Glossary of building energy terms
The terms used in energy certification and in project verification, in Romanian and English. Under each definition is the legal act it comes from; the text of the act remains the source, the glossary only explains it.
Heat and moisture transfer
- Bulk density
- The mass of a material divided by its total volume, pores included. It matters for thermal inertia and for behaviour under moisture.
- Corrected thermal resistance
- The thermal resistance of an element once the effect of thermal bridges and non-uniformities in the undisturbed area is taken into account.
- Correction factor
- A factor that adjusts the heat flow through an element when the temperature on the other side differs from the outdoor one, for example towards an unheated space.
- External thermal insulation composite system
- An insulation system applied to the outer face of walls, made of insulation boards bonded or mechanically fixed, reinforced and finished with a thin render.
- Glaser method
- A steady-state calculation procedure that compares the actual vapour pressure with the saturation pressure through the layers of an element, to locate zones of interstitial condensation.
- Glazing
- The transparent part of an envelope element, made of one or more panes of glass, possibly with special coatings and gas-filled cavities.
- Heat flow rate
- The amount of heat passing through a surface per unit of time, driven by a temperature difference.
- Internal and external surface resistance
- Thermal resistances of the air layers next to the faces of an element, accounting for heat exchange by convection and radiation at the surface.
- Interstitial condensation
- Condensation of water vapour inside the layers of a building element, where the temperature falls below the dew point. It can damage the insulation and the structure.
- Linear thermal bridge
- A thermal bridge with a constant cross-section along a length, for instance at the corner of two walls or at the junction with a floor. The extra loss is expressed per metre of length.
- Opaque element
- A part of the envelope that does not let light through, such as a wall, floor or roof, as opposed to glazing.
- Permissible accumulated moisture
- The maximum permitted increase in the moisture content by mass of the material where condensate accumulates, over the condensation period.
- Point thermal bridge
- A thermal bridge localised at a single point, such as a metal anchor or a column that breaks through the insulation. The extra loss is expressed per point.
- Shading factor
- A coefficient that reduces the solar gain through glazing because of obstructions such as neighbouring buildings, trees, parapets or facade elements.
- Solar heat gain coefficient
- The fraction of incident solar radiation that reaches the interior through the glazing, as energy transmitted directly and as energy released by the glass after it has warmed up.
- Specific heat capacity
- The amount of heat needed to raise the temperature of a unit mass of a material by one degree. It shows how easily the material warms up or cools down.
- Surface condensation
- Water deposited on the inner surface of a cold element when humid air meets a surface below the dew point. It encourages mould growth.
- Temperature factor at the internal surface
- A dimensionless quantity comparing the inner surface temperature with the difference between indoor and outdoor temperature. It is used to assess the risk of surface condensation and mould.
- Thermal bridge
- A zone of the envelope where heat flow is stronger than in the undisturbed area, because of geometry or a material of higher conductivity. It causes extra losses and cold surfaces.
- Thermal conductivity
- A material property expressing how well it conducts heat. The lower the value, the better the material insulates.
- Thermal insulation
- A layer or assembly of materials with low thermal conductivity, installed to reduce heat exchange between inside and outside.
- Thermal resistance
- The ability of a layer or element to resist the passage of heat. The resistance of an element is the sum of the resistances of its layers.
- Thermal transmittance
- The heat flow passing through one square metre of an element for a temperature difference of one degree between the two environments. It is the inverse of the total thermal resistance.
- Vapour barrier
- A layer with high resistance to the passage of water vapour, placed in the build-up of an element to limit moisture moving from the indoor air towards the cold layers.
- Vapour diffusion
- The movement of water vapour through a building element, from the side with higher vapour pressure towards the side with lower vapour pressure.
- Water vapour diffusion-equivalent air layer thickness
- The thickness of a still air layer that offers the same resistance to water vapour as the layer of material considered.
- Water vapour permeability
- A material property expressing how easily water vapour passes through it under a pressure difference.
