Wednesday, November 4, 2009

Cooling effectiveness: check!

I will repeat from my last post:

The energy cost of cooling my home 1 degree has dropped 70% due to my efforts.


Energy efficiency enthusiasts, be enthusiastic! This is an incredible number. Every kWh of energy I run through the air conditioner cools me 3.4 times more effectively than it did in 2005 when I embarked on this journey. And, in a big Energy Efficiency Man plus, almost none of the improvements that brought me these savings will break, wear out, or require maintenance. Ridge vent? No moving parts. Baffles and soffit ventilation improvements? No moving parts. Additional insulation? Will last the lifetime of the building barring roof leaks. Radiant barrier? It's foil hanging from the rafters, folks. The business end is the reflective side facing down, and it won't even get dusty after decades up there.
Yes, the more efficient A/C unit will wear out, but I have little choice but to have an A/C unit of some type here. It is definitely the weak link, and will undoubtedly give me trouble, but it's awfully nice to have when it's 100 degrees in September.

Caveats:
  1. This estimate is based on a linear analysis with a simple "slope-intercept" fit. A better analysis would take the hysteresis of the system into account.
  2. Your mileage may vary: these improvements work quite well in my 5-month cooling season-dominated climate. Effectiveness of all improvements depend on your climate and house situation.
The above notwithstanding, the data (and energy bills!) clearly show much less dependence of the house on the outside temperature as was true only 4 years ago. Truly, the house is cooler to live in as well as easier to cool through most of the year.

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