Sharing Transparency for a More Efficient Future

Glossary of Building Rating Terms

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Lack of Capacity

The inability to to do, produce or understand something.

Lack of Enforcement

The lack of observance of a particular piece of legislation. [Source: GBPN]

Lambda Value

The lambda value (thermal conductivity) of an insulation material is a measure of its ability to prevent the passage of heat at a particular thickness, in defined conditions. [Source: Isover]

Landscape Engineers

The landscape engineers are not only planners / designers of the open-spaces neighbouring the building but also contribute to the planning, urban and architectural studies. [Source: IEA Annex 31 Glossary]


The energy market’s common way of dealing with initial cost barriers is leasing. Leasing is suited to situations where physical assets form the bulk of the expenditure (rather than labour services), and where use of the asset may be denied the ultimate owner in the event of default. Leasing is an off‐balance sheet form of financing. [Source: IEA (2010) Money Matters]

Life Cycle

Consecutive and interlinked stages of a product system, from raw material acquisition or generation of natural resources to the final disposal (ISO 40). [Source: IEA Annex 31 Glossary]

Life Cycle Assessment

A concept and a method to evaluate the environmental effects of a product holistically, by analysing its entire life cycle.This includes identifying and quantifying energy and materials used and wastes released to the environment, assessing their environmental impact, and evaluating opportunities for improvement (CAN 94). [Source: IEA Annex 31 Glossary]

Life Cycle Impact Assessment

The phase of LCA aimed at understanding and evaluating the magnitude and significance of the potential environmental impacts of a product system. The main difference between LCA and LCIA is the focus on potential. [Source: IEA Annex 31 Glossary]

Life Cycle Interpretation

The phase of LCA in which the findings of either the inventory analysis or the impact assessment, or both, are combined consistent with the defined goal and scope in order to reach conclusions and recommendations (ISO 40, ISO 98). [Source: IEA Annex 31 Glossary]

Life Cycle Inventory Analysis

The phase of LCA involving the compilation and quantification of inputs and outputs, for a given product system throughout its life cycle (ISO 40). [Source: IEA Annex 31 Glossary]


The apparatus for supplying artificial light.

Lighting systems

Process of supplying the necessary illumination. [Source: EN 15603 Energy performance of buildings - Overall energy use and definition of energy ratings]

Living Floor Area

Total area of rooms falling under the concept of rooms. [Source: OECD Glossary of Statistical Terms]

Lock-in Effect

Describes the energy savings which are not going to be realized due to un-ambitious and insufficiently stringent energy requirement targets for buildings, building element and equipment. [Source: IEA Glossary]

Loss Utilization Factor

Factor reducing the total monthly or seasonal heat transfer in the monthly or seasonal calculation method, to obtain the resulting reduction of the energy need for cooling. [Source: International ISO Standard 13790- Energy performance of buildings — Calculation of energy use for space heating and cooling (2008)]

Low Energy Building

Low energy building indicates a building that has a better energy performance than the standard alternative/energy efficiency requirements in building codes. Low-energy buildings typically use high levels of insulation, energy efficient windows, low levels of air infiltration and heat recovery ventilation to lower heating and cooling energy. They may also use passive solar building design techniques or active solar technologies. These homes may also use hot water heat recycling technologies to recover heat from showers and dishwashers. [Source: European Commission (2009)]

Low Energy Windows

A low energy window is a window that significantly reduces the amount of heat lost by heat transfer across a part of the building envelope by increasing the number of window panes separated by air or other gas filled space.