Passive House Design Calculator by Avenir Developments

The free Passive House Design Calculator by Avenir Developments help you determine steps you can use passive house design strategies.

Passive House Design Calculator

Early-stage Passive House (PHI) readiness check. Estimate specific heating & cooling demand, heat-loss coefficients, and readiness vs. PH targets. Not a substitute for PHPP—ideal for concept decisions in Pakistan and worldwide.

Project Basics

Units Updates labels & conversions.

Climate Preset Prefills HDD, CDD & solar profile (editable).

HDD (base 18 °C) Heating Degree Days per year.

CDD (base 26 °C) Cooling Degree Days per year.

Geometry & Envelope

Treated Floor Area (TFA) Heated usable area.

m²

Avg. Ceiling Height For volume & ventilation.

Building Length Exterior length for wall calc.

Building Width Exterior width for wall calc.

U-value Walls Lower is better (e.g., 0.12–0.18).

W/m²·K

U-value Roof e.g., 0.10–0.15.

W/m²·K

U-value Slab/Floor e.g., 0.10–0.18.

W/m²·K

Thermal Bridge Allowance Envelope-wide ψ allowance.

W/m²·K

Windows & Solar

Window Uw (whole) PH target ≲ 0.85 W/m²·K.

W/m²·K

SHGC (g-value) Solar gain factor 0–1.

—

Vision Glass Fraction 1 − frame fraction (e.g., 0.8).

—

Shading Factor 0–1 (overhangs/films/blinds).

—

Window Area South Vertical area by orientation.

m²

Window Area East Morning sun gains.

m²

Window Area West Afternoon sun gains.

m²

Window Area North Diffuse light, low gains.

m²

Ventilation & Airtightness

Airtightness n₅₀ Target ≤ 0.6 ACH @50 Pa.

ACH50

Exposure / Shielding Affects infiltration (ACH50→ACH).

Mech. Ventilation Rate Supply air change rate.

ACH

HRV/ERV Heat Recovery Sensible efficiency (%).

Internal Gains & Solar Profile

Internal Gains Appliances/people (per m²·yr).

kWh/m²·yr

Solar Exposure Vertical irradiation profile.

Cooling Solar Fraction Share of solar during cooling.

—

Night Vent Effectiveness 0–1 benefit (cool season).

—

Passive House Targets (quick view)

Heating ≤ 15 kWh/m²·yr n50 ≤ 0.6 ACH50 HRV ≥ 75% Uw ≤ 0.85 W/m²·K

This tool is indicative. Certification requires full PHPP modelling and testing.

Method & assumptions (read me)

Heat loss: Transmission Σ(U·A) + ventilation (0.33·n·V). HRV reduces only the mechanical portion by its sensible efficiency; infiltration from n50×exposure remains unrecovered.

Solar gains: Window area × SHGC × vision fraction × orientation irradiance × shading × utilization (0.6). Cooling uses “Cooling Solar Fraction”.

Cooling: Approximate: Gains − (heat-loss at CDD), with night-ventilation relief. Results guide early design; not a substitute for PHPP or local energy codes.

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Passive House Design Calculator by Avenir Developments