In designing the super-efficient country house of the future, architects must keep in mind the R-value of two substances that pack the walls of every domicile in the Endless Mountains and, I can confidently assert, all mountains everywhere apart from the moon: cat food placed there by mice, and dead mice who have gone to their heavenly reward in a heaven of their own making. Leaving aside the deceased little greedikins who blocked the opening of the birdfeeder with his portly form last winter, the dead mice in my walls have come to a place that could not be more perfect to spend eternity: dark, winding, free from predators and packed with an excellent brand of dye-free, additive-free, naturally preserved cat food. If only the mice themselves were naturally preserved. Summertime dead-mice-in-walls for 24 hours smell like a garbage container truck that was en route from the slaughterhouse to the landfill on an August afternoon but lamentably broke down and therefore was held up at a roadside rest area for two or three days while parts where shipped in from the Midwest, but then their smell is gone. It burns itself out in a horrific maelstrom of stench, localized to a part of the wall where hopefully you do not have to go that day. By contrast, wintertime dead-mice-in-walls are more the Peruvian Ice Maiden of unreachable rodents. They start out cute little thieves intent on tanking up on the burned oil residue under the stove burners before making the big climb up to the cat bowl on the counter to ferry its contents away into the superstructure. Then they take their time over the cold, dry months turning into tiny mouse mummies who may not be wrapped in nice textiles (or who may, actually, if you consider the state of the fabric storage drawers upstairs) but who are lavishly supplied with food for the afterlife, which, since they are mummified, is going to last as long as this house stands. Which is why it is important to include their R-value in your home designs.
You may think that the heat produced by the composting process might give the dead mice an edge over the room temperature cat food, but in fact the heat is short-lived and the only way the decay process advances the mouse’s cause is by compacting him, which improves his R-value because it allows the walls to be filled with a far greater number of his deceased relatives over time. The fact that our house is almost 100 years old and still filling up with mice shows the efficacy of this process. Meanwhile, the cat food has a distinct advantage because it is smaller to begin with and therefore packs more closely. Whereas dead mice are the open-cell spray poly of organic insulations, cat food is the closed-cell: inherently more of a barrier. However, in the final analysis, we recommend that you design to make the best of the diverse heat retention qualities of dead mice and cat food used in combination. In particular because, if you live on Earth, you don’t have any choice.
P.S. The illustration shows an oxalis demonstrating heliotropism and indoor air quality management in a south-facing window during the heating season in the North. Because inside of a wall, it’s too dark to illustrate.