Glossary - Massachusetts Clean Energy Center

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Air-Source Heat Pumps
Automated Wood Heat
Clean Energy Home Solutions
Energy Efficiency
General
Ground-Source Heat Pumps
Organizations
Solar Hot Water
Solar Photovoltaics (PV)

Air-Source Heat Pumps

Air-to-water heat pumps

A type of air-source heat pump that uses water, instead of air, in the distribution system and provides heat through a radiator or baseboard. View Image

Ducted

A heat pump that uses ductwork (connected to an indoor air-handling unit) as the indoor distribution. View Image

Ductless

Heat pumps that use refrigerant pipes as the indoor distribution. Small copper refrigerant pipes are connected to indoor units that each have their own heat exchanger and fan for circulating conditioned air. View Image

Indoor Unit

The part of an air-source heat pump that release hot air in the winter and cold air in the summer into a home. Indoor units can be ducted or ductless. Ductless options include wall, ceiling, or floor mounted units. View Image

Integrated Controls

The use of one system to control two separate heating systems. Integrated controls can be a single thermostat or multiple connected thermostats. Integrated controls are sometimes used when air-source heat pumps are used in conjunction with a backup heating system such as an oil or propane boiler.

Mini-splits

A common term used to describe a ductless air-source heat pump.

Multi-Zone

A heat pump where one outdoor unit connects to more than one indoor units. Multi-zone indoor units can include a mix of ducted and ductless units.

Outdoor Unit

The part of an air-source heat pump that is outside where the refrigerant absorbs heat in the winter and rejects heat in the summer to transfer heat between the indoors and the outdoors and condition the home.

Single-Zone

A heat pump where one outdoor unit connects to one indoor unit, which could be either a ducted air-handling unit or a ductless indoor unit. A home can have multiple single-zone systems.

Automated Wood Heat

Boiler

A fuel-burning apparatus or container for heating water. In an automated wood heating system, the boiler burns wood pellets.

Bulk Pellet Storage

A large container, usually a large canvas bag, that stores wood pellets before they are burned to generate heat. A residential bulk pellet storage container typically holds between three and five tons of pellets.

Thermal Storage

A system which stores thermal energy for use in supplementing or offsetting heating system output. A hot water tank is used for thermal storage in an automated wood heating system.

Wood pellets

Small pieces of dried and compressed wood. Wood pellets are burned instead of fossil fuels in an automated wood heating system.

Wood pellet boiler

A common term used to refer to automated wood heating systems. A wood pellet boiler is a boiler that burns wood pellets as the fuel.

Clean Energy Home Solutions

Air-Source Heat Pump

A heating and cooling system that transfers heat between the indoor and outdoor air to heat your home in the winter and cool your home in the summer.

Air-source heat pumps run on electricity instead of burning fossil fuels. Colloquially they are also referred to as “mini-split” or “ductless,” although these terms refer to a specific kind of air-source heat pump. View Image

Automated Wood Heat

A heating system that burns locally sourced, sustainable wood pellets instead of fossil fuels. Also called “Modern Wood Heat” or “Wood Pellet Boiler.” View Image

Battery Storage

A device that stores energy in the form of chemical energy for use at a later time as electrical energy.

Electric Vehicle (EV)

A vehicle that uses electricity to charge a battery, which then discharges its energy to propel the vehicle. View Image

Ground-Source Heat Pump

A heating and cooling system that transfers heat between the earth and the indoors to heat your home in the winter and cool your home in the summer.

Ground-source heat pumps run on electricity instead of burning fossil fuels. Also called “Geothermal.” View Image

Heat Pump Clothes Dryer

A clothes dryer that reuses the heat used to dry clothing instead of venting it to the outdoors. All heat pump components are located inside the dryer and no connection to the outdoors, not even a vent, is needed. Heat pump clothes dryers run on electricity instead of burning fossil fuels.

