Heat pumps don't require the source to have a higher temperature. Indeed they facilitate heat transfer by having high and low pressure sections to the loop that are warmer than your dwelling and cooler than the source respectively. Obviously the more pressure required, the less efficient they are, but they're still practical down to about -20C, so unless your house is on ten metres of permafrost you could potentially use one.

Matt_B wrote:It's just an end to mains gas. You'd still be able to use bottled gas for cooking, and if that's all you're using it for, a bottle can last a long time. At least that's my experience for the past few years of doing things that way.

Same. We run off 45l bottles of LPG used only for cooking, and I just got a refill last week, 21 months after the last.

downside is cost for a heat pump afaik. A high efficiency natural gas furnace is either in or available for most urban areas in Ontario and the infrastructure in place.

Best Gas Furnaces of 2019 - Reviews of Top Furnace Brands
https://www.toptenreviews.com › Home › HVAC
Jan 29, 2019 - The Prestige Series R98V, Rheem's most efficient gas furnace, has an AFUE rating of up to 98.7 percent, making it the most efficient model we came across during our research.

98.7% is pretty impressive and lot less money than a heat pump. It would be interesting to do the calculation for a heat pump versus separate a/c and gas furnace. The infrastructure is already in place in subdivisions so sort of a no brainer.

A/c is electric in the most part but there are gas powered as well. We have very strict insulation standards for new housing for quite a while and that goes a long way. I understand UK is plagued with poor or no insulation in housing in some newer units ( due to shoddy construction ) and refitting older buildings to modern standards is $$. That will start to bite as climate change kicks 30 degree days into play.....certainly it has in Toronto but the downtown is cooled by The Big Pipe which pulls cold water from deep in Lake Ontario and circulates it through the downtown to cool the big office buildings.

For Canada with lots of gas available I don't see any move away from it for a long while and some provinces have big plays in shipping it to China.

One positive things of gov programs for insulation retrofits is the job creation.

That will slowly warm the lake, reducing oxygen content in the water. It’ll eventually turn that lake into the same as every warm water pond in redneckistan.

Do you have any idea of the scale of Lake Ontario ?? It's the 12th largest in the world.

850 cubic miles of water 800' depth ....ain't no circulation through Toronto gonna even nudge the needle

Macdoc wrote:Do you have any idea of the scale of Lake Ontario ?? It's the 12th largest in the world.

850 cubic miles of water 800' depth ....ain't no circulation through Toronto gonna even nudge the needle

You know better than that. What you wrote sounds like climate change denial.

That heat is going where it should not. It will affect that ecosystem.

I grew up on the south shore of Lake Superior. Ontario is a goddamned pond in comparison.


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I'm so tired of hearing "the earth will absorb our waste - it's huge!"

We've been establishing that it simply can't and we're doing permanent damage for centuries. We have asked way too much of the planet for way too long.

The cooling won't impact the ecosystem...it's not even a rounding error ....this is not a stagnant lake .... the entire St Lawrence Seaway water flow moves through it...

The flow volume of this section of the St. Lawrence, as measured at Cornwall, Ontario, is about 218,000 cubic feet per second (6,100 cubic metres per second).

Now the nuclear plants along the lake have some local effect...not the big pipe.
It's a very efficient form of air conditioning
An this is not waste ....its circulating cool lake water nothing else.

And the water flow from Superior goes out through Lake Ontario ....what's your point ....?

Lake Superior contains 2,900 cubic miles (12,100 km³) of water.

Lake Ontario 393 cubic miles (1,640 cubic km).

No amount of building cooling would impact either of them especially given the rate of flow.......

The fact the argument relies on the Great Lakes already being profoundly degraded is particularly worrying. Heat is a byproduct of industry and a waste that has immense potential to harm ecosystems it's pumped into.

The idea a province with a population the size of Ontario's can't possibly cause environmental harm when byproducts of industry and agriculture are diverted to natural ecosystems is delusional.

I often wish I were near death so I too could remain ignorant about the environment and consequences of industry.

Way to overstate ....of course the industrial waste is an issue FFS for the whole planet.

Your post has ZERO to do with the Toronto downtown big pipe as an alternative to mechanical air conditioning....maybe you should think it through a bit before you post.

