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Community and Q&A

SHGC Effect on Radiant Floor Heating Control

jason_v | Posted in General Questions on

We have a large amount of southwesterly facing windows planned in our bungalow design for a heating climate in Canada (Edmonton). The floor will be polished concrete slab on grade 5 inches thick, heated hydronically.

Our goal is not to passively heat our home, the orientation is for the view.

I am concerned that possible passive gains the slab will acrue will make control of the room temperature challenging. Does anyone have any experiences, resources or opinion on the matter?

Thank you in advance for your time and consideration.

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  1. jason_v | | #1


  2. Expert Member
    NICK KEENAN | | #2

    With any heating system the keys to comfort are to have quick response times and to arrange your zones so that every room in the zone has a similar heat loss and gain profile.

    When radiant floor heat first got big about 30 years ago the prevailing wisdom was that systems had to have lots of "thermal mass." That turned out to be wrong. You want your panels to have high conductivity and low heat capacity, so they can respond quickly. If you look at the literature from manufacturers like WarmBoard they stress responsiveness -- and they use aluminum as their heat conducting medium.

    So yeah, a relatively unresponsive medium like concrete might cause problems when your demand for heat is highly variable.

    1. jason_v | | #3


  3. Expert Member
    NICK KEENAN | | #4

    Have you had the system engineered? You should know what the surface temperature will be. The closer the room temperature gets to the surface temperature the less heat is emitted.

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