The Costs and Savings from Energy Efficiency Projects for the Home

Last Monday in the Wall Street Journal was an article “The Economics of Installing Solar Power.” They had a lovely chart with costs and returns that had virtually nothing resembling the actual costs and savings of my solar photovoltaic system. Though the costs of solar panels have gone down considerably since I purchased my system, and I discovered that solar panel installation costs less in San Francisco than Virginia and I assume cost less in urban centers than in rural areas. Nonetheless, the chart in the Wall Street Journal made me feel terrible, the cost of the fictional solar systems in the Wall Street Journal were all $5,500 a Kilowatt (KWh). Nonetheless, payback period is entirely dependent on the cost of electricity, rebates and incentives. Depending on how I continue to play the incentive game, my payback period could potentially fall in line with the fictional systems in the Wall Street Journal.

Right now (and for the past few years) electricity costs me $0.115 a Kilowatt. No matter how you look at it solar power costs more than the eleven and a half cents a kilowatt that NOVEC (Northern Virginia Electric Cooperative) is charging for residential power. The payback without tax credits and rebates would exceed the life of the system regardless of how good or bad a deal I got. In addition, my solar photovoltaic system cost way more on a per Kilowatt basis than the system cost they used. Prices have really come down on solar panels, but I do wonder if their costs include permits, plans and engineering, as well as the costs to change the electric panels and repair and seal the walls. The Wall Street Journal priced solar at $5,500 per KWh. The 5 KWh systems in the Journal have a listed cost of $27,500 while my installed cost was $58,540 for 7.36 KWh DC. Sizing their system up to my system size proportionally would be a cost of $40,480, but my cost included $1,500 for permits, plans and engineering. Nonetheless, you could probably install the same system today (even on the edge of nowhere) for $15,000- $18,000 less so even without the state of Virginia rebate the first year cost would be the less than my cost. 

My lifetime to date energy production

The actual cost of a solar photovoltaic system is really based on rebates, tax incentives and utility subsidies. Virginia no longer has rebates available and does not have any utility subsidies or solar renewable energy requirement, but I managed to snag a rebate when they were available and register my system in Washington DC before their market rules changed. My system was grandfathered when the market was closed. The Solar Renewable Energy Credits or SRECs are worth about $290 each right now (though I have sold them for between $95 and $350). Each SREC is a credit for each megawatt of electricity that is produced and used by me. SRECs have value only because some states have Renewable Portfolio Standards, RPS, which require that a portion of energy produced by a utility be produced by renewable solar power. Utilities in some states can fulfill that requirement by buying SRECs from solar installation owners and utilities in Washington DC are buying mine. As long as the market is not oversupplied (as is Pennsylvania) and there is a financial penalty for not meeting the solar carve out, then I can make more money selling SRECs than I save on the power I produce. With any luck I will be able to sell enough SRECs to get my payback period into the 10-15 year range. Energy savings from solar power are the most expensive no matter how you look at it.

A significantly shorter payback was from upgrading my heat exchanger. This past July I replaced my air heat pump with a new efficient system, replaced the ducting system in my attic and installed an attic fan and gable vent. The result is improved comfort and a $77 a month reduction in my electric bill during the summer cooling season and I assume an equivalent reduction in the winter bill. However, there are generally 3-4 months a year that I do not run the heating or cooling system so my annual savings will be closer to $600-$700 a year. That is about half the savings from my solar panels at fraction of the cost and I get a cooler, more comfortable home.

Though I had always assumed that when the time came I would replace my heat pump with a geothermal heat pump, that’s not what I ended up doing. After considerable research and getting several estimates I replaced my air heat pump with another air heat pump, a more efficient one, and re-ducting the attic to create a more efficient and effective system. The costs of installing a geothermal system in my existing home far exceeded the benefits. Based on the estimates I received the cost to reconfigure my finished basement ($5,000-$10,000) and install either a vertical coil or standing column well ($12,000-$18,000) on top of the cost of the heat pump and upgraded ducting combined with technical difficulties (a daylight basement and fractured rock system with no overburden), and the potential I might impact the drinking water aquifer or damage my garden ended my plans to retrofit a geothermal unit into my existing home. Instead I installed a more efficient and powerful heat pump, redesigned the ducts in my attic, and installed an attic fan. The result was heaven- a master bedroom that could hold 71 degrees at the heat of the day on a 100 degree day and the bedroom over the garage that in the past always was 10 degrees hotter than the master bedroom in summer and 10 degrees colder in winter was within 1 degree of the master bedroom and my electric bill fell by more than $77 for the month of July. (The decrease was about the same year to year or June to July.)