- Water vapour resistance factor
- A dimensionless number showing how many times more a material resists the passage of water vapour than still air does.
- Windows and doors (joinery)
- The set of external windows and doors, with their frames, sashes and seals. Together with the glazing, it is the envelope element with the highest losses per unit area.
Energy and classification
- Climatic zone
- A part of the territory for which the same climatic calculation data are used, according to the typical winter outdoor temperatures.
- CO2 emission factor
- The amount of carbon dioxide emitted for each unit of energy consumed from a given carrier. It is used to calculate the emissions of a building.
- Design indoor temperature
- The conventional indoor air temperature, set according to the use of the space, used in the thermal balance of the building.
- Design outdoor temperature
- The conventional outdoor air temperature, set by climatic zone, used to calculate heat losses and size the installations.
- Energy balance
- The comparison between the energy supplied to the building, the energy produced on site, and the losses or uses for each purpose, over a calculation period.
- Energy class
- The category in which a building is placed on the rating scale, according to its energy performance indicator.
- Energy performance of a building
- The calculated energy, according to the methodology, needed to use the building under standardised conditions, including heating, hot water, cooling, ventilation and lighting.
- Energy rating scale
- A graded graphic scale, from the most efficient buildings to the least efficient, used in the certificate to place the building.
- Final energy
- The energy delivered to the building at the delivery point, as electricity, fuel or heat, without the losses of the production and transport chain (these only enter into primary energy).
- Heat losses
- Heat leaving the building by transmission through the envelope and by ventilation or air infiltration.
- Heating degree days
- A climate indicator that adds up, over the cold season, the differences between the reference indoor temperature and the outdoor temperature. It shows how harsh the winter is in a given locality.
- Internal heat gains
- Heat released indoors by occupants, electrical appliances, lighting and other sources, which reduces the heating demand and increases the cooling demand.
- Lighting energy use
- The electricity used by artificial lighting installations. It forms part of the energy performance of the building.
- Nearly zero-energy building
- A building with very high energy performance, whose low energy demand is covered to a significant extent by renewable sources.
- Non-renewable primary energy
- The part of the primary energy that comes from exhaustible sources, such as natural gas, crude oil, coal or nuclear fuel.
- On-site energy production
- Energy generated on the building plot or nearby, for example by photovoltaic panels, and used directly or exported to the grid.
- Primary energy
- Energy from renewable and non-renewable sources that has undergone no conversion or transformation process. For a building it is obtained from the delivered energy through conversion factors covering extraction, transformation and transport.
- Primary energy factor
- A coefficient used to convert the final energy of a carrier (gas, electricity, district heating and so on) into primary energy. It reflects the efficiency of the production chain.
- Renewable energy ratio
- The share of primary energy coming from renewable sources, relative to the total primary energy of the building. It shows how much of the consumption is covered without exhaustible resources.
- Renewable primary energy
- The part of the primary energy that comes from sources that renew themselves, such as the sun, wind, water, biomass or ambient heat.
- Solar heat gains
- Heat entering the building from solar radiation, mainly through glazing but also through opaque elements warmed by the sun.
- Space cooling energy need
- The energy that must be removed from the spaces to maintain the comfort temperature in the warm season, driven mainly by solar and internal gains.
- Space heating energy need
- The energy that must be supplied to the spaces to maintain the comfort temperature, after subtracting the solar and internal gains from the building losses.
- Specific energy consumption
- The energy used in a year divided by the useful floor area. It allows buildings of different sizes to be compared.
- Thermal inertia
- The ability of a building to store heat and release it gradually, which smooths out variations in indoor temperature.
- Useful floor area
- The area of the rooms actually used, taken as the reference for expressing energy use per square metre.
Systems and renewables
- Air conditioning system
- An assembly that treats the air in rooms to control its temperature and, sometimes, its humidity and cleanliness.
- Biomass
- Fuel of plant or animal origin, such as wood, pellets or briquettes, regarded as a renewable energy source.
