Updated (Non-Official) HERs Rating

Unofficial HERs Index for my House

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 (1^st 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....

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.

February 2013 Bill and Results

Howdy Folks-

Yes...I've been slacking.  I've been busy at work...blah blah blah, yeah I know...no excuses.  Well, I received my February Duke Energy Bill and the results are posted below:

February 2012 Bill
Total Energy Consumed:  1,075 kWh
Number of Days:  29
Average Daily Usage:  37.07 kWh/day
Heating Degree Days:  566
Temperature Normalized Average Usage:  1.90 kWh/HDD

February 2013 Bill (Jan 3- Feb 4)
Total Energy Consumed:  1,050 kWh
Number of Days:  32
Average Daily Usage:  32.81 kWh/day  (11.5% Reduction)
Heating Degree Days:  606
Temperature Normalized Average Usage:  1.73 kWh/HDD  (8.8% Reduction)
Rate Adjusted Bill Savings ($0.0996/kWh):  $14.71
One Year Rate Adjusted Bill Savings (April 2011- Feb 2013):  $296.18
Cumulative Rate Adjusted Bill Savings (April 2011- Feb 2013):  $680.45

Not too bad...a 11.5% reduction in usage compared to a year ago.  And when adjusting for temperatures differences, it's still nearly a 9% reduction.  I'll take that.  I also added in my one-year and the cumulative savings.  These savings do not take into account any system maintenance...although I doubt it would be much difference.

I will say that I do like using the Heating/Cooling Degree Day Data.  It certainly puts my HVAC-Energy usage into perspective.  I've been fairly consistent over the last 3 months (Recall the bills listed above actually represent the previous months usage):

11/2012 = 1.82 kWh/HDD
12/2012 = 1.75 kWh/HDD
1/2013  = 1.73 kWh/HDD

Interesting enough...Duke Energy Announced that they filed for a Rate Hike in NC.  They are trying for an 11.8% increase in residential Rates (among lower rate hikes for Commercial, Industrial, etc).  I expect that rates will eventually flatten out once either (a) Duke gets all its coal-fired plants in line with EPA air regs or (b) somehow Republicans destroy the EPA.  But of course, Duke Energy still recorded profits which were bolstered by the nice 7% rate hike they got last year.  Must be nice to be an energy company with low risk and can pass all costs onto its customers.

I will note that if this goes through as planned, then in in the past 3 years, rates would have increased by 22.2%.  When I evaluated my Geothermal system, I assumed a 24% (conservative 1.2%/yr) hike in electricty rates over 20 years.  Well...I guess my return on investment will be faster than I expected.  

Overall, maybe I should start looking at getting solar panels.  But, I have to build a screened in porch first...

New GE Geospring Hot Water Heater!

My new GE Geospring hot water heater in series with a preheat tank (not shown)

So I finally put in a new hot water heater.  As I had discussed in previous posts, I wanted a GE Geospring air source heat pump (ASHP) hot water heater.  Well, that's what I got.

Why am I so hyped about this?  Well for starters...

1)  The Geospring is rated at an energy factor of 2.5 which saves roughly 63% of the energy as compared to normal electric hot water heater (which I had).  On an annual average basis, my former HW tank was running 0.8 hrs/day @ 4.6 kW for 3.7 kWh/day.  Thus, this is expected to be reduce to 1.37 kWh/d.  

2) I had mentioned in some of a previous posts, that the geothermal supplemental hot water generator (desuperheater) really is not optimized when using one tank.  I'd read some forums that even claimed it could be costing me energy with calls for geothermal system manufacturers to remove the 1 tank setup from its installation procedures.   Well, this new hot water tank was connected in series with my "old" hot water tank (now un-powered).  The "old" tank will act like a preheat tank allowing for maximum hot water generation via the desuperheater.  This preheated water will feed the GE Geospring.  So overall, the energy required for hot water generation is cut substantially.

