwave, and it heats your food without heating anything else. If you think about it, this seems kind of weird and maybe a little magical. Here’s how it works: a hollow-barreled magnetic tube called a magnetron emits radio waves into the oven. These waves, with wavelengths of about 12 cm, bombard the water, fat, and sugar molecules in the food, and set them flip-flopping. A microwave oven can do this while using much less energy than the oven requires, and the radio waves quickly get the molecules in motion.

The catch, which also explains the bubbling-and-freezing-at-the-same-time phenomenon, is that the microwaves only penetrate about an inch or inch and a half into your tasty treat. To get the heat deeper than that, you’re relying on conduction, just like in your conventional oven. Or, as all microwave chefs know, giving your treat a stir helps shift the unheated molecules to that all-important outer inch where the action happens.

The inside of a magnetron from a microwave, minus its magnet.

The microwaves, which are part of the same electromagnetic spectrum as visible light and X-rays, are “tuned” to a frequency that works its magic on the relatively loosely ordered molecules in your food, but that doesn’t have much effect in more solid materials like ceramics and glass. But these waves don’t penetrate all parts of your tasty treat equally, either. Water molecules, for instance, are much more readily tossed about than fat.

You can demo this yourself: take two small, identical dishes. Put water in one and the same amount of oil in another. Heat them together in the oven for about 30-45 seconds. Which is warmer when the bell rings?

Microwaves are also notorious for simply heating unevenly: you might find a pocket of much hotter lunch in your otherwise lukewarm dish. This is because, like any electromagnetic waves, microwaves bounce off of reflective surfaces (like those of the oven walls) and concentrate more in some areas than others. This is where the turntable comes in handy: it moves different parts of your food into and out of the hot spots, distributing the heating effect evenly.

You can show yourself a faint glow of this effect by using your microwave to light up an incandescent bulb. If you try your hand at this, do it carefully, and only for three seconds at a time. You’ll see the bulb light up more brightly as it moves through the hot spots, and fade a bit as it goes through the “cooler” areas. You’ll find instructions and some explanation on the Oregonian website. Or, for a little safer show, watch this video from the Discovery Channel:

There’s plenty of other fun to be had with a microwave, and also quite a few clever and potentially hazardous experiments. For safety’s sake, I’m compelled to suggest you turn to YouTube rather than your own microwave for these. One of my favorites is this lovely slow-motion film of foods theatrically exploding in the microwave. You could try these at home, but be prepared for doing some cleanup.

 Properties of Plastic Educator Guide

Exploratorium Staff Scientist Julie Yu changes and manipulates the physical and chemical properties of plastic bottles by exposing them to heat. This is how plastic bags and bottles can be recycled and used over and over again.

Here's some of the equipment you can us to create your own geothermal heat pump. And you'll need a shovel.

Henry Gifford is a man who designs mechanical systems for very energy efficient, comfortable, and affordable apartment buildings in New York City, along with his partner, architect Chris Benedict. In a recent article in Fine Homebuilding, Henry explained how geothermal heat pumps work in a way that I will always remember. I paraphrase:

Dig a hole in the ground. Put some buckets of water in the hole. If you are deep enough below ground, the temperature of the water in the buckets, after a while, will be about 55⁰F. Take the bucket into your house and put it in your refrigerator. The fridge will cool the water down to say 50⁰F, and the heat produced in the coils behind the refrigerator will add some heat to your house. Voila! You’ve created a geothermal heat pump.

Notice that the heat produced is not free. It takes electricity to run the refrigerator. And if you don’t want to spend your days hauling water in buckets from the hole in the ground to your refrigerator, you’ll want to install a water pump, which uses more electricity.

The very best residential geothermal heat pump system, according to Henry, has a coefficient of performance (COP) of about 3. This means that for every 2 watts of energy the system pulls from the ground, you have to provide only 1 watt of electricity. You get 3 watts out for 1 watt in. But a typical system has a COP of about 2.

Given that electricity is produced at power plants that use fossil fuels, and depending on the mix of fuels your utility uses to produce electricity, you will probably burn more fossil fuels using a geothermal heat pump with a COP of 2 than you would using an efficient gas- or oil-fired furnace. And geothermal heat pumps are much more expensive to install than traditional furnaces.

At Home Energy Magazine, where I work, we always tell people that if you have your house air sealed, insulated, and provided with the right amount of ventilation to keep you healthy, you can do just fine with a medium-efficiency furnace and burn much less fuel than you would with a high-end system—ike a high efficiency gas furnace—and a leaky house. For most of us, that’s the best choice of all, for heating and for cooling.

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The CCHT twin house facility in Ottawa, Canada

The Department of Energy, the Environmental Protection Agency, and others recommend that we set our thermostats at 68°F in the winter and 78°F in the summer. Some people are comfortable at home with these temperatures and some or not. So how can we save energy and still be comfortable?

Besides recommending that people replace their incandescent bulbs with CFLs, we at Home Energy also encourage people to turn their thermostats down when they are away from home during the winter, and to set them up when they are away from home in the summer. Both actions are supposed to save energy. But do they? It's not really that clear. For example, if you set your thermostat at 60°F before you leave for work in the morning, and then set it at 68°F in the afternoon when you get back, does your furnace use more energy raising the temperature of your house from 60°F to 68°F, than it saves by having the temperature at 60°F all day?

Once again the Canadians have come up with an answer. Marianne Armstrong and her colleagues at CCHT used the twin house research facility to show that thermostat set backs in the winter and thermostat set forwards in the summer really do save energy.