- Coefficient of performance
- The ratio between the useful heat delivered by a heat pump and the electrical energy it consumes, in a given operating state.
- Cogeneration
- The simultaneous production, in the same process, of thermal energy and of electrical or mechanical energy.
- Condensing boiler
- A boiler that recovers latent heat from the water vapour in the flue gases, which raises its efficiency, especially at low heating medium temperatures.
- District heating
- Supplying several buildings with heat produced centrally and distributed through a pipe network.
- Domestic hot water
- Water heated for household use, at showers, sinks and other draw-off points. A separate energy use is calculated for it, distinct from heating.
- Efficiency
- The ratio between the useful energy obtained and the energy consumed by an item of equipment or a part of the installation.
- Heat distribution system
- The network of pipes, pumps and fittings that carries the heating medium from the generator to the heat emitters. Its losses are accounted for separately.
- Heat emission system
- The equipment through which heat or cooling reaches the room, such as radiators, convectors or underfloor heating.
- Heat generator
- Equipment that produces heat for space heating or hot water, for example a boiler, a heat pump or a heat exchanger connected to the district heating network.
- Heat pump
- Equipment that takes heat from a low-temperature source (air, ground, water) and releases it at a higher level, using electrical energy.
- Heat recovery
- Taking heat from the exhaust air and transferring it to the fresh air supplied, which reduces ventilation losses.
- Heating control
- The set of devices that adapt the heat supplied to the demand, for example thermostats, thermostatic valves and outdoor-temperature-compensated controllers.
- Individual apartment boiler
- A low-power heat generator serving a single apartment, for heating and usually for hot water.
- Mechanical ventilation
- Renewing the air in the building with fans, which allows airflows to be controlled and, where needed, heat to be recovered.
- Natural ventilation
- Renewing the air by opening windows, through leaks or through purpose-made openings, driven by wind and temperature difference.
- Peak power
- The maximum power of a photovoltaic system under standard test conditions. It is used to size the system and compare it with others.
- Photovoltaic system
- An assembly of panels and electrical equipment that converts solar radiation directly into electricity.
- Radiator
- A device that releases heat from the heating medium into the room, by convection and radiation.
- Renewable energy
- Energy from sources that renew themselves naturally, such as solar, wind, hydro, geothermal or biomass.
- Seasonal coefficient of performance
- The ratio between the heat delivered by a heat pump and the energy consumed, calculated over a whole heating season rather than at a single operating point.
- Seasonal energy efficiency ratio
- The ratio between the cooling delivered by a cooling system and the electrical energy consumed, calculated over a whole cooling season.
- Solar thermal collector
- A device that captures solar radiation and turns it into heat transferred to a heating medium, usually for domestic hot water.
- Thermal storage tank
- An insulated tank in which hot water or heating medium is stored, so that heat production is decoupled from the moment of consumption.
- Underfloor heating
- An emission system in which coils carrying heating medium, embedded in the floor, warm the room mainly by radiation, at low temperatures.
The building and the climate
- Air infiltration
- Uncontrolled entry of outdoor air through leaks in the envelope, which increases heat losses and can cause discomfort.
- Airtightness
- The extent to which the envelope prevents uncontrolled air passing through cracks, joints and junctions. An airtight building has low infiltration.
- Apartment building
- A building with several apartments stacked above one another, with common areas such as the staircase, corridors and, sometimes, a technical basement.
- Basement
- A level located mostly below ground level. It may be heated or unheated, and its walls are in contact with the soil.
- Building compactness
- The ratio between the envelope area and the heated volume. A more compact building loses less heat per unit of volume.
- Building envelope
- The set of elements separating the heated space from the outdoors, the ground or unheated spaces: walls, floors, roof, windows and doors.
- Building height classification
- The number of storeys above ground of the building, counted from the ground floor, including the semi-basement, the attic storey and the technical floor.
- Ceiling below attic
- The floor separating the top heated level from the unheated attic. It is usually insulated on the attic side.
