Geothermal vs HVAC, insulation - Montreal

9 years ago

Hey guys, sorry for the long post about to follow

TL;DR

Renovating, gutted the house. Best combo of insulation, distribution and heating / A/C for savings and comfort in the next 10-15years?

Currently renovating a 1956 split-level. Main floor is 1500 sq. ft. and livable basement area is 600-700 sq. ft. Everything is currently stripped out. There was no previous insulation and was running on an old oil system and was distributed with hot water radiators (6000$ for heating last year). The exterior of the house is a mix of brick and stone brick, in the interior there's a layer of plywood on all the exterior walls. Electricity cost in my area is ~0.09$USD/KWh all-in I think. We plan on staying here 10-15 years. We have ripped out all electrical and plumbing and will be starting from scratch

For insulation the plan is to shoot 3-3.5" closed-cell foam on all exterior walls (space is precious) and standard drywall. For the roof it would be 12" of cellulose and in the garage ceiling (under dining room/kitchen) will have 9-10" cellulose. Any point in shooting foam instead of cellulose?

For distribution system the plan is simply to install a duct system. I think it will be necessary for ventilation anyways and probably A/C, but is it worth it to put something else for heating? Hear lots of good things for radiation heating but that seems to come with a really high cost

For heating right now seemed to simply be an HVAC/electric system. Not sure what GreenSpeed is, is that something to consider?

So now we are considering geothermal, as we can afford it, assuming it benefits us in the long run. First off, does it bring the value of the house up? We had an evaluator come and he said a 2 ton system should be fine, though I was thinking 3, but perhaps 2 ton would save money and for the cold days the backup electrical system would take over, hence his 2 ton recommendation? We don't have much land (no backyard, only a roughly 50x20 , width goes up to 25-30 on the widest, so I'm guessing horizontal piping is properly out of the question? I believe our basement is fairly close to the water table, is that a good or bad thing for installing a geothermal loop?

Do you guys have have suggestions? We are trying to find the right balance of comfort and long-term savings. Heating/cooling costs for an electrical system is estimated around 1500-2000$/year versus what for geothermal? If you have any suggestions for companies in Montreal, please let me know!

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Comments (10)

jonesy44
9 years ago
nstr:

Greenspeed is a type of high end air source heat pump made by Carrier which is advertised at 20 SEER/13 HSPF which is considered very efficient.

There is also a Mitsubishi air source heat pump which is also advertised for cold climate heating.

Air source is not as efficient as a ground source heat pump but it can be a lot less cost as well. You can look up the info on the manufacturer's websites.

If you decide to invest in a ground source, just make sure that it is cost effective for your situation.

When I looked at the data for my home, the cost to go ground source was only starting to pay off in about 10 years. Unfortunately with the life cycle duration of the equipment, it didn't look like a good investment in my particular case.
nster3
Original Author
9 years ago
Thanks for the reply!

how big was your home / how many tons did you need?
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thanks for the replies. I will try to touch on some of the questions: I am getting about 4 different load calcs, along with my own which include loading my Revit model into Autodeck Green Studio which analyzes everything and produces costs and loads. So once those start to get in, we can compare everything for similarities. For wells, we are building on about 1 acre. However we also need a septic in that space, so that eats up some. The house is modest size, with a footprint of around 58'x36'. There should be space for 2-3 tons worth of horizontal. THe guy digging my basement and septic can also dig trenches for the ground loops. However vertical wells cost around $2k in my area, depending on the depth of course. Most like to size up .5-1 tons worth of well around here. all windows will have coverings on them. I am toying with making the north glass triple pane. it would be roughly 800 for that upgrade for the north windows. According to the cost vs savings, that is a pay off of around 11 years....over high performance duel pane. not sure its worth it at all. I am way ahead to put in some nicer insulated shades instead of the glass. Looks nicer and is more efficient. Any thoughts on the more "DIY" approach? Meaning supply the products and just hire out the install? I have subs that can do vertical wells, grouting and hooking them up to the system for about $2k per well. I am not sure how many I need just yet, depending on the depth obviously. It looks like I can buy everything I need for 8k or less. Plus wells and install costs, I am probably around 15k or less, maybe.
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Here you go: After all rebates (there were several) & tax credit, my geothermal system ended up costing about $13,500. It looks like I'm going to be saving about 6000 kWh per year. When using an air source heat pump, I averaged about 27.5k kWh per year, and using the geothermal heat pump I'm averaging about 21.5k. Keep in mind that I don't even have a complete year of geothermal data, but I'm basing my estimates on what I have. Based on the numbers above and an electric rate of $0.11 per kWh, I'm saving $660/yr compared to my previous system. The ROI on that is about 20.5 years. So, if you have a working system and you're considering switching over to geo, based on my #s I'd strongly recommend against it as a 20+ year ROI is horrible. The reason I went with geo was that my old system died and needed replacement. I received several estimates for an air source heat pump, and they were around $9000. For me, it was a choice between a geo system for $13500, and an air source for $9000. I can't do much of an estimate comparing these two since I have no idea what sort of performance I'd be getting with a new air source heat pump. A huge plus for the geo system for me was that my geo system came with a 10 year parts and labor warranty. No one came even close for the air source heat pumps. Its also really neat that I don't have a loud evaporator in my back yard, but the value of that is very subjective.
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Where in NC? The differences between the coast and mountains are pretty significant. It is a big state. The tank of course gets filled with propane which is 3-4 times the cost of NG. The inability to give ballpark estimates is stupid. Do you have a builder? Our builder gave us ballparks based on prior builds. They were always shocking because of the lack of competition in the area. The 2 I remember were $10k to foam the attic rafters and $60k for geothermal - both of which were non-starters. Generally in NC (central and coastal), the HVAC costs are too low to justify either geothermal or foam. A well sealed house with above code insulation can cost $500 a year to HVAC without resorting to those more costly options. If you are in the mountains, then you change the picture a bit. First the basics - ducts in conditioned space and good air sealing. Then bump the attic insulation. Then bump the walls. The ducts require appropriate house plans - and don't trust the designer alone. Plenty don't leave appropriate room for the units. For a point of comparison, I have a ducts in the attic, 5000 sq ft. Conventional insulation but r-40 in the attic. Air sealed pretty well with ES standards. Seer 16 heat pumps and NG backup. I have $1000 in HVAC costs. Lose the NG backup and I'd probably go to $1200. That isn't a lot of money and 1/2 is a/c which is harder to cut. The most important thing now is the ductwork. Then the solar orientation and/or shading. Then check for rate cuts for Energy Star certification. Progress gives us 5% for life. Given the merger, they should have 80% of NC but I know there are a lot of locals.
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mike_home
9 years ago
Do you have access to natural gas?
nster3
Original Author
9 years ago
They are willing to bring in Natural Gas only if we DON'T have a heat pump, also installation wise it is a bit more than electric. Is it worth it? I was thinking with a 9 cent / KWh tax-in price at all times it may not be worth it? The advantage I see with natural gas is that we could have a gas fireplace
mike_home
9 years ago
The gas rate versus electric rate will determine which will is cheaper to operate. The added benefit of gas is using it for domestic hot water and cooking which is usually much cheaper with gas.

