ACD – Accredited Construction Details
Accredited Construction Details have been developed to assist the construction industry achieve the performance standards required to demonstrate compliance with the energy efficiency requirements (Part L) of the Building Regulations

ABE – Association of Building Engineers
ABE is the professional body for those specialising in the technology of building

ACoP – Approved Code of Practice
The Approved Code of Practice (ACoP) has special legal status and gives practical advice for all those involved in construction work. If you follow the advice in the ACoP you will be doing enough to comply with the law in respect of those specific matters on which it gives advice

ACPO – Association of Chief Police Officers
The Association of Chief Police Officers brings together the expertise and experience of chief police officers from England, Wales and Northern Ireland, providing a professional forum to share ideas and best practice, co-ordinate resources and help deliver effective policing which keeps the public safe

AD L1A – Approved Document L1A
The Building Regulations – Conservation of Fuel and Power 2010 edition came into effect on 1st October 2010

AD E – Approved Document E
The Building Regulation – Resistance to Passage of Sound has been updated to reflect the changes to the Building Regulations and came into effect on 1st October 2010

ADs – Approved Documents
ADs – Approved Documents (Building Regulations) provide help and guidance in complying with the Building Regulations however; there may well be alternative ways of achieving compliance

AI – Approved Inspector
An AI is a qualified and experienced private sector building control professionals or consultancy able to assist developers, designers and contractors achieve Building Regulations approval

Air Permeability
Air permeability is expressed as volume flow per hour (m3h) of air supplied to the space per square metre (m2) of envelope area for an internal to external pressure difference of 50 Pa, i.e. 25 mhr-1 m2 at 50Pa.

ALO – Architectural Liaison Officer
The Architectural Liaison Officer (for your area) is the same as the Crime Prevention Design Advisor and is the title given to the same role in some police forces

ANC – Association of Noise Consultants
The Association of Noise Consultants was established in 1973 to represent the interests of noise consultants in the UK
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APEL – Accreditation of Prior Experiential Learning
APEL is a process that enables people to receive formal recognition for skills and knowledge they already possess. A persons learning and experience may be formally recognised and taken into account gaining entry to a course, obtaining exemption from certain parts of a new course or qualify for an award

ARLA – Association of Residential Letting Agents
ARLA is a professional body who are solely concerned with lettings

Assessed air permeability
Is the value used in establishing the DER, and is based on a specific measurement of the dwelling concerned, or on measurements of other dwellings of the same dwelling type.

In this context, a non-continuously occupied interior space within a building, often several stories high, bounded on at least one side by occupied spaces set to the conditions determined from the activity database. There may or may not be building elements (such as glazing) surrounding the atrium (although there may need to be something for smoke control in case of fire). The atrium itself is not maintained to the conditions set by the activity database for the adjoining spaces. The technical purpose of the atrium can be one of or more of the following:-

  • Providing a buffer between the thermal conditions in the adjoining spaces and the exterior, to reduce the direct impact of the exterior of those zones. In this case it should not be maintained to conditions as though it is occupied. (If it is conditioned and the features below do not apply, in this context it is not considered to be an atrium.)
  • Providing a mean for daylight to reach the middle of the deep plan spaces that would otherwise not receive it.
  • Encouraging stack effect, or other passive ventilation, to draw extract air from the adjoining spaces.

ATTMA – Air Tightness Testing and Measurement Association
Air Tightness Testing and Measurement Association is a special interest group within The British Institute of Non-Destructive Testing (BINDT) dealing with air permeability of all building types

Automatic Blind Control
In this context internal or inter-pane (but not exterior) blinds that are motorise so that the position can be modified to control solar gain and/or glare, controlled by automatic sensors. The control regime must also open the blinds as the heat gain and/or daylight levels decrease, so that the use of these natural resources can be optimised for each zone. Note that exterior shading devices can be modelled using iSBEM in the definition of each window; however SBEM currently does not model the re-radiation effects of blinds where solar gain has entered the space before it is modulated by the shading device

AWTC – Association of Wildlife Trust Consultancies
The Association of Wildlife Trust Consultancies offer professional expertise throughout the country in ecology, landscape and planning. Profits go to their parent bodies, conservation charities with the collective aim of protecting wildlife for the future
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BBA – British Board of Agreement
The BBA is a UK approval body for new construction products and installers. Agrément Certificates are recognised by specifiers and other industry decision-makers as proof that the products covered by them have been impartially assessed, will allow compliance with Building Regulations to be achieved and will last for a defined period.

BCB – Building Control Bodies
BCB are the legal enforcers of building standards/regulations throughout England, Wales, Northern Ireland and Scotland.

BFRC – British Fenestration Rating Council
The BFRC is the operation of a UK national rating system for the thermal performance of fenestration products. The rating system is recognised within building regulations throughout the UK.

BFCMA – British Flue and Chimney Manufacturers Association
The BFCMA is a UK Trade Association for factory-made chimney products and works closely with Government, public bodies and other organisations to further the interest of the chimney & flue industry.

Biodiverse roof
A roof that is designed to create a desired habitat that will attract a particular flora and fauna; whether replicating the original footprint of the building or enhancing the previous habitat.

BIS – The Department for Business, Innovation and Skills
The Department for Business, Innovation and Skills is making a difference by supporting sustained growth and higher skills across the economy. BIS: working together for growth

BRE – Building Research Establishment
The BRE Trust Companies, BRE and BRE Global, are research, consultancy, training, testing and certification organisations delivering sustainability and innovation across the built environment and beyond

BREDEM – Building Research Establishment Domestic Energy Model
BREDEM is a model for the calculation of the monthly or annual energy requirements of domestic buildings, and for the estimation of savings resulting from energy conservation measures. SAP is based on BREDEM 9

BREEAM – Building Research Establishment Environmental Assessment Model
BREEAM is a voluntary measurement rating for green buildings that was established in the UK by the Building Research Establishment (BRE). Since its inception it has grown in scope and geographically, being exported in various guises across the globe. Its equivalents in other regions include LEED North America and Green Star in Australia, and HQE in France. BRE and CSTB (the French Building research centre) have signed a memorandum of understanding committing them to the alignment of BREEAM and HQE

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Brown roof
A biodiverse roof where the growing medium is purposely-selected to allow local plant species to inhabit the roof over time.

