NZEB Glossary

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Air-handling units (AHUs) are mechanical indirect heating, ventilating, or air-conditioning systems in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and conveyed to and from the rooms by a fan and a system of distributing ducts. (NEEB, 1997 edition)

Air Source Heat Pumps
A type of heat pump that extracts heat from the outside air and brings it inside the building. Most heat pumps in use today are air source.

Angle of Incidence
The angle created by incoming radiation and a line perpendicular to an intercepting surface.

Ambient Lighting
Lighting in a space that provides for general wayfinding and visual comfort, in contrast to task lighting, which illuminates a defined area to facilitate specific visual work.

American Society of Heating, Refrigeration and Air Conditioning Engineers. The Society and its members focus on building systems, energy efficiency, indoor air quality, refrigeration and sustainability within the industry. Examples of some ASHRAE Standards are:

Standard 55 – Thermal Environmental Conditions for Human Occupancy

Standard 62.1 – Ventilation for Acceptable Indoor Air Quality (versions: 2001 and earlier as “62”, 2004 and beyond as “62.1”)

Standard 62.2 – Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings

Standard 90.1 – Energy Standard for Buildings Except Low-Rise Residential Buildings – The IESNA is a joint sponsor of this standard.

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Biomass is biological material derived from living, or recently living organisms. It most often refers to plants or plant-based materials which are specifically called lignocellulose biomass

Building is  a roofed construction having walls, for which energy is used to condition the indoor climate; a building may refer to the building as a whole or parts thereof that have been designed or altered to be used separately;

Building Footprint
Building footprint is the area on a project site used by the building structure, defined by the perimeter of the building plan. Parking lots, parking garages, landscapes, and other non – building facilities are not included in the building footprint.

Building Envelope
The building envelope is the interface between the interior of the building and the outdoor environment, including the walls, roof, and foundation.

Building Energy Consumption
Building related: Space Heating, cooling and ventilation, Hot water, lighting and other technical installations
User related: Appliances
Construction related: Energy use on construction site

Building Footprint
Is the area on a project site used by the building structure, defined by the perimeter of the building plan. Parking lots, landscapes and other non-building facilities are not included in the building footprint.

Building Life Cycle
Building life cycle refers to the view of a building over the course of its entire life – in other words, viewing it not just as an operational building, but also taking into account the design, construction, operation, demolition and waste treatment

British Thermal Unit (BTU)
A measurement of energy representing the amount of heat needed to raise 1 pound of water by 1 degree Fahrenheit. About the same amount of energy released by a single lit match.

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Carbon  Footprint
carbon footprint is historically defined as “the total sets of greenhouse gas emissions caused by an organization, event, product or person.” The total carbon footprint cannot be calculated because of the large amount of data required and the fact that carbon dioxide can be produced by natural occurrences.

Carbon Offset
A fiscal unit measured in metric tons of carbon dioxide-equivalent (CO2e) representing six main categories of greenhouse gases. Aimed at reducing greenhouse gas emissions, one carbon offset represents the reduction of one metric ton of carbon dioxide (or its equivalent in other greenhouse gases). Carbon offsets are typically purchased by consumers of fossil fuels or products using fossil fuels, as a way to “offset” or negate their negative environmental impact.


A vertical roof window placed that is used for light, ventilation, and to collect heat.

Climate change
a longterm change in the earth’s climate, especially a change due toan increase in the average atmospheric temperature:

The distribution of heat or coolness through a material. The rate of conduction is dependent on the ability of molecules to receive and pass on energy.

Convection (Natural)
Heat transfer through a medium, such as air or water, by currents that result from the rising of lighter, warmed medium and the sinking of heavier, cool medium.

Convection( Forced)
Heat transfer through a medium, such as air or water, by current, caused by a device powered by an external energy source.

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Daylighting as a major effect on the appearance of space and can have considerable energy efficiency implications. Daylighting is achieved by orientations, space organization, location, form, fenestrations, light and thermal characteristics of the glazing materials

Daylight factor, DF
It is defined as the ratio of outdoor illuminance to indoor illuminance. It is a building property that shows how much daylight enters a space through windows or openings in the building envelope. It is in percentage.

