Stage 2: Concept Design

Work Stage Actions & Internal Guidance

01
Net Zero Operational Carbon Dioxide emissions

Net Zero operational carbon for new build and retrofit, measured as kWh/m²/year and kgCO₂e/m²/year, validated in use.

Stage Goals
Design Team Actions

Select passive-first energy strategy

Test massing, orientation, and shading.
Document rejected options.

Log early energy/overheating feasibility

Assess overheating risk and initial energy feasibility.
Plan next modelling steps.
REQUIRED OUTPUTS
✓ Operational Energy Brief
✓ Performance Gap Risk Register
02
Net Zero Embodied Carbon

Net Zero embodied carbon across the building lifecycle, measured in kgCO₂e/m², using whole-life carbon assessment and verified data.

Stage Goals
Design Team Actions

Form, grid, massing, and structural strategy dominate embodied carbon outcomes.

Compare structural options (e.g. concrete vs steel vs timber hybrids).
Test material intensity driven by spans, heights, and grids.
Carry out an early embodied carbon study to steer concept selection.
REQUIRED OUTPUTS
✓ Concept embodied carbon comparison
✓ Structural/material options appraisal
03
Sustainable Water Cycle

Minimise potable water use and manage surface water sustainably, measured through litres/person/day, runoff rates and flood-risk compliance. Achieve 40% reduction in potable water use per person per day

Stage Goals
Design Team Actions

Spatial layout and landscape strategy define SuDS success or failure.

Integrate SuDS features (basins, swales, permeable surfaces) into the design concept.
Test water efficiency assumptions against occupancy and building type.
Ensure exceedance routes are spatially resolved.
REQUIRED OUTPUTS
✓ Concept drainage strategy
✓ Water efficiency calculations (early)
04
Sustainable Land Use & Ecology

Achieve biodiversity net gain and responsible land use, demonstrated through measurable habitat uplift, soil protection, and long-term management.

Stage Goals
Design Team Actions

Layout, access, and open space design determine ecological success.

Integrate habitat retention, creation, and green infrastructure into the concept.
Test layout options against biodiversity outcomes.
Align SuDS with habitat creation where possible.
REQUIRED OUTPUTS
✓ Concept landscape & ecology strategy
✓ Early BNG calculation
05
Sustainable Connectivity & Transport

Maximise sustainable travel and minimise car dependency, demonstrated through mode share, accessibility, and reduced transport-related emissions.

Stage Goals
Design Team Actions

Layout, access, and movement hierarchies determine real-world travel behaviour.

Design pedestrian and cycle routes as primary movement networks.
Locate entrances, cycle parking, and facilities for convenience and safety.
Test parking provision against policy and behavioural objectives.
REQUIRED OUTPUTS
✓ Concept access & movement strategy
✓ Parking and cycle provision schedule
06
Sustainable Health & Wellbeing

Deliver healthy, comfortable, and safe environments, demonstrated through indoor environmental quality, thermal comfort, and occupant wellbeing indicators.

Stage Goals
Design Team Actions

Form, orientation, and layout dominate daylight, ventilation, and overheating outcomes.

Test daylight, ventilation, and overheating strategies.
Integrate access to outdoor space and views.
Avoid design moves that increase reliance on mechanical mitigation.
REQUIRED OUTPUTS
✓ Concept IEQ strategy
✓ Early overheating and daylight studies
07
Sustainable Communities & Social Value

Deliver measurable social value and inclusive community outcomes, demonstrated through access, use, safety, participation, and long-term community benefit.

Stage Goals
Design Team Actions

Spatial decisions determine whether places support interaction, safety, and belonging.

Test layout options against inclusivity, permeability, and safety.
Integrate shared spaces and community uses meaningfully.
Respond to local character and identity.
REQUIRED OUTPUTS
✓ Concept social value strategy
✓ Inclusive layout appraisal
08
Sustainable Life Cycle Costing and Procurement

Achieve demonstrably lowest whole-life cost consistent with performance objectives, assessed through structured life cycle cost analysis.

Stage Goals
Design Team Actions

Form, structure, and systems choices dominate long-term cost.

Compare options using high-level LCC (structure, envelope, services).
Test durability and replacement assumptions.
Reject options that reduce capex but increase long-term risk.
REQUIRED OUTPUTS
✓ Concept option LCC comparison
✓ Cost-informed design selection record

Recommended Reading

LETI Climate Emergency Design Guide (2020) • Net Zero Operational Carbon Dioxide emissions
CIBSE TM54 • Net Zero Operational Carbon Dioxide emissions
RICS Whole Life Carbon Assessment (2nd ed, 2023) • Net Zero Embodied Carbon
ICE Database (v3, 2020) • Net Zero Embodied Carbon
ISE Guide – How to Calculate Embodied Carbon (2020) • Net Zero Embodied Carbon
CIRIA SuDS Manual (C753) • Sustainable Water Cycle
BS EN 16941-1:2024 • Sustainable Water Cycle
DEFRA Statutory Biodiversity Metric - User Guide • Sustainable Land Use & Ecology
CIEEM Ecological Impact Assessment (EcIA) Guidelines • Sustainable Land Use & Ecology
Natural England – Green Infrastructure Framework • Sustainable Land Use & Ecology
Manual for Streets (MfS1 & MfS2) • Sustainable Connectivity & Transport
PAS 2080 – Carbon Management in Infrastructure • Sustainable Connectivity & Transport
WELL Building Standard v2 • Sustainable Health & Wellbeing
WHO Housing and Health Guidelines • Sustainable Health & Wellbeing
UKGBC Guide for Delivering Social Value on Built Environment Projects • Sustainable Communities & Social Value
UK Government Social Value Model • Sustainable Communities & Social Value
BS EN 15978 – Environmental Performance of Buildings • Sustainable Life Cycle Costing and Procurement
HM Treasury Green Book (2022) • Sustainable Life Cycle Costing and Procurement
BREEAM New Construction – Technical Manual • Sustainable Life Cycle Costing and Procurement