Heat Pump Water Heater

A hot water heating system that transfers heat from the air (often in a basement or mechanical room) to a hot water tank to heat hot water. Heat pump water heaters run on electricity instead of burning fossil fuels. View Image

Induction Stove

An electric stovetop that uses magnetic fields to generate heat in cookware instead of generating heat from an electric resistance coil. Induction stoves are more efficient and offer more temperature control precision than traditional stoves. View Image

Solar Hot Water

A hot water system that uses heat from the sun to heat a fluid in solar collectors that is then circulated to a hot water tank where the fluid transfers heat for domestic hot water use (e.g., showers, washing dishes). Also called “Solar Thermal.” View Image

Solar Photovoltaics (PV)

Solar panels that use the sun’s radiation to generate electricity. View Image

Energy Efficiency

Air Sealing

The process of ensuring that there are as few gaps in a building’s envelope as possible for conditioned indoor air to escape and unconditioned outdoor air to get in. Air leakage in buildings can represent 5%-40% of space conditioning costs. Air sealing often involves sealing gaps in attics, crawl-spaces, and floor joists; re-sealing windows; replacing broken or jammed vents; and replacing the rubber seals around door frames.

Ductwork Upgrades

Air sealing and insulating ductwork to improve the efficiency of a heating and cooling system by ensuring that more of the heated or cooled air gets delivered to where it is needed.

Energy Efficiency

The concept of using less energy to perform the same work. Weatherization is an important type of residential energy efficiency. Other examples include using more efficient lighting and appliances.

Insulation

The material used to slow heat transfer through the building envelope (walls, roof, floors, etc.). Common types of insulation include fiberglass, cellulose, and foam board.

Programmable Thermostat

A thermostat that can be set to adjust the temperature of a home based on the time of day and week, in order to use less energy when it is not needed.

Weatherization

The process of making a home better protected from extreme weather, which often involves sealing up air leaks and adding insulation in your home.

General

Carbon Footprint

The total greenhouse gas (GHG) emissions caused by an individual, event, organization, service, or product.

Clean Energy

Technologies that significantly reduce or eliminate the use of energy from non-renewable sources through efficiency or conservation or by producing energy from the sun, wind, water, biomass, or any renewable, non-depletable or recyclable fuel.

Electric Resistance Heating

Heating systems which produce thermal energy by passing an electric current through a high resistance material, converting electrical energy into heat. Electric resistance heating is not as efficient as heat pumps, another heating solution that runs on electricity.

Electrical Service

The amount of ampage that your electrical panel can handle, or the amount of electricity your electric panel is able to distribute. A fully electrified home typically needs 200-amp electrical service.

Fossil Fuels

A non-renewable fuel source that is formed in the earth from plant or animal remains. Fossil fuels include oil, natural gas, propane, and coal.

Greenhouse Gas (GHG) Emissions

A gas that traps heat in Earth’s atmosphere. Carbon dioxide and methane are examples of greenhouse gases.

Heat Load Calculation

A calculation done to determine a building’s heating and cooling capacity needed for a heating and cooling unit under design conditions. The size, orientation, and amount of weatherization, doors, windows and thickness of walls, windows, and doors is used to determine a building’s heat load calculation.

Heat Pump

Equipment that transfers heat from a colder area to a hotter area by absorbing heat from a cold space and transferring it to a warmer space using the refrigeration cycle.

Manual J

A methodology developed by the Air Conditioning Contractors of America (ACCA) to do a heat load calculation.

Net Zero Emissions

When the total amount of greenhouse gas emissions is equal to or less than the amount of carbon dioxide or its equivalent that is removed from the atmosphere and stored in Earth’s systems annually. The Commonweath aims to be net zero emissions by 2050.

Refrigeration Cycle

The process of moving refrigerants through a loop to transfer heat from one place to another. Refrigeration cycles can work to move heat in a home in the winter and also move heat out of a home in the summer.

Ground-Source Heat Pumps

Closed Loop

A type of vertical loop-ground source heat pump system where the loop field system circulates an anti-freeze solution through underground pipes. The anti-freeze solution inside the pipes is never mixed with groundwater underground.

Geothermal

A common term used to describe ground-source heat pumps. This term can also refer to energy obtained by tapping underground reservoirs of heat, usually near volcanoes or other hot spots on the surface of the Earth.

