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Case Study: Fort Bliss, 1997-1998 Family Housing, El Paso, Texas

In 1998, 155 new housing units were added to the inventory in the WBAMC and Hayes Additions at Fort Bliss in El Paso, Texas. These units were designed and built by Town and Home, Inc., of Simi Valley, California.

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humidity levels throughout much of the cooling season. In addition, the evaporative cooling units had to be replaced every 2 or 3 years and they consumed a substantial amount of water. A new solution was needed to improve the quality of life for the soldiers stationed at Fort Bliss.

Split heat pump systems with auxiliary electric-resistance heating coils were one solution. However, the high demand load costs from the electric utility made these economically unattractive. Another consideration emerged and that was to integrate a ground-coupled heat pump system design with these thoughtfully designed housing units.

A detailed analysis using DOE-2 software reviled that the heating and cooling requirements were relatively modest and that 2-ton GCHP systems were all that was required for these housing units. This raised interesting design issues because the amount of air to be circulated averaged about 0.5 cfm/sf, a very low air circulation rate that could easily result in air stratification that would result in tenant discomfort and persistent service calls.

To resolve this problem, the ceiling fans that were included in each of the conditioned rooms and were already shown to be part of the design for all of the housing units, were integrated into the final GCHP design thus solving the issue of air stratification.

The final problem was the design and cost of the vertical ground heat exchangers. The initial design required up to 350 lf per ton for the ground heat exchanger. This was a significant cost.

To reduce the ground heat exchanger requirements, desuperheaters were added to all of the GCHP’s. This served two purposes: the first was to supply up to 70% of the energy required for generating

 

These housing units were designed to meet or exceed the latest energy conservation standards. They varied from 1230 to 1630 square feet in floor area and had three or four bedrooms each.

Fig. 2: Typical four-bedroom plan
Fig. 1: Typical three-bedroom plan

These housing units were designed to meet or exceed the latest energy conservation standards. They varied from 1230 to 1630 square feet in floor area and had three or four bedrooms each.

The building construction included R30 insulation in the attic and R11 insulation in the walls. All windows were constructed of low-e double-glazing. The units were constructed on concrete slabs on grade.

The standard HVAC design in this desert climate, as it was for the older family housing units at Fort Bliss, consisted of natural gas-fired furnaces for heating during the winter and evaporative coolers for use during the summer. These systems were not popular with the tenant because of the