Home Energy Glossary

Air Sealing:  The practice of installing appropriate materials, such as caulk or foam, to stop airflow in certain areas of a home.

Blower Door Test: A test used to measure a home’s airtightness and locate air leakage paths. A blower door is a powerful fan that mounts into the frame of an exterior door. The fan moves air in or out of the house, changing the air pressure inside to exaggerate air leaks through unsealed cracks and openings. Technicians use these tests to determine the air infiltration rate of a building, identify locations to be sealed, and measure results of air sealing work.

Building Envelope: The assembly of elements comprising the exterior enclosure of a building, including walls, roof, foundation, windows, and doors.

Building Performance Institute (BPI) – A leading developer of technical standards for Home Performance and weatherization retrofit work that are recognized across North America. From these standards, BPI has developed training programs, professional credentialing for individuals, company accreditations and quality assurance programs for the industry.

Bundled Efficiency Program – An existing home program that targets consumers in existing homes by offering education and/or incentives on multiple end uses and/or systems in the home. A bundled efficiency program packages together program offerings into one touch-point with the customer and does not include a comprehensive assessment of a home’s energy usage.

Combustion Safety Test: Combustion safety is the general term for evaluating fuel-burning equipment in the home. In general, these procedures include checks for fuel leaks, carbon monoxide, and to ensure that waste gases exit the home through the chimney or venting system.

Conversion Rate – rate at which property owners follow through with retrofit measures recommended as a result of a home performance evaluation or energy audit.

Diagnostic Tests: Procedures used to measure and assess the performance of components of the home using specialized testing equipment, including blower door testing and combustion safety testing. Diagnostic tests are often conducted before and after the installation of home upgrades to measure the net improvement and to ensure that safety standards have been met.

Ductwork: A network of metal, fiberboard, or flexible tubes throughout a space which delivers air from an HVAC unit to the respective zones of a home or office.

Energy Audit: An “energy assessment” or “energy study” to determine where, when, why, and how energy is used in a home, and to identify opportunities to improve efficiency. It includes an evaluation of a home based on data from inspections, diagnostics, data collection, analyses, and reporting, which identifies opportunities for the homeowner to improve energy efficiency. See also “home performance assessment.”

Energy Efficiency: The concept of using less energy to provide the same service.

EPA Water Sense Specifications – WaterSense, a partnership program sponsored by EPA, seeks to protect the future of our nation’s water supply by promoting water efficiency and enhancing the market for water-efficient products, programs, and practices. WaterSense will help consumers identify water-efficient products and programs.

Existing Homes – Single-family and small multifamily (four units or less) housing units.

Existing Homes Programs – Energy efficiency programs that have a goal of reducing energy usage in existing homes.

Greenhouse Gas: A gas that traps the sun’s heat in the atmosphere. When these gases are trapped in the atmosphere (and not reflected back into space), the planet becomes warmer than it would be otherwise. This process is commonly referred to as the greenhouse effect. Greenhouse gases include water vapor, carbon dioxide, methane, ozone, chlorofluorocarbons, and nitrogen oxides; gases which are produced and sometimes released to the atmosphere when generating energy to power our homes.

Home Energy Assessment: An evaluation of a home based on data from inspections, diagnostics, data collection, analyses, and reporting, which identifies opportunities for the homeowner to improve energy efficiency. See also “energy audit.”

Home Energy Audit – an assessment of how much energy a home consumes and a set of recommendations for ways to decrease the home’s energy usage. Audits take a variety of forms, from the simplest do-it-yourself version to the more comprehensive versions conducted by a BPI-certified building analyst or HERS rater. An audit will pinpoint where your house is losing energy and show you how to correct the problems to save money, improve comfort, improve indoor air quality, and conserve hot water and electricity. www.energysavers.gov/your_home/energy_audits/index.cfm/mytopic=11160

Home Energy Rating Services (HERS) Index – a scoring system established by the Residential Energy Services Network (RESNET) in which a home built to the specifications of the HERS Reference Home (based on the 2006 International Energy Conservation Code) scores a HERS Index of 100, while a net zero energy home scores a HERS Index of 0. The lower a home’s HERS Index, the more energy efficient it is in comparison to the HERS Reference Home. A home energy rating involves an analysis of a home’s construction plans and onsite inspections. Based on the home’s plans, the Home Energy Rater uses an energy efficiency software package to perform an energy analysis of the home’s design. This analysis yields a projected, pre-construction HERS Index. Upon completion of the plan review, the rater will work with the builder to identify the energy efficiency improvements needed to ensure the house will meet ENERGY STAR performance guidelines. The rater then conducts onsite inspections, typically including a blower door test (to test the leakiness of the house) and a duct test (to test the leakiness of the ducts). Results of these tests, along with inputs derived from the plan review, are used to generate the HERS Index score for the home. www.energystar.gov/index.cfm?c=bldrs_lenders_raters.ng_HERS

HERS Rater – An energy analyst who is trained to compile data about a home, its building envelope and energy features, and then determine a predicted energy performance using the Home Energy Rating System (HERS). In addition to visual inspection, the rater will use testing equipment, such as blower doors and duct testers, to determine a “HERS Index” (see above) for the home. To qualify as a certified rater, the analyst must meet the requirements of RESNET(see explanation below). www.energystar.gov/index.cfm?c=bldrs_lenders_raters.nh_HERS

Home Energy Upgrade: Individual home improvement measures or packages of measures completed to reduce energy consumption in the home.

