Saving Money with Radiant Heating

In a previous post “Does Radiant Heat Save Money” I mentioned a home that I partially converted from electric baseboard to radiant heat in a few rooms. This article is a follow-up to that post.

Significant Renovation and Extension

As mentioned in the previous post, the owners so enjoyed the comfort of the radiant heating system they wanted it throughout their home including the entire extension. They replaced the electric baseboards in their kitchen, bathroom and laundry room with electric radiant heat. They also added about 2,000 additional square feet to the home. A big garage with a full granny suite above it (living room, kitchen, bathroom, and bedroom) plus a connecting hallway and a sunroom with plenty of windows were added to the home. All these areas were heated with radiant ceiling and/or radiant floor warming.

Interesting Results

In a conversation I had with them recently, I asked them how they were getting along with their system. Of course they love it (but you knew I was going to say that :) ), but they also mentioned something very interesting:

Despite adding over 2,000ft2, an additional occupant in their home and a significant hike in their cost of electricity per kwh, they said their overall electrical bill has dropped during the winter! They have not changed their lifestyle at all—no changes in how they operate the heating system, no special night-setback strategies, etc.

No Numbers, Sorry

I would dearly love to be able to provide you with hard, quantifiable data. Unfortunately the home is not independently monitored for the heating portion of their energy use. There’s not a separate meter measuring the heating system only. So we don’t really know how much of their energy consumption is for heating and which portion is for everything else (lights, tv, stove, hot water, clothes dryer, etc.) and therefore we can’t say that by changing over to and adding radiant heat that they saved X%. But we can say, all else being equal, that they certainly are enjoying a very economical heating system. They also haven’t had to spend a cent on maintenance, either.

Are You Interested in Saving Money?

If you’re contemplating a renovation, you really owe it to yourself to investigate whether electric radiant heating is a viable option for you. Having done thousands of renovations, we fully expect that you can see similar results in your own home. We have many different product lines that are well suited for renovation applications. In most cases you can make the changeover one room at a time as time and budget permit. We try to make it as easy as possible for you to enjoy the benefits (and rewards) of a radiant heated home. Why not give us a call?

September 4, 2010 | Tags: , , | 1 Comment »

How Radiant Heat Saves Energy Part 2

In the first part of this series I described how conventional hot air heating systems lose energy through conductive heat loss. In Part 2, I’ll describe how radiant heat differs from hot air systems and how that translates into energy savings.

Radiant Heat is Different

Unlike hot air systems which use energy to heat up air, then move that air around to warm objects and people, radiant heat transfers its energy directly to objects and people. There’s no middleman. That’s why on a cool day when the sun pops out from behind a cloud you instantly feel warmer. Radiant heat warms you directly (at the speed of light) and there’s no waiting around for the air to first warm up.

Radiant heat is also very different in that the operative temperature of the system (the actual average temperature of the radiating surface) is generally significantly cooler than a hot air source. Let’s take a radiant heated floor as an example. Most radiant floor systems are set to a temperature of 70oF to 74oF. Recall that in the first part of this series, a hot air baseboard emits air at 120oF. Recall, too, that the rate of heat loss is directly affected by temperature differential – the difference in temperature between the warm side and the cold side. With an outside temperate of 0oF and hot air washing up the wall at 120oF we have a temperature differential of 120. With radiant heat we have a temperature differential of only 72oF (taking an average between 70 and 74).

Revisiting the Numbers

In the first part of this series I worked through the numbers for a hot air system. To summarize: hot air washing up an exterior wall lost 6 Btus of energy per hour through an R-20 wall and 60 Btus of energy through an R-2 window. Let’s now look at the numbers for radiant heat. The math for 1 square foot of wall is as follows: 1/20*72 = 3.6 Btu per hour. For a window it is: 1/2*72 = 36 Btu/hour.

Compare 60 Btu/h versus 36 Btu/h and you’ll see that hot air systems will lose 167% more heat through a wall or window than does radiant heat! That’s 167% more energy going out through the wall or window during the heating cycle.

Not the Whole Story

A truly astute reader will notice that once the hot air system is off (because the thermostat is eventually satisfied and thus shuts the system down) the air temperature at the wall will no longer be at 120oF but 72oF (on average). That’s very true. When the room air has reached the desired temperature, both systems will lose heat at the same rate. So one cannot simply state that hot air systems always use 167% more energy than radiant heating systems. That would be overstating it. The two systems eventually (theoretically) will equalize for a portion of the heating cycle and thus have equivalent losses. The major thing to note is that while the hot air system is on, the heat lost through the wall and window (and thus not available to heat the room) is significantly higher than that of the radiant heating system.

And that’s only one way in which radiant heat saves energy.

In subsequent posts in this series I’ll describe other ways in which radiant heat is more energy efficient than conventional hot air systems. Stay tuned!

February 20, 2010 | Tags: , , , | 1 Comment »
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