Energy Solutions

Get Ready for Heat-Pump Water Heaters

Posted on September 20, 2012 by Alex Wilson

Last week I wrote about “hybrid” water heaters, a relatively new type of water heater that includes features of both storage and tankless models. This week I’ll cover another type of water heater that is also (confusingly) referred to as “hybrid”: heat-pump water heaters. These produce over twice as much hot water for each unit of electricity consumed as any other type of electric water heater (storage or tankless).

Hybrid Water Heaters

Posted on September 13, 2012 by Alex Wilson

In last week’s blog I compared tankless and storage water heaters and explained why tankless water heaters often don’t make that much sense.

The Difference Between Storage and Tankless Water Heaters

Posted on September 6, 2012 by Alex Wilson

There are two primary types of water heaters: storage and tankless. In this column I’ll try to explain the differences between these two approaches and offer some guidance on choosing between them. (There are also “hybrid” water heaters with features of both that I’ll cover in a future blog.)

Storage water heaters

Most water heaters are storage models. These are insulated tanks holding 20 to 120 gallons with either electric heating elements or gas burners. The storage tank stratifies with hot water at the top and cold incoming water at the bottom, so that as you draw off hot water (from the top), you get consistently hot water until the hot water is nearly depleted. The “first-hour rating” tells you how many gallons of hot water can be delivered in an hour. 

Saving a Little More Energy With Exit Signs

Posted on August 30, 2012 by Alex Wilson

In the years that I’ve been writing about energy and energy conservation (longer than I really want to admit), I’ve reported on several dramatic transitions in how we illuminate the exit signs in commercial buildings. For an energy geek, it’s been an exciting technology to watch.

Why care about exit signs?
Why do we even pay attention to exit signs—those ubiquitous red or green illuminated signs that direct our escape from a building should the need arise? They can’t use very much energy, can they?

Insulation to Keep Us Warm — Not Warm the Planet

Posted on August 23, 2012 by Alex Wilson

I’ve been pretty vocal about a big problem with some of our most common insulation materials: that they are made using blowing agents that are highly potent greenhouse gases.

All extruded polystyrene (XPSExtruded polystyrene. Highly insulating, water-resistant rigid foam insulation that is widely used above and below grade, such as on exterior walls and underneath concrete floor slabs. In North America, XPS is made with ozone-depleting HCFC-142b. XPS has higher density and R-value and lower vapor permeability than EPS rigid insulation.) and most closed-cell spray polyurethane foams (SPF) are made with HFC (hydrofluorocarbon) blowing agents that have global warming potentials (GWPs) many hundreds of times greater than that of carbon dioxide. (My apologies for contaminating this column with so many acronyms!)

Insulation: good news, bad news

The End of Peak Oil?

Posted on August 16, 2012 by Alex Wilson

I first wrote about “peak oil” in 1998, reporting on an in-depth article in Scientific American by petroleum geologists Colin Campbell, PhD, and Jean Laherrère. Campbell and Laherrère believed that up to that time the world had consumed about 800 billion barrels of oil (BBO), and the known reserves of conventional crude oil totaled about 850 bbl in 1996 and another 200 BBO of conventional oil was yet to be discovered.

Fixing Those Drainage Problems, 30 Years Later

Posted on August 9, 2012 by Alex Wilson

When I bought the house in West Dummerston, Vermont, where my wife and I have lived for the past thirty years, one of the first things I did was fix the drainage problems that were dumping water into our basement…

Or so I thought. Let me explain.

Expanded Cork — The Greenest Insulation Material?

Posted on August 2, 2012 by Alex Wilson

I’m always on the hunt for the latest, most interesting, and most environmentally friendly building materials, and I have particular interest in insulation products — partly because many conventional insulation products have significant environmental downsides.

Insulated Storm Windows?

Posted on July 26, 2012 by Alex Wilson

I’ve done a lot of digging into window options in the past few months — not only for a special report on windows that BuildingGreen published, but also for the renovation of the early-19th-Century farmhouse that my wife and I recently purchased.

The Continuing Revolution in LED Lighting

Posted on July 19, 2012 by Alex Wilson

A few days ago I got yet another press release about a new efficiency record with LEDLight-emitting diode. Illumination technology that produces light by running electrical current through a semiconductor diode. LED lamps are much longer lasting and much more energy efficient than incandescent lamps; unlike fluorescent lamps, LED lamps do not contain mercury and can be readily dimmed. lighting. These are almost commonplace as we ride the revolution that is redefining electric lighting.

To back up, let me provide a short synopsis of lighting technologies and history.

Incandescent lamps provided the first electric lighting, with Thomas Edison inventing the first commercially viable light bulb around 1880 (building on the inventions of many others), and the technology has changed relatively little since General Electric introduced tungsten-filament light bulbs in 1911. Electric current flows through a very thin, coiled filament made of tungsten wire and glows white-hot, producing light. With incandescent lighting, roughly 90% of the electricity is converted into heat, only 10% into light.

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