I had a request this morning to write the attached. I'm a member of Rotary International, an organization focused on making a difference to local communities. We meet weekly, and the subject of sustainability programs for the city I live in was the topic for this morning. In the course of discussion, I was asked to create a summary (attached) on my (real) experience with geothermal heating and cooling and send it out to the membership.
Here's a copy of what I submitted, primarily to help those of you who are still wondering if geothermal-based heating and cooling is 'the real deal' (it is).
Keep in mind that I live in what can be a blistering hot climate here in Dallas, and as such, my GSHPs don't get challenged until summer time, which is the reverse for most of you.
Best regards,
Bill
Thank you for your questions this morning on my geothermal heating and cooling system for my residence.
My family lives in a 3400 sf single story house near Bob Woodruff Park. The structure has a big (hot in the summer) attic where the heating & cooling equipment is, and has a standard composition roof. It has average insulation, poor air-tightness (windows, doors and over 50 recessed light fixtures ventilating direct to the attic), and a lot of unshaded glass (considerable solar gain).
We generally keep the thermostats set at 76° when cooling, and 68° when heating, with a 3° setback at night.
We made the decision to improve the energy efficiency of our home after the hot summer in 2006. Our bill got close to $1000 for just one month's worth of electricity. We had a 120 KBTU/hr gas furnace and a 2-stage 5-ton air conditioner that was 14 years old. (At the time it was near the best energy efficiency available.)
Of the many energy improvement possible actions available, we've completed two so far: converting to geothermal and replacing every incandescent light bulb with a Compact Fluorescent Lamp (CFL).
Here's the summary on why geothermal is 'the real deal.'
On an apples-to-apples basis, looking at Kilowatt-Hour (KWH) consumption (what is read from your electric meter), we've reduced it from 146 (Jul. '06) to 82 (Feb. '09) KWH per day, on a 12 month rolling average basis. This is a 44% reduction in electricity energy consumption. (Of the 64 KWH/day reduction, 12 of it is due to CFL replacement - the rest is due to geothermal.) Here's a chart showing KWH usage since year 2000: http://www.pbase.com/neukranz/image/110158907 .
Continuing to look at actual consumption before looking at costs, for natural gas we've reduced from 0.27 to 0.13 MCF per day, again on a 12 mo. rolling avg. basis. This is a 52% reduction in gas energy consumption. All of this is due to geothermal (removal of the gas furnace). Here's a chart showing NG usage since 2006: http://www.pbase.com/neukranz/image/110158982 .
Turning to the cost picture, you have to take into account individual utility rates. For us, we've reduced the monthly electric bill from a high of $925 (Jul. '06) to a low of $216 (Oct. '08). In fact, we have to go back to Feb. '04 to find a lower monthly bill ($202). Here's a chart: http://www.pbase.com/neukranz/image/110159025 .
A broader picture of what's been accomplished is available by looking at 12 mo. rolling avg. cost. Here our avg. monthly bill, each month, has declined $270/mo., dropping from $602 (Feb. '07) to $332 (Feb. '09). This is almost a reduction in half of the electric bill, on avg., every month.
On an annualized basis, this is a $3240 per year savings.
For the monthly gas bill, we've reduced our 12 mo. rolling cost by $35/mo., dropping from $95 (Nov. '07) to $60 (Feb. '09). This is slightly more than a one-third reduction (37%). Annualized, this is about $420 additional savings.
Putting the two utility savings together, total annual savings is near $3700.
After converting to the geothermal system, I installed a monitoring system to record our progress toward energy reduction, and to illustrate energy guzzling areas that can be cost-effectively attacked. If you're interested in a lot of detail for how our geothermal system is working, both real time and historically (and for what the weather's been like for the past year here in East Plano), take a look here: http://welserver.com/WEL0043/ .
One of the many things this implementation shows is energy consumption separated out just for heating and cooling. Our electricity consumption for heating and cooling was just $28 last month (Feb. '09). Our lowest consumption since putting in geothermal was $18 for Apr. '08. Our high for this past summer was $190 (Jul. '08).
If you have any questions, or would like further information, please don't hesitate to ask.
Best regards,
Bill
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