Aluminium Glazing and Al Sa’fat’s 350 kW, 1 MW and 2 MW Thresholds

Al Sa’fat, Dubai’s green building regulations, switches on extra obligations at three calculated cooling loads: 350 kW, 1 MW and 2 MW. At 350 kW a new building must recover and reuse its air-conditioning condensate. At 1 MW it must meet a whole-building air-leakage limit of 5 m³/h/m² at 50 Pa and have its building services formally commissioned. At 2 MW an existing building must be re-commissioned at least once every five years. Because the cooling load is the output of the Heat Load Calculation submitted to Dubai Municipality, the glazing specification is one of the inputs that decides which of these obligations a project carries.

That makes the envelope a compliance lever, not just a running-cost line. This guide sets out what each threshold triggers, which clauses also trigger on floor area (and so cannot be moved by the envelope), which apply to villas, and how much an aluminium glazing specification can realistically move a building’s calculated load.

What are Al Sa’fat’s cooling-load thresholds?

Every clause below is quoted from the second edition of Al Sa’fat (January 2023). Cooling capacity in the UAE is usually discussed in refrigeration tons, so the equivalent is given at one ton (TR) = 3.517 kW.

The 2 MW clause is the only one written for buildings already in use. The re-commissioning checks it lists are specific: fresh air at each ventilation outlet within ±5% of design volume, chilled water to each cooling coil within ±5% of design, and central plant tested through the full range of its capacity.

How is “cooling load” defined, and who sets the number?

Al Sa’fat defines cooling load as “the amount of cooling that a building will require to meet the conditions specified by Dubai Municipality. The cooling load will be determined by the output of the Heat Load Calculation required by Dubai Municipality.” The Heat Load Calculation, in turn, “must be submitted to Dubai Municipality for approval” and “must be based on the design of the building to be constructed”, using the form and parameters Dubai Municipality requires.

Two consequences follow. First, the threshold position is not a measured figure from a finished building; it is a design-stage number, fixed when the calculation is approved. Second, the glazing that is in the calculation is the glazing that decides it. In a well-insulated Dubai building, glazing is usually the largest single envelope component of the peak load, because it is the only element that admits solar radiation directly, so the shading coefficient and U-value written into the specification carry real weight in that number. We explain the timing trap this creates for plant sizing in aluminium glazing and AC plant sizing; the same timing applies here.

Which thresholds can the glazing actually move?

Not all of them. Several obligations trigger on cooling load or floor area, and once a building passes the area test, no envelope improvement takes it back out. The Dubai Building Code adds one more of these: G.4.5.2 requires tariff-class electrical sub-metering of every system with a load of 100 kW or more in buildings with a cooling load of at least 1 MW or a gross floor area of 1,000 m² or greater, so on almost any multi-storey building it is the area test that applies.

So the envelope genuinely decides four obligations: condensate reuse, the air-leakage limit, commissioning and, for an existing building, five-yearly re-commissioning. On a building between 1,000 m² and 5,000 m², the CCMS and water metering can be added to that list.

How much can aluminium glazing move a building’s calculated cooling load?

Our earlier plant-sizing worked example moved 160 m² of glazing from the Al Sa’fat Silver minimum (summer U-value 2.1 W/m²K, shading coefficient 0.40) to a thermally broken aluminium system with a triple-silver solar-control unit (Uw 1.5 W/m²K, SHGC 0.26), and cut the peak glazing heat gain from 25.6 kW to 18.9 kW. That is 6.7 kW, or about 42 W for every square metre of glazing. The table below carries that per-square-metre figure over to larger glazed areas.

Assumptions, stated so the arithmetic can be checked. The 42 W/m² figure was calculated for a villa’s orientation mix at that villa’s governing hour, using ASHRAE 2025 design conditions for Dubai International. A larger building will have a different orientation split and may peak at a different hour. These are heat gains, not cooling loads: building mass damps and delays the solar peak in a full calculation. Treat the table as an order of magnitude, not a prediction for any particular building.

Read that way, the result is still clear. For a mid-rise building with a few thousand square metres of glazing, the difference between a minimum-compliant specification and a high-performance aluminium assembly is in the order of 5–10% of the 1 MW threshold. A building whose calculated load lands well clear of a threshold will not be moved across it by the glass. A building whose calculation sits within that margin can be, in either direction, depending on what goes into the specification.

What does the 1 MW air-leakage limit ask of the windows?

Al Sa’fat 501.05 limits air leakage to 5 m³/h/m² at an applied pressure difference of 50 Pa, and refers to Dubai Building Code H.4.9. The code clause adds two things the regulation does not spell out: “Air tightness testing shall be carried out to verify compliance, in accordance with BS EN 13829 or ASTM E779 or as approved by the Authority”, and “positive pressure, with respect to atmosphere, shall always be maintained in the building.”

This is a whole-building test, not a window rating, but the glazing is a significant part of the envelope it measures. Two things decide the windows’ contribution: the tested air-tightness class of the units themselves, and the seal between the aluminium frame and the structure, which no laboratory classification covers. We set out how window classes translate into building figures in aluminium window air-tightness: what Class 4 means in Dubai. For a building at or above 1 MW, the perimeter seal detail belongs on the drawings, not left to site.

Do these thresholds apply to villas?

Mostly not to private villas, which Al Sa’fat treats differently in its applicability table. Clauses marked with one asterisk are optional for private villas; clauses marked with two are optional for private and investment villas.