First of all my air heat pump like most is a split heat-pump systems consisting of two parts: an indoor (blower) unit and an outdoor (condensing) unit. Both units are designed to work together. Air Heat-pump systems manufactured today, by law, must have a seasonal energy efficiency ratio (SEER) of 13 or higher. Seasonal Energy Efficiency Rating (SEER) or Heating Seasonal Performance Factor (HSPF) for heat pump systems are the efficiency ratings on heat pumps, the higher the SEER/HSPF, the more efficient the equipment. The SEER is measured in average Btu output over the season divided by the watt hours and is the standard measure of energy use efficiency. Generally, the higher the SEER/HSPF of a unit, the higher the initial cost and lower the operating cost.

My old heat pump was a 3.5 ton with a SEER of 12 and a HSPF less than 8. Once the temperature reached 90 degrees in Virginia the heat pump ran continuously and could not keep the master bedroom or the bedroom over the garage cool. The master bedroom struggled to stay below 78 degrees and the bedroom over the garage was always 10 degrees warmer despite additional insulation. The old system was only 8 years old when the coil failed, but replacing the coil ($2,500) seemed like throwing good money after bad. We decided to do it right. After getting several bids and weighing my options, I had Randy Hayes and his boys (Hayes Heating and Air Conditioning) install a 4 ton Carrier Infinity 19 seer heat pump model #25HNB948, its matched multiple speed air handler and a programmable thermostat. The high efficiency two-stage heat pump allows me to oversize the unit slightly so that it can handle the hottest days without sacrificing optimal performance on more temperate days so the old rule that if a system is oversized, the system will cycle on and off too frequently, greatly reducing its ability to control humidity and its efficiency is no longer strictly true. I rounded up from base line Manual J to get the 4 ton.

In addition we (Randy and his boys) removed the old sagging flexible ducts and installed two new galvanized steel trunk lines (one to each side of the house) with 3 inch reflective duct wrap and tied the new flex lines into the existing vent boots with as little sag as possible (thanks to Randy’s middle son) using silver flexible ducts insulated with R-8. We minimized the amount of flexible ducting in the attic using as much galvanized ducting as was feasible (at an additional cost of $3,000, but the galvanized portion of the ducting will last longer and in all real world tests gives better air flow). Flexible ducts consist of three layers an inner core of a metal helix encased in a foil film, an insulation layer and the outer vapor barrier jacket. While fully extended properly installed flexible duct can be as good at maintaining air pressure as a galvanized steel duct, performance deteriorates as the ducts sag.

In the real world there is some degree of sag even in good installations and it tends to increase over time. In poor installations (like mine was) there were sharp bends and excess lengths snaked all over the attic in a daisy chain of connection using fiberglass plenums. This caused the inner layer of the flexible duct to crumple (it is a soft spring) and the helix pop out. Instead of smooth circular tube the flexible duct turned into a bumpy pathway for the air that caused turbulent flow and very significant pressure drop from the beginning to the end of the duct. In my case, there was almost no air flow in the bedroom over the garage (the room furthest from the air blower). The reason the drop was so great is that the ducts operate at very low pressure and small resistance due to friction can have a very big impact on flow. The old ducts were also R-6 insulation and black collecting more heat. Now I have conditioned air flowing into the bedroom over the garage and you can feel the cool air come out of the duct.

Finally to help the whole system work well, we added another gable vent (on the south facing gable) and a temperature controlled attic fan in the east gable. The result was that fabulous feeling of luxury (during the test period) of lying in bed in the middle of the day on a 100 degree Sunday and pulling the covers up because it’s cold. After a week of freezing out the bedroom at all times of the day and night, we settled back at a more reasonable temperature, but still reduced our energy use by about 670 KWh for the month. Total cost $16,300 for everything-heat pump, ducting, attic fan, installation, removal of the old equipment and cleanup. Part of the cost was simply to have heating and air conditioning, part for improved comfort and the rest for energy savings.

So, I did not get a geothermal heat pump, but I am more than satisfied with the cost savings and comfort improvement of my new air heat pump over the old one. The geology of my property was not ideally suited for a horizontal coil, too many rocks. The water table is shallow (under a hundred feet). My septic field and 56 new trees were in the way of the drill rig needed for a vertical loop or standing column well, and the location of my ducting and blower were not easily accessible to a new well without digging up the driveway, patios and/or garage or moving all the utilities in the house. For another house geothermal could be an easier or better solution. I had not thought through the requirements of geothermal when I purchased the house and finished the entire basement.

