May Energy Usage, Dehumidifer

Hello all, I'm back.

Below is my May 2012 Energy Usage numbers from Duke Energy:

Total KWH:  689  (TED measured = 696 kWh)
No. of Days:  33
May 2012 Average Daily Usage:  20.88 kWh/day
May 2011 Average Daily Usage:  17.53 kWh/day
Comparison:  -19.1%

I'm not surprised by these numbers.  It was a hot May and we were forced to use our A/C for at least a week.  In addition, in May 2011, I had not yet installed the crawl space dehumidifier.  That was installed on June 6, 2011 (exactly 1 year ago...look at that).  One thing I have found since then, is that the dehumidifer is an energy hog (and it's Energy Star rated!).  I plugged it into my Kill-a-watt meter and measured the usage for  a couple days.  I found out that the unit is using roughly 7 kWh/day.  Wowza!  That's 33% of my average daily usage during the 'fringe' seasons (when the HVAC is not in use).

So what do I do about it?  Well...I think the only thing I CAN do about it, is to go ahead with my house residing project.  When I do this, I plan to install housewrap (maybe even some polystyrene insulation).  The housewrap is supposed to help reduce air movement (and thus MOIST air movement) which should help significantly and reduce crawl space dehumidifer usage.

Why do I think that?  Well...here's my thoughts:  When I turned on the A/C (which dehumidifies) last month I did not notice any reduction in crawl space dehumidifer usage (and I was watching)...as my initial theory was that the rest of the house was responsible for the permeation of humidity in the crawl space.  To test this out,  moved the dehumidifer to the house and ran it.  Guess what?  The crawls space humidity increased to 65% (slowly) even though the rest of the house was at 55%.    So that wasn't it...so my next theory formed...the humidity is entering the crawl space from the wall cavaties.  This would make sense because the walls terminate at the crawl space.  Because I have painted walls (who knows how many layers), this creates a fairly impermeable membrane on the interior walls...so where does the humidity go?  Well...down to the crawl space where the dehumidifer is drawing air and creating a gradient.  Thus, by putting on the houswrap/insulation...I'll create an effective air barrier on the EXTERIOR walls...which should significantly reduce the amount of moist air entering the crawl space. And I'm certain air is entering the wall cavity beause most of my exterior lights have holes directly to the interior wall. 

That re-siding project is going to be pretty expensive ($8-10k), but at least it will help my house look nice while simutaneously increasing energy efficiency.  I highly doubt I'm going to emark on the project soon.  Maybe this fall at the earliest...