British Standards formulated by the British Standard Institute (BSi).

BSD – Building Standards Division
Previously, SBS – Scottish Building Standards, and SBSA Scottish Building Standards Agency, is responsible for writing the Scottish building regulations

BSRIA – The Building Services Research and Information Association
The Building Services Research and Information Association is a consultancy, test, instruments and research organisation. We provide specialist services for construction, building services and facilities management
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Building Regulations – Schedule 1
Part A – Structure
Part B – Fire
Part C – Moist
Part D – Toxic Substances
Part E – Passage of Sound
Part F – Ventilation
Part G – Hygiene
Part H – Drainage and Waste Disposal
Part J – Combustion Appliances & Fuel Storage Systems
Part K – Protection from Falling, Collision & Impact
Part L – Conservation of Fuel & Power
Part M -Access & Facilities for Disabled People
Part N – Glazing Safety in relation to Impact, Opening and Cleaning
Part P – Electrical Safety
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Carbon dioxide (CO2)
Is a naturally occurring gas and one of the most abundant greenhouse gases in the atmosphere. Carbon dioxide is also a by-product of industrial processes, burning fossil fuels and land use changes.

Carbon dioxide equivalent (CO2e)
The unit of measurement used to compare the relative climate impact of the different greenhouse gases. The CO2e quantity of any greenhouse gas is the amount of carbon dioxide that would produce the equivalent global warming potential.

Carbon footprint
A carbon footprint is the total set of greenhouse gas (GHG) emissions caused by an organisation, event or product. For simplicity of reporting, it is often expressed in terms of the amount of carbon dioxide, or its equivalent of other GHGs, emitted.

Carbon neutral
Carbon neutrality, or having a net zero carbon footprint, refers to achieving net zero carbon emissions by balancing a measured amount of carbon released with an equivalent amount sequestered, avoided or offset.

Carbon offset
Carbon offsets are the ‘currency’ for offsetting. They are quantified in metric tonnes of CO2e reductions, i.e. one carbon offset equals one tonne of emissions reductions made through selected and verified carbon projects. Carbon offsets can be purchased on a voluntary basis or to meet regulatory requirements.

Carbon offset project
A third party verified project which utilises proven clean technologies including, hydropower, wind power and methane capture, to generate carbon offsets.

Carbon offset standard
A standard that helps to ensure that carbon offset projects meet certain quality requirements, such as additionality and third party verification. Several offset standards exist within the voluntary and compliance carbon markets and each has a different set of requirements depending on its focus and scope.

Carbon Neutral
When the net greenhouse gas emissions associated with an organisational unit, product, service or process are zero, through a combination of direct (internal) emission reducing actions and indirect (external) offsetting actions
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CEA – Commercial Energy Assessor
A CEA is an accredited energy assessor capable of producing Energy performance Certificates for non domestic buildings.

CER – Certified Emission Reduction
Is a carbon credit created by a Clean Development Mechanism (CDM) project. One CER corresponds to one tonne of CO2e emission reductions.

Change of Use
The erection of a new dwelling is not a material change of use. Approved Document L1 B applies where a dwelling is being created in an existing building as the result of a material change of use of all or part of the building.

CHP – Combined Heat and Power
A CHP is a heating system which can also generate electricity.

CIAT – Chartered Institute of Architectural Technologists
The CIAT represents professionals working and studying in the field of Architectural Technology

CIBSE – Chartered Institution of Building Services Engineers
The CIBSE is the professional body that exists to support the Science, Art and Practice of building services engineering, by providing members and the public with information and education services.

CIOB – Chartered Institute of Building
The CIOB is a membership body for building professionals any anything concerning the management of the total building process.

Climate change
A change in global climate attributed directly or indirectly to human activity and in addition to natural climate variability observed over comparable time periods.

CLG – Department for Communities and Local Government
The CLG is the government department in England and Wales responsible for amongst other things, Building Regulations, Housing, Planning, Urban Policies, Sustainable Communities and delivering EPCs.

Code Assessor
See Licensed Assessor

Code calculator tools
A suite of tool made available for use by the service provider to enable assessors to calculate the performance levels and credits for award under the various issues

Code Service Provider
See Service provider

Competent Person
Personnel performing work affecting product quality must be competent, based on their education, training, skills and previous experience. A competent person can perform satisfactorily with minimum supervision. BRE is accredited by UKAS under ISO 17024 to operate a competent person’s scheme for CSH to ensure competence, accuracy and professional service in offering CSH to clients.
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Means the advancement of a fixed building service following installation, replacement or alteration of the whole or part of the system, from the state of static completion to working order by testing and adjusting as necessary to ensure that the system as a whole uses no more fuel and power than is reasonable in the circumstances, without prejudice to the need to comply with health and safety requirements. For each system commissioning includes setting-to-work, regulation (that is testing and adjusting repetitively) to achieve the specified performance, the calibration, setting up and testing of the associated automatic control systems, and recording of the system settings and the performance test results that have been accepted as satisfactory.

Compliance carbon market
The segment of the carbon market for carbon offset transactions which meet regulatory requirements i.e. offsets purchased by governments and organisations to meet Kyoto targets.

Controlled service or fitting
Is a service or fitting in relation to which Part G (sanitation, hot water safety and water efficiency), H (drainage and waste disposal), J (combustion appliances and fuel storage systems), L (conservation of fuel and power) or P (electrical safety) of Schedule 1 to the Building Regulations imposes a requirement.

CPD – Continuing Professional Development
CPD is a system which shows continuous professional learning throughout you professional career. Its is usually kept as a record of what additional learning you have completed post academic qualifications.