Finally, the first energy project I did and you should too, was to seal and insulate the house. Heating and cooling account for 50% to 70% of the energy used in the average American home. Inadequate insulation and air leakage through ducts, walls and roofs are the major sources of wasted energy in most homes (see upgrading my ducting above). Though, my house was built in 2004 the insulation and thermal properties were not optimal. I turned to the Building Envelop Research of the Oak Ridge National Laboratory for guidance. The Oak Ridge National Laboratory performs their Building Envelop Research for the US Department of Energy, DOE, and publishes their guidance in their “Insulation Fact Sheet,” which is available on the blog home page and through this link. Insulation and sealing was the most cost effective project I had done. Despite having it professionally done the payback was under 4 years in straight energy savings.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               

Heat Pumps- Replace, Repair or Upgrade to Geothermal

The first sign of trouble was when I woke up one morning thinking that it smelled like rain. I was in bed with the air conditioning system on. I could think of several excuses why I might have had that thought and so ignored the first symptom and it would be a several more weeks until the heat pump failed. It was a relatively long and cool spring with nights in the 60’s cooling the house, but come the first 90 degree day  I knew my split system heat pump had failed.

My heating and cooling system like a lot of newer homes in northern Virginia is a split heat pump system that consists of an outdoor metal cabinet that contains the condenser and compressor and an attic unit that contains the evaporator coil and the air handler that sends the cool air through the duct system in summer and hot air in winter. In the heating cycle, the air-source heat pump takes heat from the air outside the home and pumps it inside passed refrigerant-filled coils. Inside the heat pump system are two fans, two refrigerator coils, a reversing valve and a compressor. The outdoor unit contains a coil and fan and the compressor. The reversing valve switches the direction of refrigerant through the cycle and therefore the heat pump may deliver either heating or cooling.

The effectiveness of a heat pump is based on the temperature difference between the source and the sink and which cycle it is in. Heat pumps are more effective for heating than for cooling if the temperature difference is held equal. This is because the energy used to power the compressor can be converted to useful heat when in heating mode and released into the house as extra heat. The condenser is normally outdoors and during the cooling cycle, and the compressor's dissipated work is not put to a useful purpose. Air heat pumps are best suited to relatively warm climates, such as the southeastern U.S. This is because when temperatures are low, a heat pump’s Coefficient of Performance, COP falls dramatically. According to the Department of Energy a7.5-ton rooftop heat pump that has a high-temperature COP of 3.0 can have a low-temperature COP of 2.0 or even lower. And at very low temperatures, a heat pump can require supplemental heat, typically in the form of electric resistance just to function further reducing effective heating efficiencies.

The most effective type of heat pump is the geothermal heat pump. In winter it collects the Earth's natural heat either through a series of pipes, called a loop, installed below the surface of the ground or submersed in a pond, lake or well. The temperature six feet beneath ground surface is cooler in summer and warmer in winter than the ambient temperature and fairly constant, but many loop systems are not installed deep enough in a suitable medium to maintain constant temperature, but nonetheless draws excess heat from the house and allows it to be absorbed by the Earth. I had always assumed that when the time came I would replace my heat pump with a geothermal unit.

Despite the fact that my heat pump system is under 8 years old and heat pumps should last 12-14 years, the evaporator coil corroded and leaked enough Freon (R22) that the system could no longer cool.  The corrosion of the coil was obvious upon inspection, but the Freon level had been fine 2 months earlier when the system had been serviced, so I was taken a little by surprise to find myself having to make the decision about whether to replace the coil, replace the entire system with an energy star heat pump or upgrade to a geothermal heat exchanger now. A heat pump should last longer than 8 years. This is the first major repair the system has required and I probably could get a couple more years out of the system if I replaced the coil, but there is no guarantee and the outdoor unit had started to show rust two years ago. If I replace the entire system, I will probably get another 8-10 years before I have any major problems.  

In truth we were never happy with the system; it could never keep the master bedroom cool in summer. The master bedroom has unobstructed southern exposure and though we installed drapery, window films and additional insulation as recommended by the Building Envelop Research of US Department of Energy Efficiency and Renewable Energy Unit, still the bedroom was never cool enough in summer. The attic, crawl spaces, and eves, were insulated with cellulose. The pipes, end caps, knee wall, sump pumps and all identified areas were sealed, while my energy bills were reduced significantly, I could not get the bedroom cool on the hottest days. In the winter the passive solar helps and I keep the house at 67 degrees Fahrenheit, which the heat pump has never had any problems maintaining. This is an opportunity to make sure that the heating and cooling system are sized and ducted optimally for my house and lot. The Manual J calculation showed my existing heat pump to be slightly undersized for the house.  The Department of Energy has lots to say about ducting problems with air handling systems.  In a typical home, about 20% of the air that moves through the duct system is lost due to leaks, holes, and poorly connected ducts. The result is higher utility bills and difficulty keeping the house comfortable, no matter how the thermostat is set. The heating and cooling represent 40%-50% of power use in the typical American home.  An analysis of my electric bills showed that the heat pump operated on average about 7 months a year and that I spent about $1,260 annually operating the system. (My electric rates have been steady for over 5 years and my solar panels supply all my other electrical needs.)

