Christopher Alexander’s ground breaking book first published in 1977.  It is part 2 of a 3-part trilogy about the nature of the built environment.  A Pattern Language includes 253 universal patterns of human nature.   Selecting and organizing the relevant patterns to solve a design problem(...)

Process whereby a porous material extracts one or more substances from an atmosphere, a mixture of gases, or a mixture of liquids. Source: (from Gatley, Understanding Psychrometrics)

(1) Process in which fluid molecules are concentrated on a surface by chemical or physical forces or both; (2) surface adherence of a material in extracting one or more substances present in an atmosphere or mixture of gases and liquids, unaccompanied by physical or chemical change. Source:(...)

A system of materials that enclose a volume of air with minimal air leakage between the enclosed air and the exterior. The effectiveness or adequacy of the air barrier can be measured by the volume of air (in cubic feet per minute) that must be added or removed from the enclosure to maintain a(...)

Uncontrolled inward leakage of air (that may contain entrained water vapor) through cracks and insterstices in any building element and around windows and doors of a building, caused by the pressure effects of wind or the effect of differences in the indoor and outdoor air density. Source:(...)

Uncontrolled and/or unintended airflow through a building enclosure or between units of occupancy. Leakage from indoors to outdoors is known as exfiltration and leakage from outdoors to indoors is known as infiltration. Air leakage can cause indoor air quality problems, condensation, excess(...)

A material or assembly that does not meet the performance requirements of an air control layer material or assembly, but that is nonetheless designed and constructed to control air flow. Source: The Passivhaus Handbook

Air Source Heat Pumps absorb heat from the outside air. This heat can then be used to heat radiators, underfloor heating systems, warm air convectors and hot water in your home. It extracts heat from the outside air in the same way that a fridge extracts heat from its inside. It can get heat(...)

The degree of leakage of air through the thermal envelope. (See air permeability and air changes per hour, above). Airtightness is a property of a building. Source: The Passivhaus Handbook

Arduino is an open-source prototyping platform based on easy-to-use hardware and software. Arduino boards are able to read inputs - light on a sensor, a finger on a button, or a Twitter message - and turn it into an output - activating a motor, turning on an LED, publishing something online.(...)

Naturally occurring fibrous minerals that because of their extreme durability and fire resistance were used extensively in residential and industrial construction. The inhalation of asbestos fibers can cause serious illnesses such as asbestosis, lung cancer and mesothelioma. Source:(...)

A structural supporting member that resists loads primarily in bending. May be vertical or horizontal and made of any material or composite.

BIM is an intelligent 3D model-based process that equips architecture, engineering, and construction professionals with the insight and tools to more efficiently plan, design, construct, and manage buildings and infrastructure. The National Building Information Model Standard Project(...)

Plant Name : Rudbeckia fulgida Height : 2'-3" Light Conditions : Sun Blooms : Summer Color : Yellow Notes : Self Sows

A machine used to test the airtightness of buildings or of smaller spaces within buildings. A blower door is mounted in an opening such as a window or door and then uses a fan to pressurize or depressurize the measured space. The more airtight the space, the less air is needed from the blower(...)

Test used to determine a home’s airtightness: a powerful fan is mounted in an exterior door opening and used to pressurize or depressurize the house. By measuring the force needed to maintain a certain pressure difference, a measure of the home’s airtightness can be determined. Operating the(...)

The system or assembly of components that provides environmental separation between the conditioned space and the exterior environment. Note: The enclosure is a special type of environmental separator. Environmental separators also exist within buildings as dividers between spaces with(...)

Exterior components of a house that provide protection from colder (and warmer) outdoor temperatures and precipitation; includes the house foundation, framed exterior walls, roof or ceiling, and insulation, and air sealing materials. Source: Green Building Advisor

Building Morphology in architecture is the study of the evolution of form within the built environment.

CAD, or computer-aided design and drafting (CADD), is the use of computer technology for design and design documentation. CAD software replaces manual drafting with an automated process. AutoCAD software was the first CAD program, and it is still the most widely used CAD(...)

CAD/CAM refers to computer software that is used to both design and manufacture products. CAD/CAM applications are used to both design a product and program manufacturing processes, specifically, CNC (computer numerical control) machining. CAD/CAM software is most often used for machining of(...)

