Building System Assessment and Ground Source Heat Pump System (GSHP)

Performed a building systems assessment of a 40-year-old, 5-storey apartment building.  The building had an inefficient radiator-type hydronic heating system, excessive air infiltration, and low performance building envelope that resulted in high utility bills and unhappy tenants.  Performed detailed designs and made recommendations to improve building envelope, replace all exterior windows and doors with low thermal conductance, and install a geothermal system (ground source heat pump system) GSHP to provide heating and cooling to the building.  Performed an economic analysis and based on the capital investment, the simple payback period was 6.6 years, while the equity based payback was 3.3 years.  Designed the ground source heat pump system.

Cutting Costs and Saving Energy With Geothermal Heating.

The building is approximately 40 years old, measures 120, 000 ft2 and is 5 stories tall with 110 suites.  Warner Levy EnviroEnergy assembled our team for a building condition assessment.  The building had issues with inefficient radiator type hydronic heating system, excessive air infiltration and low performance building envelope.  This resulted in high utility bills and unhappy tenants.  The owner made 2 key decisions 1) to bring down the operational and maintenance cost and 2) to make the building attractive to the tenants:  Improve building envelope by replacing all the exterior windows and doors with low thermal conductance, thermally broken windows and doors; decided to install geothermal system to provide heating and cooling to the building (currently the building had heating only).  Warner Levy EnviroEnergy designed the GSHP system.

The ground source heat pump system is a vertical closed loop, reverse return type, consisting of 120 vertical boreholes, each 240 ft (73 m) deep for a total pipe length of 28,800 ft (8,780 m).  The boreholes are spaced at 20 ft and a single U-tube heat exchanger is installed in each bore hole.  The system functions by using the stable deep ground temperatures which is upgraded by heat pumps to generate heat during the winter months and simply reversed during the summer for cooling.  WLEE designed Ground Source Heat Pumps (GSHPs) for these homes. Implementing GSHP’s reduces carbon footprint by 388 Tons/year and generates an annual cost savings of $79,000. GSHP systems are categorized as the most efficient HVAC systems by environmental Protection Agency (EPA) of US.

Additionally the domestic hot water is heated by the same geo-thermal source, thereby making substantial cost savings around the year.

Natural Resources Canada’s RETScreen software was used for the economic analysis.  Based payback is 3.3 years.