Industrial Evaporative Cooling Systems in Pakistan: How They Work, Where They Perform Best and How to Size Them Correctly

Pakistan’s factories, warehouses, textile mills, and workshops face some of the most extreme workplace heat conditions of any industrial nation. In Lahore, Faisalabad, and Multan, outdoor temperatures regularly exceed 44 to 47 degrees Celsius in May and June. Inside a weaving shed, a steel fabrication workshop, or a warehouse with a metal roof, radiant heat from machinery and solar gain through the roof structure pushes indoor temperatures 5 to 10 degrees above ambient — creating working conditions that reduce productivity, increase heat illness risk, and in extreme cases make continuous manual work impossible.

Conventional refrigerant-based air conditioning is technically capable of cooling any industrial space but is economically impractical at factory scale. A 10,000 square metre weaving shed would require several megawatts of refrigerant air conditioning capacity to offset its heat load — at an installation cost of hundreds of millions of rupees and operating electricity costs that make the facility uncompetitive. Industrial evaporative cooling systems solve this problem by delivering meaningful temperature reductions at a fraction of the energy cost and capital investment, using Pakistan’s most abundant cooling resource: the low relative humidity of its pre-monsoon summer climate.

This guide explains how evaporative cooling works, when it is effective in Pakistan’s climate, how to size a system correctly for a factory or warehouse, and what distinguishes a properly engineered industrial system from the small-scale residential desert coolers that many facilities incorrectly attempt to scale up. It is written by the HVAC engineering team at Bilal Switchgear Engineering, which designs, manufactures, and installs evaporative cooling and industrial ventilation systems for Pakistani industrial and commercial facilities.

How Industrial Evaporative Cooling Works: The Physics

Evaporative cooling works on the principle of latent heat absorption. When liquid water evaporates into air, it absorbs heat energy from the surrounding air to power the phase change from liquid to vapour. This heat absorption lowers the temperature of the air passing through the evaporating water. The process does not create cooling energy — it converts sensible heat (temperature) into latent heat (water vapour content), reducing the dry-bulb temperature of the supply air while raising its humidity.

The thermodynamic limit of evaporative cooling is the wet-bulb temperature of the incoming air — the lowest temperature achievable by evaporative cooling at a given humidity level. In practice, well-designed industrial evaporative coolers achieve 80 to 90 percent of the theoretical maximum cooling, measured as saturation efficiency. At 45 degrees Celsius and 25 percent relative humidity — typical conditions in Lahore in June before the monsoon — the wet-bulb temperature is approximately 27 degrees Celsius. An 85 percent efficient evaporative cooler would deliver supply air at approximately 30 degrees Celsius, achieving a 15-degree temperature reduction from outdoor conditions.

Evaporative Cooling vs Air Conditioning: A Direct Comparison for Pakistani Factories

The choice between evaporative cooling and refrigerant air conditioning for an industrial facility in Pakistan is not purely technical — it is primarily economic and climatic. Understanding the comparison in quantitative terms helps facility owners and project teams make the right decision for their specific application.

Energy Consumption

An industrial evaporative cooling unit delivering 20,000 m3/h of cooled airflow typically consumes 1.5 to 3 kW of electrical power for the fan motor and water pump combined. An equivalent refrigerant air conditioning system delivering the same airflow at comparable temperature reduction would consume 15 to 25 kW. The energy saving from evaporative cooling is 75 to 85 percent compared to refrigerant air conditioning for the same cooling airflow. At Pakistan’s current industrial electricity tariff, this difference represents millions of rupees annually for a large factory.

Capital Cost

Industrial evaporative cooling units in Pakistan are priced at PKR 150,000 to 600,000 per unit depending on airflow capacity, compared to PKR 500,000 to 2,000,000 per unit for commercial split or packaged air conditioning of comparable cooling output. For large industrial spaces requiring dozens of cooling units, the capital cost difference is significant. Installation of evaporative cooling is also simpler and less expensive than air conditioning — no refrigerant pipework, no specialist refrigerant handling, and simpler electrical supply requirements.

