Replies

1. GBA Editor
   Martin Holladay | Sep 17, 2013 04:48am | #1

   Judd,
   And your question is... ?

2. 
   gbogseth | Sep 24, 2013 02:28am | #2

   Martin, sorry I was using an Ipad when trying to post my question and not all of it was posted I guess. My question is this, I will be using strictly ductless heat pump for addition conditioning, with proper amount of XPS below and all around my slab will I still experience cold or chilly concrete floors in the winter? I plan on leaving a good portion of the slab uncovered as a finished floor, sealer aside. My location is northeast Nebraska.

3. 
   user-1115477 | Sep 24, 2013 06:38am | #3

   JuddGreg,
   Cold and chilly is somewhat subjective, but your bare concrete floor will likely feel somewhat "cool " to bare feet, unless you would install a radiant heat floor--I wouldn't. do that.

   However, the concrete doesn't need to feel cool all the time,. You didn't give a lot of information, but the formula you started, thermomass walls and insulated concrete slab thermal mass, begs to have passive solar design added to it. If you can, orient a broad wall of the addition toward solar south and get some windows in that wall. That slab will then receive, store, and then release a lot of free heat in a Nebraska winter. The concrete could feel as cozy as having radiant heat in the floor, much of the time, all the while keeping the design about as simple and "green" as you can get.

   You need a designer, or become one, but even northeast Nebraska gets enough winter sun, so that you can finish the formula you started by adding passive solar design elements.

4. GBA Editor
   Martin Holladay | Sep 24, 2013 08:27am | #4

   Judd,
   Even when concrete is at room temperature (72°F), it will feel cold to your bare feet, for two reasons: concrete is fairly conductive, and your skin temperature is warmer than room temperature. That means that heat will flow continuously from the bottom of your feet to the cooler concrete.

   In-floor hydronic tubing (a so-called "radiant" system) will not solve this problem, because the system will not be operating for most of the time during the winter (assuming the house is well insulated). If the system is designed to handle the peak heating load -- and it should be -- then those conditions are only experienced for a few hours of the year. Most of the time, the heating system is off, and your concrete will be at room temperature.

   A well-insulated concrete floor is all you need. If you like to walk around in your bare feet, install a few carpets.

5. 
   user-1115477 | Sep 25, 2013 09:06am | #5

   JuddGreg,

   The discussion about passive solar in the next question on this site, Moisture and energy efficiency in ICF Cape Cod design , may interest you. Keep the carpets to a minimum, or none at all, for insulated concrete floors in a passive solar environment.