07/07/2026
🌡️ Why do engineers consistently undersize AC systems in the Gulf — and how to avoid it?
I have seen it happen on projects across the region: a building is handed over, the AC runs non-stop, occupants complain — and the post-mortem reveals the cooling load was underestimated at the design stage.
Here is one reason why:
A typical villa in Dubai with west-facing glass can experience solar heat gain through glazing alone of 350–450 W/m² during peak afternoon hours. That is not a figure you can estimate by thumb rule. It must be calculated — wall by wall, glass panel by glass panel, hour by hour — using the CLTD/CLF method developed by ASHRAE.
Yet many engineers working on small to mid-size buildings in the UAE, Saudi Arabia, Qatar and Kuwait are still sizing systems using oversimplified rules such as "1 TR per X square feet" — without accounting for:
✅ Orientation and shading of each wall and window
✅ Peak solar time (which shifts by compass direction)
✅ Internal heat gains from occupants, lighting, and equipment
✅ Ventilation and fresh air loads — critical in Gulf climates
✅ Latent heat load driven by high outdoor humidity in coastal cities
The result is either an oversized system wasting energy — or an undersized one that never reaches setpoint.
After 44 years in HVAC and MEP engineering, including the design of the World's First LEED Platinum Garment Factory (Brandix Casualwear Seeduwa — US Green Building Council, 2008 — 40% energy reduction), I decided to write this down in a form that working engineers can actually use on site.
My new eBook — Cooling Load Calculations: A Practical Guide — Step-by-Step for Small to Mid-Size Buildings — walks through the complete CLTD/CLF calculation method with five fully worked examples across international cities, including a Dubai villa. All formulas are presented in both SI and Imperial units.
If you are an HVAC engineer, MEP consultant, or building services professional working in the Middle East, this guide was written with your projects in mind.
🔗 Available now on Gumroad:
https://lmendisstudio.gumroad.com/l/xemcoe