Horizontal Loop

A type of ground-source heat pump system where the outdoor heat exchanger is a loop field laid out horizontally, typically at a depth of around eight to ten feet underground.

Loop Field

A loop field is the system of pipes that are run underground to act as the heat exchanger for a ground-source heat pump system. The constant temperature of the ground is used to warm the loop fluid in the winter and cool the loop fluid in the summer to increase the efficiency of the heating and cooling system. The loop field can be at a depth of eight feet in a horizontal loop or hundreds of feet deep in a vertical loop.

Open Loop

A type of vertical loop ground-source heat pump system where the loop field system exchanges water directly with an underground well. Ground water is returned to the well after passing through the heat pump.

Vertical Loop

A type of ground-source heat pump system where the outdoor heat exchanger is an underground loop field drilled hundreds of feet into the group in one or more boreholes.

Organizations

DOER

The Massachusetts Department of Energy Resources (DOER) is a state agency that develops and implements policies and programs aimed at ensuring the adequacy, security, diversity, and cost-effectiveness of the Commonwealth’s energy supply to create a clean, affordable, and resilient energy future.

Energy New England (ENE)

A municipal light plant cooperative owned by light departments of Braintree, Taunton, Concord, Hingham, and Wellesley, Massachusetts that serves as a wholesale risk management and energy trading organization serving the needs of municipal utilities in the northeast, including managing their power supplies and promoting conservation, efficiency, and environmental stewardship.

Energy Star

The federal government-backed symbol for energy efficiency.

Executive Office of Energy and Environmental Affairs (EEA)

A cabinet-level office that oversees Massachusetts’ environmental and energy agencies.

Green Energy Consumers Alliance

A non-profit that serves Massachusetts and Rhode Island residents with a mission to harness the power of consumers to speed the transition to a low-carbon future.

MassCEC

The Massachusetts Clean Energy Center (MassCEC) is a state economic development agency dedicated to accelerating the growth of the clean energy sector to meet the Commonwealth’s clean energy, climate, and economic development goals.

Mass Save

Collaborative of Massachusetts’ natural gas, electric utilities, and energy efficiency service providers to help Massachusetts’ residents save money and energy through energy efficiency measures.

MMWEC

The Joint Action Agency for Massachusetts municipal utilities, delivering the wholesale power supply, financial, risk management and other services needed by municipal utilities to participate effectively in today’s electric utility industry.

Muni HELPS

An MMWEC program that delivers free home energy audits and innovative energy technology to MMWEC customers.

Northeast Energy Efficiency Partnership

Northeast Energy Efficiency Partnership (NEEP) is a non-profit accelerating energy efficiency in the Northeast and Mid-Atlantic states. It is one of six Regional Energy Efficiency Organizations (REEOs) funded, in part, by US Department of Energy to support state efficiency policies and programs.

Solar Hot Water

Evacuated Tube

Solar collectors with thin, copper tubes filled with fluid, inside a vacuum-sealed clear glass plastic tube. Evaporated tube collectors typically perform better during the winter than flat plate collectors, but they are not as efficient at warmer temperatures. View Image

Flat Plate

Solar collectors with a clear glass or plastic casing over a dark metal collector with embedded copper tubes with fluid inside. Flat plat collectors traps heat like a greenhouse.

Flat plate collectors can operate at a wide range of temperatures. View Image

Ground Mounted

Solar collectors mounted on the ground often near a building. Collectors are tilted on the ground to optimize solar exposure. View Image

Roof Mounted

Solar collectors mounted on the roof of a building. Collectors are generally mounted directly to the roof, but sometimes they are tilted up at a different angle (especially on flat roofs) to optimize their solar exposure. View Image

Solar Collectors

Solar collectors are devices that collect solar radiation from the sun. These devices are primarily used for heating water for personal use. These collectors are often mounted on the roof, although they can also be mounted on the ground or on the side of a building. View Image

Wall Mounted

Solar collectors mounted on the side of a building. Collectors can be mounted flush to the wall or tilted at a different angle to optimize solar exposure (sometimes called an awning mount). View Image

Solar Photovoltaics (PV)

Net Metering

A billing mechanism that credits solar energy system owners for the electricity they add to the grid.