Demand Side Management
Demand-side management (DSM), includes energy efficiency and demand response (DR), works from the other side of the equation – instead of adding more generation to the system, it pays energy users to reduce consumption. Utilities pay for demand-side

Demand Side Technology
District energy systems produce steam, hot water or chilled water at a central plant. The steam, hot water or chilled water is then piped underground to individual buildings for space heating, domestic hot water heating and air conditioning. As a result, individual buildings served by a district energy system don’t need their own boilers or furnaces, chillers or air conditioners.

Development Footprint
Is the area affected by development or by project site activity Hardscape, access roads, parking lots, non-building facilities and the building(s) itself are all included in the development footprint.

District Response
Demand response allows energy users of all kinds to act as “virtual power plants,” adding stability to the grid by voluntarily lowering their demand for electricity. Participants in demand response programs get paid for providing demand response capacity.

Double glazed unit (DGU) or Insulated Glass (IG) unit.
Two sheets of glass separated by a structural and impermeable spacer to create a sealed cavity. Air is generally trapped, but air may be replaced by other gases to further improve thermal insulating performance.


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End User
The ultimate consumer; a business or individual that purchases electricity for its own consumption.

Energy Efficiency
The reduction of electrical consumption via upgrades and/or retrofits while retaining the same output or performance.

Energy Conservation Building Code (ECBC)
The Energy Conservation Building Code (ECBC), was launched by Ministry of Power, Government of India in May 2007
The code provides three options for compliance:

  1. Compliance with the performance requirements for each subsystem and system;
  2. Compliance with the performance requirements of each system, but with trade-offs between subsystems; and Building-level performance complianc

Energy Efficiency Index (EEI)
    3. The computation of Energy Efficiency Index aims to raise awareness of the building efficiency of the Proposed Model against the Actual Building’s performance so that building owners can gauge and set targets for improvement over time.

Energy Performance of a building
means the calculated or measured amount of energy needed to meet the energy demand associated with a typical use of the building, which includes inter alia energy used for heating, hot water, cooling, ventilation and lighting;

Energy from Renewable Sources”
means energy from renewable non fossil sources, namely wind, solar, aero thermal, geothermal, hydrothermal and ocean energy, hydropower, biomass, landfill gas, sewage treatment plant gas and biogases;

Electricity Grid
An electric grid is a network of synchronized power providers and consumers that are connected by transmission and distribution lines and operated by one or more control centres. When most people talk about the power “grid,” they’re referring to the transmission system for electricity.

ENERGY STAR is a U.S. Environmental Protection Agency (EPA) voluntary program that helps businesses and individuals save money and protect our climate through superior energy efficiency. To maintain consumer trust and improve the oversight of ENERGY STAR certified products, homes, and commercial facilities, EPA has implemented third–party certification requirements and testing.

Embodied Energy
Embodied energyis defined as the energy used during the entire life cycle of a product including the energy used for manufacturing, transporting, and disposing of the product.

This term refers to the movement of water to the air (evaporation) and the movement of water within a plant and the subsequent loss of water as vapour through its leaves (transpiration).

Evaporative Cooling
Evaporative Cooling lowers indoor air temperature by evaporating water. It is effective in hot and dry climate where the temperature humidity is low. In evaporative cooling, the sensible heat of air is used to evaporate water, thereby cooling the air

 is the energy that is available to be used. After the system and surroundings reach equilibrium, the exergy is zero. Determining exergy was also the first goal of thermodynamics

Extensive Green Roofs
Green roofs not designed for public use and mainly developed for aesthetic and ecological benefits.

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Final energy
Form of energy available to the user following the conversion from primary energy carriers – crude oil, natural gas, nuclear energy, coal, regenerative energies. Final forms of energy include, among others, heating oil, fuels, gas, current, district heat. Final energy consumption covers energy supplied to the final consumer for all energy uses

Fossil Fuels
Fossil fuel is a general term for buried combustible geologic deposits of organic materials, formed from decayed plants and animals that have been converted to crude oil,coal, natural gas, or heavy oils by exposure to heat and pressure in the earth’s crust over hundreds of millions of years.

