Posts tagged energy facts

Windows of opportunity

The modular units for Hickory Hall have begun arriving at Emory & Henry.  They look pretty nondescript right now.  They’re just modular building blocks sitting on trailers.  The above picture is the foundation for Hickory, and if you look far off into the distance you can see the trailers lined up in front of the baseball field.

 One thing you might notice in the picture below is the little sticker that says “Made in Ireland” in the bottom right corner of one of the panes.Why did we order windows from Ireland?  Well, it turns out that to get a Passive House Certified window, you have to go across the pond.  As you can imagine, these aren’t your average windows.  They are triple glazed, filled with argon gas, and have a low-e coating.  What does all that mean? Excellent insulation characteristics, of course, to meet  rigorous Passive House standards.

Take a look at the window cross section below.  This is from a double glazed, high-performance window:

Now, look at the cross section of this triple glazed Passive House style window:

Notice a difference? The first window isn’t a bad window at all.  In fact, it’s not even a standard builder’s grade window.  It’s still got a low-e coating and inert gas.  But the second window, well, it’s just plain impressive.  It’s got an extra pane of glass in there, with an extra layer of inert gas for insulation.  In addition, it’s fully thermally broken, meaning that the window and the frame won’t transfer much thermal energy from the outside or inside (called thermal bridging).

The result is astonishing.  Preliminary modeling suggest that just changing the windows lowered our heating load by 20-25%.  How is this possible? Well, a good double glazed window will have a u-value of about .3 (equal to an R-value of about 3.3).  A triple pane window will be about half that, or .15 (equal to an R-value of about 6.6).  So, it’s only twice as a efficient, right?  Not quite.  Take a look at this chart of u-value to performance:

Notice that it’s a nonlinear relationship going from a u-value of 1 to .5 gains a little, going from .3 to .15 gains a lot.  It’s the same for walls.  If you look at the chart again, you’ll see that you gain a lot more by going from u-value of .2 to .1 than from .3 to .2.  These windows are also tilt-and-turn instead of double-hung, which means a much better seal and far less air leakage.

So that’s the story of our fancy Irish windows.  Hopefully next time you look at a building, you’ll have a new appreciation for the windows and the role they play in a building’s energy performance.


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Low natural gas prices: the good and the bad

In January, natural gas prices hit 10-year lows.  This is due to a couple of factors, mostly increased supply and decreased demand.  The increase in supply comes courtesy of the newly tapped gas fields using hydraulic fracturing, or fracing (pronounced “fracking”), to extract previously unrecoverable gas reserves.  The decrease in demand is a result of our slow economic recovery and an unseasonably warm winter.  Currently, spot prices for natural gas are about a quarter of what they were during the 2008 peak.  These low prices will result in over $100,000 in savings on our gas bills at both schools next year.

So, low prices sound great, right?  They’re saving us (and the rest of the US) a lot of money.  Additionally, electric utilities are beginning to switch from coal to natural gas for generation (increases in coal prices have helped this trend), which results in less CO2 and other pollutants being emitted.  For example, in Ohio, a traditionally coal-dominated state, electricity generated from natural gas has surged from 1% in 2001 to 9% by the end of 2011.

Now for the bad news.  Most new gas production in the US is a result of fracing (see shale gas increase below), which has unknown environmental consequences.  A study released by EPA last year found carcinogenic fracing compounds in an aquifer in Wyoming, but the gas industry, as always, insists that it’s a safe process.  A nationwide safety study on fracing is expected to be completed later this year.  While links between fracing and aquifer contamination are still not yet known, the process of any oil and gas drilling usually results in surface spills and other environmental damages.

There is another drawback to lower gas prices.  As prices decline, the relative competitiveness of renewable and alternative energies decreases.  Natural gas is often referred to as a “bridge fuel,” meaning it is a relatively clean fuel that can displace coal and oil until renewable energies are cost-competitive.  If low prices become the norm, this bridge will begin to extend farther into the future.  Government policy, such as tax credits for wind and solar (currently in effect, but set to expire soon) could help alleviate the effects of natural gas prices on renewables.

Current projections of our natural gas supply are around 100 years, but many feel that is grossly overstated and could be as low as 20 years.  Futures prices for gas don’t rise above the $5 mark until 2016, though, which means we could have several more years of low prices.  The key takeaway is that there is considerable uncertainty in future prices, supply, and regulations.

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The Energy Cost of Dining on Campus

The graph above is the demand curve for the Moody Student Center over the last two weeks.  You might notice something different about the middle portion of the graph.  That long, flat part in the middle is Thanksgiving break.  While our students were gone, we used 14416.7 kWh less than we normally would have.  That’s like powering down an average house for an entire year!

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Watts it to you?

In addition to vampire power, our various gadgets and devices draw power while they’re in operation.  There’s a great little device out there called a Kill-A-Watt that measures energy consumption at the plug level.  I have one at home (and you should too!) and recently did some testing.  It’s actually kind of fun (especially if you’re a huge energy nerd like me), and some of the results are pretty interesting.  As far as vampire power, most of my devices were at 0 or 1 watt while not in use.  The bad news is things like my cable modem and router are always on, and they draw about 6 watts each.  That means it costs me about $10 per year just in electricity costs for internet access (or 105 kWh).

The big surprise during this exploration was my home theater system.  The whole thing draws about 150 watts, which means that each episode of Parks and Recreation that I watch (currently my favorite show) uses 75 watt hours, and  watching the entire season will use 1.6 kWh.  It may not sound like a lot, but if I were to watch 5 hours per day (currently the US average), I’d be using 276 kWh per year.  That’s about $30 a year in energy costs just for television.  On a larger scale, we spend over $2 billion a year in electricity just on TV as a country!

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