CPSU – Combined Primary Storage Unit
A CPSU is a single appliance that provides both space heating and domestic hot water. A CPSU contains a burner and a primary store with a capacity of over 70 litres

Credit – CSH credit
Credits are awarded for specific environmental performance within the CSH. Credits are aggregated within issues and categories, and weighted to calculate a point score. Points are then added together to produce an overall rating.

CSH – Code for Sustainable Homes
Government owned environmental assessment method for certifying and rating new homes in England. It was launched in December 2006. The CSH gives an indication of the overall sustainability of a dwelling. CSH differs from SAP Calculations by taking into account the type of materials used, water consumption and higher levels of building practice etc.

CSH service provider
An organisation offering part or all of the CSH services including: assessor training; registration & monitoring; quality assurance of assessments; certification; investigation and resolution of complaints; and maintenance of records. (BRE Global, 2007)

CSH system
A web based tool allowing assessors to complete and process registrations and reports, and request the issue of certificates for individual dwellings at DS and PCS
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D&P – Design and Procurement Assessment
For more information see Design Stage assessment

DEA – Domestic Energy Assessor
A DEA is a trained and qualified individual who can assess existing domestic dwellings and produce EPCs for use in the sales and rented markets.

DEC – Display Energy Certificate
A DEC is an energy rating based on the actual energy use of a building, currently required in large public buildings in England & Wales and Northern Ireland.

DECC – Department of Energy and Climate Change
The Department of Energy and Climate Change (DECC) was created in October 2008, bringing together energy policy previously with BERR (Department for Business, Enterprise & Regulatory Reform) and DEFRA.

DEFRA – Department for Environment, Food and Rural Affairs
DEFRA is responsible, in England and Wales, for wide environmental issues and previously owned the Standard Assessment Procedure (SAP). SAP is now owned by the Department of Energy and Climate Change (DECC).

Demand Controlled Ventilation
Is defined as supply and/or extract ventilation that is modulated to match the needs of the actual occupation level of each zone, rather than operating at a constant level defined by the activity database. Thus the energy required to adjust the condition of the supply air and that required to move the air can be reduced. The rate of ventilation would typically be controlled by presence detectors, CO2 sensors or another device that senses the varying requirement.
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Demonstrating compliance to Approved Document L1A
In the Secretary of State’s view, compliance with the energy efficiency requirements could be demonstrated by meeting all five criteria set out in the following paragraphs. Criterion 1 is a regulation and is therefore mandatory, whereas Criteria 2 to 5 are only guidance

  • Criterion 1 DER must be not greater than TER
  • Criterion 2 the performance of the building fabric and the fixed building services should achieve reasonable overall standards of energy efficiency following the procedure set out in Approved document L1A paragraphs 4.18 to 4.24
  • Criterion 3 the dwelling should have appropriate passive control measures to limit the effect of solar gains on indoor temperatures in summer, irrespective of whether or not the dwelling has mechanical cooling
  • Criterion 4 the performance of the dwelling, as built, should be consistent with the DER. Extra credits will be given in the TER/DER calculation where builders provide robust evidence of quality assured procedures in the design and construction phases
  • Criterion 5 the necessary provisions for energy efficient operation of the dwelling should be put in place
  • Common areas in buildings with multiple dwellings The common areas of buildings containing more than one dwelling are not classified as dwellings, and therefore fall outside the scope of the five criteria outlined above. For such areas, reasonable provision would be:oa- if they are heated, to follow the guidance in Approved Document L2A; orob- if they are unheated, to provide fabric elements that meet the fabric standards set out in Approved Document L1A paragraphs 4.20 to 4.22
  • Conservatories and porches Where conservatories and porches are installed at the same time as the construction of a new dwelling, the guidance in Approved Document L1A applies. For conservatories and porches added as extensions to a dwelling, see guidance in Approved Document L1B
  • Swimming pool basins Where a swimming pool is constructed as part of a new dwelling, reasonable provision should be made to limit heat loss from the pool basin by achieving a U-value no worse than 0.25 W/m2.K as calculated according to BS EN ISO 13370. In terms of Criterion 1, the dwelling should be assessed as if the pool basin were not there, although the pool hall should be included. The area covered by the pool should be replaced with the equivalent area of floor with the same U-value as the pool surround

DER – Dwelling (CO2) Emission Rate
The DER is calculated from SAP Software which is used for the purposes of compliance with building regulations. It is equal to the annual CO2 emissions per unit floor area for space heating, water heating, ventilation and lighting, less the emissions saved by energy generations technologies, expressed in kg/m2/year

Design air permeability
Is the target value set at the design stage, and must always be no worse than the limiting value.

Design Stage
See DS Assessment
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Designated operational entity (DOE)
A DOE is an independent auditor accredited by the CDM Executive Board to validate project proposals or verify whether projects have achieved planned greenhouse gas emission reductions.

DFPNI – Department of Finance and Personnel Northern Ireland
The DFPNI is the government department in Northern Ireland responsible for amongst other things Building Regulations and delivering Energy Performance Certificates.

DIAG – Directive Implementation Advisory Group
The European Energy Performance of Buildings Directive DIAG was established in 2002 to advise the UK Government on the energy performance of buildings and the implementation of the EPBD.

DIN Standards
Deutsches Institut für Normung which means ‘German Institute for Standardization’. DIN Standards are the published results of DIN’s work.

Double counting
Occurs when two or more individuals, or organisations, claim ownership of specific emission reductions or carbon offsets.

DPC – Damp Proof Course
A DPC is a course of some impermeable material laid in the foundation walls of building near the ground to prevent dampness from rising into a building

DS – Design Stage Assessment
Is an assessment made against the CSH standard on the basis of the detailed design of one or more dwellings (typically between RIBA stages A-G) resulting in a DS certificate.
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Drainage layer/Reservoir board
Available in a variety of materials, including hard plastic, polystyrene, foam, coarse gravel and crushed recycled brick, depending on the functional requirements. Allows excess water to drain away, thereby preventing the water logging of the substrate. Some drainage layers also incorporate water storage cells to retain additional water that can be diffused to the plant support layer during prolonged dry periods.

