RIBA Architecture Parts 1, 2 and 3 Environmental Design and Building Services Syllabus

List the core Passivhaus design principles.

Continuous high-performance insulation; elimination of thermal bridges; high-performance (typically triple-glazed) windows; excellent airtightness; mechanical ventilation with heat recovery (MVHR); and optimised solar gain/shading and compact form.

State the key Passivhaus certification performance criteria.

Space heating demand $\leq 15\,\mathrm{kWh/m^2/yr}$ (or heating load $\leq 10\,\mathrm{W/m^2}$); airtightness $\leq 0.6$ air changes per hour at 50 Pa ($n_{50}$); total primary energy (or PER) within the set limit; and overheating frequency $\leq 10\%$ of hours above $25\,^{\circ}\mathrm{C}$.

What is MVHR and roughly what heat-recovery efficiency does Passivhaus require?

Mechanical Ventilation with Heat Recovery supplies fresh air while extracting stale air, passing them through a heat exchanger so outgoing warm air pre-heats incoming cold air. Passivhaus certified units typically recover $\geq 75\%$ (often $80$–$90\%$) of the heat.

Classify renewable heat and power technologies suitable for buildings into 'low/zero carbon' categories.

Heat: ground-source and air-source heat pumps, solar thermal collectors, biomass boilers. Power: photovoltaics (PV), small-scale wind. Combined: combined heat and power (CHP). Heat pumps move heat (high efficiency) rather than generating it by combustion.

Define the Coefficient of Performance (COP) of a heat pump and give a typical value for an air-source unit.

COP is the ratio of useful heat output to electrical energy input: $COP = \frac{Q_{heat}}{W_{input}}$. A typical air-source heat pump achieves a COP of about $3$ to $4$ (delivering 3–4 units of heat per unit of electricity); the seasonal average is the SCOP/SPF.

Distinguish operational carbon from embodied carbon in a building's whole-life carbon assessment.

Operational carbon is emitted from energy used to run the building (heating, cooling, lighting, equipment) over its life. Embodied carbon is emitted from materials and processes — extraction, manufacture, transport, construction, maintenance and end-of-life disposal — independent of energy use in operation.

As operational carbon falls (grid decarbonisation, efficient fabric), why does embodied carbon become proportionally more significant?

Embodied carbon is largely 'locked in' up-front at construction and cannot be reduced later, whereas operational emissions shrink as fabrics improve and the grid decarbonises. So embodied carbon becomes a larger share of whole-life carbon, making material choice and reuse increasingly critical.

In the RIBA whole-life carbon framework, which lifecycle modules cover embodied carbon stages?

Product stage (A1–A3), construction/transport (A4–A5), use-stage embodied — maintenance, repair, replacement (B1–B5), end-of-life (C1–C4) and benefits beyond the system boundary (Module D). Operational energy/water is B6–B7.

What is the RIBA 2030 Climate Challenge, and what are its core target areas?

A voluntary stepped framework setting progressively stricter targets to 2030 for new and retrofitted buildings across three metrics: operational energy use intensity ($\mathrm{kWh/m^2/yr}$), embodied carbon ($\mathrm{kgCO_2e/m^2}$), and potable water use, aligning practice with net-zero pathways.

Give the RIBA 2030 Challenge headline domestic targets for operational energy and embodied carbon.

For domestic buildings the 2030 targets are operational energy $< 35\,\mathrm{kWh/m^2/yr}$ and embodied carbon $< 625\,\mathrm{kgCO_2e/m^2}$ (with intermediate 2025 milestones), alongside reduced potable water use of $< 75\,\mathrm{litres/person/day}$.

Define 'net-zero carbon' for a building and the distinction between net-zero in operation and net-zero whole life.

Net-zero carbon means the total carbon emissions associated with the building are reduced as far as possible and any residual is offset to net zero. Net-zero operational covers only in-use energy emissions; net-zero whole life additionally includes embodied carbon across construction, maintenance and end-of-life.

What is the general principle of an all-air HVAC system versus a wet (hydronic) system?

An all-air system conditions and distributes air via ductwork for both heating/cooling and ventilation (e.g. VAV, CAV). A wet/hydronic system circulates water to terminal units (radiators, fan coils, chilled beams) for heating/cooling, usually with separate, smaller ventilation ducts.

Distinguish CAV, VAV and fan-coil HVAC systems.

CAV (Constant Air Volume) supplies a fixed airflow and varies supply temperature. VAV (Variable Air Volume) keeps supply temperature roughly constant and varies airflow to each zone for efficiency. Fan-coil units recirculate room air over heating/cooling coils locally, with ventilation supplied separately.