A

Air Sealing

The process of ensuring that there are as few gaps in a building’s envelope as possible for conditioned indoor air to escape and unconditioned outdoor air to get in. Air leakage in buildings can represent 5%-40% of space conditioning costs. Air sealing often involves sealing gaps in attics, crawl-spaces, and floor joists; re-sealing windows; replacing broken or jammed vents; and replacing the rubber seals around door frames.

Air-Source Heat Pump

A heating and cooling system that transfers heat between the indoor and outdoor air to heat your home in the winter and cool your home in the summer. Air-source heat pumps run on electricity instead of burning fossil fuels. Colloquially they are also referred to as “mini-split” or “ductless,” although these terms refer to a specific kind of air-source heat pump. View Image

Air-to-water heat pumps

A type of air-source heat pump that uses water, instead of air, in the distribution system and provides heat through a radiator or baseboard. View Image

Automated Wood Heat

A heating system that burns locally sourced, sustainable wood pellets instead of fossil fuels. Also called “Modern Wood Heat” or “Wood Pellet Boiler.” View Image

B

Battery Storage

A device that stores energy in the form of chemical energy for use at a later time as electrical energy.

Boiler

A fuel-burning apparatus or container for heating water. In an automated wood heating system, the boiler burns wood pellets.

Bulk Pellet Storage

A large container, usually a large canvas bag, that stores wood pellets before they are burned to generate heat. A residential bulk pellet storage container typically holds between three and five tons of pellets.

C

Carbon Footprint

The total greenhouse gas (GHG) emissions caused by an individual, event, organization, service, or product.

Clean Energy

Technologies that significantly reduce or eliminate the use of energy from non-renewable sources through efficiency or conservation or by producing energy from the sun, wind, water, biomass, or any renewable, non-depletable or recyclable fuel.

Closed Loop

A type of vertical loop-ground source heat pump system where the loop field system circulates an anti-freeze solution through underground pipes. The anti-freeze solution inside the pipes is never mixed with groundwater underground.

D

DOER

The Massachusetts Department of Energy Resources (DOER) is a state agency that develops and implements policies and programs aimed at ensuring the adequacy, secruity, diversity, and cost-effectiveness of the Commonwealth’s energy supply to create a clean, afforable, and resilient energy future.

Ducted

A heat pump that uses ductwork (connected to an indoor air-handling unit) as the indoor distribution. View Image

Ductless

Heat pumps that use refrigerant pipes as the indoor distribution. Small copper refrigerant pipes are connected to indoor units that each have their own heat exchanger and fan for circulating conditioned air. View Image

Ductwork Upgrades

Air sealing and insulating ductwork to improve the efficiency of a heating and cooling system by ensuring that more of the heated or cooled air gets delivered to where it is needed.

E

Electric Resistance Heating

Heating systems which produce thermal energy by passing an electric current through a high resistance material, converting electrical energy into heat. Electric resistance heating is not as efficient as heat pumps, another heating solution that runs on electricity.

Electrical Service

The amount of ampage that your electrical panel can handle, or the amount of electricity your electric panel is able to distribute. A fully electrified home typically needs 200-amp electrical service.

Electric Vehicle (EV)

A vehicle that uses electricity to charge a battery, which then discharges its energy to propel the vehicle. View Image

Energy Efficiency

The concept of using less energy to perform the same work. Weatherization is an important type of residential energy efficiency. Other examples include using more efficient lighting and appliances.

Energy New England (ENE)

A municipal light plant cooperative owned by light departments of Braintree, Taunton, Concord, Hingham, and Wellesley, Massachusetts that serves as a wholesale risk management and energy trading organization serving the needs of municipal utilities in the northeast, including managing their power supplies and promoting conservation, efficiency, and environmental stewardship.

Energy Star

The federal government-backed symbol for energy efficiency.

Evacuated Tube

Solar collectors with thin, copper tubes filled with fluid, inside a vacuum-sealed clear glass plastic tube. Evaporated tube collectors typically perform better during the winter than flat plate collectors, but they are not as efficient at warmer temperatures. View Image

Executive Office of Energy and Environmental Affairs (EEA)

A cabinet-level office that oversees Massachusetts’ environmental and energy agencies.