DS certificate
Certificate of performance against the CSH based on the design of a dwelling, including site related issues

DS Registration
Registration of forthcoming post construction assessment on the CSH system

DS report
Design stage report containing details of all categories and issues assessed, all credits achieved

DSM – Dynamic Simulation Model
DSMs are systems which should be used on complex buildings instead of the SBEM to produce energy calculations for building regulation approval and EPCs.

Is a self-contained unit designed to accommodate a single household. Buildings exclusively containing rooms for residential purposes such as nursing homes, student accommodation and similar are not dwellings, and in such cases, Approved Document L2A applies.
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Dwelling type
Is a means of allocating each dwelling on a development to a particular group to provide the basis for assessing the pressure testing regime. The allocation of each dwelling to a dwelling type should be the responsibility of the person carrying out the pressure testing. To be classed as of the same type dwellings have to:

  • Be of the same generic form (i.e. detached, semi-detached, end terrace, mid-terrace, ground-floor flat (inc. ground-floor maisonette), mid-floor flat, top-floor flat (inc. top-floor maisonette);
  • Be of the same number of storeys;
  • Be of the same design air permeability;
  • Have similar adjacency to unheated spaces such as stairwells, integral garages, etc.
  • Have the same principal construction details (as identified by the Accredited Construction Details (ACD) or bespoke detail reference codes);
  • Have a similar (i.e. ?1) number of significant penetrations, i.e. for windows, doors, flues/ chimneys, supply/exhaust terminals, waste water pipes;
  • Have envelope areas that do not differ by more than 10 per cent

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ECD – Enhanced Construction Details
Enhanced Construction Details have been developed to assist the construction industry achieve the performance standards required to demonstrate compliance with the energy efficiency requirements (Part L) of the Building Regulations

ECF – Energy Cost Factor
An ECF is based on the cost of space and water heating within a property.

BREEAM version for new homes first launched in 2000 and now replaced in England for new dwellings by the Code for Sustainable Homes. EcoHomes remains in operation for refurbished homes in the UK, and all dwellings in Scotland.

EIR – Environmental Impact Rating (CO2 emissions)
The EIR is displayed on an EPC and is the rating about the impact the home has on the environment. Better-rated homes should have less impact through carbon dioxide (CO2) emissions. A property that emits very little carbon would score an A and a more polluting property would score G

Energy efficiency requirements
Are defined as the requirements of regulations 4A, 17C, 17D and 17E of, and Part L of Schedule 1 to, the Building Regulations

Envelope Area
The envelope area of the building, or measured part of the building, is the total area of all floors, walls and ceilings bordering the internal volume. This includes walls and floors below external ground level. Overall internal dimensions are used to calculate this area and no subtractions are made for the area of the junctions of internal walls, floors and ceilings with exterior walls, floors and ceilings. The envelope are of a terraced house includes the party wall(s). The envelope area of a flat in a multiple storey building includes the floors, walls and ceilings which are shared with adjacent flats.

EPBD – Energy Performance of Buildings Directive
The EPBD is an European directive that had to be enforced across all member states by the 4th of January 2009, which will amongst other things enforce the provision of Energy Performance Certificate (EPCs) when buildings are Constructed, Sold or Rented.

EPC – Energy Performance Certificate
An EPC records a home’s energy and CO2 emission performance rating which is calculated using SAP for dwellings. Energy Performance Certificates display the energy efficiency of a home on a scale of A-G. The most efficient homes, which should have the lowest fuel bills, are in band A. The Certificate also shows, on a scale of A-G, the environmental impact of the home. Better-rated homes should have less impact through carbon dioxide (CO2) emissions.
The average property in the UK is in bands D-E for both ratings. The Certificate includes recommendations on ways to improve the home’s energy efficiency to save you money and help the environment

EPR – Energy Performance Report
EPRs are EPCs which are not officially lodged in the Governments central database

EST – Energy Savings Trust
The EST is a non-profit organisation that provides free impartial advice on saving energy. Our advice can help you save money and fight climate change by reducing carbon dioxide emissions from your home

Exemption – Buildings exempt from the energy efficiency requirements
No new dwellings are exempt from the energy efficiency requirements of the Building Regulations.

Extensive green roof
A lightweight, low-maintenance roof system, typically with succulents or other hardy plant species (often sedum) planted into a shallow substrate (typically less than 100 mm) that is low in nutrients. Irrigation is not normally required.
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FAERO – Federation of Authorised Energy Rating Organisations
FAERO is no longer in existence, but was previously a confederation of approved SAP software providers (including Elmhurst Energy Systems) that encouraged and promoted the use of certified energy calculations.

Filter fleece/ fines layer
Prevents fines and sediments from being washed out of the green roof into the drainage system.

Final Certificate
Certificate of performance against the CSH based on the completed dwelling

Refers to the time when a post construction assessment can be done. Finished is the point at which the construction of a property is sufficiently advanced so as to make a post construction assessment possible. (Community and Local Government legal definition)

Fixed building services
Is any part of, or any controls associated with:
– fixed internal or external lighting systems, but does not include emergency escape lighting or specialist process lighting; or
– fixed systems for heating, hot water, air- conditioning or mechanical ventilation

Forschungsgesellschaft Landschaftsentwicklung Landschaftbau’s (German Landscape Research, Development and Construction Society).
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GJ – Giga Joules
A joule is the derived unit of energy in the International System of Units, a Gigajoule is 109 Joule.

Global warming
The increase in the average temperature of the Earth’s surface as a result of the accumulation of greenhouse gases in the atmosphere

Global warming potential (GWP)
Global warming potential (GWP) is a measure of how much a given amount of greenhouse gas is estimated to contribute to global warming, relative to the same amount of carbon dioxide. See CO2e.