What is a chilled beam, and what is the difference between passive and active types?

A chilled beam cools a space by passing water through a coil; passive beams rely on natural convection (cool air falls, warm air rises through the coil) while active beams induce primary ventilation air across the coil to boost cooling and provide fresh air. Beams must run above dew point to avoid condensation.

State the minimum fresh-air ventilation rate commonly used for offices and the typical CO₂ concentration target for good indoor air quality.

Around $10\,\mathrm{l/s}$ of fresh air per person for offices (CIBSE guidance). Indoor CO₂ is kept below about $1000\,\mathrm{ppm}$ (ideally under $800$–$1000\,\mathrm{ppm}$) as a proxy for adequate ventilation; outdoor ambient is roughly $400\,\mathrm{ppm}$.

Distinguish the main building cold-water supply arrangements: direct versus indirect (tank-fed) systems.

In a direct system all cold outlets are fed straight from the rising main at mains pressure. In an indirect system the main fills a cold-water storage cistern (usually in the roof) that gravity-feeds most outlets, providing storage and reducing demand peaks on the main (only the kitchen tap is mains-fed for drinking).

Distinguish a single-stack drainage system from the principles of trap seal and venting.

A single-stack system combines all soil and waste discharges into one vertical stack, designed so airflow within the stack prevents traps being siphoned. Each appliance has a water-filled trap maintaining a seal against sewer gases; venting (stack ventilation or anti-siphon/AAVs) protects trap seals from pressure fluctuations.

What is SuDS, and what is the principle of the SuDS management train?

Sustainable Drainage Systems manage surface water close to source to mimic natural drainage, reducing flood risk and pollution. The management train sequences from source control (green roofs, water butts, permeable paving) through site controls (swales, filter strips) to regional controls (detention basins, ponds, wetlands), promoting infiltration, attenuation and treatment.

Name the four pillars of SuDS design ('the four pillars' / SuDS triangle).

Water quantity (managing flood risk by controlling runoff rates/volumes), water quality (removing pollutants), amenity (creating better places for people), and biodiversity (creating/enhancing habitat). Good SuDS deliver on all four, not just drainage.

Distinguish single-phase from three-phase electrical supply and state UK nominal voltages.

Single-phase supplies one alternating live conductor at a nominal $230\,\mathrm{V}$ (used for most dwellings/small loads). Three-phase supplies three live conductors $120^{\circ}$ out of phase at $400\,\mathrm{V}$ line-to-line, used for larger buildings and heavy plant (motors, lifts), giving smoother power and higher capacity.

State the relationship between illuminance, luminous flux, luminous intensity and the inverse-square law in lighting design.

Illuminance $E$ (lux) is luminous flux (lumens) per unit area: $E = \frac{\Phi}{A}$. From a point source of intensity $I$ (candela) on a surface normal at distance $d$: $E = \frac{I}{d^{2}}$ — the inverse-square law. Off-normal, add a cosine factor: $E = \frac{I\cos\theta}{d^{2}}$.

Give typical maintained illuminance recommendations for an office desk, a circulation corridor, and detailed drawing/technical work.

Office/general desk work about $300$–$500\,\mathrm{lux}$; corridors and circulation about $100$–$150\,\mathrm{lux}$; detailed technical drawing or fine work around $750$–$1000\,\mathrm{lux}$ (CIBSE/SLL Code for Lighting).

How are passenger lifts broadly classified, and which type suits low-rise versus high-rise buildings?

Hydraulic lifts (ram-driven) suit low-rise (up to about 4–6 storeys) — slow, no overhead machine room, larger pit loads. Traction lifts (rope/sheave, geared or gearless) suit mid- to high-rise — faster, more energy efficient; machine-room-less (MRL) traction lifts are now common. High-rise may also use double-deck or sky-lobby arrangements.

What basic parameters govern lift provision (vertical transportation) in an office building?

Handling capacity (percentage of population moved in a 5-minute peak, typically $\sim 12$–$15\%$ for offices) and interval/waiting time (average time between lift arrivals, target $\sim 25$–$30\,\mathrm{s}$). These set the number, speed and car size of lifts based on population, floors and travel height.

Why is early coordination of building services with structure and fabric critical, and what is a 'services zone'?

Services (ducts, pipes, cable trays, drainage) need routed space; clashes with beams, slabs and walls cause costly redesign and reduced ceiling heights. A services zone is the allocated depth (e.g. in the ceiling void or raised floor) reserved for distribution, coordinated against structural depth so floor-to-floor heights and penetrations are resolved early — ideally via a BIM coordination/clash-detection model.

