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I am looking for a new place to live and I know the winters will be very cold (-20 C). Coming from a warm climate country, I want to learn what to look for in a heating system.

From the bit I understand, steam heating loses a lot of energy to the walls and surroundings, but it doesn't need the pumping that water based heating uses (which spends more energy). Is there a clear advantage of one over the other? Electric heaters don't use the propane usually burnt in furnaces, but then again, it will spend loads of energy.

EDIT: Following directions given in comments, I split this question leaving the insulation part to What is the most sustainable house insulation suitable for a cold climate?

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    There's a lot of questions here that each could have a pretty sizeable answer... they would really be best asked as separate questions. – Highly Irregular May 6 '13 at 8:57
  • I felt that if I separated heating and insulation, people would comment the opposite, that there is no way to talk about one without the other. But if it's a consensus that the question is too broad, I'll separate it. – MeloMCR May 6 '13 at 13:41
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    Insulation shouldn't make much difference in the most sustainable form of heat. Adding insulation definitely adds to sustainability of the home by reducing the energy needed to heat the home, but doesn't really have much effect on heat source (unless the house is so small and well insulated that body heat alone can heat it, but then you'd probably call it a "sleeping bag" rather than a home :-) ) – Johnny May 6 '13 at 19:22
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    @Johnny - what you're written is true; and so is the converse: in a really well-insulated home, sustainability of the heating supply doesn't make much difference to the overall total. There are indeed properties that can be heated by incidental gains alone - they're called "passive houses", or more commonly, "passivhausen" – EnergyNumbers May 7 '13 at 5:51
  • @EnergyNumbers They wouldn't be called "passivhausen" in any language. German plural would be "Passivhäuser". – gerrit Sep 7 '18 at 17:12
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The absolute most sustainable heat sources are sunlight and waste heat from your body and the appliances you are already using. However, unless you have the resources to build to passivhaus standards, these won't be your primary heat sources in the winter.

Geothermal heat systems (not to be confused with ground source heat pumps) also take advantage of naturally-available heat, but they are only possible near certain geologic features.

After that, the next most sustainable options are probably in-floor systems using solar-heated water and heat pumps (air-source and ground-source are the most common varieties). Solar water heat generally requires a back-up heat source in cloudy climates and at extreme latitudes, but it might be a good option for cold but sunny regions. Such systems typically require electric pumps to circulate the water through tubing in the floor. Heat pumps also run on electricity, so you can power them using clean sources, but even if you are using grid power from a coal-fired plant, heat pumps are more fuel-efficient than electric resistance heating or even many combustion furnaces[1]. While high-efficiency furnaces compete well with heat pumps for fuel efficiency, they can't take advantage of clean energy sources like the sun or wind.

[1] Clarification: If 25% of the energy from the fuel makes it to your home as electricity, a heat pump with a coefficient of performance of just 2.5 will be more fuel efficient than a 70% efficient furnace in perfect condition. A COP of 3 will compete with or beat an 80% efficient furnace with a duct system for fuel efficiency. This doesn't account for differences in fuel (coal vs. fuel oil or natural gas), but it also assumes that the furnace is operating at its rated efficiency which is often not true.

  • The last sentence isn't necessarily true: there are too many heat pumps out there operating with a SPF of 2.5 or worse. – EnergyNumbers Jun 5 '13 at 6:31
  • Did some rough math and added clarification. Thanks! – Evan Johnson Jun 5 '13 at 14:40
  • My understanding is that the performance of heat pumps plummets in very cold conditions such as those described. I wonder if a conventional heating system might be better, but combined with active ventilation and heat exchange (yes, this does then mix with the insulation question!) – Flyto Nov 13 '13 at 10:10
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In addition to the tips from Evan: it is possible to combine water based heating systems with modern high efficient wood furnaces and stoves. The modern heating systems have an efficiency of about 80% or more and wood as fuel is ecological & economic as well. The water is needed to store a high amount of heat (and to have hot water for your bathroom), but there exists also systems that have an integrated water - air heat exchanger so the heat is transferred to the air. The air is delivered by a the ventilation to all rooms.

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