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Unofficial HERs Index for my House
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So the other day I was bored and came across my former
HERs rating report completed last May. The report showed my house had a rating of 71 which meant that it was ~55% more efficient than a typical existing home (HERs rating =130) and ~29% more efficient than a standard new home (HERs rating = 100). Since I've done a whole bunch of projects since then (most notably the attic radiant barrier and the GE Geospring), I was curious what my new score would be.
So looking through the report, in the footer it noted that the report was completed using the "REM/Rate - Residential Energy Analysis and Rating Software v12.99". Using Google, I input the information and found the website for the software. As I hoped, they provided a download for the software. So I downloaded v14.1. It's a 90-day trial version that's full featured except I can't print anything. That's fine by me...I'm just playing anyway.
Luckily, my previous energy auditor, AltruEnergy, had sent me the REM/Rate file for my house (*.blg). This was great because it meant I didn't have to re-enter all the information from the report! Time saver! After opening the file and doing the all-important "Save-As", I verified that my previous HERs rating did not change (it didn't) and then I started updated. I added the following:
- Added
in R-5 to the foundation walls for the XPS I added this winter.
- Added
in R-5 to the Rim and Band Joist via the XPS I added this winter (1st floor only).
- Note: I have not added ventilation to the
crawl space yet. I’m waiting for my spring tune-up. At that time,
my HVAC guy is going to install the new vent in the crawl space. So I
didn’t update that in the file.
- Added
in Radiant Barrier to the ceiling (all except the small vaulted part in the bonus room) which I installed last
fall.
- Updated
water heater to be my GE Geospring (EF=2.4) which includes an extra R-10
blanket I added myself. It also runs in series to maximize desuperheater production.
- Updated
the geothermal system such that only 1 unit has a desuperheater (only the
downstairs unit has one).
- Added
in my new fridge. I got one of those French door fridges. Not only
is it bigger than my old one, but it uses nearly half as much energy per year.
- I
updated the dishwater information to reflect the actually kWh/yr via the Energy Guide.
- I
updated the dryer to have moisture sensing which it has.
- I
updated the clothes washer with the actual information for my unit via the Energy Guide.
- I
updated my lighting to be 100% CFL. It’s really more like 80% CFL and 20%
LED. But there's no option for LED in the software. My exterior and garage fixtures are all CFL also so I put those to
be 100% compliant.
- I
updated the ceiling fan CFM/watt to ~92 CFM/watt. We have 5 ceiling fans
in the house, all of which are energy star. The old file said we only had 1. I actually replaced the one
in my master bedroom (which we use nearly every night in the summer) with one
of those DC motor ceiling fans. It uses 327 CFM/watt…which is about 3x
better than other energy star ceiling fans! It’s still on clearance at
Home Depot online (Hampton Bay Winfield).
The results are below (it's also in the pic above if you were paying attention)...drum roll please....
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| Unofficial Home Energy Rating (HER) Certificate Note: The NO PRINT is because I'm using the trial version. |
My unofficial revised HERs rating is a 54. Sweetness! So I'm nearly 50% more efficient that a new standard home. And by energy star standards, my house is house is ~30% more efficient than a new standard home...assuming an energy star home is 30% more efficient than a standard home which would give it a HERs rating of 70. In case you're wondering from the certificate above, I don't actually use $1,379/yr for energy. I'm much below that ($1,091). The above number is scaled for a family of 5. There's only 2 of us now, although soon we'll be close with twins on the way.
Side note: I'm not advocating that anybody else do this...I'm just an Engi-nerd that enjoys tinkering.
I did send my file back to my Auditor for a QA/QC check...so I will say these results are preliminary. Although I'm not sure he'll say anything definitive just because he probably doesn't want to advocate for folks to use this software who don't know what they are doing. Being a modeler myself, I understand that when it comes to models, "junk in = junk out". So if you don't know what you are doing, you could just producing useless numbers.
One of the nice things about having the software is that I can run some scenarios for projects that I was contemplating. These include:
- Replacing the siding and including R-5 XPS insulation (continuous barrier)
- Replacing the windows with new Low-e, Argon filled windows
- Install Solar Panels
Replacing the siding and the windows is an expensive proposition. The siding itself would be ~$15k while the windows would probably be another $10k. Well, the software essentially told me not to bother. Adding in the extra R-5 on the outside walls only saved be $50/yr! The windows were another $50. Obviously, doing it for energy saving purposes does not make sense. Maybe for the windows installing a window film would make more sense because its significantly cheaper and would reduce the solar heat gain in the summer and the heat loss in the winter. The return on investment would be significantly better while providing a similar benefit, although definitely not as great. But it would be a fraction of the cost...if you believe the
websites it's 10% of the cost. So $1k vs $10k. That could be palatable for my wallet.
The only thing that did make sense was the
solar panels....but I pretty much already
knew that. The panels lowered my HERs rating to a 43. However, that's a $4-5k investment.
