Blair's adventures in energy efficiency contine as she learns about BTU's and Solar Thermal. Read Part 1 here, Part 2 here, Part 3 here and Part 4 here.

As I was doing research on alternative heating methods for my home, I kept coming back to wood. We have a small fireplace already - one that we have never used - and my first instinct was to either install a wood stove or a pellet stove to use wood to offset our oil costs.

Of course, the issue with this is you have to buy the wood to burn, pellet stoves are known to be dusty and messy and right now the demand for pellet stoves has not only made them less available but also more expensive. Also, I realized I didn't know nearly enough about what it actually takes to heat my home.

I've mentioned AltE before, and this time I was actually chatting with their CEO, Sascha Deri, about home heating. He started to tell me all about solar thermal technology and how excited he was to begin really getting the word out about solar air heaters and solar water heaters. He relayed a number of the benefits of using solar thermal technology as a supplemental heat source to offset the cost of oil and my eyes narrowed - I was intrigued!

Then we talked about the cost. I had priced out pellet and wood stoves. The pellet stove that I liked was going to run about $2000.00 and then I was going to have to have it installed. My husband is handy, but our chimney is old and also needs a "tucking and pointing" so with something like that, I felt more comfortable with a professional. The installation cost was going to run at least $1000.00. Sum total would be $3000.00 (at least) and I was going to have to pay for pellets as well.

Considering the efficiency of a pellet stove and the heat it would be putting out, the pellet stove could well be worth it - but that cost was going to be tough to absorb! As I explored the cost of the solar air heater with Sascha, I learned that this renewable technology which would require no additional fuel and very little maintenance on our part was roughly half the cost of a pellet stove and installation!

Depending on the system, solar air heaters run between $1500 and $6000. For me specifically, the cost for a single solar air heater which is all I really need would be around $1500.00. I was really excited at the prospect of truly integrating a renewable energy source and the return on investment, so I decided to learn more.

Solar air heaters are based on solar thermal technology. Solar thermal technology uses the warmth of the sun to heat air or water and then feed that air or water into your home. Solar thermal is extremely efficient, more so than solar electric conversion, performing at 55-85% efficiency, meaning that 55-85% of the sun's heat hitting a solar thermal collector is converted into usable heat.

In the case of a solar air heater, the panel requires an intake and an outlet. The solar heater pulls in the cooler air, heats it, and blows it back into the room or duct system. You can find solar air heaters that will wire into your electric system to power the fan, or solar air heaters that even harness the fan power from the sun. One solar air heater can heat up to about 750 square feet and can offset your fuel usage by as much as 30-40% overall. As I learned about this technology I could literally see it sitting on my sunroom roof and making my home warmer and helping me to use less oil.

But I quickly deduced that I needed to get educated. After all, how can you make an intelligent decision about heating your home without even understanding how your home is heated - other than flipping the "on" switch of your thermostat! So I started doing basic home heating research so I could understand what I was really dealing with.

First, all heating options for your home are measured in BTU's which are British Thermal Units. This term is widely used in North America to describe heat value. "BTU" became invaluable to me so that I could really look at different heat sources and see how they measured up to each other.

Here is a very basic "apples to apples" comparison, so we can be clear on the costs and benefits of oil, pellet stoves or solar air heating systems. Please bear in mind that these figures are estimates and also change depending on many variables!:

So, here is this data processed through my personal perspective.

Right now, my oil cost is $3.60 per gallon which means that at 140,000 BTU per gallon of oil, with a need for approximately 600 gallons of oil per year, I am paying $2,200.00 annually for heat and hot water.

Taking the math one step further, I need about 84,000,000 BTU's for home heating and hot water. Now, I can calculate that about 22% of my oil consumption goes to hot water heating. This means I actually need 65,520,000 BTU to heat my home.

So, if I need 65,520,000 BTU to heat my home, my cost is roughly 450 gallons of oil or $1620.00 (at the current rate). Now, if I bring in a solar air heater, at a cost of $1500.00, I will be bringing in 7,000,000 BTU (because of where I live and my insulation data). That is about 10% of my annual home heating need - and I'll get that forever with minimal additional costs.

At the current rate of $3.60 per gallon of oil which provides 140,000 BTU, the 7,000,000 Solar Thermal BTU offsets approximately 50 Gallons of Oil which is equivalent to $180.00. This means, the solar air heater, for me, will easily pay for itself in 8 Years - but it may pay for itself more quickly depending on the cost of oil.

Also, because I did my research and improved the energy efficiency of my home with increased insulation and replacement windows, it may also pay for itself sooner because we are sure to need less oil.

Now, if I bought a Pellet Stove for $2000.00, plus $1,000.00 installation or $3000.00 total (some are more than this) and then I bought one ton of pellets for $299.00 (current rate of my local guys) then we're looking at $3300.00 for 13,000,000 BTU (per ton of pellets) - assuming I only buy one ton.

13,000,000 BTU would offset my home heating needs by almost 20%. Twice the money up front would offset twice the home heating need. Annually, with just one ton of pellets, the pellet stove would offset 92 gallons of oil or $331.20.

So, the pellet stove would "pay for itself" in roughly 10 years EXCEPT that I need to buy fuel for it every year so really, it will never actually catch up with itself. Additionally, I'm still dependent on someone delivering a ton of pellets whenever I need them. Also, with the increase in demand for alternate fuel sources, pellet prices are up 50% over last year so that is certainly something to take into account.

So what's my decision?

Well, because of my green sensibilities and my current budget, I am definitely going with the solar air heater in the short term. But, I am also going to look at installing a small wood or pellet stove and I'm going to look at replacing my oil furnace with one that is more efficient in the next 3 years, as well. Why am I going hybrid in my home heating?

Well, I have a fireplace already - but burning wood in a fireplace as a heat source is incredibly inefficient, so in my case, I believe that the most important goal should be the efficient use of ALL fuels in my home - be they traditional ones like oil and wood, or alternative sources like the sun. That means a pellet stove and an upgraded furnace will ensure any fuel is being used optimally and I'll get maximum flexibility. My ultimate goal will be to consistently reduce my need for oil, but I also know that I need to be realistic and make smart choices for the short and long term.

Now, if you've been following my adventure here, you may wonder why didn't I just get the solar air heater and forego the other upgrades to the efficiency of my home?

That would have been like putting a band aid on a gaping wound. When you can physically feel a breeze through storm windows and double thick fleece curtains, you know you have a serious energy efficiency problem and just putting on the solar air heater would have been like blowing half of that hot air back out into the cold winter landscape.

By upgrading the insulation and replacing the worst of the windows, we are requiring less work on the part of our fuel heating systems. And we are adhering to one of the most important tenets of the environmental movement - consume less! It's not a dumb rule on the money front either, by the way, because for every $1 you invest in efficiency you can save $3-5 off your ultimate renewable energy electric system.