Explore upgrade pathways, moisture and heritage risks, and staged sequencing — preview updates with your inputs.
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For your 92 m² retrofit (EPC C) · M23 — ROI north star
Pathway: efficient electrified — unknown
Preference-aligned pathway "Efficient Electrified" — readiness not evaluated; preference order only (score unchanged).
Planning aid only — not SAP, PHPP, or HEM certification.
Explore upgrade pathways, moisture and heritage risks, and staged sequencing — preview updates with your inputs.
One-click presets from architect test cases — populates inputs and regenerates the preview.
Paste briefing notes or upload .txt / .md / .pdf — we draft-populate inputs for review. Not SAP/PHPP extraction.
Moisture survey, EPC lodgement check, asbestos/damp flags before fabric changes.
Loft/top-up, draught reduction, targeted glazing — avoid trapping moisture in solid walls.
Plan MVHR or balanced ventilation before major airtightness gains.
Right-size ASHP after fabric improvements; avoid oversizing on pre-improvement loss.
PV and battery after demand profile is understood; label export assumptions.
Smart meter or sensor upload to improve Evidence Grade — planned capability.
Preference-aligned pathway "Efficient Electrified" — readiness not evaluated; preference order only (score unchanged).
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.
Planning bands only — not SAP, PHPP, or HEM model outputs. Verify with qualified assessor.
Indicative bands are planning aids — see how we test score assumptions on our validation benchmarks page. Not SAP, PHPP, or certification output.
Recommendations sharpen as facts move from estimated → known. Score confidence bands reflect the same honesty.
Client-stated floor area, confirmed build type
U-values from archetype; glazing ratio from concept drawings
Site location not confirmed — climate and orientation assumptions provisional · Solid-wall construction — moisture-risk review before insulation specification
What improves confidence: site survey, EPC lodgement, blower-door test, measured post-occupancy data (planned).
What we are assuming, what is still missing, and who should verify before technical design.
For your 96 m² retrofit (EPC D) — ROI north star
Recommended pathway (preference-ranked): efficient electrified — unknown
Climate profile: Temperate (UK)
Occupied retrofit — phased sequencing and dust/noise constraints apply
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
floor: Confirm existing floor U-value before extension junction design
Confirm notional vs actual specification path
Overheating screening method for high-risk façades and summer comfort
Renewable contribution accounting if PV included later
Thermal bridge Psi-values for preferred junction details
Heating/cooling load after fabric specification locked
Ventilation summer bypass strategy with MVHR
Site location not confirmed — climate and orientation assumptions provisional
Verifier: Site survey / assessor
Next: Confirm on site or with client before technical design
Solid-wall construction — moisture-risk review before insulation specification
Verifier: Site survey / assessor
Year built not confirmed — heritage and construction assumptions provisional
Verifier: Site survey / assessor
Next: Confirm on site or with client before technical design
No blower-door test scheduled — airtightness target is design intent only
Verifier: Site survey / assessor
Next: Confirm on site or with client before technical design
Fabric and plant choices affect notional vs actual performance path.
Verifier: SAP / HEM assessor or regional equivalent
Next: Lock U-value targets and confirm assessment route at technical design
Glazing balance and shading drive summer comfort before heating load drops.
Verifier: SAP / HEM assessor + architect comfort review
Next: Run orientation/glazing review; specify shading and ventilation bypass strategy
MVHR requires airtightness QA and summer bypass planning.
Verifier: Ventilation designer / assessor
Next: Document intended ventilation route and extract strategy
Heat pump sizing must follow fabric-first heat loss, not rule-of-thumb.
Verifier: Heating engineer / MCS installer
Next: Align with Air-source heat pump sized after heat loss — low-temperature distribution…
Solid walls need breathable or verified safe insulation strategy.
Verifier: Retrofit coordinator / moisture-risk assessor
Next: Confirm wall build-up and monitoring plan before insulation install
Evolving Home does not lodge SAP, PHPP, or HEM files.
