Climatology and Sustainable/Low-Energy Design
This paper tests passive design reasoning first and calculations second: how form, orientation and envelope respond to Iranian climate zones, and how مبحث ۱۹ sets the minimum thermal performance of the envelope.
Core rules
- Four zones: معتدل و مرطوب (Caspian), سرد (northwest and highlands), گرم و خشک (central plateau), گرم و مرطوب (southern coast).
- Vernacular responses: courtyard and badgir with qanat in the hot-arid zone, deep verandahs and cross ventilation in the hot-humid zone, compact plans with south glazing and thermal mass in the cold zone, raised floors and large roofs in the Caspian zone.
- مبحث ۱۹ sets envelope requirements by climate group: R-values for walls, roofs and windows, plus air-tightness and equipment efficiency. Compliance is a thermal calculation, not a construction habit.
- The passive hierarchy is: reduce demand (form, orientation, insulation) → use free gains (solar, daylight, night flush) → efficient systems → renewables last.
Worked example
Compute a wall's U-value: 2 cm plaster (k = 0.5), 20 cm brick (k = 0.7), 5 cm EPS (k = 0.04). Resistances: 0.04 + 0.286 + 1.25 + 0.04 = 1.616 plus surface films 0.13 + 0.04 = 1.786 m²K/W. U = 1 / 1.786 = 0.56 W/m²K. Convert every thickness to metres, add surface resistances, then compare with the مبحث ۱۹ limit for that climate group.
Traps
- Confusing R (resistance, added) with U (transmittance, reciprocal).
- Forgetting internal and external surface resistances.
- Entering thicknesses in centimetres into the k formula.
- Assuming double glazing alone solves a hot-climate problem where shading matters more.