Greenhouse gas (GHG)
Greenhouse gases are gases in the atmosphere that absorb and emit infrared radiation. This process is the fundamental cause of the greenhouse gas effect. The main greenhouse gases are water vapour, carbon dioxide, methane, nitrous oxide and ozone.

Green roof
A roof or deck onto which vegetation is intentionally grown or habitats for wildlife are established, including: extensive, intensive and semi intensive roofs; roof gardens; biodiverse roofs; brown roofs; public and private amenity spaces.

Green roof system
The component layers of a green roof build-up.

Growing medium/Substrate
An engineered soil replacement that contains a specified ratio of organic and inorganic material; specifically designed to provide green roof plants with the air, water and nutrient levels that they need to survive, whilst facilitating the release of excess water.

GRO – Green Roof Organisation
The Green Roof Organisation is the industry forum for green roof development and promotion in the UK. GRO is facilitated by the NFRC and acts as the technical arm of

GSHP – Ground Source Heat Pumps
GSHP make use of energy stored in the earth, which comes from solar radiation. Heat pumps take heat from one source and release it a higher temperature through a series of ground collectors, heat exchangers and the use of circulating fluid
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HBF – House Building Federation
HBF is a members body representing the home building industry in England and Wales.

HCR – Home Condition Report
A HCR is a voluntary survey which can be added to the HIP, if required; the HCR is a report on the physical condition of the property.

HEED – Homes Energy Efficiency Database
HEED is a database tracking the level of domestic energy efficiency measures across the country.

HETAS – Heating Equipment Testing and Approval Scheme
HETAS is the official body recognised by Government to approve solid fuel domestic heating appliances, fuels and services. Its work in Approving products covers boilers, cookers, open fires and stoves and room heaters.

HI – Home Inspector
A Home Inspector is a trained and qualified individual who can undertake a Home Condition Report (HCR) and Energy Performance Certificates (EPC).

HLP – Heat loss parameter
A HLP is a value based on the external surface area, insulation (U value) of those surfaces and air-tightness of a dwelling and forms part of the SAP calculation.

See dwelling

One or more people sharing a dwelling

HS&W – The Workplace (Health, Safety and Welfare) Regulations 1992
The Workplace (Health, Safety and Welfare) Regulations 1992, as amended, apply to the common parts of flats and similar buildings if people such as cleaners, wardens and caretakers are employed to work in these common parts. These Regulations contain some requirements which affect building design. The main requirements are now covered by the Building Regulations, but for further information see Workplace health, safety and welfare, Workplace (Health, Safety and Welfare) Regulations 1992, Approved Code of Practice and guidance, HSE publication L24, HMSO, 1996.

HSE – Health and Safety Executive
The Health and Safety Executive is the national independent watchdog for work-related health, safety and illness and are an independent regulator that acts in the public interest to reduce work-related death and serious injury across Great Britain’s workplaces

Hydro seeding
Spraying a specially designed blend of seeds and growing medium.
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Independent certification schemes
There are many UK product certification schemes. Such schemes certify compliance with the requirements of a recognised standard that is appropriate to the purpose for which the material is to be used. Materials which are not so certified may still conform to a relevant standard.
Many certification bodies that approve products under such schemes are accredited by the United Kingdom Accreditation Service (UKAS). Such bodies can issue certificates only for the categories of product covered under the terms of their accreditation.

Inspection chambers
Situated over all internal rainwater outlets to constrain the surrounding landscaping but allow easy access for maintenance. Unit allows water entry, but helps prevent unwanted silt, debris or vegetation from entering and obstructing free drainage.

Intensive green roof
A version of a green roof, often referred to as a roof garden, that provides benefits akin to a small urban park or domestic garden. Designed primarily for recreational use, intensive roofs are typically configured with 200 mm+ of substrate and often require regular maintenance and irrigation.

Interim Certificate
See DS certificate

IoSH – Institution of Occupational Safety and Health
The IOSH is the Chartered body for health and safety professionals. With more than 39,000 individual members, we’re the biggest professional health and safety organisation in the world

ISBEM – Interface with Simplified Building Energy Model
ISBEM is a freely available software tool used to determine the energy performance of non-domestic buildings (commercial buildings)

International Organization of Standardisation

ISO 14001
Independently audited environmental management scheme operated by the British accreditation bureau British Accreditation Bureau

ISO 9001
Independently audited quality management scheme operated by the British accreditation bureau

A source of impact on the environment which can be assessed against a performance requirement and awarded one or more credits
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A measure of energy (see kWh), is the international technical term for defining electric and/or motive power, symbol J. One Joule is one Watt for 1 second (1J=1Ws), see Wikipedia entry for a complete definition
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kWh – Kilowatt Hour
The kWh is a convenient unit for electricity (1kWh = 1000 Watt/hour). For example using a 60 watt light bulb for one hour consumes 0.06 kilowatt hours of electricity
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Kyoto Protocol
An international protocol to the United Nations Framework Convention on Climate Change (UNFCCC), that requires industrialised country signatories to meet greenhouse gas emission reduction targets relative to their 1990 levels.


When an emission reduction from a carbon offset project in one area causes an increase in emissions somewhere outside of the project scope i.e. where conserving a forest in one region shifts logging activity to another area of forest.

Level – CSH rating
Results of CSH assessments are expressed as a rating or Level from 1 to 6, with 6 being the lowest environmental impact, or the highest environmental performance

Licensed assessor
A competent person trained, examined and licensed by a Service provider (see Service provider) to carry out CSH assessments and recorded on the Service provider register of licensed assessors. Assessors may provide guidance on meeting the standard and may be a member of the design team. Where this is the case, the assessor shall advise the Service Provider of their position within the design team (e.g. Architect, Design Engineer, Energy Consultant, etc.) They shall also identify, document, review and manage all possible conflicts of interests so that these are eliminated. The Service provider reserves the right to audit such documentation and processes.