In the research house where they set the thermostat back to 64°F at night and during work hours, from 72°F, it saved more than 10% on heating costs compared to the house that was set at 77°F all day and night. A 61°F setback saved more than 13%.

In the summer, a set forward to 77°F at night and during work hours from 72°F saved 11% on cooling costs. Now for the big winner: Setting the thermostat up to 75°F all day and all night saved 23% of cooling costs compared to the house set at 72°F. That's a savings of about 8% for every degree adjustment.

If you lower your thermostat a few degrees when you are away from home this winter, or when you are asleep, you'll save energy and money. If you set your thermostat up a few degrees when you are away from home or asleep this Indian Summer, you'll save energy and money. And you won't be uncomfortable.

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A confession: When I first got the assignment to do a story about air conditioner efficiency, I didn't exactly leap from my seat in excitement. (Which is why extra kudos go to those who've made it as far as this web page!) But, really, I should have known better.

AC seems mundane because it's ubiquitous – but because it's ubiquitous, its impact is astonishing. If you took air conditioning out of the picture, there might not be such thing as the California energy crisis. We could put dozens of power plants offline. In terms of global warming, it would be like taking hundreds of thousands of cars off the road, permanently.

Why air conditioning and not, say clothes dryers or refrigerators? Well, partly because AC sucks lots of power (especially central AC systems though, bought new, even those may be more efficient than your old window unit), partly because of the way we use them: all at once. When heat waves hit, Californians turn on their ACs practically in unison, hitting up a beleaguered electricity grid that fires up every creaky last turbine to handle the load.

So, it comes as no surprise that a number of Californians are putting serious energy into making air conditioning work better. At the top of that list is California Energy Commission Commissioner Art Rosenfeld, the efficiency guru who, perhaps more than any other person, can be credited for California's remarkable efficiency gains over the last 30 years. We also hear from AC inventor and entrepreneur John Proctor. And thanks also go to Jeff Scalier, of Antioch-based Blue Star Heating and Air Conditioning, who introduced me to his very satisfied customer, Al Mason, and whose mother I hope enjoys the CD we send her.

If you want to retrofit your central AC system to tailor it to California climate (and make it 20 percent more efficient) a number of Bay Area installers are ready to do it. Here are some of them, courtesy of Proctor Engineering:

– Vtech HVAC Services, Antioch, 925-752-6075

– Bland A/C & Heating, Inc., Bakersfield, 661-836-3880

– Herrera Heating & Air Conditioning, Bakersfield, 510-750-6972

– Action Air Conditioning, Clovis, Fresno, 559-292-8640

– California Indoor Comfort, Fresno Area, 559-276-7457

– Certified Heating and Air Conditioning, Fresno County, 559-273-8048

– ReNu, Marin County, 415-462-0245

– Queirolo's Heating & Air Conditioning, Inc., San Joaquin County, 209-464-9658

– Leo's Heating & Air Conditioning, San Joaquin Valley, 209-271-7873

– Air Solutions Heating & Air, Stanislaus County, 209-380-3032

– Air Flo Pro, Stockton, 209-915-4730

– University Refrigeration, Stockton, 209-609-8400

– CPR Sheet Metal, Inc., Vacaville, 707-628-7495

– Right Now Air, Vacaville, 707-447-3063

Listen to the Air Conditioning Reinvented radio report online.

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Each big storm with a high tide and an
onshore wind takes a big bite out of Sarichef.Photo By Shishmaref Erosion and Relocation Coalition

In an email this week from John Woodward, an Alaska builder and Home Energy author, he wrote, "I put together a working/management group to manage the relocation of the community of Shishmaref sustainabely. They live on Sarichef, a barrier island that global warming is wiping out."

Shishmaref is home to a small community of Inupiat, a Native American tribe. John is working with the Inupiat Tribal Government, the City of Shishmaref, and the Shishmaref Erosion & Relocation Coalition, to salvage as much of the village as possible before it goes under water and move it, along with the island inhabitants, to a new plot of land in the interior of Alaska.

The Army Corp of Engineers gives the island about 5 or 10 more years of livability. But as the ocean and permafrost warm and the ocean rises, unpredictable storms take a heavy toll on the island. "Each big storm with a high tide and an on-shore wind takes a big bite out of Sarichef," says Woodward.

The community is seeking funds for a comprehensive alternative energy plan, an anaerobic pump/methane generator, and the retrofit of all existing buildings, including more than 110 homes, community buildings and a school. The homes will be retrofit to use less than 5 Btu per square foot to heat. Heating load calculations can be pretty complicated, but in general, contractors recommend furnaces that can provide 30-50 Btu per square foot to heat homes in the Bay Area. To reach such a high level of energy efficiency, the Shishmaref homes will have the insulation installed on the outside of the structure, a technique that Woodward has successfully used in the past. The new village will have the look and functionality of the Inupiat culture as defined and designed through community planning.

"Our community planning process involves community charettes with the whole community gathered in the school gym," say Woodward. "The goal of these meetings is the rough-out of a comprehensive community plan for sustainable relocation of the existing salvageable infrastructure and the development of the new village site."

The Inupiat will build their new village to suit their needs and lifestyles, to be efficient, and to be in harmony with its surroundings-in other words, sustainabely. Let's keep an eye on our northern neighbors, who may teach us some valuable lessons. How long before whole towns in California will have to relocate because of water shortages? We all witnessed what happened in New Orleans a few years ago. How long before towns and cities on the coast of California will have to move inland or be seriously reconfigured because of the rising Pacific Ocean?

You can e-mail John Woodward with questions, comments, ideas, and offers of help at panuktuk@yahoo.com.

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