Passive Solar

Variable-base degree-day analysis. Solar and internal gains lower the balance temperature, reducing the degree days actually counted — results update live.

Setpoints & gains

Heating setpoint (°C)Cooling setpoint (°C)

Default internal gains

Internal gains (W/m²)Energy cost ($/kWh)

Defaults: residential 4 W/m², commercial 8 W/m² (currently residential).

SHGC override (blank = from glazing selection)

Single clear0.75 – 0.85

Double clear0.65 – 0.70

Double low-e0.50 – 0.60

Triple glazing0.40 – 0.50

Tinted / reflective0.30 – 0.50

Shading & attenuation

North — interior (IAC)North — external shading (%)

South — interior (IAC)South — external shading (%)

East — interior (IAC)East — external shading (%)

West — interior (IAC)West — external shading (%)

Shading devices

Neighbouring buildings, trees, fences and landforms. Each device is turned into an angular obstruction mask (bearing, angular width, elevation) and tested against the sun path for every 10 minutes of the representative day in each month.

No shading devices yet. Add a neighbouring building, tree, fence or landform and give it a direction, distance and height — the solar gains, heating and cooling results update immediately.

Solar radiation on vertical surfaces

New Zealand (typical) · lat -41.3° · kWh/m²·day

Month	North	South	East	West
Jan	2.82	2.59	4.15	4.15
Feb	3.00	1.87	3.57	3.57
Mar	3.08	1.32	2.82	2.82
Apr	2.89	0.92	1.91	1.91
May	2.72	0.60	1.38	1.38
Jun	2.45	0.48	1.09	1.09
Jul	2.66	0.53	1.25	1.25
Aug	2.92	0.74	1.70	1.70
Sep	3.04	1.14	2.43	2.43
Oct	2.90	1.62	3.16	3.16
Nov	2.75	2.30	3.78	3.78
Dec	2.70	2.68	4.05	4.05

Monthly mean daily global horizontal irradiation and air temperature normals — NIWA (CliFlo / SolarView). Vertical-surface irradiation derived with the Liu–Jordan isotropic sky model and the Erbs diffuse-fraction correlation.

Zone solar inputs

Zone	Glazing m²	SHGC	Solar kWh/yr	Internal kWh/yr
Primary zone	0.0	0.00	0	0

Glazing area includes the vision-glass share of curtain wall, window-wall, structural silicone and double-skin facades, counted on every storey. Spandrel-only panels are opaque and admit no solar gain — choose a vision/spandrel average curtain wall to model gains.

Monthly heating: with vs without gains

Jan

0/0

Feb

0/0

Mar

0/0

Apr

0/0

May

0/0

Jun

0/0

Jul

0/0

Aug

0/0

Sep

0/0

Oct

0/0

Nov

0/0

Dec

0/0

Solid bar = heating demand with passive gains · grey = without gains (kWh).

Passive solar fraction by zone

Primary zone0.0 %

Savings summary

Zone	Base kWh	With gains	Saved	%
Primary zone	0	0	0	0.0
Whole building	0	0	0	0.0

Annual saving

Heating intensity

0.0 kWh/m²·yr

Passive solar fraction

0.0 %

Cooling demand

0 kWh

Validation

Useful gains never exceed the base heating demand

Base 0 kWh; with gains 0 kWh

Passive solar fraction within a physical range (0–90 %)

0.0 % of the gross winter energy balance

Balance temperature stays at or below the heating setpoint

Setpoint 18.0 °C

Heating intensity plausible for NZ housing (< 250 kWh/m²·yr)

0 kWh/m²·yr

Solar gain per m² of glazing below the incident radiation limit

No glazing entered