Home Performance – A comprehensive whole-house approach to identifying and fixing comfort and energy efficiency problems in a home. A drafty house, rooms that are too hot or too cold, and high energy bills are all common issues for homeowners. A quality installation of a new heating or air conditioning system, buying replacement windows, or adding more insulation may fix part of the problem, but home performance looks at the entire package, including energy efficiency, comfort, durability, cost and health and safety.

Home Performance Assessment:  An evaluation of a home’s condition and energy performance conducted by an expert in Home Performance with ENERGY STAR.

Home Performance Contractor – Companies or sole proprietors engaged in Home Performance retrofitting in accordance with EPA guidelines, including before and after testing procedures, combustion safety testing, and a house-as-a-system approach incorporating multiple remediation measures. Contractors may be general contractors who oversee subcontractors, or businesses that run internal crews to conduct retrofitting projects on homes. Contractors may be licensed and insured as required by their state or jurisdiction of operation. This company or person may specialize in energy assessments, home inspections, or improvements related to air or duct sealing, insulation, HVAC, or other related services.

Home Performance Measure: The installation or modification of equipment or other building components, in order to improve a building’s performance and energy efficiency (e.g., insulation, air sealing, duct sealing, appliance replacement).  See also “Energy Efficiency Measure.”

Home Performance with ENERGY STAR (HPw/ES) – A national program from the U.S. EPA and U.S. DOE that offers a comprehensive, whole-house approach to improving energy efficiency and comfort at home, while helping to protect the environment. HPwES programs are currently offered in 29 states. Under this program model, each home is assessed comprehensively by properly trained and certified contractors and/or consultants. Home Performance with ENERGY STAR takes a whole home approach to achieve not only energy efficiency, but also health, safety, and comfort. www.energystar.gov/index.cfm?c=home_improvement.hm_improvement_hpwes

HVAC: The equipment, distribution system and terminals that provide, either collectively or individually, the processes of heating, ventilating or air conditioning to a building or portion of a building.

Indoor Air Quality: Attributes of the air inside a building (indoor climate), including gaseous composition, humidity, temperature and contaminants.

Insulation: Insulation materials run the gamut from bulky fiber materials such as fiberglass, rock and slag wool, cellulose and natural fibers to rigid foam boards and sleek foils. Bulky materials resist conductive and, to a lesser degree, convective heat flow in a building cavity. Rigid foam boards trap air or another gas to resist conductive and convective heat flow. Highly reflective foils in radiant barriers and reflective insulation systems reflect radiant heat away from living spaces, making them particularly useful in cooling climates. Other less common materials such as cementitious and phenolic foams and vermiculite and perlite are also available.

Non-Energy Benefits (NEBs) – The additional benefits created when a homeowner completes home performance upgrades. These include: cost savings, improved comfort and health, industry development, job creation, and reductions in GHG emissions.

Prescriptive Measures – Programs that focus on providing incentives for the purchase and proper installation of specific energy saving equipment, such as furnaces and water heaters, super-high-performance major appliances such as refrigerators and washing machines, or changes to a building’s envelope such as insulation and duct sealing.

Property Assessed Clean Energy (PACE) – Financing mechanism that enables local governments to finance renewable energy and energy efficiency projects on private property, including residential, commercial and industrial properties. The programs eliminate the chief barrier to clean energy installations– the large upfront cost– by offering the property owner a loan that can be repaid in fixed payments as part of their property tax bill. Generally, PACE is rooted in traditional land-secured municipal finance. A local government creates an improvement district; a bond, secured by real property within the district, is issued; and the bond proceeds are used to fund renewable energy and energy efficiency projects.

Renewable Energy Technologies: Technologies that produce sustainable, clean energy from sources such as the sun, the wind, plants, and water.  These include biomass, geothermal, hydrogen, hydropower, ocean, solar energy, and wind.

Residential Energy Services Network (RESNET) – a membership 501(c)(3) nonprofit organization that set the standards of quality for the building energy performance industry, including standards for building performance software, HERS raters’ knowledge base & skill sets, and quality assurance evaluations. RESNET’s standards are officially recognized by the U.S. mortgage industry for capitalizing a building’s energy performance in the mortgage loan, certification of “White Tags” for private financial investors, and by the federal government for verification of building energy performance for such programs as federal tax incentives, the Environmental Protection Agency’s ENERGY STAR program and the U.S. Department of Energy’s Building America Program. www.natresnet.org

Weatherization: A category of home energy upgrades which includes sealing and insulating the building envelope. Also a term used to refer to DOE’s Weatherization Assistance Program, which provides home energy upgrades to low income populations.

Weatherstripping: An energy efficiency measure that involves installing a material to seal air leaks around components that open, close and generally move (exterior doors and windows).

Whole Home Program – A program that incorporates building science principles to comprehensively assess existing conditions of a home’s energy usage, as well as how all the systems within the home interact. This assessment is then used to create a detailed work scope, or plan, to achieve the greatest energy savings for the home over a long period of time. A whole home program relies on properly trained and certified technicians to complete the installation of measures incorporating best practices to nationally recognized standards, typically followed up with third-party quality assurance inspections. www.cee1.org