 Most manufacturers advertise energy savings of up to 35%-75%; using an average existing system as a starting point and converting to a geothermal system. DOE states that with an energy star system,  it is possible to save 10%-20% of energy cost from an existing system, giving an implied savings of 15%-35% for a geothermal system versus a new energy star system. If I assumed that the geothermal heat pump would save me 50% of the electricity used for operating the heat pump that is about $600 per year.  There are several calculators on manufacturer's web sites to perform better calculations. I found the Bosch calculator and used it  for projecting savings from a geothermal system as compared to an EER 13 air to air heat pump.  The Bosch website calculator gave me a savings of about $971 with $295 of the savings from hot water heating using inputs for a well-insulated home in the Washington DC metropolitan area converting to a geothermal heat exchanger from a propane heated water and air heat pump. So my back of the envelope calculation was not a bad guess and the hot water heating cost is an important element in the cost calculation.

 Until December 31,2016 a 30% federal tax credit is available on the total cost of a qualifiedheat exchanger, reducing the capital cost. The largest hurdle to the widespread adoption of GHP technology is the one I am facing now- the capital cost for initial installation. The heat exchange loop portion of the GHP system can be half or more of the overall geothermal heat pump system cost (and equal to the total cost for a traditional furnace and air conditioner). However, the geothermal heat pump requires st least 75 feet of tubing (in my case either vertical wells or standing column wells) for each ton of size. The costs I have been quoted were $3,000-$4,000 per ton for installation of the heat exchange loop or well.  The difference in cost was the amount of damage that would be done to my garden. If indeed it is a 4 ton system that the house needs, the additional cost of the geothermal heat pump would be a minimum of $12,000 and could be as much as $16,000 plus any costs to reconfigure piping in my completely finished basement. Even with a 30% federal tax credit for the entire system the payback might take 10 or more years if the actual savings turned out to be 50% of the electricity used by the air heat pump system.

It now appears that this decision is a close call and I need to get detailed proposals to determine the actual cost, the damage to the house and garden, the Coefficient of Performance, COP, and Energy Efficiency Ratio, EER to obtain a better estimate of capital versus operating costs. Also, I need time to think about the benefits of an absolute reduction in energy usage while still maintaining my creature comforts. Installing the right size equipment for the home is essential to getting the best performance and comfort, and now is my opportunity to verify that the new system I install is sized correctly for the house and lot. A system that’s too large will not keep your home comfortable because of frequent ‘on/off’ cycling, but a system that is too small will not be able to cool the house on the hottest of days. Also the duct system which has already had all the leaks sealed needs to be evaluated for adequacy and optimal layout. The system selected will have an impact on reliability- at least according to Consumer Reports.  Finally, I need to make sure that the HVAC contractor I hire has insurance, contractor’s license without complaints, and good references for similar sized and types of projects. 

Energy Efficiency and the Passive House

The past year has been one of weather extremes. The winter of 2009-2010 in Virginia saw more snow than had fallen in over a quarter of a century. The summer saw almost seven weeks of days near 100 degrees. Nonetheless, Virginia has a moderate climate and I benefit in the winter by having my roof absorb heat and the southern open orientation of my house. Throughout the summer the same southern orientation results in extra load on the air conditioning/heat exchanger, but provides the optimal conditions for my solar photovoltaic panels. (My husband enjoys the cooler months when he is allowed to open the southern drapes to experience the full beauty of our setting.) My most successful sustainable living project to date has been the insulation of my attic which effectively thermally isolated the attic from the rest of the house. According to the US Department of Energy heating and cooling account for about 56% of the energy use in a typical U.S. home, making it the largest energy expense for most homes.

To further improve the energy efficiency of my home I have been saving up to install a ground source heat exchanger (commonly called a geothermal heat exchanger) when my existing system reaches the end of its life or just before the 30% federal tax credit expires whichever comes first. This past spring, the O’Neill home in Sonoma, CA became California’s first certified Passive House, and the first certified to the new retrofit standards. A Passivhaus or Passive House in English is simply a very well-insulated, virtually air-tight building that is primarily heated by passive solar gain and by internal gains from people, electrical equipment, etc. Energy losses are minimized. Any remaining heat demand is provided by a small heat exchanger. Though the standard was developed in cooler climates and at this time tends to work best at passive heating avoidance of heat gain through shading and window orientation is also part of the standard and helps to limit the cooling load. An energy recovery ventilator provides a constant, balanced fresh air supply. Overall, a Passivhaus is reported to have an R-value of 60.