Verifier: Qualified assessor
Next: Export intent pack and schedule formal modelling
7–12 kW (indicative peak, not SAP/PHPP) peak heat loss · 4872–7656 kWh/yr space heating/cooling demand band annual heating
Verifier: SAP / HEM assessor
Next: Replace planning bands with modelled outputs after fabric lock
Indicative bands are planning aids — see how we test score assumptions on our validation benchmarks page. Not SAP, PHPP, or certification output.
Unified compliance-adjacent checks and brief risk signals — for professional review, not regulatory sign-off.
Where Evolving Home fits in early design — planning aid only, not a compliance or approval substitute.
Where EH helps · North-star routing across 90+ pathways with readiness caveats — helps frame client priorities before concept sketches.
Not a claim · Not a business-case sign-off or planning approval predictor.
Where EH helps · Quick-spec presets, climate profiles, and indicative quantity bands — turns assumptions into a shareable brief draft. Heritage, occupancy, and wall-type inputs shape staged sequencing and moisture warnings.
Not a claim · Not lodged SAP, PHPP, or HEM files; figures are indicative for professional review.
Where EH helps · Design-stage risk register, compliance-adjacent flags, and consultant handoff pack — surfaces what to verify before technical design. Moisture and conservation flags stay visible alongside envelope upgrade options.
Not a claim · Not Part L, Part O, or building-control compliance certification.
Inputs suggest elevated overheating screening at concept — schedule orientation, shading, and ventilation review with your assessor. Evolving Home does not lodge Part O or TM59 reports.
Next step: run glazing/orientation review and specify shading and summer ventilation bypass before technical design lock-in.
Flags for professional review — Evolving Home does not sign off Part L, Part O, SAP, PHPP, or HEM.
| Issue | Why it matters | Who verifies | Evidence | Next action |
|---|---|---|---|---|
| Part L / energy performancePart L | Fabric and plant choices affect notional vs actual performance path. | SAP / HEM assessor or regional equivalent | assumed | Lock U-value targets and confirm assessment route at technical design |
| Part O / overheating & summer comfortPart O | Glazing balance and shading drive summer comfort before heating load drops. | SAP / HEM assessor + architect comfort review | partial | Run orientation/glazing review; specify shading and ventilation bypass strategy |
| Ventilation strategyVentilation | MVHR requires airtightness QA and summer bypass planning. | Ventilation designer / assessor | assumed | Document intended ventilation route and extract strategy |
| Heating plant sizingHeating | Heat pump sizing must follow fabric-first heat loss, not rule-of-thumb. | Heating engineer / MCS installer | assumed | Align with Air-source heat pump sized after heat loss — low-temperature distribution… |
| Moisture & solid-wall retrofitMoisture | Solid walls need breathable or verified safe insulation strategy. | Retrofit coordinator / moisture-risk assessor | partial | Confirm wall build-up and monitoring plan before insulation install |
| Design intent onlyDesign intent | Evolving Home does not lodge SAP, PHPP, or HEM files. | Qualified assessor | assumed | Export intent pack and schedule formal modelling |
Embodied carbon figures are indicative ranges from published guidance — not a whole-building LCA. Use a qualified LCA practitioner for project-specific results.
Share with clients before consultant appointments — highlights intent, risks, and decisions without certification language.
For your 96 m² retrofit (EPC D) — ROI north star
Stage investments by payback confidence; electrify heating only after fabric targets are set. This brief ranks pathways for your stated priority — it does not replace accredited energy modelling.
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.
For your 96 m² retrofit (EPC D) — ROI north star. Illustrative pack contents — not a lodged SAP, PHPP, or HEM file. Pro exports include versioned assumptions from your saved project.
Demo export from current planning view. Sign in and save to unlock Pro persisted exports.
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View retrofit sample brief · HEM for architects (source) · Score an address