DSEER: certifying seasonal performance for desert conditions

When Eurovent Certification introduced its Desert Certification option - used to measure the performance of products destined for the Middle East - it also introduced a new performance metric: the Desert Seasonal Energy Efficiency Ratio (DSEER). Designed to measure seasonal efficiency based on real-world, part-load conditions, DSEER represents a shift away from product performance metrics based on temperate climates, to something designed specifically for the extreme temperatures experienced in the Gulf region.

In this article Eurovent Certification explores seasonal performance metrics, how DSEER is calculated, and explains more on the Desert Certification option.

Why do we need seasonal performance metrics?

In the real world, units very rarely operate at full power, 100% of the time. Demand will vary throughout the seasons, and so units will spend much of the year cycling up and down at partial load. A metric called the Seasonal Energy Efficiency Ratio (SEER) was created to give a truer reflection of this day-to-day use over a year. As an evolution of the Energy Efficiency Ratio (EER), SEER replicates seasonal use, rather than give efficiency at a set point.

However, SEER is usually based on temperate-climate test assumptions and rating points that are less severe than Gulf operating conditions. This means a unit can look acceptable on a standard SEER basis yet perform poorly or consume more power when exposed to sustained 46-52°C ambient heat. This is where DSEER enters the frame. DSEER differs in two big ways: it uses desert-specific temperature testing, and it is intended to represent part-load performance in a hot climate rather than a generic cooling season.

How has seasonal energy efficiency been traditionally calculated?

SEER is calculated using temperatures usually experienced in a temperate European or American climate. SEER uses a set indoor temperature, along with different outdoor temperatures and load capacities to simulate real life, according to the EN 14825 standard. SEER is calculated at the following conditions:

Air source:

Water source:

The SEER rating is calculated by dividing the total cooling output in watts (or BTUs depending on country) at the different conditions, by the total electric energy used in watts.

What’s changed for DSEER and why?

Units destined for the Middle East operate in extreme heat. The data provided by SEER at temperate conditions, does not give a full picture of performance at 45-50°C. The DSEER bridges this gap, by creating data that is relevant to Gulf climates, where equipment is often pushed far harder than in Europe.

Eurovent Certification spent years working with manufacturers, to develop DSEER. DSEER calculates seasonal efficiency based on four part-load conditions:

Again, the DSEER rating is calculated by dividing the total cooling output at the different conditions, by the total electric energy used. Only this time, it is at capacities and temperatures that mimic a Gulf climate.

The Desert Certification option

The Desert Certification option was introduced in 2025 after a sustained period of work between Gulf Cooperation Council (GCC) governments, Eurovent Certification and Eurovent Middle East. The certification is designed to provide reliable performance data for products operating in hot, desert-like conditions, and is open to chillers, air conditioners, VRF units, rooftop units and IT cooling units.

Designed specifically for Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, and the UAE, Desert Certification also tests cooling capacity and Energy Efficiency Ratio (EER) at T1 conditions (35°C), T3 conditions (46^oC), plus operability at 52°C. For units destined for the Kuwait market, certification is available for cooling capacity and EER at T4 (48^oC). These metrics, combined with DSEER, provide independently verified data that is more trustworthy for local conditions.

Final thoughts

The goal of DSEER is to give governments, specifiers, developers, installers, and end users reliable, accurate performance data. For governments, DSEER helps with policy, grid planning, and energy-efficiency regulation because it is based on real-world conditions. For developers, consultants and HVACR professionals, it improves product comparison and reduces the chance of selecting equipment that underperforms or fails in summer operation. For owners and users, it is a more practical predictor of electricity cost, comfort, and reliability in the harshest months.

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