In addition a heat pump has much more wear and tear than either a gas furnace or a AC condenser. It is something else to consider if you plan to live in the house 10 - 15 years.
ionized_gw
9 years ago
Geez, how are they going to know that you'll have a heat pump or not?

Just throwing these thoughts out there, but other advantages of nat gas could be a CNG compressor for a vehicle and fuel for a serious back up genset.
fsq4cw
9 years ago
Ã¢ÂÂGeez, how are they going to know that you'll have a heat pump or not?Ã¢ÂÂ

In Montreal, where the OP is located, the cost of the gas line installation and rebates for Energy Star gas appliances is predicated on anticipated gas usage and NOT having a HP installed nor the Ã¢ÂÂDualÃ¢ÂÂ electrical rate which is ~4.4ÃÂ¢/kWh at temperatures above
-12ÃÂC/10.4ÃÂF (most of the year) and ~18.4ÃÂ¢/kWh at temperatures below -12ÃÂC/10.4ÃÂF (a small portion of the year). The Ã¢ÂÂregularÃ¢ÂÂ non-dual rate for electricity is ~8ÃÂ¢/kW year-round.

This dual energy rate makes electricity VERY competitive with gas at temperatures above -12ÃÂC/10.4ÃÂF and still competitive even below. A geothermal HP with a modest COP of 4 will cost just 1.08ÃÂ¢/kW of heat DELIVERED into the house - that VERY hard to beat! The same kW of heat delivered into the house with a 98% efficiency gas furnace in our region will cost about 8.6ÃÂ¢/kW of heat delivered into the house. Geothermal wins hands down at all temperatures above -12ÃÂC/10.4ÃÂF. However, the electrical rate jumps to ~18.4ÃÂ¢/kW once the temperature drops below -12ÃÂC/10.4ÃÂF. ThatÃ¢ÂÂs still only ~4.6ÃÂ¢/kW of heat delivered into the house at the same COP-4 with geothermal, still not bad and still better than gas. The rest of the electrical consumption remains at the very high rate of ~18.4ÃÂ¢/kW for temperatures below -12ÃÂC/10.4ÃÂF.

Keep in mind that with geothermal the backup gas comes on to assist the geothermal and they work in tandem till the T-stat is satisfied. That is usually for only a short period of time and then everything shuts off except the blower that is usually on low stage. Or the geothermal can be shut off all together below -12ÃÂC/10.4ÃÂF as the electrical utility expects and gas only is used for heating.

BTW: The gas company monitors gas consumption and they WILL know if you have a HP. You can have gas and a HP but donÃ¢ÂÂt try to take advantage of the rebates or incentives! If you do take the incentives, then youÃ¢ÂÂre Ã¢ÂÂinÃ¢ÂÂ for about 5-years of gas no HP.

SR
nster3
Original Author
9 years ago
nvm

This post was edited by nster on Fri, Aug 15, 14 at 14:47
ionized_gw
9 years ago
Wow, Hydro-Quebec needs to send more of that inexpensive electricity South! Very interesting rate electricity rate structure and very interesting interaction with the gas rates, but kind of complicated for the average homeowner.
nster3
Original Author
9 years ago
They are working on it ;) for now we have a surplus so they are doing a HUGE project for High capacity lines that go from Montreal to the border

Geothermal vs HVAC, insulation - Montreal

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Geothermal vs HVAC, insulation - Montreal

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