EPRI Integrated Water Loop/Dual Path HVAC System
Wal-Mart Corporation built an innovative
energy-efficient environmental demonstration superstore in
Through work with companies, such as Safeway, Delchamps, Kroger, and K-Mart, EPRI had extensive knowledge of the issues for supermarkets and related facilities. Further, EPRI had been involved in advanced HVAC, dehumidification and refrigeration systems development and testing.
The project team (Wal-Mart and EPRI) developed the following objectives for the project:
· a design applicable to most climates,
· increased ventilation air,
· low humidity to keep refrigeration energy use down,
· maximum refrigeration heat recovery for energy efficiency,
· use of non-CFC refrigerants,
· a design that met the different HVAC needs of the grocery and retail sections of the store,
· use of only proven available equipment, and
· cost minimization.
After considering various alternatives to the base HVAC system, the project team selected an innovative integrated water loop heat pump system. EPRI provided the system's conceptual design and assisted with final design review. Mechanical Engineering Consulting Engineers was the general contractor. The ~18,952-m2 (204,000-ft2) store is realizing a 22% energy savings over the base HVAC system. These energy savings equate to cost savings of USD 102,806.
The key innovation in this project is a non-CFC dual-path heat pump that provides space heating, cooling, and dehumidification. The ClimateMaster ClimaDry™ Model 30/25 units use a 25-ton water-cooled direct-expansion cooling system for ventilation and a 30-ton water-source heat pump for the recirculation path.
Additional advantages of this system include efficient variable ventilation air control, excellent zone control, tempering outside air in winter, efficient dry-out mode, superior energy efficiency and zero ozone depletion potential refrigerant.
The completed store includes ~18,952 m2
(204,000 ft2) of grocery, retail, stock, and office space. Though this store is
The base case energy use was estimated at 5.06M kWh annually, while the integrated system design was forecast at 3.89M kWh-a predicted savings of ~23%. The actual use of the system has closely matched this projection, with measured energy usage of 3.91M kWh-22% below the baseline design.
The fully optimized store's annual energy cost savings were estimated at USD 102,806. This figure includes electrical savings of USD 87,573 and gas savings of USD 15,233.
The innovative dual path configuration addresses the vital indoor air quality issues associated with the reduction of mold, bacteria, and other contaminants. Additionally, the carbon dioxide level has been kept below 1000 ppm for the entire space.
Electric Power Research
Mukesh K. Khatmar
Mechanical Engineering Consulting Engineers
One West Third,