I keep seeing electric radiant people dismissing electric baseboard as somehow inefficient.

Last I knew, all electric resistance heating was "100%" in terms of kwH delivered to the emitter being turned into heat.

Is there really a difference of efficiency, and if so, why? Or is electric radiant simply a comfort upgrade?

Comparing the efficiency of electric baseboard to electric in-floor would be the same as comparing the efficiency of hot water baseboard to in-floor hydronics.

You're raising the temperature of your electricity to run baseboard?

that's the primary culprit in hydronics. I don't think that's the same issue with electric.

Are you guys just talking about stratification of air?

There is no way around it. In terms of the energy conversion, both are 100% efficient.

There may be comfort differences, but not efficiency.

John Thurston
Juneau, Alaska

NRT:

Naturally, electricity used to make heat utilizing an element is 100% efficient in it's conversion, that's a given.

Can you clarify what it is exactly you're looking to say/ask?

Baseboard electric doesn't have a way of creating more heat. Their wattage output is set to their specific design. That's not the case with low voltage radiant.

What do you mean by "that's the culprit in hydronics"?

What I'm asking is, specifically, by what method is there a claim that electric radiant is "more efficient" than electric baseboard?

Since both convert at 100%, that doesn't leave a *whole* lot of room for efficiency improvement at the emitter. I'm assuming someone looked into it though, since I've seen more than one electric guy mention electric baseboard as being less efficient, so someone must have some specifics as to where this claim is coming from.

The efficiency of the system isn't only based on the source. But you know that. Baseboard (electric or hydro) is convection heat and in-floor is ... well, you know all that too..So, it appears as though all you're trying to do with your question is to discredit the efficiency of in-floor electric (low voltage or line) by comparing it to electric baseboard.

As a moderator, is that your position or do you really think that baseboard offers the same heating efficiency as in-floor and only when electricity is the source?

I'm just looking for specifics, warms.

I don't like those marketing claims in hydronic either, such as blanket statements that radiant is "more efficient". You can spend a few minutes doing some finds on the forums and see that about me quite easily. It *can* be more efficient, but it's not *always* more efficient. A high temperature joist system over a cold basement, for example, is LESS efficient than a baseboard system in many cases (especially if the baseboard is designed for a lower temperature so it won't stratify as much, and can run the heat source cooler).

Knowing the assumptions behind those claims is very important, so you don't accidentally sell that little old lady a 180 degree hydronic joist system for her kitchen and call it an 'efficiency' upgrade, which would be a lie. Yet it happens all the time because even the installers don't understand this. It's a comfort upgrade in that case, perhaps, but it's not an efficiency upgrade.

Stratification of air varies in importance. In a cathedral space, I might consider it a 20% efficiency difference between a primarily-radiant and a primarily-convective method, as a ballpark guesstimate since each situation is going to be different. In grandma's kitchen, though, it's unlikely to be anwhere near that (but much more comfortable, sure!) even without the high joist temperatures. So if stratification is the sole mechanism at work in that efficiency claim, then now I know when and how important that is... kind of. More than before, at least.

But I don't know how hard electric baseboard drives air movement (compared to hydronic baseboard), or what impact the construction of these items has on their efficiency (in part, because I almost literally know nothing about electricity, that's my partner's end of things)... I don't THINK the construction matters much but I don't KNOW either, that's why I'm asking.

Do you agree this is reasonable, or do you still feel like I'm setting up a straw man to burn down?

dear NRT Rob:-
I just came to know about this forum and read few discussions about different heating types and could not refrain myself from replying to your post.
The first most important question is when we talk about heating a room What do we want to achieve?
Is our Aim to heat the House or is our Aim to use the heat to provide comfortable environment to the person living inside the house even if the whole house is at less temperature.
If our aim is the second one then infloor Radiant is the most eficient form of heating.
first of all what is the difference between convection and radiation heating?
in convection the heat needs a medium to travel. for example if a convection heating system is intalled at one wall and a person is sitting at some distance then he will only recieve the heat when first the heat is transfered to Air in the medium and then the air carries that heat to that person and trasfers the heat to that person . more the distance between the person and the system more the air in between and more the heat required to heat that air first in order to send some heat to that person. also since heat is absorbed by the air more heat has to be produced by the system in order to make the person recieve required amount of heat.

In radiation heating the heat does not require a medium to travel . ie if there is a vacume then convection heating is not possible but radiant heat is possible ( sun heating earth is perfect example.)
hence if radiant heating system nedd to heat a person sitting in the room at some distance it will not heat the air in between the radiant heat will directly reach the person and heat his body.( in a perfectly cold morning in shelter you feel cold but outside shinning sun you immidiatly feel warm because radiant heat immidiatly heats your body). hence in a radiant heating system heat required will always be less than in convection system.
Now other important aspect is the tempearture difference between the two medium betwenn whom the heat transfer is occuring . more the temperature diference is faster will be the heat transfer. hence if the difference between temperature of heating system and outside tempearture is high then more heat loss will occure in the room compared to the condition where temperature difference is less.
in convection system since more heat is required the tempearture of the system is higher as compared to radiation system and hence heat loss( to outside atmosphere) is also high as compared to radiation system.
for a radiation system if we want to improve efficiency ( ie how heat out of the total generated heat is utilised in greating cofortable environment for person) then temperature of the system should be minimum but lower temperature mean lower heat generation hance to main tain heat required you have to increase the area that is radiating heat. and this should be the chalange of designing new efficient systems.
in the reallife scenario in every system there will be combination of all three conduction convection and radiation. if we can reduce conduction and,convection as much as we can and increase radiation as much as we can keeping the temperature of the system as low as possible then we can increase the efficiency of the heating system.