Licensed CSH assessor organisation
An organisation which employs one or more competent persons with respect to the Code, and also pays a licence fee to BRE Global or a sub-licensee to BRE Global to cover provision of support services including: management of the system; free telephone helpline; regular updates, and access to a private extranet.

Lifetime Homes

Lifetime Homes are ordinary homes incorporating 16 Design Critera that can be universally applied to new homes at minimal cost. Each design feature adds to the comfort and convenience of the home and supports the changing needs of individuals and families at different stages of life.

Light Pipes

A light pipe is a tube/pipe, consisting of internal reflective surfaces, which channels daylight to an internal area.

Limiting air permeability
Is the worst allowable air permeability

Live-work units
If a unit contains both living accommodation and space to be used for commercial purposes (e.g. workshop or office), the whole unit should be treated as a dwelling as long as the commercial part could revert to domestic use. This could be the case if, for example:
a – there is direct access between the commercial space and the living accommodation; and
b – both are contained within the same thermal envelope; and
c – the living accommodation occupies a substantial proportion of the total area of the unit.
Sub-paragraph c means that the presence of (e.g.) a small manager’s flat in a large non-domestic building would not result in the whole building being treated as a dwelling. Similarly, the existence of a room used as an office or utility space within a dwelling would not mean that the building should not be treated as a dwelling.

LLL – Life Long Learning
LLL is exactly the same as CPD; a professional is expected to continue to learn throughout a career, post qualifications.

A lightwell is a space surrounded by the walls of a building but that has no roof or glazing above it. It is therefore similar to a courtyard in appearance. The walls that surround the lightwell are exposed to external air.
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Light Pipes
A light pipe is a tube/pipe, consisting of internal reflective surfaces, which channels daylight to an internal area.

LPG – Liquid Petroleum Gas
LPG is available to serve gas appliances in areas without mains gas. A storage tank is the common method used for holding reserves of LPG

LA – Local Authority
A LA is an administrative unit of local government

LABC – Local Authority Building Control
LABC promotes the design and construction of buildings that are safe, accessible and environmentally efficient to comply with the Building Regulations. LABC builds awareness of local authority building control amongst the public, developers, designers and contractors. It also works with trade organisations, manufacturers, distributors, research establishments, test houses and professional institutions to support innovation in building.

LEL – Low Energy Lighting
LEL is lighting in building that has a low energy demand. These lights include compact fluorescent, fluorescent and to meet Building Regulations should not exceed 40 lumens per circuit watt.

LZC – Low to Zero Carbon
LZC energy sources are increasingly being installed in buildings e.g. micro CHP, photovoltaic panels, solar panels and wind turbines

LZT – Low to Zero (Carbon) Technologies
LZT are energy sources which are increasingly being installed in buildings e.g. micro CHP, photovoltaic panels, solar panels and wind turbines
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A compulsory minimum entry performance requirement for achieving a Code rating

MEES – Minimum Energy Efficiency Standard
The (Minimum Energy Efficiency Standards) Regulations make it unlawful from April 2018 to let buildings (both commercial and domestic) in England and Wales which do not achieve a minimum Energy Performance Certificate (EPC) rating of ‘E’. The official government information can be found (here)

MEV – Mechanical Extract Ventilation
A MEV is a fan driven ventilation system which only extracts air from a building

Mixed-use developments
When constructing a dwelling as part of a larger building that contains other types of accommodation, sometimes called a mixed-use development, this Approved Document L1A should be used for guidance in relation to each individual dwelling. Approved Document L2A gives guidance relating to the non-dwelling parts of such buildings such as heated common areas, and in the case of mixed-use developments, the commercial or retail space.

MVHR – Mechanical Ventilation Heat Recovery
MVHR is a system of mechanical ventilation within a building that extracts internal air, but recycles the heat from the extracted air, back into the building

Moisture / Protection layer
A geotextile blanket, available in varying thicknesses (typically between 2-12 mm), performs a dual function. Firstly, protecting the waterproof membrane during the installation of the green roof system; and secondly, increasing the water holding capacity of the green roof system.
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NAEA – National Association of Estate Agents
The NAEA is the is the UK’s leading professional body for estate agency

NCD – Newly Constructed Dwellings
NCD is a new build dwelling where full SAP methodology applies rather than RdSAP

NFOPP – National Federation of Property Professionals
The NFOPP is the group name for a number of membership organisations that currently comprise, NAEA, ARLA and a number of other smaller groups

Night Ventilation Strategy

Can be defined as the presence of suitable systems, controls and operating strategy such that overnight ventilation (passive and/or mechanical) is used to cool down the exposed building mass and thereby offset daytime cooling demands. If no such operation and subsequent offset is possible through the automatic operation of systems and controls then night ventilation strategy is deemed to be not present as part of the building energy asset rating

NOS – National Occupational Standards
NOS set out measurable performance outcomes to which an individual is expected to work in a given occupation. Developed by employers across the UK, NOS set out the skills, knowledge and understanding required to perform competently in the workplace.

NVQ – National Vocational Qualification
NVQs are vocational awards in England and Wales that are achieved through assessment and training. In Scotland they are known as Scottish Vocational Qualification (SVQ). They are practical qualifications based on being able to do a job. There are five levels of NVQ ranging from Level 1, which focuses on basic work activities, to Level 5 for senior management
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OCDEA – On Construction Domestic Energy Assessor
An OCDEA is a trained and qualified individual who can undertake building regulation calculations and produce EPCs for newly constructed dwellings.

OFTEC – Oil Firing Technical Association
OFTEC are an oil heating and cooking trade body and works closely with Government, public bodies and other organisations to further the interest of the oil heating and cooking appliances.