• Optional for private villas: 501.05 air leakage, 503.05 central control and monitoring system, 601.03 condensate reuse.
• Optional for private and investment villas: 503.01 commissioning and 503.02 re-commissioning.

Al Sa’fat defines an investment villa as “a complex of separate, connected or semi-connected private villas in which outdoor spaces and recreational services can be shared”. Developers of such schemes stay inside the air-leakage, CCMS and condensate clauses where the thresholds are met; how the load is counted across a compound is a question for the MEP engineer and Dubai Municipality, not one to assume. For an individual villa owner, the envelope rules that apply are the Al Sa’fat glazing performance bands and the Part K requirements, not these thresholds.

Should a project be designed to sit under a threshold?

Our view is that the thresholds are better used for predictability than for avoidance. Commissioning, air-tightness testing and condensate reuse are good practice for a building of that size, and a design that only just clears a line is fragile. Three points are worth settling early:

• The wording at 350 kW differs between the two documents. Al Sa’fat 601.03 applies at “not less than 350 kW”; Dubai Building Code H.5.2.4 applies “where the cooling load is greater than 350 kW”. Only a calculation landing exactly on 350 kW is affected, but if yours does, confirm the reading with Dubai Municipality rather than choosing one.
• Lock the glazing before the Heat Load Calculation is submitted. If the approved calculation assumed a high-performance unit, a later substitution to a lower-specification glass means the approved figure no longer describes the building that is being built.
• Use the spec, not a generic value. A calculation that uses the actual Uw, shading coefficient and frame data of the chosen aluminium window system gives an honest position against the threshold. Our aluminium glazing specification tool lists published Uw and depth data by system.

Frequently asked questions

What cooling load triggers condensate reuse in Dubai?

Al Sa’fat regulation 601.03 requires condensate from air-conditioning equipment and air handling units to be recovered and reused in all new buildings with a cooling load of not less than 350 kW, about 99.5 refrigeration tons. The Dubai Building Code’s parallel clause, H.5.2.4, words it as greater than 350 kW. Al Sa’fat marks 601.03 as optional for private villas.

Which Al Sa’fat requirements apply at a cooling load of 1 MW?

At 1 MW, about 284 refrigeration tons, Al Sa’fat adds a whole-building air-leakage limit of 5 m³/h/m² at 50 Pa (501.05), commissioning of building services (503.01) and condensate reuse under 502.10. A central control and monitoring system (503.05) and additional water sub-metering (602.01) also apply at 1 MW, but are triggered by a gross floor area of 5,000 m² or more as well.

How is the cooling load for these thresholds worked out?

Al Sa’fat defines the cooling load as the output of the Heat Load Calculation required by Dubai Municipality. That calculation must be based on the design of the building, use Dubai Municipality’s parameters and be submitted for approval. The figure that decides which thresholds apply is therefore fixed at design stage, with the specified glazing as one of its inputs.

Do Al Sa’fat’s cooling-load thresholds apply to villas?

Mostly not to private villas. Al Sa’fat’s applicability table marks air leakage (501.05), the central control and monitoring system (503.05) and condensate reuse (601.03) as optional for private villas, and commissioning (503.01) and re-commissioning (503.02) as optional for private and investment villas. Investment villas, defined as a complex of villas with shared outdoor and recreational space, remain inside the first three.

Can better aluminium glazing take a building below the 1 MW threshold?

It can move the calculated load by a meaningful amount. Carrying over the per-square-metre result from LAA’s published plant-sizing example, each 1,000 m² of glazing upgraded from the Al Sa’fat Silver minimum to a high-performance thermally broken assembly removes roughly 42 kW of peak glazing heat gain. Whether that changes a building’s side of a threshold depends on how close its approved calculation sits to the line.

How is the 1 MW air-leakage limit tested?

Dubai Building Code H.4.9.1 requires air tightness testing to verify the 5 m³/h/m² at 50 Pa limit, in accordance with BS EN 13829, ASTM E779 or a method approved by the Authority. It is a whole-building test, so window air-tightness class and the seal between frame and structure both contribute to the result. The same clause requires the building to be kept at positive pressure.

Specifying aluminium glazing for a building near a threshold

For a building whose calculated cooling load sits near 350 kW, 1 MW or 2 MW, the aluminium glazing specification is one of the few inputs that moves the number at design stage, and one of the easiest to lose later through substitution. LAA works with consultants and MEP engineers to fix the glazing performance data, the air-tightness class and the perimeter detail before the Heat Load Calculation goes in, across our aluminium windows and aluminium sliding doors. If you are working on a project in Dubai, we would welcome a specification conversation.

Sources

• Dubai Municipality, Al Sa’fat – Dubai Green Building System, 2nd edition (January 2023): definitions (Cooling Load, Heat Load Calculation, Villa), applicability table, regulations 501.05, 502.10, 503.01, 503.02, 503.05, 601.03, 602.01.
• Dubai Municipality, Dubai Building Code, 2021 edition: G.4.5.2, H.4.9.1, H.4.14.2, H.5.2.4, H.5.2.6.2, H.8.
• Dubai Municipality, Al Sa’fat – Dubai Green Building System (programme page).
• LAA, Aluminium Glazing and AC Plant Sizing in a Dubai Villa: worked example and assumptions behind the 42 W/m² figure (ASHRAE 2025 Handbook – Fundamentals design conditions, Dubai International, WMO 411940).