You cannot confuse comfort and efficiency.

The fact is there is *usually* a difference in comfort between radiant and convective heating methods. but not always, and the difference in comfort is not always large. In superinsulated shells, for example, convection can eventually "soak" enough heat into the objects of the room (if allowed to operate consistently) to achieve a high degree of comfort. If you can run a low temperature convector, you reduce stratification as well and reduce the efficiency hit from that effect.

In a regular house, radiant typically has a comfort benefit that is noticeable and has value. Perhaps quite a lot of value!

But that does not mean it is more efficient; you might be able to achieve more comfort, but if you put in a 180 degree joist system over that crawlspace, you may have just magnified your downward heat loss many times over a baseboard system's additional upward loss. then the value proposition of the comfort increase comes into play again, beyond the initial cost proposition, and it deserves to be inspected full on along with all the other factors that cause people to consider radiant as one option to achieve their comfort and efficiency goals.

That is a loss of efficiency, even if you have increased the comfort.

It serves no one to muddy that water, especially in this climate of rising energy prices. Discuss the two parameters separately, or not at all, IMHO. Because ultimately, if you are less efficient, many people will lose out on some of that extra comfort by turning down their thermostats to save money at the expense of the comfort they reached for initially.

Dear NRT,
Yes you can have same comfort with convection and radiation but for that same comfort covection will always take more heat. You dont need complex calculations to prove that.
take an ideal scenario and asume that there is no heat loss from the room to the outside.
a Radiation system generates X amount of heat and it is used to heat firs the person sitting in the room the walls and all othe objects that are in direct line to the system . The Air is not heated by radiation.
If we take a convection system then it will work by heating the air hence to get the same comfort level . X amount will be utilised by the person and the other objects PLUS extra energy that will be used UP to heat the AIR so that all the other objects and the person are heated. this energy to heat the AIR is say Y
hence for same comfort level if radiation system requires X energy then Convection system will require X+Y .
and y is always positive. if we will do exact calculations then few coeficients will also come into play but X+Y will always be greater than X. FOR SAME COMFORT .

tekfot,

convection will not always take more heat to get a person comfortable however. to a theoretically equal level of comfort, true. noticeable in the real world, not always. especially if convection is weak and heat load is low.

Your arguement is technically sound, but also not borne up in the field. that whole idea that people with radiant systems are more comfortable at equal thermostat settings may be true... but it does not equal lower thermostat settings in the field.

People accept a lower level of comfort in the name of lower costs all the time. not everyone with FHA is running 74 degrees to get "really comfortable".

This is why comfort and efficiency must be discussed separately. Because they are treated separately by building occupants. And is it them, not our calculations, that dictate how the system will be used.

It is easy to prove. Have you seen the outside of a house shot with an infra-red camera? You can see the heat emiters on the wall. Due to the hotter surface losing heat at a faster rate. You won't see this with a radiant heated house. I have also measured much lower ceiling temps. in radiant heated homes. Heat loss is increased as temp. difference is increased. Lower surface temp= lower temp. difference= less heat loss. It doesn't change because of the source other than installation method and competence.

Troy;

are all electric baseboards the same?

What about downward losses on your radiant systems?

Perhaps it's a bigger deal for electric than it is for hydronic (where I can turn down my water temps and lessen stratification), but I'm wondering if there is an analog in the electric world to me turning down my water temp. Is there a "variable output" electric baseboard or are they all ON at full power when they turn on?

Rob,
for equal comfort lets say a person feels maximum comfort when he is at 74 deg for a convection system to achieve this the air near the person needs to be say at 75 deg and for this the air at the ceiling needs to be at 80 deg and for this the convection baseboard heater has to through air at 85 deg hence the thermostat setting of 85 in baseboard will give comfort to the person.
for this same level of comfort in the infloor radiant system the floor temperature may be required at 78 deg and to achieve the thermosat of radiant infloor set at say 80 deg . hence 80 deg setting can give same comfort as 85 deg setting in baseboard . hence radiant will have lower settings for same comfort. lower settings will mean lowers cost and better efficiency of the system at same comfort.
regarding the downward losses the insulation boards available taday minimizes the downward losses. These losses are very less as compared to loss of heat in convection system to heat up air near the ceiling and that heat totally goes waste.ceiling temperatures are quite high and lot of heat is wasted through the ceiling