3) The Geospring is so efficient because its an ASHP hot water heater.  Essentially that means its an air conditioner connected to hot water heater.  So it will "condition" (remove heat and humidity) the air and instead of discharging the heat outside, it takes the heat and pumps it into the hot water tank.  Why does this benefit me?  Well, recall I've been using a dehumidifier in my crawl space to reduce moisture...and its been a fairly large energy consumer.  Well, the Geospring will now take the place of the dehumidifier by simultaneously conditioning the air (removing moisutre) as it heats the hot water.  Thus, I'll hopefully be able to negate using the dehumidifier entirely! That should save me somewhere around 7 kWh/day alone.

Overall, I'm hoping this work will reduce my overall power consumption by about 9.33 kWh/day.  It could be higher including optimization of the desuperheater, but I have not way to quantify this yet.  Even at 9.33 kWh/day this is about 280 kWh/month!  If you consider that in the last year (Sept 2011 - Sept 2012), I've averaged 853 kWh/month, then the 280 kWh/month will result in a roughly 33% reduction in consumption!  That equates to roughly $31/month.    This project cost me about $1200 to install, so that's a 3.19 ROI (not assuming any rate increases).  I'll take that... Only time will tell what I actually achieve...   

 

Geothermal Heat Pump System

OK...yesterday, I called up a HVAC place, Pantherhvac (pantherhvac.com), and they came out to check out my house.  Mike, the owner of the company, was great.  We walked around the house...looked at my POS existing heat pumps and talked geothermal. Did I say it was great yet?  Because if not, here it is again...it was great and it was fun.  I guess having a spend a lot of money isn't fun, but talking about saving energy and money is.

Anyhow, so the best places for the wells will be in the front yard...and I really liked his idea of putting the wells under the driveway, since I was already planning on tearing out my beat up driveway anyway and putting in something permeable.  The nice thing for them about putting the wells there is no utilities and no sprinkler system to deal with. Plus, the drill rig doesn't have to deal with trees.  So, the wells would under the driveway and then I'd have a small trench that would run two 1.25" lines (supply and return) to the crawl space.  This is nice because it would be minimal yard repair from the excavation in the front yard.   And before you ask...the well system has a 55 year warranty.

So the system will include two @ 2 ton units.  The downstairs unit would be a combined unit with all brand new insulated duct work.  Next to that unit would be the "liquid half" of my upstairs unit, so it would be a split system.  Then the air handler would be in the attic like the way it is now.  The main duct work in the attic would be replaced with insulated stuff.  However, the current "drops" to each room are already insulated and new, so they can be reused.  Only the duct run to the bonus room would be replaced since the insulation is falling off of it.   Oh, and we discussed putting on a different supply vent in our master bathroom to redirect the air...because the ventilation fan for that bathroom is literally 3" from the supply duct.  So...when the ventilation fan is running and the heat turns on, the heat literally goes straight outside.  This is why I have that vent in the bathroom is closed.

Ok...for hot water, I'm getting two quotes.  One for the normal system with the desuperheater to give me free hot water in the summer (the reject heat from A/C is used to heat the hot water).  The other will be for "priority" hot water which essentially is using the geothermal system to heat your hot water.  It's also called geothermal hot water.

So, when talking dollars and sense we discussed round numbers until I get the official quote on Monday.  The unofficial quote is $30k.  So, take that $30k and minus the 30% federal tax credit ($10k), and now it's $20k.  Then, the State of NC has a 35% tax credit capped at $8.4k.  So minus the $8.4k, and I'm at $11.6k.  Fantastic.  I got a quote from my current HVAC contractor for a new high efficiency air source heat pump (16-18 SEER, 9.X HSPF) that was $14k. So, after tax breaks, this system will cost me less than installing the air source heat pumps while being significantly more efficient!

Now I just need the official quote.  I also need to call up two other HVAC places to get quotes from them to keep everyone 'honest'.

Oh...and BTW, I showed the HVAC guy my TED 5000.  He loved it.  He's probably going to start including one with his geothermal systems to show folks how much energy/money they are saving.