CAM software is used to design and manufacture products. CAM software uses the models and assemblies created in CAD software to generate tool paths that drive the machines that turn the designs into physical parts. Source: http://www.autodesk.com/solutions/cad-cam,(...)

See Sealant.

Cellulose is made from recycled newsprint and other recycled paper with one of the highest percentages of post-consumer waste content of any insulation. It is treated with recognized safe fire retardants. Cellulose insulation is blown onto attic floors, into wall and ceiling cavities, or is(...)

An individual who has trained (taken a Passivehouse-Institute-of-the United States [PHIUS]-recognized Certified Passive House Consultant [CPHC] course and PHIUS CPHC examination) and qualified in the principles and methodology needed to design a Passivehouse. Source: PHIUS

A material or assembly that forms the exterior face of a wall. Examples of cladding include stucco, EIFS, metal panels, brick/stone veneer, wood siding, and vinyl siding. Source: IRC FAQ: Cladding Attachment Over Insulating Sheathing, Info-305: Reservoir Claddings, BSI-058  

The exterior environmental conditions that will impose a load on the building enclosure, including temperature, humidity, rainfall, wind, and solar radiation. Dividing a map into climate zones allows designers, code bodies, and others to make recommendations based on expected regional(...)

A climate zone is a classification of the type of weather that is experienced in a specific geographic region of the world.  Climate zones are differentiated based on average temperatures, precipitation, and heating degree-days (HDD) that occurs in an area.  The US Department of Energy(...)

A quality assurance process during and following building construction, prior to occupancy. Tests and inspections should note any problems to be fixed immediately (“fix and tune”). Tests should be conducted for duct leakage, building enclosure leakage, air pressure relationships under all(...)

The change of state from vapor to liquid. A common factor in moisture damage. Occurs on surfaces, which must be cooler than the air containing vapor next to it. Vapor supply to the condensation surface is usually by airflow but can be by diffusion. Source: BSD-163: Controlling Cold-Weather(...)

The part of the building that is designed to be thermally conditioned (heated or cooled), either for the comfort of occupants or for other reasons such as preserving temperature-sensitive goods. Source: BSI 022: The Perfect HVAC

A Connected Home is a home that contains a communication network that connects security, lighting, sound, TV’s, appliances, HVAC, and energy monitoring allowing the owner to control the network from a single app on a tablet, phone, or computer both locally and remotely.

Heating degree days and cooling degree days are climatological metrics used to express the magnitude of the heating or cooling load in a given location. These metrics are expressed in terms of a "base temperature" (e.g., "Cooling Degree Days Base 65 F"). Cooling degree days are calculated by(...)

The deterioration of metal by chemical or electrochemical reaction resulting from exposure to weathering, moisture, chemicals or other agents or media. Source: RR-0605: Assessing the Durability Impacts of Energy Efficienct Upgrades Using Hygrothermal Modeling

Certified Passive House Builder.  An individual who has successfully completed the training and exam administered by PHIUS to build buildings that meet the Passive House building standard.

Certified Passive House Consultant.  An individual who has successfully completed the training and exam administered by PHIUS to design and engineer buildings that meet the Passive House building standard.

Certified Passive House Designer.  An individual who has successfully completed the training and exam administered by PHI to design and engineer buildings that meet the Passivhaus building standard.  

The efficient use of natural light in ways that minimize the need for artificial light in buildings. It is achieved by control strategies and adapted components which fall mainly into three categories: • conduction components - spaces used to guide or distribute light towards the interior of a(...)

Removal of water vapor from air. Source: from Gatley, Understanding Psychrometrics. Related Resources: RR-0215: Dehumidification Systems Research Results; RR-1008: Building America Special Research Project—Enhanced Dehumidification

A method of insulation application that results in insulation that is less prone to air filtration and settling. Source: www.buildingscience.com.

The temperature at which the relative humidity of a sample of air with constant water vapor reaches 100%. The air is saturated with water when it reaches the dew point and condensation will occur on a surface. Source: BSI-049: Confusion About Diffusion; RR-0203: Relative Humidity

The movement of individual molecules through a material. The movement occurs because of concentration gradients and (to a much lesser degree) thermal gradients, independent of airflow. A mode of water vapor transport in building enclosures that is much slower than airflow. Source: BSI 049:(...)

Drainage planes are water repellent materials (building paper, housewrap, foam insulation, etc.) which are designed and constructed to drain water. They are interconnected with flashings, window and door openings, and other penetrations of the building enclosure to provide drainage of water to(...)

