Radiant floor heating energy saving.
herbert
| Posted in Energy, Heating & Insulation on
I am rebuilding my cottage in Quebec and converting it into a permanent home. I have been investigating various types of heating systems am leaning towards a radiant floor system as part of the house is over an unheated crawlspace.Suppliers of these systems claim a significant reduction in energy consumption relative to ‘conventional’ systems (up to 30%) . My research has only turned up one study on houses in Nova Scotia which showed only a very marginal improvement in favor of radiant systems.
Is there any concrete evidence to support the suppliers claims?
Replies
For me, the advantage is in comfort. Feet warm and no air blowing around my head--can't beat that. I think some of the claims come from the belief that the comfort issues allow one to lower temp by a few degrees and get savings that way. I don't sell it that way to design clients. I think that the comfort alone is a strong enough selling point, even if operational costs are equal. Hell, I'd even pay a premium!
I agree with Cloud that the big advantage is comfort and it is so much better as to worth a lot. I find my own house is about 1 or 2 degrees cooler (by thermostat) to feel the same as a baseboard house. Which in turn is maybe a degree or two better than forced air. But that won't add up to much, as the study you saw indicated.
Using lower temperature water only helps if you are using solar or a heat pump to provide the heat. A boiler or hot water heater will be set the same for RFH with the water mixed in a tempering valve to get down to RFH temps. So BTUs are BTUs and you don't gain efficiency in the boiler or HWH.
David Thomas Overlooking Cook Inlet in Kenai, Alaska
Herbert,
"Is there any concrete evidence to support the suppliers claims?"
No.
I'll echo what the other two said, it is primarily a matter of comfort. I actually had this discussion last night with an HVAC contractor that I work with frequently and hold in high regard. He found what you found: no savings or no real numbers to support the savings claims.
I reasearched this issue extensively four years ago, prior to remodelling and adding on to my home. The claimed savings is that the heat is at the floor where you need it and is more "useful" and therefore the greater comfort results in lower energy use. If having warm floors means that you will be comfortable with an inside air temperature of 60 instead of 70 for instance, then you will use less energy, because heat loss is directly related to the temperature difference inside to outside. What I found, because most boilers are not as thermally efficient as condensing furnaces, is that hydronic heating will cost you more, not less. There are very efficient boilers and there are less efficient furnaces, so this is not absolute.
If energy costs are your primary concern, get a high efficiency, two-stage, variable speed, natural gas furnace. If comfort is more important, go with RFH.