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Glossary of Building Rating Terms

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Calculation Methodology

Presumptions, and inputs used to attain an asset rating. In the EU, national policies for energy performance certification are required to develop an official methodology under the EPBD legislation. [Source: Institute for Market Transformation]

Calculation with Coupled Zones

Multi-zone calculation with thermal coupling between zones, taking into account any heat transfer by thermal transmission and/or by ventilation and/or by air infiltration between zones. [Source: International ISO Standard 13790- Energy performance of buildings — Calculation of energy use for space heating and cooling (2008).]

Calculation with Uncoupled Zone

Multi-zone calculation without thermal coupling between zones, not taking into account any heat transfer by thermal transmission or by ventilation or by air infiltration between zones. [Source: International ISO Standard 13790- Energy performance of buildings — Calculation of energy use for space heating and cooling (2008).]

Carbon Dioxide

Carbon dioxide (CO2) is a colourless, odourless and non-poisonous gas formed by combustion of carbon and in the respiration of living organisms and is considered a greenhouse gas. Emissions means the release of greenhouse gases and/or their precursors into the atmosphere over a specified area and period of time. [Source: OECD Glossary]


Cooling Degree-Days are the number of degrees per day that the daily average temperature is above a given temperature (18°C or 65°F). This temperature is the point above which the consumer is assumed to use energy for space cooling. During the cooling season, warmer-than-normal temperatures tend to lead to increased electricity use, with increased demand for electricity often met by incremental use of oil products and natural gas.[Source: IEA, Oil Market Report Glossary]

Central Government

Central government means all administrative departments whose competence extends over the whole territory of a Member State. [Source: EU Directive 2012/27/EU on Energy Efficiency]

Climate Change

A change in the state of the climate that can be identified (e.g., by using statistical tests) by changes in the mean and/or the variability of its properties and that persists for an extended period, typically decades or longer. Climate change may be due to natural internal processes or external forcings, or to persistent anthropogenic changes in the composition of the atmosphere or in land use. [Source: IPCC - Annex II Glossary of Terms]

Climate Shell

The integrated elements (walls, windows, roofs, skylights, etc.) and materials (insulation, vapour barriers, siding etc.) that enclose a building. The building envelope is the thermal barrier between the indoor and outdoor environments and is a key factor in the sustainability of a building. A well-designed building envelope will immunise energy consumption for cooling and heating, and promote the influx of natural light. [Source: IEA Glossary]

Climate Works

The ClimateWorks Foundation supports public policies that prevent dangerous climate change and promote global prosperity. ClimateWorks partners with an international network of affiliated organizations—the ClimateWorks Network—to support smart policies in the geographic regions and economic sectors that have the greatest potential for reducing greenhouse gas emissions. The Network’s goal is to inspire adoption of effective policies to limit annual global greenhouse gas emissions to 44 billion metric tons by the year 2020 (a reduction of 17 billion metric tons, or about 25 percent below business-as-usual projections), and 35 billion metric tons by the year 2030 (50 percent below projections). [Source: Climate Works]

Climate Zones

Climate classifications are often based on the Köppen Climate Classification system, which proposes six general climate types: A) tropical, B) dry, C) mild latitude, D) serves latitude, E) polar and H) for highland. Each of these classes is divided into sub categories according to the type of winter or summer. The 6 basic climates is subdivided at least 23 different sub-climates. The Köppen climate classification has been the basis for different systems of building energy efficiency regulations setting up different requirements for different climatic zones. [Source: Laustsen (2009) Energy Efficiency Requirements in Building Codes, Energy Efficiency Policies for New Buildings]


The benefits of policies implemented for various reasons at the same time, acknowledging that most policies designed to address greenhouse gas mitigation have other, often at least equally important, rationales (e.g., related to objectives of development, sustainability, and equity). The term co-impact is also used in a more generic sense to cover both positive and negative side of the benefits. [Source: UNFCC]


Cogeneration means the simultaneous generation in one process of thermal energy and electrical or mechanical energy. [Source: EU Directive 2012/27/EU on energy efficiency]

