The goal of the ESTAR and ZEMH improved floor insulation and air-sealing and the ZEMH perimeter insulation is to increase the percentage of heat transfer between the crawlspace air and the ground, while limiting heat transfer from the house to crawlspace.
Figure 5 shows the average monthly ambient, crawlspace, and crawlspace slab surface ground temperatures for both the ZEMH and ESTAR (base) homes.
Anecdotal Feedback on maintenance and Operation Issues Case Year Number of Location Repairs Sections ZEMH 2001 Double Lapwai, ID None ESTAR 2001 Double Lapwai, ID Pipe froze near vent, condensate leak WSU 1999 Triple Olympia, WA None ODOE 2003 Double Salem, OR None Vincent 1996 Single Kennewick, WA None, condensate plug (one home) BPS 2000 Double Cle Elum, WA None, motor replaced (one home) NBI 2003 Double Mosier, OR Indoor blower relay failed in 2006 Clayton 2002 Single Southeast USA Limited, related to plant training
The ZEMH, ESTAR, and ODOE home floorplan located the unit in a utility room at the opposite side of the home from the bedrooms and no significant occupant noise complaints were observed.
Changing the ZEMH defrost cycle from a 60-to 90-minute runtime is estimated to have saved a maximum 65 kWh/year, assuming the setting could be changed without impacting system efficiency due to ice on the coils.