- Climatic data
- The temperature, solar radiation, humidity and wind values of a locality, used as input data in the energy calculation.
- Facade
- Each of the vertical outer faces of the building, comprising opaque parts and glazed openings.
- Flat roof
- A flat roof, or one with a very slight slope, with waterproofing and, as a rule, a layer of thermal insulation above the floor slab.
- Floor over basement
- The floor separating the first occupied level from an unheated or partly heated basement. The losses through it depend on the basement temperature.
- Ground floor
- The level of the building at or very close to ground level. Its floor may rest on the ground or over a basement.
- Heated space
- A room or group of rooms in which a comfortable indoor temperature is maintained by heating installations.
- Heated volume
- The volume of the heated interior spaces, bounded by the building envelope. It is used to calculate ventilation and compactness.
- Orientation
- The direction a facade or glazing faces. It determines how much solar radiation it receives.
- Parapet
- The low wall running around the edge of a flat roof. Its zone is often a thermal bridge and a point sensitive to water ingress.
- Relative humidity
- The ratio between the amount of vapour in the air and the maximum amount the air can hold at the same temperature.
- Roof framing
- The structure of timber or another material that supports the covering of a pitched roof.
- Single-family house
- A building intended for a single family, with its own entrance, either detached, terraced or semi-detached.
- Solar radiation
- Energy emitted by the sun and received by the building surfaces, partly direct and partly diffuse. It matters for solar gains.
- Thermal comfort
- The state in which occupants feel neither too warm nor too cold. It depends on air temperature, surface temperature, humidity and air movement.
- Thermal zone
- A part of the building with similar indoor conditions and use, treated as a single unit in the energy calculation.
- Unheated space
- A room with no heating source of its own, such as an attic, a stairwell or a basement, which reduces the losses of the adjacent heated spaces.
Certification and attestation
- Annex to the energy performance certificate
- The part of the certificate that details the building data, the calculation results and the recommendations, complementing the main page that shows the energy class.
- As-built survey
- The on-site measurement and drawing of an existing building, which fixes the dimensions and make-up of the elements for the calculation.
- Attestation
- The official recognition of a specialist's competence to carry out a regulated activity, following a procedure set by the authority.
- Attestation grade
- The level of competence at which an energy auditor is attested, which sets the types of buildings and works for which they may prepare documents.
- Building owner
- The person who owns the building and who, in certain situations, must hold a certificate, for example on sale or letting.
- Certificate validity
- The period during which the energy performance certificate can be used, provided no major renovation is carried out in the meantime that changes the building's energy consumption.
- Certified energy auditor
- A specialist who has obtained the attestation needed to prepare energy performance certificates and audit reports for buildings.
- Energy audit
- The systematic analysis of a building's energy use, which identifies losses and proposes measures to improve performance.
- Energy audit report
- A document prepared by the auditor presenting the condition of the building, its consumption, its losses and the proposed measures, with their estimated effects.
- Energy certification
- The process of assessing the energy performance of a building and issuing the certificate that attests it.
- Energy performance calculation methodology
- The set of official rules and formulae used to determine the energy indicators of a building and place it in a class.
- Energy performance certificate
- An official document showing the energy performance of a building or of a unit within it, with the energy class and recommendations for improvement.
- Existing building
- A building that is already constructed and in use, for which the certificate describes the actual condition of the envelope and the installations.
- Heating and air conditioning inspection
- A periodic check, carried out by certified technical experts, of the accessible parts of heating and air conditioning systems, assessing generator efficiency and sizing against demand.
- Input data
- The information on geometry, materials, installations and use entered into the calculation. Its accuracy determines the quality of the certificate.
- Major renovation
- Extensive work on the envelope or installations of an existing building, after which it must meet the energy performance requirements.
- Minimum energy performance requirements
- The performance levels that new buildings, and existing buildings undergoing works, must reach, as set by regulations.
