Stage 4: Technical 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

Protect targets through specification

Specify controls + user interfaces intentionally.
Set no-degradation rules for substitutions.

Lock commissioning and metering strategy

Define metering/sub-metering.
Embed commissioning + seasonal commissioning requirements.
REQUIRED OUTPUTS
✓ Operational Energy Brief
✓ Stage 7 POE One-Pager
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

Specification choices either protect or erode earlier carbon gains.

Specify materials with verified EPDs and minimum performance thresholds.
Avoid “gold-plating” through unnecessary finishes or tolerances.
Record assumptions for future verification.
REQUIRED OUTPUTS
✓ Carbon-aligned specifications
✓ Updated WLC assessment
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

Specification choices directly affect real-world water consumption.

Specify fittings to meet or exceed target l/p/d rates.
Detail SuDS components clearly to avoid substitution on site.
Finalise adoption and maintenance documentation.
REQUIRED OUTPUTS
✓ Water-efficient specifications
✓ Technical drainage details
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

Poor detailing and substitution can undermine biodiversity commitments

Specify soils, planting, and habitat features clearly.
Protect retained habitats during construction via method statements.
Finalise management and monitoring plans.
REQUIRED OUTPUTS
✓ Detailed landscape specifications
✓ Landscape & Ecology Management Plan (LEMP)
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

Detailing determines usability and inclusivity.

Specify cycle parking, storage, and end-of-trip facilities.
Detail inclusive access routes and crossings.
Confirm signage and wayfinding strategies.
REQUIRED OUTPUTS
✓ Detailed access & mobility specifications
✓ Inclusive access compliance check
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

Detailing and specification determine real-world comfort.

Specify ventilation, shading, acoustic, and comfort-critical elements.
Confirm controls are usable and intelligible.
Detail safety and security features.
REQUIRED OUTPUTS
✓ IEQ-aligned specifications
✓ Technical comfort details
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

Detailing affects dignity, comfort, and real-world accessibility.

Specify inclusive access features clearly.
Ensure materials and details support safety and comfort.
Protect social spaces from value engineering.
REQUIRED OUTPUTS
✓ Inclusive access specifications
✓ Detailed public realm designs
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

Specification determines maintenance, replacement, and operational costs.

Specify materials and systems with known service lives.
Align warranties, maintenance regimes, and access requirements.
Confirm replacement and renewal assumptions.
REQUIRED OUTPUTS
✓ LCC-aligned specifications
✓ Maintenance and replacement schedule

Recommended Reading

RICS Whole Life Carbon Assessment (2nd ed, 2023) • Net Zero Embodied Carbon
ISE Guide – How to Calculate Embodied Carbon (2020) • Net Zero Embodied Carbon
CIRIA SuDS Manual (C753) • Sustainable Water Cycle
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
BS EN 15978 – Environmental Performance of Buildings • Sustainable Life Cycle Costing and Procurement
BREEAM New Construction – Technical Manual • Sustainable Life Cycle Costing and Procurement