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GHG emissions
Gases that trap heat in the atmosphere are called greenhouse gases.Carbon dioxide enters the atmosphere through burning fossil fuels (coal, natural gas and oil), solid waste, trees and wood products, and also as a result of certain chemical reactions (e.g., manufacture of cement). 

A phenomenon wherein an occupant or observer experiences visual discomfort, which sometimes contributes to temporary visual impairment. It is caused by strong contrasts or large ratio of luminance between surfaces.

A glass, plastic or transparent/translucent covering.

Is a site not previously developed or graded that could support open space, habitat or agriculture.

Greenhouse Effect:
The build-up of heat in an interior space caused by energy input through a transparent membrane such as glass.

Green Space
Are areas that are vegetated, pervious and ‘on grade’. It is usually calculated as the site area minus the development footprint. Roof gardens are not counted as green space (see ‘open space’). 

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Hard Coats
Coatings applied to glass that are generally more robust than soft coats being applied directly to the molten glass in the float process.

Consists of the inanimate elements of the building landscape. Examples include pavements, roadways, stone walls, concrete paths and sidewalks, concrete, brick and tile patios or plazas, etc.

Heat Capacity:
A measurement of the specific heat of a material multiplied by its density. See “specific heat.”

Heat Sink:
A body which is capable of accepting and storing heat or cool and, therefore, may also act as a delayed heat source.

High performance glazing
By definition, high-performance windows need to perform better than conventional window system. They need to exhibit superior thermal control related to heat transfer, solar transfer, Visible light transmission and air infiltration.

Heating, Ventilating, and Air Conditioning) is the technology of indoor and vehicular environmental comfort. Its goal is to provide thermal comfort and acceptable indoor air quality. HVAC system design is a sub discipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics, and heat transfer.

Hybrid Solar System:
A system that combines passive solar collection with active elements for transport of heat to an isolated storage system.

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The uncontrolled flow of air into, and out of, a building through cracks, openings, doors, or other areas which allow air to move.

Insolation (Incident Solar Radiation):
A term denoting the amount of solar radiation (all wavelengths) which strikes the earth. The basic unit of measurement is the Langley, a unit of heat energy equivalent to one calorie falling on one square centimetre of surface. One BTU per square foot is the equivalent of 0.27125 Langley.

Thermal insulation is the reduction of heat transfer (the transfer of thermal energy between objects of differing temperature) between objects in thermal contact or in range of radiative influence.

Intensive Green Roofs
Green roofs developed to be accessible to the public. They are also known as roof gardens.

A reversal of the normal atmospheric situation where the temperature decreases with height. Under inversion conditions, the atmosphere actually gets warmer with height. Atmospheric conditions associated with inversion conditions are the absence of wind and hazy, smoggy views associated with trapped air pollutants.

ISO 7730:2005
Ergonomics of the thermal environment — Analytical determination and interpretation of thermal comfort using calculation of the PMV and PPD indices and local thermal comfort criteria

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Low Emissivity (Low-E)
The effect of a low-e coating is to reduce the radiation of long wave length energy or emissions. However, it is increasingly used as a general term for all performance coatings to glass that change the glasses reflectance, absorption and transmission properties.

Measurement of lumens per square meter.

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Measurement and Verification
Measurement and Verification refers to the process and activity associated with ensuring a particular energy efficiency measure or system improvement is producing the expected results.

The climate of a defined local area, such as a house or building site, formed by a unique combination of wind, topography, solar exposure, soil and vegetation of the site.

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Nearly Zero Energy Buildings (NZEBs)
Net Zero Energy Building is a building with greatly reduced energy demand that allows the energy demand to be balanced by an equivalent generation of electricity (or other energy carriers) from renewable sources. A NZEB is connected to one or more energy infrastructures; electricity grid, district heating and cooling system, gas pipe network, biomass and biofuels distribution networks.

Net Zero Site Energy
A site ZEB produces at least as much energy as it uses in a year, when accounted for at the site.

