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Saving Energy and Resources in Durham, NC

Energy and Resource Saving, Durham, North Carolina.

Our home is in central North Carolina, United States, at a latitude of 36 degrees North *.

Basic details about our home:

  • Built in 2003, wood framed, 3016 square feet, three floors and crawl space
  • Insulation to 2003 North Carolina Building Code.   Radiant Barrier added in Attic spaces since Solar Domestic Hot Water (SDHW) and Photovoltaic (PV) installation in 2007
  • We use Compact Fluorescent Bulbs (CFL's) throughout our home.  CFL's use about 25% of the energy of Incandescent Bulbs and I support Australia's lead in making these bulbs something we will hopefully soon see only in museums.  We have CFL's in our dimmable and chandelier circuits too (NOTE: You must select CFL's rated for such devices)
  • We use two zones of controllable heating and cooling using Programmable Thermostats.  We only heat / cool the home when we are home.  We use ceiling fans to circulate air and make use of the summer and winter settings.  We change our HVAC air filters every three months and have the system serviced twice per year
  • In the summer, we cool our home to 79F when we are home, and let it rise to 83 when out.  In the Winter we heat from 68F and let the temperature drop to 55F when we are out, and in the middle of the night while we sleep
Season Morning During the day Evening Through the night
Winter 68F (20C) 62F (17C) 68F (20C) 55F (13C)
Summer 80F (26C) 83F (28C) 79F (26C) 83F (28C)

Radiant Barrier
  • We use an EnergyStar Washing machine certified to the more stringent 2007 code
  • We do not (DELIBERATELY) own a clothes dryer.  We line dry all our clothes in modified attic space (our drying room).  Please note that EnergyStar.gov do not rate "Clothes Dryers".  They all use similar amounts of energy ..... which is actually TOO MUCH energy, hence our active decision not to use one
  • We use Watt Stoppers to help reduce our Phantom Loads.   From our PV meters, our static load in our home is less than 200 Watts
  • Although, not in the home we also drive a Hybrid car
    .
    We cycle, walk and carpool as often as we can
  • We shop at the local farmers market too
  • Connected to the local electricity grid with Duke Energy as our supplier
  • City natural gas with PSNC Energy as our supplier
  • City water and sewage Durham Water
  • * We have a split roof. A recommended (to us) rule of thumb is that in the northern hemisphere the optimal angle for PV panels is 15 degrees under latitude in the SUMMER, and 15 degrees over latitude in the WINTER. So, in this part of North Carolina, the best angle in the summer will be a roof of 21 degrees, and in the winter 51 degress. We have a split roof (please see our pictures) and our roof angles are 22 and 46 degrees.
No dryer
Our drying room

We moved in to the home in the Summer of 2006.  In late February 2007 we installed a 80 gallon Solar Domestic Hot Water (SDHW) system.  In May 2007 we further added a 2.3kw Photovoltaic (PV) system.

Details of our resource usage are available.

Solar Domestic Hot Water system (SDHW).

Our SDHW system was installed in late February 2007.  Our first day of use was 1st March 2007.  At the time of installation we calculated that our average monthly hot water heating bill was $35.43.  We planned that we would have 80% of our future hot water heated by the sun, leaving us to pay for the remaining 20%, a cost of $7.09 per month.

All in, at the time of installation we planned on a monthly saving of $28.34, which equates to $340.08 per year.  Our actual SDHW system performance based on collected data does vary from our targeted 80% solar hot water hearting.

To June 20, 2009 we calculate that 83.52% of our hot water was heated by the sun, so 16.48% was heated by our electric water heater.   This equates to a cost of $5.83 per month, which based on our pre-installation hot water heating costs means an estimated saving of $29.60 per month.  Annually, this means a total cost of $69.96 and a total estimated annual annual saving of $355.20 .

Ignoring tax credits and assuming energy prices stay the same, payback (ROI) occurs in 218 months (18.25 years).  Including tax credits (Federal and State) payback occurs in 78 months (6.5 years).  However, energy prices will not stay the same, a 3% rise per year reduces payback to less than 5.5 years, after 20 years (the rated service life of the thermal collectors) from date of installation the net benefit is $10,400.

If energy price rises are higher, some projections have suggested 10% per year, then at this rate the payback is 4.9 years, and after 20 years the net benefit is almost $20,000.

Photovoltaic (PV) Electric generation.

Prior to installation of our PV system we calculated an average monthly electricty cost of $50.85.  To June 20, 2009 we calculate that our monthly electricity cost is an average of $16.62 ( $199.44 per year).  Our estimated saving is $34.23 per month.  Annually, this equates to a saving of $410.76 .

Ignoring tax credits and assuming energy prices stay the same, payback (ROI) occurs in 701 months (58.5 years).  Including tax credits payback occurs in 219 months (18.25 years).  However, energy prices will not stay the same, a 3% rise per year reduces payback to 14 years, after 20 years (the rated service life of the PV panels) from date of installation the net benefit is $3,900.

If energy price rises are higher, some projections have suggested 10% per year, then at this rate the payback is 10.25 years, and after 20 years the net benefit is more than $17,000.

Additionally, we have battery backup for our PV system and therefore expect to be isolated by all but the most extreme of power outages.  When the sun shines we will be recharging our batteries.

Email: darrell AT nearto.us
Web: http://www.nearto.us/
Copyright (c) 2007-2009 Darrell Edgley