Architect Glossary

A national landscape designation protecting areas of exceptional scenic quality. AONBs have significantly tighter planning controls than non-designated land, particularly for new development. About 15% of England is designated AONB, including over half of the Isle of Wight.

The UK's independent regulator of architects. You can only legally call yourself "architect" if you're on the ARB Register. ARB administers the Architects Code, handles professional misconduct complaints and maintains the Register.

A direction by a local planning authority that removes specific permitted development rights in a defined area. Common in conservation areas. Means that works which wouldn't normally need planning permission (e.g. changing a window) do need consent in that area.

Drawings that record a building exactly as it was constructed, including any variations from the design drawings. Produced at project completion and handed to the client as part of the O&M manual.

A detailed breakdown of every material and labour element in a construction project, prepared by a quantity surveyor. Used for tendering and cost control. Less common on smaller residential jobs, standard on larger commercial projects.

Building Research Establishment Environmental Assessment Method. A sustainability rating system for non-residential buildings. Ratings go from Pass through Good, Very Good, Excellent and Outstanding. Often required as a planning condition for commercial projects.

National technical standards for building construction in England and Wales, covering structure (Part A), fire (Part B), ventilation (Part F), thermal performance (Part L), access (Part M) and more. Separate from planning permission. Approval is issued by Building Control (either local authority or an approved inspector).

Health and safety regulations for construction projects. The 2015 version places duties on clients, designers (including architects), principal designers and contractors. Applies to all projects including domestic clients.

A formal confirmation from the planning authority that a proposed development is lawful (i.e. doesn't need planning permission) or that an existing use/building is lawful. Useful where you want legal certainty that something falls under permitted development rights.

An area of special architectural or historic interest designated by the local planning authority. Conservation Area designation brings tighter planning controls, restrictions on demolition, and usually Article 4 directions removing PD rights.

The role (usually held by the architect) of administering the construction contract between the client and the contractor. Includes site inspections, issuing instructions, agreeing variations, certifying payments, handling variations and managing the contract through to practical completion.

A written document submitted with most planning applications explaining the design approach, context analysis, and how the proposal addresses local planning policies. Required for major applications and listed building consent. Typically 10–30 pages.

Typically 6 or 12 months after Practical Completion, during which the contractor is obliged to return and fix any defects that emerge. At the end of the period, the final certificate is issued and retention is released.

The CO₂ emitted during manufacture, transport and installation of construction materials — as distinct from operational carbon (heating, lighting). For new buildings, embodied carbon often exceeds operational carbon for the first 30–50 years of the building's life. A growing focus of sustainable design.

The Passivhaus Institute's certification standard for retrofitting existing buildings to near-Passivhaus performance. Slightly relaxed from full Passivhaus because existing fabric limits what's achievable, but still dramatically lower energy use than typical UK buildings.

A design philosophy that prioritises building envelope performance (insulation, airtightness, windows) over bolt-on renewable technology. The idea: reduce demand before generating supply. Almost always the most cost-effective route to low-energy buildings.

A short, focused piece of work — typically 2–4 weeks and £1,500–£5,000 — testing what's possible on a site before committing to a full commission. Includes site analysis, design options, planning risk and preliminary cost range.

The statutory instrument that sets out what you can build without planning permission. Currently the GPDO 2015 (as amended). Covers householder extensions, agricultural buildings, commercial change of use and more.

A national planning designation that restricts development in land around major urban areas to prevent sprawl. Different from (and usually more restrictive than) AONBs. Most extensions and new builds in Green Belt are refused.

A written assessment of a heritage asset's significance and how a proposal respects it. Required for applications affecting listed buildings, scheduled ancient monuments, or heritage assets in conservation areas.

See "Certificate of Lawfulness". Legally confirms that a proposal falls within permitted development rights — worth obtaining for any work at the edge of PD limits.

Formal consent required for any works affecting the character of a listed building — internal or external. A criminal offence to carry out works without it. Issued separately from planning permission but usually applied for in parallel.