Net Zero Source Energy
A source ZEB produces at least as much energy as it uses in a year, when accounted for at the source. Source energy refers to the primary energy used to generate and deliver the energy to the site. To calculate a building’s total source energy, imported and exported energy is multiplied by the appropriate site-to-source conversion multipliers

Net Zero Energy Costs
In a cost ZEB, the amount of money the utility pays the building owner for the energy the building exports to the grid is at least equal to the amount the owner pays the utility for the energy services and energy used over the year.

Net Zero Energy Emissions
A net-zero emissions building produces at least as much emissions-free renewable energy as it uses from emissions-producing energy sources.

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Open Space
Are areas that are pedestrian oriented and are not part of the building footprint or fully enclosed spaces (i.e. can be semi-enclosed). Examples include green space, roof gardens, amphitheatres and hardscape plaza areas.

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Passive Cooling Strategies


Primary energy
Primary energy
 is an energy form found in nature that has not been subjected to any conversion or transformation process. It is energy contained in raw fuels, and other forms of energy received as input to a system. Primary energy can be non-renewable or renewable. Examples of primary energy resources include coal, crude oil, sunlightwind, running rivers, vegetation, and uranium.

Passive Solar Design
The key to designing a passive solar building is to best take advantage of the local climate. Elements to be considered include window placement and size, and glazing type, thermal insulation, thermal mass, and shading. Passive solar design techniques can be applied most easily to new buildings, but existing buildings can be adapted or “retrofitted”.

Water, in either liquid or solid form, which falls from clouds. Includes rain, hail, sleet, snow, etc.

Predicted Mean Vote (PMV)
The PMV index predicts the mean response of a larger group of people according to the ASHRAE thermal sensation scale where
+3 hot
+2 warm
+1 slightly warm
0 neutral
-1 slightly cool
-2 cool
-3 cold

Percentage of People Dissatisfied (PPD)
Predicted Percentage Dissatisfied – PPD – index is a quantitative measure of the thermal comfort of a group of people at a particular thermal environment.

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Radiant Energy
Low temperature infrared energy emissions from the sun.

Along with convection and advection, one of the three major processes in transferring heat energy from place to place. In the radiation process, heat is transferred in the form of waves of energy. The sun transfers its heat and light energy to the earth by this process. The earth loses heat to space by this process.

Recycled material
Recyclable materials include many kinds of glass, paper, metal, plastic, textiles, and electronics. The composting or other reuse of biodegradable waste—such as food or garden waste—is also considered recycling.

Relative Humidity:
A measure of the ability of air to hold gaseous water vapour. The warmer the air, the more water it can hold. Relative humidity is usually expressed as a percentage of saturation: 0% = totally dry air, and 100% = fully saturated air. Relative humidity becomes important for human comfort as at high values perspiration is not readily evaporated and thus discomfort is felt. Relative humidity is also important from the standpoint of the atmosphere’s ability to lose heat to space at night (water vapour absorbs and retains heat exceedingly well). Drier climates thus have a greater potential for night ventilation cooling than do more humid ones.

renewable energy sources
Renewable energy is generally defined as energy that comes from resources which are naturally replenished on a human timescale such as sunlightwindraintideswaves and geothermal heat

Roof Ponds:
Passive heating/cooling system. Enclosed water above and in immediate contact with ceiling elements, with movable insulation, which expose ponds to the winter sun for heating, and to the night sky for summer cooling.

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Solar Energy
Solar energy
 is radiant light and heat from the sun harnessed using a range of ever-evolving technologies such as solar heating, photovoltaics, solar thermal energysolar architecture and artificial photosynthesis.

Solar water heating system
Solar water heating 
(SWH) is the conversion of sunlight into renewable energy for water heating using a solar thermal collector. Solar water heating systems comprise various technologies that are used worldwide increasingly.

Soft Coats
Coatings applied to glass sheets individually once they have been cut into the required or a manageable size. Some can be heat processed, but generally are susceptible to damage and are generally used inside DGU.

Shading coefficient (SC)
A property that quantifies a window’s ability to transmit solar heat, as compared to a base case of 6 mm clear single glazing. It is expressed as a number between 0 and 1; the lower the SC, the less heat gets transmitted through the window. It is unit-less.