OR – Operational Rating
OR is the methodology to produce an energy calculation for Display Energy Certificates (DECs)

OSB – Oriented Strand Board
Oriented strand board, also known as OSB, waferboard, Sterling board or Exterior board (UK) and SmartPly (UK & Ireland), is an engineered wood product formed by layering strands (flakes) of wood in specific orientations. In appearance, it may have a rough and variegated surface with the individual strips (around 2.5 by 15 cm (approx. 1 in by 6 in) each) lying unevenly across each other
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PCR – Post Construction Review
Now known as Post construction stage assessment

PCS – Post Construction Stage Assessment
PCS is the assessment of finished dwellings leading to a post construction Code certificate. (See definition of Finished)

PCS Certificate
Certificate of performance against the CSH based on the built dwelling, including site related issues

PCS registration
Registration of forthcoming post construction assessment on the CSH system

PCS report
Report resulting from post construction stage assessment by licensed assessor

PEA – Predictive Energy Assessments
PEAs are derived from SAP Calculations and are provided for any new dwelling that is to be marketed prior to its completion.

Percentage points
The weighted value of a category expressed as a percentage contribution to the whole. For instance the Energy and CO2 emissions category is 36.4 per cent of the total. (See also Total percentage points)

Performance requirement
The Code assigns one or more performance requirements to all of the environmental issues (except four), which when achieved, will result in the award of a Credit. Credits for each issue are summed to give a total number of available credits for each Category.

An offset quality criteria which relates to the robustness and durability of the emission reduction generated by a carbon offset project.

PI – Professional Indemnity
PI is insurance that protects professional persons for sums they may have to pay as compensation to clients because of problems with work undertaken.

PIV – Positive Input Ventilation
PIV is a fan system by which air is forced into a building, at a low level, usually in domestic situations this air is taken from the warm air in a loft space

Used synonymously in the guide with “dwelling”

PL – Public Liability
PL is insurance that covers against loss, or of damage to, third party property, or persons, arising from the activities of a business.

Points Score
See Total percentage points score
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The state of a site immediately before the development under assessment

PV – PhotoVoltaics
PV are modules that convert sunlight directly into DC electricity and can be integrated into buildings.

Pressure Testing
Pressure Tests detect uncontrolled air leakage paths within the external envelope of the dwelling and the process is required in England, Wales and Northern Ireland to comply with Building Regulations
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QCDA – Qualifications and Curriculum Design Authority
The QCDA work closely with Government and other agencies, to maintain and develop the national curriculum and associated assessments, tests and examinations
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See Level

RDL – Robust Details
Robust Details Limited is a UKAS accredited product certification body No.4171 and certifies that stated Robust Details are capable of being used as an alternative to pre-completion sound testing (PCT) to demonstrate compliance with Requirement E1 in Schedule 1 of the Building Regulations (England and Wales).

RdSAP – Reduced Data Standard Assessment Procedure
RDSAP has been developed by the government for use in existing dwellings based on a site survey of the property, when the complete data set for a SAP calculation is not available.

A publicly accessible database that tracks ownership of various data i.e. carbon offsets over their lifetime, Energy Performance Certificates, Code Assessments, etc.

To permanently remove carbon offsets from market to ensure that they are not re-sold. Offsets are usually retired by giving them individual serial numbers and placing them in an official registry.

RIBA – Royal Institute of British Architects
The RIBA is the UK body for architecture and the architectural profession. They work with the Government to improve the design quality of public buildings, new homes and new communities.

RICS – Royal Institution of Chartered Surveyors
RICS is a professional body and its membership represents the property profession, giving support an advice on a diverse range of land, property, construction and related environmental issues.
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Room for residential purposes
Is a room, or a suite of rooms, which is not a dwelling- house or a flat and which is used by one or more persons to live and sleep in and includes a room in a hostel, a hotel, a boarding house, a hall of residence or a residential home, whether or not the room is separated from or arranged in a cluster group with other rooms, but does not include a room in a hospital, or other similar establishment, used for patient accommodation and, for the purposes of this definition, a ‘cluster’ is a group of rooms for residential purposes which is separated from the rest of the building in which it is situated by a door which is designed to be locked; and is not designed to be occupied by a single household.

Root barrier
A layer (membrane) designed to prevent roots from penetrating the waterproofing layer and building fabric.

RRN – Report Reference Number
An RRN is the unique reference number for each individual Energy Performance Certificate produced when lodged in the central register.

RSL – Registered Social Landlord
RSLs are government-funded not-for-profit organisations that that provide affordable housing. They include housing associations, trusts and co-operatives, and work with local authorities to provide homes for people in housing need.

RTPI – Royal Town Planning Institute
The RTPI is a professional body representing town planners
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SAP – Standard Assessment Procedure
The SAP is the UK Government’s recommended method system for measuring the energy rating of residential dwellings. The first version was published in 1995, to be replaced by newer versions in 1998, 2001 and 2005. It calculates the typical annual energy costs for space and water heating, and, from 2005, lighting. The CO2 emissions are also calculated. SAP 2005 has been used as the basis for checking new dwellings for compliance with building regulations in the United Kingdom requiring the conservation of fuel and power.

SBEM – Simplified Building Energy Model
SBEM is the methodology used to determine the energy performance of non-domestic buildings (often referred to as commercial buildings)

SEDBUK – Seasonal Efficiency of Domestic Boilers in the UK
SEDBUK is a national database which gives efficiencies of boilers.

A genus of about 400 species of low-growing, leafy succulents that are wind, frost and drought tolerant and found throughout the northern hemisphere. Not all species are suitable for roofs.

Semi Intensive green roof
Intermediate green roof type with characteristics of both extensive and intensive green roofs. Typically 100mm to 200mm substrate depth, sometimes irrigated, occasionally managed, and usually planted with a range of species.

Service provider
A Service provider is any organisation licensed by (and including) BRE Global which offers training and accreditation services to Code assessors. All Service providers have to operate to the same high standards that BRE Global are required to do under its contract with Communities and Local Government and with mechanisms that clearly demonstrate the avoidance of conflicts of interest. For further information see CSH Guidance Notes, which sets out the basic requirements for organisations carrying out these activities.