Temperature Reduction Achievable

Refrigerant air conditioning can achieve any target temperature regardless of outdoor conditions, limited only by equipment capacity and energy input. Evaporative cooling can reduce indoor temperature to approximately 3 to 5 degrees above the outdoor wet-bulb temperature. In Pakistani pre-monsoon conditions, this means evaporative cooling can reliably achieve indoor temperatures of 30 to 33 degrees Celsius when outdoor temperatures are 44 to 47 degrees. This is not the 24 degrees achievable with air conditioning but is sufficient to bring factory workers out of the dangerous heat stress zone and restore productivity.

Performance During Monsoon

Refrigerant air conditioning maintains full performance regardless of outdoor humidity. Evaporative cooling performance degrades when outdoor relative humidity exceeds 60 percent. During Pakistan’s monsoon season, evaporative cooling systems should be operated in pure ventilation mode — fans running without water pump activation — to provide air movement without adding humidity to already-humid indoor air. This is an important operational consideration that must be communicated to facility management during system commissioning.

Types of Industrial Evaporative Cooling Systems

Direct Evaporative Cooling Units

Direct evaporative cooling units pass outdoor air directly through wetted cooling pads, delivering cooled humidified air into the factory space. This is the most common and most cost-effective evaporative cooling technology for Pakistani industrial applications. Direct units are available in floor-standing, wall-mounted, and roof-mounted configurations with airflow capacities from 5,000 to 60,000 m3/h per unit.

Cooling pad construction significantly affects system performance and maintenance requirements. Cellulose honeycomb pads provide the highest saturation efficiency (85 to 92 percent) and lowest air resistance, but degrade faster in hard water conditions common in Pakistani industrial areas without water treatment. Rigid fiberglass or plastic media pads are less efficient (70 to 80 percent) but significantly more durable in untreated water conditions and have service lives of 5 to 10 years versus 2 to 4 years for cellulose pads. The choice between pad types should be made based on the local water hardness and the client’s maintenance capability.

Indirect Evaporative Cooling Systems

Indirect evaporative cooling systems cool the supply air without adding humidity to it, by using a heat exchanger where the primary (supply) air is cooled by a secondary air stream that is passed through wetted pads. The secondary air absorbs both heat and humidity from the heat exchanger surfaces, while the primary supply air is cooled with no humidity addition. This allows evaporative cooling to be used in applications where humidity addition is unacceptable — textile production areas where yarn tension is humidity-sensitive, pharmaceutical manufacturing, and food production environments.

Indirect systems are less common in Pakistan due to their higher capital cost and lower temperature reduction compared to direct systems at equivalent airflow. They are specified where the process quality or product specifications prohibit the humidity addition inherent in direct evaporative cooling.

Ducted Evaporative Cooling Systems

Ducted evaporative cooling systems use a central evaporative cooling unit connected to a duct distribution network that delivers cooled air to specific zones within a large factory space. Ducted systems provide better control of air distribution, allowing cooled air to be directed precisely to occupied work zones rather than relying on general space cooling. They are more expensive to install than direct-discharge units but are preferred for factories with high internal heat loads where the cooling must be concentrated at specific workstations or production lines.

How to Size an Industrial Evaporative Cooling System for a Pakistani Factory

Correct system sizing is the most critical engineering step in an evaporative cooling project. Undersized systems fail to achieve comfortable working temperatures. Oversized systems waste capital and may create excessive air velocity discomfort. The sizing calculation follows three steps.

Step 1: Calculate the Total Heat Load

The total heat load comprises solar gain through the roof and walls (calculated from roof construction, area, and orientation), internal heat generated by process machinery and lighting, and metabolic heat from workers. For a typical Pakistani textile weaving shed, solar roof gain alone can reach 150 to 200 W/m2 during peak June conditions. Process machinery heat loads vary widely — a modern weaving shed with air-jet looms generates approximately 15 to 25 kW per loom from motor heat and friction. Both must be quantified before specifying equipment.

