Evolving Home · Architect brief
New build — 120 m² · sustainability
For your 120 m² detached project — Sustainability north star
Generated 30/08/2026, 04:35:22
Design brief summary
Preference-aligned pathway "Efficient Electrified" — readiness not evaluated; preference order only (score unchanged).
Envelope targets
- walls: U ≤ 0.15 W/m²K (concept target)
- roof: U ≤ 0.12 W/m²K (concept target)
- airtightness: ≤ 1.0 ACH @ 50 Pa (design target)
- glazing: Balance g-value and Uw by orientation; avoid overglazing south façades
Risk flags
- [medium] Overglazing risk — Large unshaded south glazing increases overheating before heating load drops.
- [medium] Thermal bridge detailing — Junctions at balconies, corners, and extension ties need explicit psi-value strategy.
This pack is design-stage decision support from Evolving Home. It is not a SAP calculation, PHPP balance, HEM assessment, or Energy Performance Certificate. A qualified On Construction Domestic Energy Assessor (or PHPP consultant) must produce the authoritative compliance model for Building Regulations and/or Passive House certification.
Passive House (PHPP) certification and UK Building Regulations (SAP/HEM) are separate workflows. This brief supports early design intent only.
Assumptions ledger (compact)
Key assumptions, evidence gaps, and verification hooks for consultant handoff.
- Project assumptionsEstimated
For your 120 m² detached project — Sustainability north star
- Project assumptionsEstimated
Recommended pathway (preference-ranked): efficient electrified — unknown
- Project assumptionsEstimated
Climate profile: Temperate (UK)
- Project assumptionsEstimated
2 storeys (design intent)
- Project assumptionsEstimated
Budget sensitivity: balanced
- Envelope & glazingEstimated
walls: U ≤ 0.15 W/m²K (concept target)
- Envelope & glazingEstimated
roof: U ≤ 0.12 W/m²K (concept target)
- Envelope & glazingEstimated
airtightness: ≤ 1.0 ACH @ 50 Pa (design target)
- Envelope & glazingEstimated
glazing: Balance g-value and Uw by orientation; avoid overglazing south façades
- Envelope & glazingEstimated
Glazing: ~18% floor area — balanced glazing
- Evidence gapsMissing
Site location not confirmed — climate and orientation assumptions provisional
- Evidence gapsMissing
Loft depth / roof build-up not verified on site
Consultant handoff preview
Live previewPreview onlyProject assumptions
- ·For your 120 m² detached project — Sustainability north star
- ·Recommended pathway (preference-ranked): efficient electrified — unknown
- ·Climate profile: Temperate (UK)
- ·2 storeys (design intent)
- ·Budget sensitivity: balanced
Envelope & glazing
- ·walls: U ≤ 0.15 W/m²K (concept target)
- ·roof: U ≤ 0.12 W/m²K (concept target)
- ·airtightness: ≤ 1.0 ACH @ 50 Pa (design target)
- ·glazing: Balance g-value and Uw by orientation; avoid overglazing south façades
- ·Glazing: ~18% floor area — balanced glazing
Evidence gaps
- ·Site location not confirmed — climate and orientation assumptions provisional
- ·Loft depth / roof build-up not verified on site
- ·No blower-door test scheduled — airtightness target is design intent only
- ·Battery / thermal storage sizing not locked — solar readiness is design intent only
Questions for SAP / HEM assessor
- ·Confirm notional vs actual specification path
- ·Overheating screening method for primary living rooms
- ·Renewable contribution accounting if PV included later
- ·Which PCDB product categories apply to heating and MVHR?
- ·What air permeability target is assumed for Design SAP / HEM?
- ·Are thermal bridge psi-values from accredited details or bespoke calc?
- ·What evidence will be collected for as-built sign-off?
Questions for PHPP consultant
- ·Thermal bridge Psi-values for preferred junction details
- ·Heating/cooling load after fabric specification locked
- ·Ventilation summer bypass strategy with MVHR