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The Eartha Madre Project

Wirsbo tubing in the beginning layout stages

After careful consideration, we decided on hydronic radiant floor heat for the bedroom wings of the home.  The high insulation value of our stem walls and the thermal mass of the adobe walls in both wings made this the obvious choice for the lowest cost, highest output and most energy efficient heating source for these spaces.

Hydronic Radiant Floor Heating System

Radiant heating systems involve supplying heat directly to the floor or to panels in the wall or ceiling of a house. The systems depend largely on radiant heat transfer: the delivery of heat directly from the hot surface to the people and objects in the room via the radiation of heat. Radiant heating is the effect you feel when you can feel the warmth of a hot stovetop element from across the room. When radiant heating is located in the floor, it is often called radiant floor heating or simply floor heating. 

This type of heating system has a number of advantages: it is more efficient than baseboard heating and usually more efficient than forced-air heating because no energy is lost through ducts. Hydronic (liquid-based) systems use little electricity, a benefit for this home designed to be mostly off the power grid.  This hydronic system is heated with a standard propane gas boiler that stores the heated water in a hot water holding tank, then releasing the hot water through the tubing system through a series of hydronic controllers set to operate based on the individual room thermostats.  We used slightly less linear feet of tubing in some areas than is sometimes recommended however we are extremely happy with the end result and energy savings.

Our radiant system makes use of the large thermal mass of both the concrete slab floor and the adjacent adobe walls.  The installation was a  "wet installation" meaning that the concrete was poured directly over the wirsbo tubing and then the concrete was finished normally. Despite their name, radiant floor heating systems also depend heavily on convection, the natural circulation of heat within a room, caused by heat rising from the floor.  The floor becomes the warmest surface in the room, not the coldest and valuable energy isn't lost at the ceiling, because radiant rooms don't "stack" hot air like forced systems.  The energy is broadcast to all parts of your room and the floor will be the warmest surface while the ceiling will be the coolest. We have found that our thermostat can be set lower (65 F), yet our comfort level is higher. Heat loss through infiltration and windows is reduced saving money and keeping the environment warm even on the coldest of days.

Special placement of tubing to accommodate fixture placement and future interior walls, etc.

We have found a radiant atmosphere is stimulating, quieter, cleaner and easier to breath.  When you look at a floor warmed by radiant heating with an infrared camera, one can see that energy is broadcast from the floor.  All the objects in the room are bathed in radiant comfort from the floor and the added benefit of not having hot air blowing through vents and ducts creates a much more comfortable environment. 

As the front of the home faces north and during the winter months an accumulation of snow builds up across the front walk, we added a snowmelt feature to the system.  The same system supports this feature by circulating glycol solution fluids through tubing embedded underneath the front flagstone walkway.  It is only necessary to use this feature for a few hours while it is snowing and it saves a lot of snow shoveling!