A building enclosure rain control strategy (or ground water control) that accepts that some water will penetrate the outer surface (the cladding, which “screens” rain) and removes this water back to the exterior by gravity drainage over a drainage plane, through a drainage gap, and exiting via(...)

The capability of a building, assembly, component, or product to maintain serviceability over a specified time. Source: BSD 144: Increasing the Durability of Building Constructions; RR-1207: Vancouver Field Exposure Facility—Phase III Exterior Insulation Analysis

Off-site construction refers to the planning, design, fabrication, and assembly of building elements at a location other than their final installed location to support the rapid and efficient construction of a permanent structure. Such building elements may be prefabricated in a different(...)

Energy is a measurable quantity of heat, work, or light. Potential energy is stored energy, like a cord of wood. Kinetic energy is transitional energy, like a flame. Source: Residential Energy

An energy audit is an assessment of the insulation, building structure, heating and hot water systems and electrical use. It is a practical way to protect your biggest asset, save money and live healthier. Our approach to auditing is based on the House as a System concept, balancing air(...)

The measure of a building energy efficiency.

The Environmental Protection Agency, in cooperation with the Department of Energy, has created a brand that identifies the most energy-efficient products on the American market. Source: Residential Energy

The Passivhaus Institut's energy performance standard for retrofits. It allows a maximum annual [specific] space heated demand of 25kWh/m^2.a and an upper airtightness limit of 1.0ACH, if the 0.6ACH target can be shown to be impracticable, and also sets requirements for individual elements of(...)

Thermodynamic quantity equal to the sum of the internal energy of a system plus the product of the pressure-volume work done on the system. Enthalpy cannot be directly measured; however, enthalpy differences between the initial and the final state points of a process can be(...)

Exchanges the energy contained in air exhausted from a building and uses this to heat or cool the building’s incoming outdoor ventilation air. Source: Zehnder Passive House Blog

Energy Use Intensity (EUI) is a measure of a building’s energy use as a function of its size.  It’s calculated by dividing the total energy consumed by the building in one year (measured in kBtu or GJ) by the total gross floor area of the building.

"Flashing refers to thin continuous pieces of sheet metal or impervious material installed to prevent the passage of water into a structure from an angle or joint. Flashing generally operates on the principle that, for water to penetrate a joint, it must work itself upward against the force of(...)

A horizontal section drawing showing the basic layout of a building, including the placement of walls, windows and doors.

A substance formed by trapping pockets of gas in a liquid or solid. Solid foams can be divided into closed-cell foams (where each pocket is separated) and open-cell foams (where the pockets connect with each other). Foams have many possible uses in building. A common use is as an insulator.

Studs, joists, plates (tracks), bridging, bracing, and related accessories manufactured or supplied for wood or light gauge steel framing. Source: Future of Framing is Here

A framing member that goes over a window, door, or other opening. A beam placed perpendicular to joists and to which joists are nailed in framing for chimney, stairway, or other opening. Source: BSI-030: Advanced Framing

Home Energy Rating System (HERS) a standard for measuring a home's energy efficiency. Developed by the Residential Energy Services Network (RESNET). The HERS Index measures a home's energy efficiency. It includes the energy consumption from heating, cooling, water heating, lights, and some(...)

Any of the numerous artificial polymer rolled sheet goods designed to function as drainage planes, a class of sheathing membranes. Some are also used as part of an air barrier system. Can be made of spun-fiber polyolefin, perforated plastic films, or coated and micro-perforated polymers.(...)

Written by Stewart Brand, who brought us “The Whole Earth” catalog, “How Buildings Learn” explores what happens to buildings after they’re built.  These post construction insights allow us to “design-in” the inevitable evolution of our rooms and spaces. Buy the Book Here

Also known as HRV, mechanical ventilation heat recovery, or MVHR, is an energy recovery ventilation system using equipment known as a heat recovery ventilator, heat exchanger, air exchanger, or air-to-air heat exchanger which employs a counter-flow heat exchanger (countercurrent heat exchange)(...)

HVAC equipment performs heating and/or cooling for residential, commercial or industrial buildings. The HVAC system may also be responsible for providing fresh outdoor air to dilute interior airborne contaminants such as odors from occupants, volatile organic compounds (VOC’s) emitted from(...)