F

Flat Plate

Solar collectors with a clear glass or plastic casing over a dark metal collector with embedded copper tubes with fluid inside. Flat plat collectors traps heat like a greenhouse. Flat plate collectors can operate at a wide range of temperatures. View Image

Fossil Fuels

A non-renewable fuel source that is formed in the earth from plant or animal remains. Fossil fuels include oil, natural gas, propane, and coal.

G

Geothermal

A common term used to describe ground-source heat pumps. This term can also refer to energy obtained by tapping underground reservoirs of heat, usually near volcanoes or other hot spots on the surface of the Earth.

Green Energy Consumers Alliance

A non-profit that serves Massachusetts and Rhode Island residents with a mission to harness the power of consumers to speed the transition to a low-carbon future.

Greenhouse Gas (GHG) Emissions

A gas that traps heat in Earth’s atmosphere. Carbon dioxide and methane are examples of greenhouse gases.

Ground Mounted

Solar collectors mounted on the ground often near a building. Collectors are tilted on the ground to optimize solar exposure. View Image

Ground-Source Heat Pump

A heating and cooling system that transfers heat between the earth and the indoors to heat your home in the winter and cool your home in the summer. Ground-source heat pumps run on electricity instead of burning fossil fuels. Also called “Geothermal.” View Image

H

Heat Load Calculation

A calculation done to determine a building’s heating and cooling capacity needed for a heating and cooling unit under design conditions. The size, orientation, and amount of weatherization, doors, windows and thickness of walls, windows, and doors is used to determine a building’s heat load calculation.

Heat Pump

Equipment that transfers heat from a colder area to a hotter area by absorbing heat from a cold space and transferring it to a warmer space using the refrigeration cycle.

Heat Pump Clothes Dryer

A clothes dryer that reuses the heat used to dry clothing instead of venting it to the outdoors. All heat pump components are located inside the dryer and no connection to the outdoors, not even a vent, is needed. Heat pump clothes dryers run on electricty instead of burning fossil fuels.

Heat Pump Water Heater

A hot water heating system that transfers heat from the air (often in a basement or mechanical room) to a hot water tank to heat hot water. Heat pump water heaters run on electricity instead of burning fossil fuels. View Image

Horizontal Loop

A type of ground-source heat pump system where the outdoor heat exhanger is a loop field laid out horizontally, typically at a depth of around eight to ten feet underground.

I

Indoor Unit

The part of an air-source heat pump that release hot air in the winter and cold air in the summer into a home. Indoor units can be ducted or ductless. Ductless options include wall, ceiling, or floor mounted units. View Image

Induction Stove

An electric stovetop that uses magnetic fields to generate heat in cookware instead of generating heat from an electric resistance coil. Induction stoves are more efficient and offer more temperature control precision than traditional stoves. View Image

Insulation

The material used to slow heat transfer through the building envelope (walls, roof, floors, etc.). Common types of insulation include fiberglass, cellulose, and foam board.

Integrated Controls

The use of one system to control two separate heating systems. Integrated controls can be a single thermostat or multiple connected thermostats. Integrated controls are sometimes used when air-source heat pumps are used in conjunction with a backup heating system such as an oil or propane boiler.

Islanding Capability

Islanding capability allows your solar and battery storage system to power critical loads in your home in the event of a grid electricity power outage. For the safety of utility line workers, solar and battery storage systems are designed by default to stop feeding electricity into your home during power outages. Islanding capability changes this while still protecting utility workers and allows you to isolate your home from the grid during a power outage. You can then power critical loads with your solar and battery system.

L

Loop Field

A loop field is the system of pipes that are run underground to act as the heat exchanger for a ground-source heat pump system. The constant temperature of the ground is used to warm the loop fluid in the winter and cool the loop fluid in the summer to increase the efficiency of the heating and cooling system. The loop field can be at a depth of eight feet in a horizontal loop or hundreds of feet deep in a vertical loop.

M

Manual J

A methodology developed by the Air Conditioning Contractors of America (ACCA) to do a heat load calculation.