What are 'riser' and 'horizontal distribution' zones, and how do they interact with structural penetrations?

Risers are vertical shafts carrying services between floors; horizontal distribution spreads services across each floor from the riser. Beam penetrations (for ducts/pipes) must be agreed with the structural engineer (size/location of holes, avoiding shear zones) so coordination prevents weakening the structure or blocking service routes.

What is BREEAM and how is a building's performance rated under it?

BREEAM (Building Research Establishment Environmental Assessment Method) is a UK sustainability assessment method. Credits are scored across categories (Energy, Health & Wellbeing, Water, Materials, Waste, Pollution, Transport, Land Use & Ecology, Management, Innovation), weighted into an overall percentage giving a rating: Pass, Good, Very Good, Excellent or Outstanding.

Compare BREEAM, LEED and the WELL Building Standard in terms of focus.

BREEAM (UK-origin) and LEED (US-origin) both assess whole-building environmental/sustainability performance via credits and tiered ratings. WELL focuses specifically on occupant health and wellbeing (air, water, light, comfort, mind, etc.) rather than environmental impact — they are often used together.

Distinguish SAP from SBEM in UK energy compliance modelling.

SAP (Standard Assessment Procedure) is the government methodology for assessing energy performance of dwellings, producing the EPC rating and demonstrating Part L compliance for homes. SBEM (Simplified Building Energy Model) does the equivalent for non-domestic buildings. Both compare the actual design against a notional/target building.

What outputs do SAP/SBEM calculations produce for compliance, and what does 'notional building' mean?

They produce the building's CO₂ emission rate and primary energy/fabric energy efficiency, compared against a Target produced from a 'notional building' — a same-shape reference building with standardised compliant fabric and services. The design must not exceed the notional building's emissions/energy (TER/TFEE limits).

What does Part L of the Building Regulations cover, and what are its two domestic and two non-domestic volumes?

Part L — Conservation of Fuel and Power — sets requirements limiting energy use and carbon emissions from buildings. It is split into L1A (new dwellings), L1B (existing dwellings), L2A (new non-dwellings) and L2B (existing non-dwellings), covering fabric U-values, airtightness, services efficiency and emission targets.

Define the U-value (thermal transmittance) and give its units, plus typical indicative Part L new-build limiting values for walls and windows.

The U-value is the rate of heat transfer through $1\,\mathrm{m^2}$ of an element per $1\,\mathrm{K}$ temperature difference, $U$ in $\mathrm{W/m^2K}$ — lower is better. Indicative new-build values: walls around $0.18\,\mathrm{W/m^2K}$, roofs around $0.11$–$0.15$, and windows around $1.2$–$1.4\,\mathrm{W/m^2K}$.

How is the overall U-value of a multi-layer element related to its thermal resistances?

It is the reciprocal of the total thermal resistance: $U = \frac{1}{R_{total}}$, where $R_{total} = R_{si} + \sum \frac{t}{\lambda} + R_{se}$ (internal and external surface resistances plus each layer's thickness $t$ divided by its conductivity $\lambda$). Adding insulation increases $R$ and lowers $U$.

What is Post-Occupancy Evaluation (POE) and why is it valuable?

POE is the systematic study of a building's performance after it is occupied — measuring energy/water use, indoor environmental conditions and occupant satisfaction (e.g. via BUS surveys, metering, walkthroughs). It verifies whether design intentions were met, informs fine-tuning, and feeds lessons back into future projects (closing the loop).

Define the 'performance gap' and name common causes.

The performance gap is the discrepancy between a building's predicted (modelled) energy/carbon performance and its actual measured in-use performance, where real consumption is typically higher. Causes include unrealistic modelling assumptions, poor workmanship and airtightness, thermal bridging, inadequate commissioning, unaccounted plug/occupant loads, and controls not used as intended.

What is Soft Landings and how does it help close the performance gap?

Soft Landings is a framework (often paired with Government Soft Landings, GSL) that keeps the design and construction team involved before, during and for up to three years after handover — setting performance targets early, ensuring proper commissioning, training occupants, and using aftercare with POE to tune the building and verify outcomes against targets.

What is the difference between 'free-running' and 'mixed-mode' buildings in environmental design?

A free-running (passive/naturally ventilated) building uses no mechanical heating or cooling at the time considered, relying on fabric, ventilation and gains. A mixed-mode building combines natural ventilation with mechanical systems — switching or zoning between them (concurrent, changeover or zoned) to maintain comfort while minimising energy use.