Une pompe à chaleur géothermique sous le parking d'un supermarché

Un nouveau supermarché Walmart situé à Burlington (Canada), est équipé d'un système de chauffage et de refroidissement par échange de chaleur géothermique utilisant 15km de tuyauteries situées sous le parking.
Walmart’s new 12,540 m² prototype store in Burlington, ON, Canada is equipped with a geo-heat exchange heating and cooling system using 15 km of pipes under the store’s parking lot.

The piping was inserted in only six days thanks to a type of plowing technology often used for oil and gas applications. Plowing also reduces ground disturbance, achieves depths over 2m and enabled the creation of a horizontal field on two levels at 2.3m and 1.7m.
 Auxiliary equipment includes a boiler, two fluid coolers to meet summer and winter peak load conditions and a low-cost roll out radiant mat system in the concrete slab. CO2-based refrigeration systems and 1,3-Propanediol (25 mixture) is used for heat transfer while any heat from refrigeration is reclaimed and used to heat the store.

Humidification became the first priority where it was critical for the floor slab not to create moisture at its surface and to avoid condensation at refrigerated display-cabinet level. Temperature was the second priority in conjunction with the radiant slab operation. Third and fourth priorities were CO2 control for ventilation and pressurization in order to minimize infiltration through the main sliding doors.

The store also features other energy-saving features such as LED lighting, daylighting, energy recovery, dehumidification using compressor reject heat and a white reflective roof.

An extensive energy model using TRNSYS software, a transient thermal analysis software tool, was developed for the store. It predicted a reduction in energy of 57%, close to an actual overall reduction of 60%, 40% being electricity use.

ASHRAE Journal, November 2013