Geothermal heat pumps: How a regular house fared in the nasty winter of 2013-14

That’s my house in Lebanon, Connecticut.  Nothing special, but we like it.  It’s a 2400 square foot colonial with a somewhat passive solar assist.  It has a geothermal heat pump in it, but the unit design dates from 1979.  System efficiency has been greatly enhanced since then.  The unit is from a pioneering Swedish/Canadian firm called Cantherm.  Unfortunately they have been gone for a while.  The unit doesn’t seem to care as it is still running great.  We have no back-up heat.  By the way, I install geothermal heat pumps for a living.  Just like the shoemaker’s kids who have no shoes, this geo guy has no back-up heat.  This proves a heat pump can do the whole job.  For over twenty years, this house has been heated with ONLY geothermal.  We started building the house in August of 1988, and moved in on June of 1990.  

My company has been involved in many energy efficient homes over the years, and we’ve seen many really high end approaches to energy efficiency.  My house is OK, but nothing like Energy Star houses are today.  Spray foam insulation and blower door tests weren’t around back then.  The age of things is important.  Back then, for example, when I insisted on Low-E glass, my supplier had to ask what it was.  I have R-19 walls, and R-30 in the ceiling.  R-38 is now better in the ceiling and new energy star rules look for R-25 walls.  Probably the most progressive item I have is that I surrounded the exterior basement walls with R-10 stryofoam, all the way from the footing to the first floor plate.  Many builders use styrofoam, but then they cut it off above grade since it’s a pain to cover it (bad move).  Many other conservation strategies post date my house.  I keep telling my wife, ‘Next house’.  We could do much better.  She’s not buying it.  She’s home a lot, and the thermostat is usually at 72, 65 overnight.  Still, when I talk to folks with oil or propane heat, it’s clear we’re doing well.  Let’s take a look.  These are my last 12 months electric bills.  Remember, Connecticut has a very high (16 to 17 cents/khw) electric rate.

Jan 2014          $393.05      (33 Days)

Dec 2013         $333.98      (30 Days)

Nov 2013        $250.87      (31 Days)

Oct 2013         $169.52      (29 Days)

Sept 2013        $229.41      (30 Days)

Aug 2013         $234.47      (29 Days)

Jul 2013           $347.21      (33 Days)

Jun 2013          $238.62      (30 Days)

May 2013        $215.10      (31 Days)

Apr 2013         $245.44      (30 Days)

Mar 2013        $288.03      (29 Days)

Feb 2013        $357.14      (32 Days)

Total            $3,302.84      (367 Days)

Next, a real quick and dirty estimate of the heat pump versus the lights and all the other stuff.  Take the two lowest (Oct $169.52 and May $215.10), and average  them ($192.31).  Then multiply by twelve ($2307.72).  This is a reasonable number for the cost of running the lights, fridge, well pump, home entertainment, etc.  This includes the domestic hot water which comes off of the heat pump.  How many people get a $150 electric bill when they have oil or propane for heat and hot water?  Most.  The difference between my total annual bill ($3,303.10) and the calculated cost of incidentals ($2,307.72) is $ 995.12.  This can be assumed to be the heat pump.  I sleep well at night knowing my geo system has heated and cooled my house for about $83/month.  This is not a projection.  My unit has been doing it for years.  I did this analysis ten years ago, and the heat pump cost me $720 annually then.  Inflation eh?  I never worry about oil deliveries and other than filter changes, I don’t worry about annual maintenance.  No ‘fire’ in my house, unless the fireplace is preferred for mood, or the small wood stove is required to temper the man cave in the basement.  It’s like having a real big refrigerator in my basement.  My customers share the same experiences.  They nod sympathetically to friends when they complain about the cost of the last oil fill-up.  ‘Yeah, that’s a bunch of money’, and ‘How long will it last?’, are common comments.  In the end, my customers love seeing the oil truck just drive on by.