Geothermal employs the warmth of the sun that has collected in the earth below the surface at depths unaffected by seasonal ambient temperatures.
At our latitude in central and southern Alberta, seasonal temperatures have an extreme range of more than 80 degrees C. A vast amount of sun and heat in summer with temperatures reaching 40 C., and the extremes of cold weather in winter, sometimes below – 40 C..
These seasonal temperatures penetrate and change the temperature of the ground down to a depth of around ten feet, however beyond ten feet of depth lies the stabled warmth of many millennia of solar gain. For each 70 feet or so of depth beyond ten feet, the constant temperature of the earth is warmer by about 1. degree.
A properly installed geothermal system uses a vertical earth exchanger, constructed by drilling wells 200 – 400 ft deep and installing “loops” which are typically two 1″ polyethylene water pipe prefabricated together with a tight “U” bend at the bottom. A series of wells are constructed with these loops installed and grouted in place, and manifolded together, (see video in our “products” section ) the total size of the earth exchanger is determined by the required load. The well depths are decided by geology, available land space, and the best use of a budget.
With wells constructed to 300 ft depth the exchanger is sized to maintain the temperature of the water circulating through the loop system at around + 9 C. This constant temperature medium is employed to deliver heat or cooling to your home or building using a dual cycle heat pump..
Once the earth loop is constructed, the source of the energy used for space heating, cooling, and hot water is on the property you own. The only further energy required, is for delivery. A heat pump using a constant temperature medium as described will deliver a performance coefficient starting at 400 % + when heating, which means it will take less than 1 KWH of energy to deliver 4 KWH of heat energy into your building. Solar thermal collection can also be easily added to increase heating performance, the theoretical maximum potential for a heat pump to deliver stored heat, is 880 %, or 8.8 KWH of return for each KWH spent.
When used for cooling, the loop water temperature at + 9 C., is already bit lower than room temperature, so cooling requires very little energy to deliver.
A geothermal heat pump also delivers energy for domestic Hot water in the same way in both heating and cooling cycles. Winter or summer, whenever the geothermal system is providing home comfort, it can also provide domestic hot water.