Combined Hydronic Space and Water Heating

December 3, 2010
Today we spent all day at the Santa Cruz Police Station.  Why?  The nice large community room at the police department was where Pacific Gas and Electric Company (PG&E) held a public class titled, “Combined Hydronic Space and Water Heating for Homes.”  Somehow we managed to register for this class that was targeted for experienced HVAC/mechanical contractors, and building performance consultants.  I liked how the instructor, Rick Chitwood of Chitwood Energy Management, Inc., taught the class with just enough explanation for us homeowners to digest the information while succinctly answering the questions from experienced people in the room.  Several people at class have taken other classes from Rick and reviewed him favorably and we definitely recommend his class.
This class offered by PG&E was open to the public and it’s *free*!  PG&E provided catered breakfast and lunch.  It was quite good too.  To see a listing of other classes offered by PG&E please visit their energy efficiency class registration site.
Towards the end of the class we did a design exercise which really drove the point of source of heat loss.  Each student did a simple heat loss calculation for an example house plan  with 1116 s.f. of conditioned floor area with windows and doors shown.  We did 6 simple heat loss calculation for ceiling, floor, walls, windows, door and air infiltration.  When we completed our calculation Kurt and I looked at each other and said, “This is why passive house makes sense — most of the heat loss is caused by air infiltration (lack of air tightness) and by windows!”
Other take away points for me were
  • Simpler is better because higher complexity triggers higher cost of installation and higher maintenance needs.
  • Tankless water heater is not what we want because it takes a long time (20 seconds) for the water to get warm, thus wasting water and they can’t take the pre-heated water from solar thermal system because the modulated power burner can’t modulate to accommodate a smaller temperature difference.
  • Huge opportunity for energy efficiency is on the table — Even in California (state with the strictest building code) one can achieve 50% reduction in energy consumption from a house that only adheres to title 24 by doing insulation effectively and further reduce the energy consumption by half by doing mechanical system effectively.
  • Generally, heating systems are over-sized for California’s mild climate.
Tomorrow we go to another PG&E class titled, “Integrating Energy Efficiency and Renewables in Home Retrofits,” in San Mateo.

About the Author

Chie Kawahara

Chie is one of the co-creator of Midori Haus. When she is not sharing her stories of transforming an old house and giving tours, she enjoys trail running and hiking.

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