Cogeneration Unit

Cogeneration unit means a unit that is able to operate in cogeneration mode. [Source: EU Directive 2012/27/EU on Energy Efficiency]

Combined Heat and Power

A system by which multiple usable energy outputs (both electricity and steam/heat) are derived from a single fuel supply using an integrated system. [Source: ACEEE Glossary]

Commercial Buildings

A commercial building is a building that is used for commercial use. Types can include office buildings, warehouses, or retail (i.e. convenience stores, ‘big box’ stores, shopping malls, etc.) [Source: BPIE]


Commissioning is a quality assurance process for new construction projects that begins with pre-design and continues through design, construction, and early operation. Commissioning is intended to ensure that building systems and equipment have been designed, installed, and tested to perform in accordance with the design intent. [Source: ACEEE Glossary]


Compliance is whether and to what extent countries adhere to the provisions of an accord or individuals or firms adhere to regulations. Compliance depends on implementing policies ordered, and on whether measures follow up the policies. [Source: IPCC - Annex I Glossary of Terms]

Conditioned Floor Area

Space within a building provided with heated or cooled air, or both (or surfaces); and, where required, with humidification or dehumidification means, to maintain conditions for an acceptable thermal environment. (US) [Source: ASHRAE]

Construction Industry

A branch of commercial enterprise concerned with the construction of buildings, bridges, etc [Source: Collins Dictionary]

Construction Surveyors

The construction / quantity surveyors use construction costs data bases to assess if a project cost is realistic regarding a given budget.They can also estimate the indirect costs of a construction, by establishing a relationship between investment budget and operating budget, etc. [Source: IEA Annex 31 Glossary]

Consumption based rating

An energy rating based on measured amounts of delivered and exported energy. NOTE: The measured rating is the weighted sum of all energy carriers used by a building, as measured by meters or other means. It is a measure of the in-use performance of a building. This is particularly relevant to certification of actual energy performance. [Source: CEN Standard - EN 15217 Energy Performance of Buildings - Methods for expressing energy performance and the energy certification of buildings]

Contingency Financing

In contrast to the financing mechanisms described above, contingent financing represents money not included in the balance sheet. That sort of financing is usually a cushion buffer provision in case something goes sour in the process, or an extensive liability happens. Contingency financing is usually provisioned for such events as lawsuit settlements, provision for default payment, etc. In the case of energy efficiency financing, contingency financing can be a useful provision for capacity building as well as potential default, risk guarantee provision. [Source: IEA (2010) Money Matters]


The contractors are the builders and installers working on the building site (e.g. general and trade-specific contractors, artisans, etc.) [Source: IEA Annex 31 Glossary]

Control Offices

The control offices are in a broad sense the engineers and technicians commissioned to control the quality and check the safety (conformity controls, project documentation checking and on-site construction checking). [Source: IEA Annex 31 Glossary]

Cooled Space

Room or enclosure, which for the purposes of a calculation is assumed to be cooled to a given set-point temperature or set-point temperatures. [Source: International ISO Standard 13790- Energy performance of buildings — Calculation of energy use for space heating and cooling (2008).]


The process of supplying or removing air by natural or mechanical means to or from any space. Such air is not required to have been conditioned. [Source: ASHRAE]

Cooling Systems

Apparatus for lowering the temperature of a space or product to a specified temperature. [Source: ASHRAE]

Cooperative Electric Utility

An electric utility legally established to be owned by and operated for the benefit of those using its service. The utility company will generate, transmit, and/or distribute supplies of electric energy to a specified area not being serviced by another utility. Such ventures are generally exempt from federal income tax laws. Most electric cooperatives have been initially financed by the Rural Utilities Service (previously the Rural Electrification Administration), U.S. Department of Agriculture. [Source: EIA Glossary]

Cost Effectiveness

A measure or package of measures is cost-effective when the cost of implementation is lower than the value of the benefits that result, taken over the expected life of the measure. (EU) [Source: EPBD].

Cost Optimal Level

Cost-optimal level means the energy performance level which leads to the lowest cost during the estimated economic lifecycle [Source: EPBD, recast, 2010/31/EC]