Though the concept was first pursued in New England in the 1970’s, the first Passivhaus were built in Darmstadt, Germany in 1990 and the standards were developed out of those projects. The Passivhaus standard includes an airtight building shell measured by blower-door test; an annual heat requirement ≤ 1.39 kWh/sqft/year; and primary energy ≤ 11.16 kWh/sqft/year. In addition, there are some recommendations that vary with climate. Worldwide the estimated number of passive houses ranges from 15,000 to 25,000. Passive houses incorporate high performance triple-glazed windows with solar films and argon gas, super-insulation, an airtight building shell, limitation of thermal bridging and balanced energy recovery ventilation make possible extraordinary reductions in energy use and carbon emission. The result is home that reportedly saves up to 90% of space heating costs, and reportedly provides excellent indoor air quality. If every building in America was a Passivhaus we could reduce our energy use by almost half.

The O’Neill home in Sonoma cost $500/sqft to retrofit, my house cost less than one fifth of that to purchase and came with acres of land. It is fair to say that I will never spend $500/ft sq to retrofit my home as a certified Passivhaus nor for that matter a LEEDs certified home. (About 39-percent of the points for LEED certification are energy related.) However, I think that despite the currently fashionable push into renewable energy, the real progress in reduction of energy use will be in insulation, strategies to reduce thermal bridging, and passive house techniques. Modifying our transportation behavior and reducing the energy used in our homes and buildings could change our national energy use significantly and it is within our control. Now that I have taken care of the attic insulation retrofit, I suspect that thermal bridging on the exterior walls combined with air leakage are the primary locations of heat loss and gain for my home and many others. To maximize the effectiveness of any future planned energy use improvement projects, I plan to investigate and incorporate (if possible) some of the design principals gleaned from the new Passive House retrofit standard and US Department of Energy recommendations in my next energy project.

More Thoughts on Sustainable Living, Energy Use and Ecological Impact

Last spring Dr. Chu, US Energy Secretary, advocated for "white roofs everywhere". He said lightening roofs and roads in urban environments would offset the global warming effects of all the cars in the world for 11 years. Unfortunately, I’ve discovered that blanket statements like that need to be more closely examined before blindly accepting them even from Nobel Prize winning physicists working for the government. Both Lawrence Livermore Laboratory and Con Edison performed studies of different roofing materials. Livermore Lab only looked at the reduction in energy used for air conditioning probably because their Lab is located in California.
Con Edison divided their training center's roof into three parts: a traditional dark roof section, a section painted white, and a green section with plants growing on it. An energy-efficiency study by Columbia University was designed to help researchers understand how each kind of roof performs. The green and white roofs were found to perform equally well in preventing the “heat island effect,” in which conventional dark roofs absorb sunlight during the day and radiate heat back into the atmosphere at night which is postulated to create along with asphalt pavement the increased temperatures associated with urban and suburban areas.
However, the green roof is beneficial in summer and winter as well as reducing rain water runoff. The green roof reduces summer heat gains by up to 84% and winter heat losses by up to 37% compared to a black roof. The white roof reduces summer heat gains by up to 67%, but reflects heat in the winter when it is desirable to maintain heat. In a cold climate, a dark roof can lower heating costs by soaking up the winter sun. White-roof advocates counter that, in the continental United States, the "winter penalty" is just 10 percent of the overall savings because the roof is covered with snow for much of the winter, but many locations with freezing or near freezing temperatures do not have significant amounts of snow throughout the winter.
Green roofs are clearly the better choice for energy consumption year around. The obvious problem is green roofs only work with flat roofs, my house has a traditional peaked roof so a green roof is not really and option. I can not even imagine my neighbor’s reactions to a white reflective roof glaring at all drivers from the end of the cul-de-sac. Another problem I did not even imagine is maintenance requirements for a green roof. I went to see the Wetland Studies and Solutions, Inc. building in Gainesville, VA which was one of the first LEEDS certified buildings in Virginia and was dismayed to discover that weeding and replanting after extreme weather was necessary. WSS actually utilizes its interns to weed the roof. I can barely keep up with the hand weeding of my garden (because I do not use weed killers or other chemicals, I dig out the weeds in my beds).
Living in a moderate climate (last winter not withstanding) my roof does not spend the greater part of the winter covered in snow and I might benefit by having my roof absorb heat in the winter. Though, throughout the summer a dark roof would results in extra load on the air conditioning/heat exchanger. One of my goals in the insulation of my attic was to thermally isolate the attic from the rest of the house. For the insulation project, the attic and accessible areas of the basement and crawl spaces were inspected for adequate insulation. Then following the recommendations by the Oak Ridge National Laboratory the attic, crawl spaces, eves, ductwork, underside of a large portion of the main level floor were insulated with cellulose. The pipes, end caps, knee wall, sump pumps and all identified areas were sealed, the garage was insulated and an insulated garage door installed. My total electricity bills for the following 12 months were 27% less than I paid in the 12 months before I added the additional insulation to the house, and the winter liquid propane usage (as measured in volume use December through March both years) was reduced by 25%. Also, the overall comfort in the bedroom over the garage and the master bedroom has been vastly improved. I was very surprised at the energy savings for what was a well insulated home. The payback on this project was under 4 years, unbelievably good.
My solution to the roof question was to begin to fill the southern roof span with solar panels. I have covered about 60% of that span with solar panels (so far). The goal is to test their production and function and save up more money for more panels down the road, though my estimate is that the savings from the solar panels will be about the same as from the insulation project. The problem is they cost (before rebates, tax credits and sale of SRECS) ten times as much. A more cost effective next step would be to convert the entire house heating and cooling to “geothermal” heat exchangers, though in truth, I have yet to find any models to estimate my cost and savings from that conversion.
Other recommendations for sustainable living or energy efficiency are based on a set of assumptions that may not be true for all situations. People’s patterns of living are starting to diverge. As an example we live, work and relax from home. I leave the house a few times a week to purchase supplies, pray, and volunteer. I rarely go more than 10 miles from home and drive (my little hybrid) only a few thousand miles a year. My water supply and waste disposal are private and sustainable. According to research performed in Dutchess county the average daily aquifer recharge (from rain and snow only excluding septic recycling) for Soils types C, C/D and D prevalent in this part of Virginia are estimated 326-583 gallons per acre. It is essential in a sustainable system that the groundwater level be maintained with recharge and adequate surface water is supplied to maintain the ecology even during drought years. My property totals more than 10 acres and our total indoor and outdoor household water usage was clocked during the early summer at between 100 and 150 gallons a day. We do not water our garden; trying to plant only what will thrive in the natural environment unaided. Virginia gets plenty of rainfall and it seems silly to plant anything that requires irrigation. Thus, not only is my septic system non-consumptive, the recharge rate vastly exceeds our water usage (and hopefully our neighbors since our water supply is dependent on total demand and recharge of the aquifer). I have an alternative septic system and I am incredibly careful of its operation, management of the load and maintenance.
Yet, with that I use a large amount of electricity for entertainment, to store my meat bought in bulk and the wine put up for the next decade. Thought my refrigeration units are energy star, there are several of them. Our home theatre is an LCD which is far more energy efficient that plasma, but less energy efficient than the now available LED TVs. It may be an LCD, but its large. Sustainable living is about thoughtfully using the earths resources. A fun place to start thinking about the sustainablility of your life is to go to the energy star home page and measure your home energy score.

