Natural Gas Vs. Ground Source
We have a major decision to make, and fast. From the beginning of the design process we had determined we would use radiant in-floor heating with a ground source heat pump if it were something we could afford. However we had preconceived notions about GSHP costs so we concluded a High Efficiency Natural Gas Boiler would have to do though it was a second best choice, a compromise due to price.
As we got into the process and learning curve we learned that the cost of the two technologies were closer together than we first understood. And when we considered that the GSHP could also provide heating for the pool on the same system, we realized that we were very close to making it a reality. So chopping we went, through the plan, to find room in the budget to go the rest of the way to afford the GSHP.
Recently, through investigating insulation and high performance building standards, we have come across research and recommendations from leading researchers that perhaps the NG Boiler may still be the better choice.
Here’s the debate. Let’s start by talking about money. It is our belief that for every dollar we have to earn, despite our efforts to reduce the industrial impact of our business, we inevitably mow down some trees, create some C02, and fuel our computers on Panda tears. So the most cost effective route needs to be involved in the sustainable equation. Simply, you can’t throw money at the sustainable problem without considering that the high footprint money spent outweighed the positive results unless, the positive results were infectious on others – another story.
So understanding that factor here’s the score card with other factors as we understand it:
GSHP Cons vs. NG Boiler
+ $ cost of money is higher for GSHP
+ the $ spent on GSHP could go to another sustainable feature with more immediate benefits
+ $ cost of electricity is currently higher than natural gas
+ environmental cost of electricity is greater than natural gas in Ontario (we burn coal!)
+ disturbance impact on your building site is greater for GSHP (drilling or excavating your yard)
+ GSHP requires a higher performance envelop to operate efficiently with lower output temperatures — requiring high insulation values, tighter sealing
+ not ideal for all situations, particularly extreme hot or cold average climate zones
GSHP Pros vs. NG Boiler
+ GSHP can easily be powered by solar, lessoning the environmental impact
+ GSHP uses only 1 fuel, NG Boiler 2 (NG and Electricity) – less dependency on utilities
+ GSHP has a lifetime supply of fuel from the get go, the ground, while the NGB is forever dependent on utilities
+ GSHP doesn’t introduce exhaust or venting issues into the home
+ GSHP uses less energy to operate within ideal ranges*
What’s the conclusion? If it weren’t possible to heat the pool with the GSHP and also install solar to run the GSHP we’d be immediately back to NG. Over the next few weeks we’ll conclude what’s involved in heating the pool and weigh in again. If the pool drops out of the equation, then NG it will be.
*For a comprehensive debate, see the attached document from John Straube, PHD, of Waterloo University and Building Science. bsd-gshp.pdf
March 23rd, 2008 at 1:12 pm
I’d like to correct a few points
“GSHP has lifetime supply of fuel from the get go, the ground, while the NGB is forever dependent on utilities”.
The fuel for GSHP is actually electricity, not the ground. It’s “pumping” heat from one location (outside) to another, just like an air conditioner “pumps” heat from inside your room to the outside, and refrigerator pumps heat from inside the box into the surrounding room.
The amount of electricity required to run a GSHP is so much that you are forever going to be tied, and dependent on, the electrical grid. Generating the electricity to run a GSHP via solar PV is not at all cost-effective. Not for wind either. Hydroelectric is the only possibility if you have a decent constant head drop locally. While there is electricity required to run a blower motor or hydronic pumps for a NG-based system, it could easily be powered by one or two PV panels. A standard NG boiler is only going to properly run on piped natural gas, however there are boilers out there for each type of various biofuels, solid, liquid or gas. For gas something like a methane biodigester that uses methane from locally produced compost is possible. And for the others, there’s grass pellets, wood, biodiesel, and so on.
If you want off-grid and non-fossil fuels I’d go with a boiler that could use biodiesel or solid fuel, and electricity powered by PV. And of course a very tight building envelope. GSHP is a better solution for much larger buildings which couldn’t run on biofuels.
Solar thermal can be used for both GSHPs and NG boilers, pools and domestic hot water.
March 23rd, 2008 at 4:50 pm
Thanks for the clarification! It’s this kind of feedback that makes decisions a lot easier.
Barry
April 5th, 2008 at 6:44 am
Good site for comparing the running cost of systems here. It’s UK specific but should still be worth a look. Important figure is the cost per KWH after taking into account “boiler” efficiency.
http://www.nottenergy.com/energy-costs-comparison2
June 17th, 2009 at 3:02 pm
With your Burlington location, did you consider air-source heat pump?
I live in Belleville ON and find it very economical.
They have got some bad press in the past but if you purchase a high end unit
and outfit it will auxilliary controls (WarmFlo controller)they are
very good.
My 30 year old home has ~2400sq ft of heated space and my annual
heat bill is $425 for electrical plus $200 for firewood. I could not justify
going Geo based on Capital and running costs.