SFP – Specific Fan Power
A SFP is used to calculate the annual energy use of fans and where applicable, the gains to the building from the fans for use within energy calculations

SPF – Seasonal Performance Factors
The SPF is the ratio of useful energy output of a device to the energy input, averaged over an entire heating season

Standard/traditional/conventional roof
Un-vegetated and non-absorbent roofs i.e. asphalt, single ply, mineral felt, liquid applied, metal deck etc.

Sustainable (Urban) Drainage Systems
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TER – Target (CO2) Emission Rate
The TER is calculated from SAP Software which is used for compliance with building regulations. It is a notional figure expressed in kg/m2/year which sets the maximum permitted emissions for an individual dwelling, taking into account the previous building regulations, a betterment factor (currently 20%) set by the Government and fuel factor.

TFA – Treated Floor Area
The TFA is used for energy calculations; it is the total of all the floors including main building and any extensions if present.

TM49 – Design Summer Years for London
CIBSE Design Summer Year (DSY) for London is the most appropriate year of weather data to assess the summertime cooling needs of buildings in London. Detailed information may be found (here)

TM52 – The Limits of Thermal Comfort: Avoiding overheating in European Buildings
Overheating has become a key problem for building design. The need to reduce energy consumption whilst dealing with global climate change has reduced the options available for building comfortable, low-energy buildings. Research has been directed towards methods for increasing indoor winter temperatures but this can lead to lightweight, highly insulated buildings that respond poorly in the summer. CIBSE has responded by forming the CIBSE Overheating Task Force. Further details may be found (here)

TMP – Thermal Mass Parameter
The TMP is an overall figure for the thermal mass of a building; which is derived from the admittance of individual elements within the building.

TRV – Thermostatic Radiator Valve
TRVs are placed on radiators and sense room temperature and can be adjusted by the householder to their required comfort temperature.

Total percentage points score
Is sometimes referred to as Points score – for every category, the number of credits achieved is divided by the total available and multiplied by the category weighting factor to give a percentage points score. The percentage point scores are then summed over all the categories to arrive at a total percentage points score for the dwelling
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The United Kingdom Accreditation Service is the sole national accreditation body recognised by government to assess, against internationally agreed standards, organisations that provide certification, testing, and inspection and calibration services. Accreditation by UKAS demonstrates the competence, impartiality and performance capability of these evaluators

Unique ownership
In Carbon Reduction terms it is the concept of clear ownership rights to the emission reductions that a carbon offset represents, to avoid more than one individual or organisation claiming the benefit of the reduction. See double counting and retire.

UPRN – Unique Property Reference Number
Each building in the UK is given a UPRN by the government which is unique to that property.
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An independent assessment of the carbon offset project design and baseline calculations by an accredited third-party auditor that takes place before the project activity is underway.

Vapour barrier
A layer, typically a plastic or aluminium foil cored bituminous sheet that resists diffusion of moisture through the building fabric.

Variable Speed Drive systems
HVAC system designs are increasingly incorporating variable speed drives (VSDs) to provide control, and reduce the energy consumption of, the motors on fans and pumps.
The term Variable-Speed Drive describes the equipment used to control the speed of pumps, fans and compressors. Variable speed drives may be purely mechanical, electromechanical, hydraulic, or electronic. It is generally accepted that variable speed pumping systems offer significant benefits compared to constant flow systems.
For alternating current (AC) electric motors this is achieved by controlling the frequency and/or voltage of the electrical power supplied to the motor. As the motor reduces the operating speed of the fan, pump or compressor the power required to operate the system is greatly reduced.

Ventilation Strategies

  • Night Ventilation
    Can be defined as the presence of suitable systems, controls and operating strategy such that overnight ventilation (passive and/or mechanical) is used to cool down the exposed building mass and thereby offset daytime cooling demands. If no such operation and subsequent offset is possible through the automatic operation of systems and controls then night ventilation strategy is deemed to be not present as part of the building energy asset rating.
  • Ventilation with Enhanced Thermal Coupling to Structure
    This is a further development of the Night Ventilation strategy such that significant components of the building structure in addition to its ordinary surfaces are exposed to night ventilation, in order to enhance the building’s capability of offsetting daytime cooling demands. An example of this procedure is the TermoDeck system where night ventilation is passed through ducts in the solid floors of the building, thereby increasing the ‘coolth’ contained in the thermal capacity of the building structure available to offset subsequent summertime daytime cooling loads.

An independent assessment of quantification of actual emission reductions achieved by a carbon offset project, carried out by an accredited third-party auditor after the project is underway.

Verified emission reduction (VER)
Verified Emission Reductions (VER) – a carbon credit created by a project which has been verified outside of the Kyoto Protocol. One VER corresponds to one tonne of CO2e emission reductions.

In Carbon Reduction terms it is the corresponding year in which the emission reduction, that a carbon offset represents, were created.

Voluntary carbon market
The segment of the carbon market for carbon offset transactions outside of government-related regulatory schemes i.e. offsets purchased by organisations wishing to offset their carbon on a voluntary basis.

VRQ – Vocationally Related Qualification
VRQs are similar to NVQs in that they are work related and practical, developing your employment skills. A VRQ focuses on assessing and recognising what you know and how well you understand it. It will focus on one industry and cover a range of related subjects
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Weighting factor
The weighting factor shows the contribution made by each category to the total performance recognised and rewarded by the Code. The total available contribution from all the categories is expressed as 100 per cent. Raw credit scores for environmental performance are multiplied by the weighting factor assigned to each Category resulting in an overall points score which can then be summed to result in an overall rating
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Zero Carbon Hub
The Zero Carbon Hub facilitates the mainstream delivery of low and zero carbon home. The UK Government has set out an ambitious plan for all new homes to be zero carbon from 2016. The Zero Carbon Hub sets out to help you understand the challenges, issues and opportunities involved in developing, building and marketing your low and zero carbon homes
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