MassCEC

The Massachusetts Clean Energy Center (MassCEC) is a state economic development agency dedicated to accelerating the growth of the clean energy sector to meet the Commonwealth’s clean energy, climate, and economic development goals.

Mass Save

Collaborative of Massachusetts’ natural gas, electric utilities, and energy efficiency service providers to help Massachusetts’ residents save money and energy through energy efficiency measures.

Mini-splits

A common term used to describe a ductless air-source heat pump.

MMWEC

The Joint Action Agency for Massachusetts municipal utilities, delivering the wholesale power supply, financial, risk management and other services needed by municipal utilities to participate effectively in today’s electric utility industry.

Multi-Zone

A heat pump where one outdoor unit connects to more than one indoor units. Multi-zone indoor units can include a mix of ducted and ductless units.

Muni HELPS

An MMWEC program that delivers free home energy audits and innovative energy technology to MMWEC customers.

N

Net Metering

A billing mechanism that credits solar energy system owners for the electricity they add to the grid.

Net Zero Emissions

When the total amount of greenhouse gas emissions is equal to or less than the amount of carbon dioxide or its equivalent that is removed from the atmosphere and stored in Earth’s systems annually. The Commonweath aims to be net zero emissions by 2050.

Northeast Energy Efficiency Partnership

Northeast Energy Efficiency Partnership (NEEP) is a non-profit accelerating energy efficiency in the Northeast and Mid-Atlantic states. It is one of six Regional Energy Efficiency Organizations (REEOs) funded, in part, by US Department of Energy to support state efficiency policies and programs.

O

Open Loop

A type of vertical loop ground-source heat pump system where the loop field system exchanges water directly with an underground well. Ground water is returned to the well after passing through the heat pump.

Outdoor Unit

The part of an air-source heat pump that is outside where the refrigerant absorbs heat in the winter and rejects heat in the summer to transfer heat between the indoors and the outdoors and condition the home.

P

Programmable Thermostat

A thermostat that can be set to adjust the temperature of a home based on the time of day and week, in order to use less energy when it is not needed.

R

Refrigeration Cycle

The process of moving refrigerants through a loop to transfer heat from one place to another. Refrigeration cycles can work to move heat in a home in the winter and also move heat out of a home in the summer.

Roof Mounted

Solar collectors mounted on the roof of a building. Collectors are generally mounted directly to the roof, but sometimes they are tilted up at a different angle (especially on flat roofs) to optimize their solar exposure. View Image

S

Single-Zone

A heat pump where one outdoor unit connects to one indoor unit, which could be either a ducted air-handling unit or a ductless indoor unit. A home can have multiple single-zone systems.

Solar Collectors

Solar collectors are devices that collect solar radiation from the sun. These devices are primarily used for heating water for personal use. These collectors are often mounted on the roof, although they can also be mounted on the ground or on the side of a building. View Image

Solar Hot Water

A hot water system that uses heat from the sun to heat a fluid in solar collectors that is then circulated to a hot water tank where the fluid transfers heat for domestic hot water use (e.g., showers, washing dishes). Also called “Solar Thermal.” View Image

Solar Photovoltaics (PV)

Solar panels that use the sun’s radiation to generate electricity. View Image

T

Thermal Storage

A system which stores thermal energy for use in supplementing or offsetting heating system output. A hot water tank is used for thermal storage in an automated wood heating system.

V

Vertical Loop

A type of ground-source heat pump system where the outdoor heat exchanger is an underground loop field drilled hundreds of feet into the group in one or more boreholes.

W

Wall Mounted

Solar collectors mounted on the side of a building. Collectors can be mounted flush to the wall or tilted at a different angle to optimize solar exposure (sometimes called an awning mount). View Image

Weatherization

The process of making a home better protected from extreme weather, which often involves sealing up air leaks and adding insulation in your home.

Wood pellets

Small pieces of dried and compressed wood. Wood pellets are burned instead of fossil fuels in an automated wood heating system.

Wood pellet boiler

A common term used to refer to automated wood heating systems. A wood pellet boiler is a boiler that burns wood pellets as the fuel.

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