Reducing My Energy Consumption

I have been systematically making small changes to my home to reduce my energy consumption. I started with the easiest steps; lowering the thermostat in the winter and raising the temperature in summer, purchasing energy star eligible appliances and choosing an LCD TV over a plasma (an LED TV is even more energy efficient, but was not available at the time). The next simple step was to change all the incandescent light bulbs for florescent bulbs and when I installed additional lighting it was florescent fixtures. (Though, I warn that the clothes in my closet look oddly colored in florescent light.) The next project was to install solar films on the windows and patio door and drapes and curtains on all the windows. These were small steps, but I learned over the years that small steps do add up.

The following year, after servicing the heat exchanger and furnace to ensure they were working properly, and appropriately sized for the house, and inspecting the attic and accessible areas of the basement and crawl spaces for adequate insulation, I turned to the Building Envelop Research of the Oak Ridge National Laboratory for guidance. The Oak Ridge National Laboratory performs their Building Envelop Research for the US Department of Energy, DOE. The DOE publishes their guidance in their “Insulation Fact Sheet,” which is available on the blog home page. Following the recommendations by the Oak Ridge National Laboratory the attic, crawl spaces, eves, ductwork, underside of a large portion of the main level floor were insulated with cellulose. The pipes, wall end caps, knee walls, sump pumps and all identified areas were sealed, the garage ceiling was insulated and an insulated garage door installed. I was actually surprised at the winter energy savings and pleased with the improved comfort in the master bedroom and bath.

My next project was to spend the winter saving money eating and entertaining at home, watching DVDs for “nights out” on my LCD, eliminating trips to the mall and saving up money for my next energy saving project. Back in October 2008 President Bush had signed the Emergency Economic Stabilization Act of 2008 (P.L. 110-343). The Act extends the 30% investment tax credit for residential solar Photovoltaic or geothermal heat pump installation for eight years through December 31, 2016 and removed the cap on qualified solar photovoltaic projects and geothermal projects (from the previous $2,000). This allows taxpayers to use the credit to offset dollar for dollar their federal tax liability, and to carry unused credits forward to the next succeeding taxable year. Essentially Uncle Sam was now willing to pay 30% of the cost of my next energy savings project. I couldn’t believe it.
According to the DOE heating and cooling account for 56% of the energy use in a typical U.S. home, making it the largest energy expense for most homes. So that is where I looked for my next project. A wide variety of technologies are available for heating and cooling your home, and they achieve a wide range of efficiencies in converting their energy sources into useful heat or cool air for your home. Heat pump systems provide both heating and cooling and offer the benefit of delivering more useful energy than they consume. Unfortunately, on very hot days or very cold days they do not do as effective a job as an air conditioner and a furnace. For climates with moderate heating and cooling needs, heat pumps offer an energy-efficient alternative to furnaces and air conditioners.