Step 2: Determine the Required Airflow Volume

Required airflow is calculated from the total heat load and the achievable temperature difference between supply and exhaust air. For direct evaporative cooling in Pakistani pre-monsoon conditions, the supply air temperature is typically 30 to 32 degrees Celsius at the cooler outlet. The exhaust air leaving through roof ventilators or wall louvres is typically 38 to 40 degrees Celsius. This 8 to 10 degree temperature rise across the space, combined with the air density and specific heat of air, gives the required airflow volume in cubic metres per second using the equation: Q = P / (rho x Cp x dT), where P is total heat load in watts, rho is air density (approximately 1.1 kg/m3 at Pakistani summer conditions), Cp is specific heat of air (1005 J/kg/K), and dT is the temperature rise across the space.

Step 3: Select Unit Quantity and Placement

The total required airflow is divided among individual cooling units based on the available unit capacities. For large factory spaces, multiple units distributed around the perimeter provide more uniform coverage than a single large central unit. Unit placement should ensure that cooled air paths traverse occupied work zones before being exhausted — cross-flow ventilation patterns from coolers on one wall to exhaust louvres on the opposite wall are the most effective configuration for Pakistani factory buildings.

Evaporative Cooling Applications in Pakistan by Industry

Textile Mills and Weaving Sheds

Textile production is the largest single market for industrial evaporative cooling in Pakistan. Weaving and spinning facilities in Faisalabad, Lahore, Gujranwala, and Sialkot have installed hundreds of thousands of square metres of evaporative-cooled production space over the past 20 years. The temperature reduction achieved extends productive working hours, reduces worker absenteeism in peak summer months, and in some cases improves yarn quality by maintaining lower relative humidity than air conditioning would achieve.

Warehouses and Logistics

Large-volume warehouses for FMCG, retail, and manufacturing logistics in Pakistan are adopting evaporative cooling rapidly as the alternative to conventional warehouse fans that provide insufficient temperature reduction for workers during peak summer. Evaporative cooling in warehouses is most cost-effective when the warehouse has good natural inlet louvre provision for air entry and roof-mounted exhaust ventilators for spent air discharge.

Food Processing and Cold Chain

Fresh food processing facilities including packing houses, fruit processing plants, and meat processing facilities in Pakistan require worker areas to be maintained below 30 degrees Celsius for both food safety and worker welfare compliance. Evaporative cooling provides this temperature level at a fraction of the cost of refrigerant air conditioning, and in dry storage and packing areas where product humidity sensitivity is low, direct evaporative cooling is the standard specification.

Manufacturing Workshops and Assembly Plants

General manufacturing facilities including automotive component plants, engineering workshops, and assembly operations across Pakistan’s industrial estates are major evaporative cooling users. Plants such as Atlas Honda and other automotive manufacturers in Lahore and Sheikhupura use evaporative cooling in their production and painting preparation areas. Bilal Switchgear Engineering’s evaporative cooling systems have been installed in manufacturing facilities for clients including Coca-Cola, Metro Cash and Carry, and industrial complexes across Punjab.

Maintenance Requirements for Industrial Evaporative Coolers in Pakistan

An evaporative cooling system requires more routine maintenance than an equivalent mechanical ventilation system because water is continuously circulated through the cooling pads and distribution manifolds. Without proper maintenance, scale build-up from Pakistan’s hard water, algae growth in water reservoirs, and cooling pad degradation significantly reduce system performance within one to two seasons.

• Weekly: inspect water level in reservoir, check pump operation, inspect cooling pads for uneven wetting or scale build-up
• Monthly: clean water reservoir and distribution tray, check pad condition and replace if damaged or heavily scaled, inspect fan belt tension and condition on belt-driven units
• Seasonally: replace cooling pads if cellulose type showing degradation, flush water system and clean all distribution headers, inspect and lubricate fan bearings, check motor insulation resistance
• At season end: drain and clean complete water system before winter shutdown, inspect pad frames and enclosure for corrosion, cover units to protect from winter dust accumulation
• Water treatment: in areas with hard water (TDS above 500 mg/l), a simple bleed-off or dosing system to control scale formation extends pad life significantly and is a worthwhile addition to any industrial installation

Bilal Switchgear Engineering: Evaporative Cooling System Design and Supply

Bilal Switchgear Engineering designs and installs industrial evaporative cooling systems for Pakistani factories, warehouses, and commercial buildings through our Ventilation Division. Our engineering team carries out site heat load assessments, system sizing calculations, unit selection, and installation supervision for complete turnkey cooling projects. We supply both direct evaporative cooling units and combined ventilation and cooling systems that integrate axial fans, evaporative coolers, and duct distribution within a single engineered design.