The quality of air within buildings, in regard to both health and comfort. Indoor air often contains a complex mixture of contaminants and common pollutants, including smoke, volatile organic compounds (VOCs) and molds. The level of carbon dioxide (CO2) in indoor air also relates to IAQ, and(...)

Non-structural insulating board products with varying R-values and a wide variation in vapor permeability and drainage characteristics. Materials include expanded polystyrene (EPS), extruded polystyrene (XPS), polyisocyanurate (most often foil-faced), rigid fiberglass, and mineral(...)

(1) Thermal insulation: Any material which significantly slows down or retards the flow or transfer of heat. Building insulation types are classified according to form (e.g loose-fill, batt, flexible, rigid, reflective, and foamed-in-place) or material (mineral fiber, organic fiber, foam(...)

The Internet of Things is the network of physical objects including devices, vehicles, buildings and other items embedded with electronics, software, sensors, and network connectivity that enable these objects to collect and exchange data. Source: Internet of Things Global Standards Initiative

The vertical side or edge of a doorway, window, or other opening. Source: Water Management Guide

A flexible, short, U-shaped duct (typically 10-inch diameter) that connects a room to a common space as a pressure balancing mechanism. Jump ducts serve the same function as transfer grilles. Used when return ducts are not located in every room. Source: Info-604: Transfer Ducts and Grilles;(...)

Most often used in reference to a coating for high-performance windows. The "E" stands for "emissivity," which is the degree of efficiency. A thin metallic oxide coating increases the U-value and/or decreases the SHGC of the window by reducing heat flow from a warm(er) surface to a cold(er)(...)

A regular process of inspection, cleaning and minor repairs of building elements and exterior systems. Cleaning removes dirt, impurities, or extraneous matter as required on a regular basis, such as removing leaves from gutters and drains in the fall or cleaning lint from dryer vents. Minor(...)

A thin pliable or flexible sheet forming A thin pliable or flexible sheet forming a lining, covering, or layer.a lining, covering, or layer.

A substance resembling matted wool and made from inorganic mineral material, used chiefly for packing or insulation. Source: www.cellulose.org.

A type of fungus that is different from plants, animals and bacteria. Molds are decomposers of dead organic material such as leaves, wood and plants. Molds sometimes can infect living plants and animals. The spores and hair-like bodies of individual mold colonies are too small for us to see(...)

A building which generates as much energy as it uses.

A net zero building is a building the produces as much energy on site as it consumes on an annual basis. From the DOE: an energy-efficient building where, on a source energy basis, the actual annual delivered energy is less than or equal to the on-site renewable exported energy. Source: US(...)

A net zero building is a building the produces as much energy on site as it consumes on an annual basis. From the DOE: an energy-efficient building where, on a source energy basis, the actual annual delivered energy is less than or equal to the on-site renewable exported energy. Source: US(...)

Air outside the building. Source: RR-9901: Air Distribution Fan Outside Air Damper; Info-610: Central Fan Integrated Ventilation Systems

“Passive House” is today’s most energy efficient building standard. Buildings that meet the Passive House standard use 80% less energy for heating and cooling than conventional buildings yet are markedly more comfortable and healthy than traditional buildings. A Passive House conserves(...)

Utilizing solar in passive manner such as with thermal masses or solar light tubes instead of actively with photovoltaic panels or solar hot water systems. Source: Energy Audit Blog

A residential building construction standard requiring very low levels of air leakage, very high levels of insulation, and windows with a very low U-factor. Developed in the early 1990s by Bo Adamson and Wolfgang Feist, the standard is now promoted by the Passivhaus Institut in Darmstadt,(...)

The Passive House Institute (PHI) is an independent research institute lead by Dr Wolfgang Feist with a continuously growing interdisciplinary team of employees.  PHI has played an especially crucial role in the development of the Passive House concept. The first pilot project (Kranichstein(...)

PHIUS+ rater.  An individual who has successfully completed the training and exam administered by PHIUS to verify that PHIUS precertified Passive House projects are constructed as design..  PHIUS+ raters perform onsite testing and inspection during multiple site visits to ensure QA/QC.

A PHIUS certified Passive House is a building certified by the Passive House Institute US (PHIUS) to meet the PHIUS + building standard.  The PHIUS + building standard is a global building energy standard designed to create comfortable, healthy, and energy efficient buildings.    