Higher energy efficiencies are achieved with geothermal (ground-source or water-source) heat pumps, which transfer heat between your house and the ground or a nearby water source. Although they cost more to install, geothermal heat pumps have low operating costs because they take advantage of relatively constant ground or water temperatures. However, the installation is expensive because of the need to bury coils to deliver constant temperature fluid or install a groundwater pump and injection well to supply constant temperature water to the system. Ground-source or water-source heat pumps can be used in more extreme climatic conditions than air-source heat pumps, and are more effective at cooling and heating at the extremes.
According to the heating and cooling experts and the manufacturers of the various equipment that I have, my heating and cooling system, which is a split system with a gas furnace and air conditioner for the lower level and an air heat exchanger for the upper level, should last another 7-12 years. The most sustainable approach would be to use the current system for its entire expected life despite the fact that I could probably reduce my energy consumption somewhat by changing from my current equipment to two geothermal (ground source) heat exchangers. Though geothermal heat exchangers are more expensive to purchase and install than a traditional furnace and air conditioner, they are far more efficient, reportedly consuming 25-30% less energy to operate. The most reasonable thing to do was to wait and continue using my current system even with availability of the tax credit. Thought for the next several years I will continue to keep an eye on my equipment condition.

In October 2009 Virginia announced that a portion of the stimulus dollars for the state would be allotted to its Residential and Commercial Solar and Wind Incentive Program to provide rebates to partially reimburse the costs of renewable energy systems. For residential users on the first 10 kilowatts, the rebates will be $2.00 per watt for Photovoltaic Solar systems, $1.50 per watt for small wind turbines and $1.00 per watt for solar thermal units (solar hot water heaters). The rebate is less than you might think because system capacity is defined as the installed system’s predicted peak alternating current (AC) output which is around 75%-80% of the DC rating. Combining this incentive with the federal tax credit of 30% and the sale of the renewable energy credits, REC’s, which can be sold to utilities needing RECs and suddenly, there is a positive return on the investment. It was still a big decision because even with rebates and tax credits we have to come up with the cash to pay for the system and while current prices quoted for RECs are $220-$300 per kilowatt/year and are sold in 4 or 5 year contacts there is no guarantee that the REC’s will have any value in the future.

One of the selection criteria for my home was the large southern roof span, perfect for solar panels. I was able to reserve funds from the Virginia Renewable Energy Rebate Program for a 6 kilowatt solar photovoltaic system before all the money was gone and we put the deposit down for an American made solar photovoltaic system installed by a local company. We will be installing a 6 kilowatt system that we estimate will save us approximately $1,300 per year on our electric bill. That is about twice the savings we achieved by insulating the house; however, the cost (before rebates and incentives) is more than ten times the cost of the insulation project. Even after all the rebates and incentives (assuming I successfully navigate these) this energy savings was many more times more expensive than the insulation project.

Geothermal Heat Pumps

The most effective type of heat pump is the geothermal heat pump, GHP. It doesn't create heat by burning fuel, like a furnace does. Instead, in winter it collects the Earth's natural heat through a series of pipes, called a loop, installed below the surface of the ground or submersed in a pond or lake. As you may have experienced in a cave, the temperature six feet beneath ground surface is cooler in summer and warmer in winter than the ambient temperature. Using this temperature as its source the GHP can operate within its most efficient range. In winter, fluid circulates through the loop and carries the heat to the house. There, an electrically driven compressor and a heat exchanger concentrate the Earth's energy and release it inside the home at a higher temperature. Ductwork distributes the heat to different rooms. In summer, the process is reversed. The underground loop draws excess heat from the house and allows it to be absorbed by the Earth. The system cools your home in the same way that a refrigerator keeps your food cool by drawing heat from the interior, not by blowing in cold air.

