Radiant Heat… Convective Heat… What’s The Difference?


There are a lot of different ways you can heat a house. Though there are huge differences in individual approach and ultimate efficiency, pretty much all systems fall into two categories: Radiant Heat and Convective Heat.

Radiant Heat refers to the infrared heat that hot bodies emit. If you put your hand near a fire you can feel the heat even if the air around you is cold, this is because of the radiant heat of the fire.  Or say you’re standing outside on a winter’s day.  It’s 30 degrees out, but you’re standing in the bright sun.  And now you step behind the house into a shadow.  It’s still 30 degrees out, but you feel colder.  That’s because you’re not directly receving the radiant energy from the sun. Underfloor heating, as we discussed last time, is a great example of a radiant heating system.

Convective Heat relies on the movement of air to warm a house, usually aided by the use of ducts, filters and fans. Forced Air Heating (a type of convective heating) is the most widely used heating scheme in Northern America. It has the advantage that the ductwork can double as a delivery system for cool air in summer.

All heating schemes have their pluses and minuses and it is important to carefully consider the specifics of your home before making any decisions. You will want to think about the size, architecture and existing infrastructure of your house, local climate, and the cost and availability of fuel, amongst other things. We highly advise that you talk to a professional HVAC contractor before deciding on a new heating system for your home, as an improperly sized or spec’d furnace or boiler can end up costing you in utility bills.

And this concept extends beyond your HVAC system to what we call the “shell” or “envelope” of you home, the walls, windows, attic, and foundation.  The better air-sealed they are, the less convective heat loss you have.  And the better insulated they are, the warmer the inside surfaces stay, and the less they suck the heat out of you through radiant heat loss.  (I didn’t talk about conductive heat loss, the third transfer mechanism, but I’ll work that concept in in the future.)

The point is this.  If you’re looking around for options for future renovations or new construction keep tuned to this blog. Over the next few weeks I’ll go over the basics of different heating schemes as well as touch on some innovative new designs that are pushing the envelope of energy efficiency in the home.

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