A PHIUS CPHC (Certified Passive House Consultant) is a professional in the building industry trained by PHIUS to apply the rigorous Passive House approach to creating comfortable, healthy, and energy efficient buildings.  The training is focused on the principles of passive building design and(...)

Passive House Institute US (PHIUS) is a 501(c)3 organization committed to making high-performance passive building principles the mainstream best building practice, and the mainstream market energy performance standard.  PHIUS has trained more than 1,700 architects, engineers, energy(...)

Sill plate: or “mud sill”: a horizontal member anchored to a masonry wall. Sole plate: bottom horizontal member of a frame wall. Top plate: top horizontal member of a frame wall supporting ceiling joists, rafters, or other members.  

A wood product made of three or more layers of veneer joined with glue, and usually laid with the grain of adjoining plies at right angles.

1. A building, manufactured in standardized parts or sections ready for quick assembly and erection. 2. A structure fabricated at an offsite location and brought to the site as fully assembled for installation. 3. A broad term that encompasses several different types of building.(...)

The primary air enclosure boundary separating conditioned air and unconditioned air. Typically defined by the air control layer system. Source: BSD-104: Understanding Air Barriers; Info-401: Air Barriers—Airtight Drywall Approach

Primary energy is the raw fuel that is burned to create heat and electricity, such as natural gas or fuel oil used in onsite generation.  When primary energy is consumed on site, the conversion to source energy must account for losses that are incurred in the storage, transport, and delivery(...)

Photovoltaics (PV) is a method of generating electrical power by converting solar radiation into direct current electricity using semiconductors that exhibit the photovoltaic effect. Photovoltaic power generation employs solar panels composed of a number of solar cells containing a(...)

Quantitative measure of an assembly or material resistance to heat flow for a unit temperature difference and a unit area. It is the reciprocal of the U-factor. The units for R-value are ft2 °F hr/Btu (English) or m2 °K hr/W (SI or metric). As R-value increases, conduction through an assembly(...)

The movement of energy by electromagnetic waves; can occur through a gas or a vacuum. One of the three modes of heat transfer (in addition to convection and conduction). At normal temperatures, radiation is in the infra-red region of the spectrum, whereas solar radiation is at visible(...)

A truss with a raised heel height, or the depth of the attic space at the eaves (the vertical distance from the top plate to the underside of the roof sheathing), measured at the outside wall. This leaves more room for insulation. Source:(...)

Randek develops, manufactures and markets high-performance machines and systems for prefabricated house manufacturing. The product range consist of: cut saws, wall floor and roof lines, roof truss system, butterfly tables and special machines. The automation level stretches from fully(...)

An individual, certified to perform Building Energy Efficiency Ratings for the building type and in the rating Class for which the Rater is certified. There are three classes of residential Rater certification: Class 3 - requiring the certified capability to complete Ratings based on(...)

A measure of the quantity of water vapor in a given volume of air, expressed as a percentage of the maximum quantity of water vapor that volume can contain before it becomes saturated (after which condensation will occur). Variants : RH Source: The Passivhaus Handbook

In April 1995, the National Association of State Energy Officials (NASEO) and Energy Rated Homes of America founded the Residential Energy Services Network (RESNET) to develop a national market for home energy rating systems and energy efficient mortgages. Source: Building Science Corporation

A layer of flexible insulation typically installed under roof tiles when a home is being constructed.  It consists of aluminum foil laminated onto paper or plastic backing with a flame retardant adhesive and fiberglass reinforcing mesh, and is manufactured in sheet form. Sarking performs a(...)

The outer layer of cladding of a rainscreen wall system. "Rainscreen walls consist of the outer layer of cladding (the rainscreen), an air cavity, and a drainage plane on a rigid, water-resistant, and airtight support wall. Simple rainscreen walls, such as brick cavity walls and furred-out(...)

A flexible, polymer-based elastomeric material that is used in the assembly of the building enclosure to seal gaps, seams, or joints, making them waterproof or airtight (as part of the air or water control layers) or to provide a clean finish. Sealants are typically applied wet and may be(...)

The heat (energy) exchanged that affects only the temperature. Compares to latent heat which is the heat (energy) that is not observable as a change in temperature. Examples include vapor condensing from air or ice melting into water. In both cases, the material stays the same temp until the(...)