The geothermal loop that is buried underground is typically made of high-density polyethylene, a tough plastic that is extraordinarily durable but which allows heat to pass through efficiently. The fluid in the loop is water or an environmentally safe antifreeze solution that circulates through the pipes in a closed system. Earliest systems were open loop, but those could impact the groundwater supply and are not used as much today. There are two types of closed loops used to provide constant temperature to the GHP. Horizontal ground loops are usually the most cost effective when trenches are easy to dig and the size of the yard is adequate. Workers use trenchers or backhoes to dig the trenches six feet below the ground in which they lay a series of parallel plastic pipes. They then backfill the trench. Fluid runs through the pipe in a closed system. A typical horizontal loop will be 400 to 600 feet long for each ton of heating and cooling.

The vertical loop is used where there is little yard space, when surface rocks make digging impractical, or when you want to disrupt the landscape as little as possible. Vertical holes are typically 150 to 450 feet deep and contain a single loop of pipe with a U-bend at the bottom. Each vertical pipe is then connected to a horizontal underground pipe that carries fluid in a closed system to and from the indoor exchange unit. Vertical loops are generally more expensive to install, but require less piping than horizontal loops because the Earth's temperature is more stable farther below the surface.

Geothermal heat pumps (GHPs), more accurately called ground-source heat pumps, have been proven capable of producing large reductions in energy use and peak demand in buildings. Although the U.S. was once the world leader in GHP technology and market development, European markets now absorb 2 to 3 times the number of GHP units annually as do the U.S. domestic markets. In 2007 the Intergovernmental Panel on Climate Change identified the building sector as having the highest green house gas emissions, but also the best potential for dramatic emissions reductions. In their report GHPs were specifically identified as a solution that is economically feasible under certain circumstances‖ in continental and cold climates. Their report cited cases where total electricity use decreased by one third and heating energy use by 50 to 60 percent.

Tax credits for home and business owners investing in GHP systems were enacted in October 2008 through 2016 and increased in the stimulus plan of 2009. Hopefully these tax credits will help GHP achieve wider market acceptance despite its large upfront capital costs. The largest hurdle to the widespread adoption of GHP technology seems to be the capital cost for initial installation. The outside portion of the GHP system can be half or more of the overall GHP system cost (and equal to the total cost for a traditional furnace and air conditioner). The technology while economically viable, is little known or understood and has suffered from the high upfront and installation costs. If the costs of the exterior coils were excluded, GHP systems have about the same price as competitive alternatives. In addition, due to the lack of demand, there are few design and installation firms in the market.

Buildings, both residential and commercial, account for about 40 percent of primary U.S. energy consumption, 72 percent of U.S. electricity consumption, 55 percent of U.S. natural gas consumption, and significant heating oil and propane consumption in the Northeast. While industrial use of electricity has been flat for about 15 years, electrical use to power commercial and residential building has grown by more than 50 percent since 1985. U.S. resources and investment have been deployed to build the infrastructure required to generate, transmit, and distribute electricity to serve that growth. Reducing the peak electricity demands for air conditioning and heating could alleviate peak demand on the electrical grid. Buildings present one of the best opportunities to economically reduce energy consumption and limit green house gas emissions. A recent study by McKinsey & Company study performed for the Department of Energy found that reducing the consumption of energy in buildings is the least costly way to achieve large reductions in carbon emissions.

A study by the U.S. Environmental Protection Agency (EPA) comparing the major HVAC options for residential applications determined that GHPs were the most energy efficient and environmentally benign option. Yet only about 60,000 units are installed each year in the combined new built and retrofit market. This languishing of the market is attributed to several federal policy lapses. A program at the DOD ran for several years in the late 1990’s intended to increase use of GHPs in federal buildings. This program’s authority was allowed to lapse. Although DOD took the initiative to restore the program 14 months later by then much of the GHP project pipeline had diffused away. A second policy mistake damaging to federal agency use of GHPs occurred in 2005 when the Energy Policy Act defined renewable energy that counted toward agency renewable goals as power generation only, excluding thermal forms of renewable energy such as GHPs. No lobbyists were paid to identify this oversight. Federal utilization of GHPs might have created the critical mass for the market; instead it was once more forgotten.

The basics of GHP technology have changed very little over the decades but awareness, understanding, and acceptance of the systems is limited. The systems are truly misnamed, GHPs are often confused with geothermal power production, in which the extreme heat of subsurface geological processes is used to produce steam, and ultimately to generate electricity. GHPs are also sometimes confused with the direct use of geothermal heat in which greenhouses, aquaculture ponds, and other agricultural facilities are heated using lower-temperature sources such as hot springs. Ground source heat pumps can be used economically anywhere and utilize the earth stored solar energy to function. There are at least 16 manufacturers of GHPs in the United States that participate in the residential and commercial markets. The GHP market began to develop in the late 1970s, and has had its ups and downs due to the cyclic nature of the buildings industry and volatility in government and utility support and the prices of competing forms of energy. The current tax incentives and awareness of US energy consumption may serve as an opportunity for the GHP market to achieve critical mass.