Choosing Windows for Kerman's Hot, Dry Climate

Design each elevation deliberately

East and west glazing receives low-angle sun that is difficult to shade with a simple horizontal overhang; west-facing rooms can experience intense afternoon gain. South-facing openings can often be controlled more predictably with properly sized external shading. North-facing glass receives less direct sun but still affects heat transfer and daylight.

Map orientation, glass area, room use and existing shade before choosing one build-up for the whole building. A bedroom, showroom and stairwell do not need identical opening areas or solar-control targets.

Use SHGC and U-factor for different questions

SHGC indicates how much solar heat passes through a window; lower values reduce unwanted solar gain. U-factor describes overall heat transfer; lower values mean better insulation. Visible transmittance indicates daylight passage. These values should be balanced rather than selected independently.

In strong sun, a suitable Low-E or solar-control coating can reduce cooling loads and improve comfort near the glass. External shading stops solar energy before it reaches the pane and is often more effective than an interior blind. The glass appearance, reflectance and daylight effect should be reviewed with an approved sample.

Airtightness is central to dust control

Dust enters through unintended air paths as well as through open windows. Fixed lights and compression-sealed casement, awning or tilt-and-turn units generally offer better control than conventional sliding systems. When sliders are required, specify interlocks, seals, drainage and track maintenance clearly.

The perimeter joint between frame and wall is part of the air barrier. A good factory-made sash can still leak around its outside edge if the opening is uneven or the joint is filled without a continuous interior air seal.

Select a frame for size and exposure

uPVC can provide good thermal separation for conventional residential sizes when reinforcement, profile color and system limits suit the exposure. Thermally broken aluminum can support large panes and slim sightlines, provided the thermal barrier and corner assembly are effective.

Dark exterior frames absorb more solar energy. Allow for expansion, follow manufacturer size and fixing limits, and avoid choosing a tall sash solely to remove visual divisions. Glass weight and hardware capacity must be checked together.

Detail for a dry climate that still gets rain

Dry weather does not eliminate water-management requirements. Local storms and wind-driven rain still need sloped sills, clear drainage openings, compatible exterior seals and an uninterrupted path to the outside. Sealant exposed to strong ultraviolet radiation should be suitable for the substrates and expected movement.

Dust and construction debris can block weep holes or wear hardware. Protect tracks during building work, clean them before handover and provide a maintenance routine for residents or facility staff.

A climate-based specification checklist

• record orientation, shade and approximate glass area for each elevation;
• state target whole-window U-factor, SHGC and air leakage where project data supports them;
• define the full glass build-up and coating surface;
• confirm frame color, reinforcement or thermal break, and size limits;
• choose opening types around ventilation, dust and cleaning access;
• detail anchorage, interior air seal, exterior weather seal and drainage;
• retain product sheets, approved samples and the final window schedule.

The strongest specification is not the one with the longest feature list. It is the one that connects Kerman's actual sun, dust, temperature and building use to measurable window and installation decisions.