A material used to provide structural stiffness to the wall framing and to provide structural backing for the cladding and sheathing paper. Typical materials are OSB (oriented strand board), plywood, or various forms of gypsum board. Source: Info-500: Building Materials Property Table;(...)

Site energy represents the total nonrenewable energy consumed by a building measured on site.

Source energy represents the total amount of raw fuel that is required to operate the building. It incorporates all transmission, delivery, and production losses.

Wood fiber insulation. More information

An exterior cladding formed in place on the wall and made of inorganically bonded sand and small aggregate. Typically Portland cement-based, but with additives of lime, surfactants, water repellents, etc. Source: BSI-029: Stucco Woes—The Perfect Storm; BSI-013: Face Lift for Old Buildings

A resource, energy or material which can be extracted and used in a manner which is viable over an indefinite period. Compare with finite resources like petroleum. Source: Energy Audit Blog

Defined by Dr P. Ole Fanger as "the condition of mind which expresses satisfaction with the thermal environment."  Dr Fanger identified thermal comfort as being determined by: air temperature, 'radiant' temperatures (the temperatures of walls, floor and ceiling), air movement (draughts),(...)

The component or components that are designed and installed in an assembly to control the transfer of thermal energy (heat). Typically these are comprised of insulation products, radiant barriers, or trapped gaps filled with air or other gases. Source: BSI-024: Vocabulary; BSI-001: The(...)

The area of floors, walls, windows and roof or ceiling that contains the building's internal warm / heated volume. Source: The Passivhaus Handbook

An intentional opening used to relieve HVAC supply pressure, preventing unintentional pressurization or depressurization of spaces. Source: Info-604: Transfer Ducts and Grilles; RR-0006: Discussion of the Use of Transfer Grilles to Facilitate Return Air Flow in Central Return Systems

A quantitative measure of heat flow or conductivity; the reciprocal of R-value. While building scientists will use R-values for measures of the resistance to heat flow for individual building materials, U-factor is usually used as a summary metric for the ease of heat transfer through building(...)

Also known as vapor closed, a vapor barrier is a material that has a permeance of 0.1 US perm or less. A vapor barrier is a material that is essentially vapor impermeable (e.g., metal, glass, thick plastics, unperforated epoxy paint). A vapor barrier is a Class I vapor control layer. The test(...)

1. A non-loadbearing layer of masonry on the exterior of an enclosure. 2. A thin slice or sheet of wood or other material that is glued onto a base of wood, fibreboard, or other material to create a flat panel (furniture, counter tops, etc.).  

Wall cladding separated from the framed wall by an air cavity, allowing for ventilation. Source: www.buildingscience.com

WarmFörm™ Slab Forms are remain-in-place, self-shuttering, insulated concrete formwork used to create slab-on-grade foundations.  WarmFörm is based on decades of testing and tens of thousands of installed examples in Northern Europe where it is has evolved as the preferred formwork system, as(...)

A sheet, spray- or trowel-applied membrane or material layer that prevents the passage of liquid water even after long or continuous exposure to moisture. Source: RR-1101: Evaluation of Cladding and Water-Resistive Barrier Performance in Hot-Humid Climates Using a Real-Weather, Real-Time(...)

A manufactured assembly of a frame, sash, glazing and necessary hardware, made to fit an opening in a wall. Components of a window may include the following: Window sill: horizontal member at the base of a window opening. Window head: horizontal member at the top of a window(...)

The stationary part of a window unit; the window sash fits into the window frame. Source: RR-1203: Measure Guideline—Wood Window Repair, Rehabilitation and Replacement

The phenomenon of air movement driven by wind pressures wind passing through or behind the thermal insulation within enclosures, causing significant loss of heat flow control and potentially causing condensation. Typically occurs at exposed building edges, such as at the outside corners and(...)

A net zero building is a building the produces as much energy on site as it consumes on an annual basis. From the DOE: an energy-efficient building where, on a source energy basis, the actual annual delivered energy is less than or equal to the on-site renewable exported energy. Source: US(...)

Any house that averages out to net zero energy consumption. A zero energy home produces as much energy over a year as it consumes, typically using photovoltaics, or combined heat and power (CHP) to generate electricity on site. In a zero energy home, efficiencies in the building enclosure and(...)

See Zero Energy Home (ZEH) and Zero Energy Building (ZEB). Source: Building Science Corporation