A ventilation system that extracts stale air from kitchens and bathrooms while drawing fresh air into living spaces, recovering up to 90% of the heat in the outgoing air. Essential for airtight, low-energy buildings.

The government document setting out national planning policy in England. Most recently updated 2023. Sets the policy framework for all local plans and planning decisions. Contains key provisions on housing, Green Belt, design and heritage.

Operation and Maintenance Manual. A handover document prepared at project completion containing as-built drawings, product datasheets, warranties, commissioning certificates and maintenance schedules. Provided to the client on practical completion.

A planning application that establishes the principle of development without fixing all the details. Useful for testing whether something is acceptable before spending on detailed design. "Reserved matters" must be approved before work starts.

The NPPF paragraph (currently para 80, previously 79 and 55) allowing exceptional new houses in the countryside that "reflect the highest standards in architecture" and "significantly enhance their immediate setting". Very difficult to achieve — fewer than 100 approvals nationally per year.

The Building Regulations part dealing with conservation of fuel and power — the legal minimum for thermal performance. Most recently updated 2022, significantly tightened. New builds must now achieve roughly 30% lower emissions than the 2013 standard.

1996 legislation governing works affecting walls shared with neighbours (party walls), excavations near neighbouring buildings, and new walls on the line of junction. Requires formal notice and often a Party Wall Agreement between neighbours.

An international low-energy building standard originating in Germany. Passivhaus buildings use roughly 90% less heating energy than typical new buildings. Achieved through high insulation, airtightness, triple glazing and MVHR — not renewable technology.

The automatic rights to carry out certain types of development without applying for planning permission. Set out in the GPDO. Restricted by Article 4 directions, conservation areas, AONBs and listed building status.

The logbook that Part 1 and Part 2 architecture students keep during their "year out" in practice. Records experience across design, technical, practice and professional tasks. Required to qualify for Part 3 examination.

Professional Indemnity Insurance. Mandatory for ARB-registered architects. Covers claims arising from professional negligence. Typical levels range from £500,000 to several million pounds depending on practice size and project complexity.

The point at which the building is substantially complete and ready for occupation. Issued as a certificate by the Contract Administrator. Triggers the defects liability period, release of half retention, and start of building insurance responsibility.

Paid consultation with the local planning authority before a full planning application is submitted. Gives written feedback on whether a proposal is likely to be approved. The single biggest way to reduce planning risk.

The details (appearance, access, landscaping, layout, scale) that must be approved after an outline planning permission is granted. A reserved matters application must be submitted within 3 years of outline consent.

The professional body for architects in the UK, founded 1834. Separate from ARB — you can be ARB-registered without being a RIBA member. RIBA runs Part 3 examinations for most UK architects, publishes the Plan of Work, and runs the Code of Professional Conduct.

The standard framework organising architectural work into eight stages (0–7), from Strategic Definition through In Use. Used industry-wide as a common language between clients, architects, engineers and contractors. See our Process page.

The ratio of drawing size to real-life size. Common architectural scales: 1:1000 (master plans), 1:200 (site plans), 1:100 (general arrangements), 1:50 (plans and sections), 1:20 (room details), 1:5 (junction details), 1:1 (full-size details).

Drainage techniques that mimic natural water handling — permeable paving, attenuation tanks, swales, green roofs — rather than piping rainwater directly into the mains. Increasingly required on new developments by planning conditions.

The process of inviting contractors to submit priced proposals for constructing a project. Usually 2–4 contractors on a residential project. Returns are analysed on price, programme, method and proposed team — not price alone.

A legal order protecting specific trees. Any work to a TPO'd tree — pruning or felling — requires consent from the planning authority. TPOs are common near housing sites and can significantly affect development proposals.

A measure of how quickly heat passes through a construction (wall, window, roof). Lower U-value = better insulation. Part L 2022 minimum for new walls is 0.18 W/m²K; Passivhaus typically targets 0.10–0.15. Whole-window U-values for triple glazing run 0.8–1.0.

Any change to the agreed scope of work during construction. Variations are managed through written instructions from the Contract Administrator, with cost and programme implications understood before proceeding.