Solar Heat Gain Coefficient (SHGC)
The SHGC is the fraction of incident solar radiation admitted through a window, both directly transmitted and absorbed and subsequently released inward. SHGC is expressed as a number between 0 and 1. The lower a window’s solar heat gain coefficient, the less solar heat it transmits.

Solar Constant:
The amount of heat energy delivered by solar radiation to a square foot of material set perpendicular to the sun’s rays for one hour at the outer edge of the earth’s atmosphere.

Solar Radiation:
See “insolation.”

Solar Reflectance Index (SRI)
It is a value that incorporates the two radiative properties above, with a single value produced to represent a material’s temperature in the sun.  SRI is measured on a scale from 0-100 or 0%-100%.  Zero refers to a temperature as hot as a black surface, while 100 refers to a temperature as cool as a white surface

Solar reflectivity or Albedo
This measures a roof’s ability to reflect sunlight and heat away from a building.  It is rated on a scale from 0 to 1 (or 0%-100%), with higher values representing a cooler roof. 

Specific Heat:
The amount of heat, measured in BTU’s for a given mass. A material can hold when its temperature is raised one degree Fahrenheit.

Spectrally selective glass
A tinted or coated glazing that has solar/optical properties which vary across the solar spectrum. Typically these glazing’s have high transmission of visible light but low transmission of solar gains. Spectrally-selective glazing’s are best suited to buildings that require high light levels and have a long cooling season.

Sub metering is used to determine the proportion of energy use within a building attributable to specific end uses or subsystems (e.g., the heating subsystem of an HVAC system).

Sun Spaces
A sunspace or solarium is the combination of direct and indirect gain systems. Solar radiation heats up the sunspace directly, which, in turn, heats up the living space (separated from the sunspace by a mass wall) by convection and conduction through the mass wall.

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Thermal Chimney:
An air heating device that provides a constant vacuum which may be used to vent the house, bring warm air from collectors, or pull air from cool towers, earth tubes or rock bed coolers. This creates what is called a “stack effect.”

Thermal Comfort
A state in which an occupant feels satisfied with his environment; it is affected by five major factors – air temperature, mean radiant temperature, humidity, air velocity, clothing level, and activity level.

Thermal Emittance
This refers to a roof’s ability to release absorbed heat.  A high thermal emittance is preferable in warmer areas so that the heat is not held within the roof and, therefore, the building.  Thermal emittance is also rated on a scale from 0 to 1 or 0%-100%.

Thermal Energy
Heat energy

Thermal Insulator
material that provides a high resistance to heat flow

Thermal Storage Mass:
A thermal element that has heat or cooling storage capacity in a given assembly or system. Water storage tanks. Concrete floors, rocks, and masonry are examples of thermal mass.

Trombe Wall
A concrete, stone or masonry wall that has vents at regular intervals both along the floor and just below the ceiling. The exterior. South-facing side is dark in colour and fronted with glass. Air is warmed between the glass and wall and circulates by convection through the vents. It is named after Dr. Felix Trombe, one of its developers.

Tvis-glass indicates the percentage of the visible portion of the solar spectrum that is transmitted through a given glass product.

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Urban Heat Island Effect
Urban heat island effect refers to the elevated temperatures in developed areas compared to more rural surroundings. Urban heat islands are caused by development and the impact from buildings on the local micro-climate. For example, tall buildings can slow the rate at which cities cool off at night. It refers to the absorption of heat by hardscapes such as dark, non-reflective pavements and buildings and its radiation to surrounding areas. Particularly in urban areas, other sources may include vehicle exhaust, air-conditioners and street equipment; reduced air flow from tall buildings and narrow streets exacerbates the effect.

Overall heat transfer coefficient, expressed in W/m²K; a property that quantifies a material or construction’s ability to conduct heat. The higher the u-value, the more heat passes through the material.

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Visible Light Transmittance (VLT)
The percentage of visible light that passes through a window or other glazing unit is called the Visible Light Transmittance (VLT). An opaque wall would have a VLT of 0%, while an empty opening would have 100%.

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Window-to-wall ratio (WWR)
The proportion of window area to total wall area, expressed as a number between 0 and 1.unit-less

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