You live and benefit by an industrial civilization that can be sustainable....take your ire out on Ohio coal plants

There was a time when burning all the coal we could find was sustainable, too. Waste heat is pollution.

waste heat . eh Jesse - better think it through a bit.

Weren't you just extolling the virtues of heat pumps which in most of the US requires carbon based electrcity to run.

We don't have carbon based electricity but it's a damn sight more efficient cooling high rises with deep lake water than with mechanical A/C power by .....yeah nuclear reactors or from Hydro

https://water.usgs.gov/edu/wuhy.html
Jun 27, 2018 - Basic information about hydroelectricity, the USGS Water Science School. ... Water flowing through the dams spin turbine blades (made out of ... For nuclear power plants there are waste-disposal problems ... Operating a hydroelectric power plant may also change the water temperature and the river's flow.

Cooling requires moving heat energy - every a/c or heat pump does the same. It's a nonsense argument you are trying to make and you should know that.

If any lake is threatened by eutrophic development it's Lake Erie which is warm, shallow and surrounded by farmland putting too much nitrogen in the water.

I grew up 500 meters from Lake Erie ...I 'm very aware of that mess - used to be good fishing ...then became horrid



now almost too clear thanks to zebra mussels. There are lots of issues but the big pipe isn't one.

Whatever you have to tell yourself to rest easy. Go ahead. The lake is an un-ending heat sink. It’ll be fine in our lifetimes, anyway.


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Whatever you have to tell yourself to rest easy. Go ahead. The lake is an un-ending heat sink. It’ll be fine in our lifetimes, anyway.


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For what it's worth, I believe the water from deep lake cooling systems is usually destined for the domestic water supply system, so heat isn't directly returned to the environment it came from, and it doesn't stiff the ecosystem that's dependent upon that temperature range.

Rather, the main downsides are the huge infrastructure costs and the limited geographical opportunities to pull something like that off; it's pretty much a non-starter except for cities adjacent to the Great Lakes and a few other suitable bodies of water. Cooling with deep ocean water is also possible but has severe technological challenges, plus you can't drink the stuff.

On the whole, I'd much rather see the effort go into cookie cutter designs that you can deploy practically everywhere people live. Ground source heat pump systems are in large part expensive because they're comparatively rare, and most existing houses need additional work for an installation. Designing as many new houses as possible where they're optimal out of the box still seems like a good idea to me.

They are not that rare these days. They are not big and supply a limited number of buildings. My old office had one. Very efficient and was earning the whole time.

The_Metatron wrote:Whatever you have to tell yourself to rest easy. Go ahead. The lake is an un-ending heat sink. It’ll be fine in our lifetimes, anyway.


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Actually, the waste heat from colling is used to “warm up” Toronto’s potable water supply, effectively balancing out any heat load on the lake.

The_Metatron wrote:Whatever you have to tell yourself to rest easy. Go ahead. The lake is an un-ending heat sink. It’ll be fine in our lifetimes, anyway.

If I move heat from one spot to another … how is that waste?

Thanks to Matt for correcting me on the efficiencies of heat pumps … the "waste" is much reduced.

Ideally the waste heat should be recovered at the point of generation … ie power stations. The question is can it be used usefully there?

The current point under discussion seems to be what do we do with the energy that is coming from the sun and going into downtown Toronto buildings? Do we transfer it to the Great Lakes or to the air?

The question I am not sure about is how does the enthalpy of the heat to be transferred to the Great Lakes compare to the heat capacity of the water flow through the lake. Bearing in mind the warmed water will report to the surface layers.

romansh wrote:

The_Metatron wrote:Whatever you have to tell yourself to rest easy. Go ahead. The lake is an un-ending heat sink. It’ll be fine in our lifetimes, anyway.

If I move heat from one spot to another … how is that waste?

Thanks to Matt for correcting me on the efficiencies of heat pumps … the "waste" is much reduced.

Ideally the waste heat should be recovered at the point of generation … ie power stations. The question is can it be used usefully there?

The current point under discussion seems to be what do we do with the energy that is coming from the sun and going into downtown Toronto buildings? Do we transfer it to the Great Lakes or to the air?

The question I am not sure about is how does the enthalpy of the heat to be transferred to the Great Lakes compare to the heat capacity of the water flow through the lake. Bearing in mind the warmed water will report to the surface layers.

The transfer of heat is virtually none. See post above