New heating and AC system in Franklin Field development will be well grounded and not use natural gas

The Boston Housing Authority and National Grid announced Friday they will replace the current gas-fueled boiler system in seven Franklin Field buildings with a new system that uses heat pumps connected to pipes drilled deep into the ground.

The new system, which would be National Grid's second networked heat-pump system for multiple buildings, will also give the residents of the 129 apartments in those building air conditioning because of the way heat pumps work - using the way gases give off heat or become chilled depending on whether they are being compressed or released - which will let them ditch the more inefficient window air conditioners many residents have purchased on their own.

The city says the pilot program is a step towards a BHA goal of eliminating its reliance on fossil fuels completely by 2030. BHA and National Grid hope to begin construction next year.

The city will pay for the required electrical work and water heating equipment, while the utility will build the geothermal network on which the system will sit - in which pipes will be drilled down into the ground, to levels where the temperature stays around 55 degrees year round.

Networked geothermal is a highly efficient renewable heating technology and source of energy that uses the ground temperature to provide heating and cooling to buildings through an underground piping network. The underground temperature serves as a heat source during winter and transfers indoor heat to the ground for cooling during the summer. ...

As part of the pilot, National Grid will connect Buildings 7-13, located on Ames Way, Ames Street, and Stratton Street in Dorchester, with a horizontal distribution loop and a thermal bore field. Geothermal bore holes will allow the system to extract and deposit heat from the ground. National Grid will also install a pumphouse on BHA property to operate the geothermal network serving the designated Franklin Field buildings. BHA will be responsible for all work within the envelope of the connected buildings necessary to convert these buildings from gas heating to networked geothermal heating and cooling, including retrofits, electrical upgrades, and appliance and heating equipment replacement.

National Grid will develop the geothermal network leading to the building’s exterior, and both parties will collaborate on complementary energy efficiency investments funded by the state’s energy efficiency programs.

Separately, the city will use a $1-million federal grant to replace 80 gas stoves in BHA apartments with electric induction stoves - and will work with the BHA and the Codman Square Neighborhood Development Corp. to identify apartments to get the new stoves at Franklin Field and the Talbot Bernard Homes and with Boston University to study the potential health benefits of replacing gas stoves with units that don't emit potentially harmful gases.