Energy Audit Results! HERS Index = 71

Well, I finally got my energy efficiency results in....drum roll please....

I got a HERS index rating of 71. 

So, what does this mean?  Well, let's start with the basics...HERS (Home Energy Rating System) is the standard by which a home's energy efficiency is measured.  Here's a good explanation:  http://www.resnet.us/hers-index

From above my house is roughly 30% more efficeint that a standard newly built home in the US (HRES = 100).  As compared to "existing homes" (HERS = 130), I'm about 55% more efficient. 

Based on ASHRAE 90.2 (1993) Annual Energy Consumption Compliance, my home surpasses the minimum compliance by 22.1%.  For a house of my size, ASHRAE has an annual consumption score of 2,197 while my house has a score of 1,737.  My house also exceeds 2003 IECC compiance by 10.3% (IECC = 67.9 MMBTU vs 60.9 MMBTU).

The blower door test confirmed by infilration at 0.29 ACH (Natural).  This exceeds the ASHRAE 62.2 standard of 0.35 ACH. This also means that I need some mechanical ventilation because my house is becominng 'too tight'.  An Energy Recovery Ventilator (ERV) was recommended to maintain "healthy air".

What else was recommeded?  See below:

1) Radiant Barrier in the Attic to reduce radiant heat loads to the upstairs and to the upstairs HVAC system.  (I was planning on this, however, I need a ridge vent first so all the hot air can be directled out of the attic efficiently).
2) Tighten the ducts on the first floor (I already knew this and this should already be fixed when I HVAC taped the filter door shut.
3)  Install ERV (see previous comments).
4)  Seal all holes/cracks/ and seams @ the Garage to the House.  (I'm not sure what this means since we didn't find any cracks/seams with the garage).
5)  Block joists at rim band at bay windows (OK...I can probably do this with some polystyrene foam board)
6)  Block Floor Band at Bay Window with blue board and foam (Same as #5 as I can best figure)

7)  Conidtion Crawl space to improve HVAC performance.  (I was getting to this.  I just need to insulate the crawl space walls and I'll be ready to allow some conditioned air into the crawl space.
8)  Condition attic to improve HVAC performance.  (I have no intention of doing this.  At most I'm planning is the radiant barrier- #1).
9)  Replace windows to improve wall u-value.  Yeah...at most I'll probably just replace all my window shades to be the "light filtering" double wall cellulose shades.  These should increase the R-value of the window (with the shade closed) substantially.

What I found interesting was the annual energy profile:

 One note...due to RESNET standards (I believe), this is based on a worst case scenario (4 bedrooms + 1) Family of 5 living in my house.  So I'm not actually spenting ~$1750/yr on my home.  Last year is was only $1050.  And the "Family of 5" is what is pushing my Lighting and Appliances up so high.

This table is neat because it says what's contributing to heating/cooling. 

So ignoring lights/appliances for now since it's way overinflated...this essentially shows that heating is predominate followed by cooling and water heating.  To reduce heating costs, it appears I need to do the siding project which would reduce infiltration and add insulation to the above grade walls.  However...if you really think about it...that project doesn't save me such.  Let's say I can reduce the infiltration and wall costs by 50%...That only saves me $137 per YEAR.  The siding project will cost me at least $10k for an ROI of 73.3 years.  Yes, it will make my house look nicer, but it isn't the energy monster I was hoping for.

For cooling, I really don't have a big winner unless I can reduce the internal gains...uhh...how do I do that?  Stop the fridge?  No indoor cooking during the summer?  Sleep outside?

And then there's hot water.  If I install one of those air source heat pump hot water heaters (such as a GE Geospring) then I could probably reduce that number to about $90/year.  And if you count reducing the crawl space dehumidifer usage by 50%, then I get about $180 per YEAR savings.  Yes...again...not a lot..even with the further optimization of my geothermal desuperheater (using two tanks in series).

Going back to the lighting and appliances.  If I look at the months that I am not using any HVAC, I'm essentially using 610 kWh/mo (20 kWh/d) of electricity.  About 30% of this goes directly to the crawl space dehumidifier (6 kWh/day).   Then there's hot water which is currenly about 20% (4 kWh/day).  So 50% is going to two things. Best as I can tell...after that is the fridge (709 kWh/yr * 1/365 = 1.94 kWh/d), the HTPC (1.64 kWh/d), then the dryer (6 kW * 1.5hrs/week * 52 weeks/365 days = 1.28 kWh/day).  Then maybe we have cooking (who knows where this math pans out...maybe 1 kWh/d?) and then freezer at 0.7 Kwh/d. 

So if I really want to make a large dent in my energy usage, my next target really should be the Air Source Heat Pump Hot Water Heater which should save me roughly 2,000 kWh/year (5.5 kWh/d) if I assume a 60% reduction in hot water generation cost (using GE's value) and a 50% reduction in dehumidifer usage since the hot water heater is a glorified dehumidifer.   I'm more than liklely going to hold off on this project until November for the "Energy Star Tax Holiday" in NC where we get a tax free day for Energy Star appliances.  The total project cost will probably be about $1.2k.