- Ministry of Development, Public Works and Administration
- The central authority that regulates construction and energy performance and issues the attestation documents for specialists.
- New building
- A building in design or under construction, before acceptance on completion of the works, which must meet the current energy performance requirements.
- Professional liability insurance
- Insurance by which a specialist covers damage caused to clients through errors or omissions in the exercise of their work.
- Recommendations for energy improvement
- Measures proposed in the certificate to reduce consumption, for example insulating the envelope or replacing installations, with their estimated effect.
- Reference building
- A virtual building with the same geometry, use and location as the one assessed, but with standard characteristics, used for comparison in the calculation methodology.
- Thermal rehabilitation
- A set of works that improve the insulation and installations of an existing building, to reduce energy use and increase comfort.
Construction: design, verification, execution
- Architect
- A specialist who conceives and coordinates the architectural solution of a building and is responsible for compliance with planning and functional requirements.
- Building permit
- An administrative act issued by the competent public authority, allowing building works to be carried out under the conditions of the approved documentation.
- Certified design verifier
- A certified specialist who examines the design for one or more fundamental requirements of buildings and issues the verification report.
- Certified technical expert
- A specialist certified by field and sub-field, including building services, who prepares technical expert reports on buildings, execution and designs.
- Client
- The holder of a real right or a claim over the property on which the construction is carried out.
- Construction technical file
- The set of documents on the design, execution, acceptance and operation of a building, kept by the owner throughout its life.
- Design code
- An officially approved technical act that sets the rules for design, execution or assessment in a given area of construction.
- Designer
- The authorised natural or legal person who prepares the design of a building or of one of its specialities.
- Determining stage
- A stage of execution, set by the designer in the control programme, after which the work cannot continue without the written consent of the client, the designer and the contractor.
- Developer
- The person who finances the work, carries out the acceptance and takes over the construction.
- Documentation for the building permit
- The documentation accompanying the permit application, with the drawings and description of works that the authority needs to decide on issuing the permit. The former name was DTAC.
- Execution details
- Large-scale drawings and specifications showing how the junctions and elements of the design are actually built on site.
- General urban plan
- A planning document for a locality that sets the functional zones and the general building rules across its whole territory.
- Seismic assessment
- The analysis of the capacity of an existing building to withstand an earthquake, leading to its placement in a risk class and to a decision on possible strengthening.
- Seismic risk class
- A category assigned to an existing building after assessment, according to the degree to which its structure is exposed to loss of safety in an earthquake.
- Site supervisor
- A specialist authorised by I.S.C. who checks, on behalf of the client, that the works are carried out in accordance with the design, the permit and the regulations.
- State Inspectorate in Construction
- The authority that controls quality in construction, checking compliance with regulations on sites and in the operation of buildings.
- Strengthening
- Strengthening the load-bearing capacity of the structural components of an existing building, to improve its behaviour under various kinds of actions, especially earthquakes.
- Technical design
- A design stage (the technical design for execution) containing the written and drawn documents needed for execution, with the construction solutions and installations. Execution details are a separate stage.
- Technical documentation
- All the documents, designs, approvals, agreements and titles submitted to the authority for the issue of the permit.
- Technical execution manager
- A specialist authorised by I.S.C., appointed by the contractor, who is responsible for compliance with the design and for the quality of the works on site.
- Technical expertise
- A study carried out by a certified expert that establishes the technical condition of a building and the intervention solutions, where these are needed.
- Technical verification report
- A document in which a certified verifier records the findings and conclusions of the design verification, for the requirement that was checked.
- Urban planning certificate
- An information document showing the legal, economic and technical status of a plot or a building and the approvals required for permitting.
- Verification level
- A level of technical design verification, set according to the consequence class of the building, showing how thoroughly the documentation is checked before execution.
- Works acceptance
- Verification by the client and the acceptance committee that the executed work matches the design, before it is taken over and put into use.
- Zonal urban plan
- An urban planning document that details the regulations for a defined zone of a locality, where they do not follow from the general plan.