Evaporative cooling projects are typically delivered as part of a complete facility ventilation and cooling design that addresses both temperature reduction and air quality. Our MEP services include the electrical supply, switchgear, and controls for evaporative cooling systems as part of turnkey mechanical and electrical project delivery. All cooling system installations include commissioning under loaded conditions and handover training for facility maintenance staff on seasonal operation and maintenance procedures.

Contact our cooling system engineering team to discuss your factory or warehouse cooling requirements, request a preliminary heat load assessment, or obtain a formal quotation for evaporative cooling system supply and installation.

Frequently Asked Questions

How much temperature reduction can evaporative cooling achieve in Pakistan?

In Pakistan’s pre-monsoon climate (May and June), when outdoor relative humidity is typically 20 to 35 percent, well-designed industrial evaporative cooling systems achieve supply air temperature reductions of 12 to 15 degrees Celsius below outdoor dry-bulb temperature. If the outdoor temperature is 45 degrees Celsius, the cooler outlet temperature will be approximately 30 to 33 degrees Celsius. This 12 to 15 degree reduction is consistent across Lahore, Faisalabad, Multan, Gujranwala, and Sialkot during peak summer months before the monsoon arrives. During the monsoon period, performance reduces to 4 to 8 degrees reduction due to higher outdoor humidity.

Is evaporative cooling effective during Pakistan’s monsoon season?

Evaporative cooling effectiveness reduces significantly during the monsoon season (July to September) when outdoor relative humidity exceeds 60 to 70 percent. At 80 percent outdoor humidity, the achievable temperature reduction is only 2 to 4 degrees Celsius, which is insufficient for meaningful factory cooling. During the monsoon, industrial evaporative cooling systems should be operated in pure ventilation mode with water pumps switched off, using the fan alone to provide air movement and fresh air supply. The water pump should be reactivated when outdoor humidity drops below 60 percent, typically in October and again in April.

How does evaporative cooling compare to air conditioning for a textile mill in Pakistan?

For a large textile weaving shed in Faisalabad, evaporative cooling typically provides 12 to 15 degree temperature reduction at 75 to 85 percent lower energy consumption than equivalent refrigerant air conditioning. Air conditioning achieves greater temperature reduction (to 24 to 26 degrees) but at a capital cost 4 to 6 times higher per unit of cooling capacity and operating costs that make large textile facilities economically uncompetitive. Most Pakistani textile manufacturers use evaporative cooling as the primary cooling system and accept 30 to 33 degree indoor temperatures as economically appropriate for their production environment.

How much water does an industrial evaporative cooler use in Pakistan?

Water consumption for an industrial evaporative cooling unit in Pakistan depends on the airflow capacity, the ambient conditions, and whether a bleed-off system is used to control water quality. A typical 20,000 m3/h unit consumes approximately 8 to 16 litres of water per hour during operation in Pakistani summer conditions. For a factory with 50 units operating 10 hours per day, total daily water consumption is approximately 4,000 to 8,000 litres. Where water supply is from a bore well (common in Pakistani industrial areas), this consumption level is generally manageable. A bleed-off system that removes a portion of reservoir water continuously to prevent scale concentration adds approximately 20 to 30 percent to the base water consumption figure.

Can evaporative cooling be used alongside air conditioning in the same facility?

Yes. A hybrid approach using evaporative cooling for general factory floor cooling combined with refrigerant air conditioning for specific climate-sensitive areas (quality control rooms, server rooms, offices, pharmaceutical production areas) is common in Pakistani industrial facilities. The evaporative system handles the majority of the factory floor area at low cost, while air conditioning serves only the small areas where the 24-degree target cannot be met by evaporative means. This hybrid approach is typically 60 to 70 percent less expensive to operate annually than full air conditioning coverage of the complete facility.