’Twas the Night Before Christmas

’Twas the night before Christmas, when blizzards and chills
Strain my budget by raising my energy bills;
All the stockings were swaying — a cold winter breeze
Made my home’s leaky envelope feel like Swiss cheese
(The old windows and ceilings have so many gaps
That the kids have to sleep in their kerchiefs and caps) —
When out on the lawn there arose such a clatter,
I sprang from the bed to see what was the matter.

Away to the window I flew like a flash,
And I yanked up the creaky old single-pane sash.
When, what to my wondering eyes should appear,
But an energy expert — a trained engineer!

The sign on his truck said, “We’ll fix your old home.
If you’ve got any cracks, we’ll fill them with foam!”
A bespectacled fellow came out of the van,
And asked if I needed an infrared scan.

“Lord have mercy!” I muttered. “I certainly do!
Any chance that you came with a blower door, too?”
“Yes I did!” said the man. “I’m an energy geek!
And I promise to find every defect and leak!”

And he whistled, and shouted, and leaned in the van,
While his helper unloaded a door-mounted fan.
“Get the Duct BlasterCalibrated air-flow measurement system developed to test the airtightness of forced-air duct systems. All outlets for the duct system, except for the one attached to the duct blaster, are sealed off and the system is either pressurized or depressurized; the work needed by the fan to maintain a given pressure difference provides a measure of duct leakage.! Caulk gun! A bottle of Windex!
It’s time to reduce this home’s dismal HERSIndex or scoring system for energy efficiency established by the Residential Energy Services Network (RESNET) that compares a given home to a Home Energy Rating System (HERS) Reference Home based on the 2006 International Energy Conservation Code. A home matching the reference home has a HERS Index of 100. The lower a home’s HERS Index, the more energy efficient it is. A typical existing home has a HERS Index of 130; a net zero energy home has a HERS Index of 0. Older versions of the HERS index were based on a scale that was largely just the opposite in structure--a HERS rating of 100 represented a net zero energy home, while the reference home had a score of 80. There are issues that complicate converting old to new or new to old scores, but the basic formula is: New HERS index = (100 - Old HERS score) * 5. Index!
We’ll battle your dampness and foul condensation!
And make sure that your house has enough insulation!”

And then up to the attic the engineer flew,
With a cellulose hose and a spray foam gun, too.
And then, in a twinkling, I heard a strange sound
As the cellulose bales were chopped up and ground.
When the recycled fibers were blown deep enough,
He came down through the hatchway all covered in fluff.

His eyes — how they twinkled! his dimples, how merry!
His cheeks were like roses, his nose like a cherry!
He was chubby and plump, a right jolly old elf,
And I laughed when I saw him, in spite of myself;
He was real — flesh and blood! No mere Christmas illusion!
He even knew all about vapor diffusionMovement of water vapor through a material; water vapor can diffuse through even solid materials if the permeability is high enough. !

And laying his finger aside of his nose,
And giving a nod, up the chimney he rose.
Then back down the chimney the engineer came,
And he scolded me gently by saying, “For shame!
If you’re not burning wood and you’re not burning coal,
You don’t need this chimney — so plug up the hole!”

Then he sprang to his van, and he waved his farewell,
And he said, “Since you’ve got an improved building shell —
One that’s tight — it’s important to ventilate right!
Merry Christmas to all, and to all a good night.”

Last week's blog: "Martin's Energy Quiz."