Munters vs. Traditional Cooling: What Data Center Operators Need to Know

India's Data Center Boom: Scale, Location, and the Cooling Question

India's data center market is experiencing extraordinary growth. Capacity across the major hubs — Bengaluru, Chennai, Hyderabad, Mumbai, and Pune — has expanded from approximately 500 MW of IT load in 2020 to over 1,300 MW by the end of 2024, with another 1,000 MW or more under construction or in advanced planning. Operators including NTT, STT GDC, Yotta, CtrlS, Equinix, and several hyperscale cloud providers are investing billions of dollars in Indian data center capacity. The drivers are clear: digital transformation across Indian enterprise, government digitisation programmes, the growth of cloud computing adoption, and increasingly, the deployment of AI training and inference workloads.

What makes India different from data center markets in Northern Europe or the Pacific Northwest — the regions where many of the world's largest data centers are concentrated — is climate. India's major data center cities experience dry-bulb temperatures of 35°C to 42°C during summer, with relative humidity ranging from 60% to 85% during the monsoon season. Both heat and humidity are enemies of efficient data center cooling. In Stockholm or Dublin, outside air can be used directly for free cooling during most of the year. In Chennai or Mumbai, the outside air is often too hot and too humid to be useful without significant conditioning.

This climate reality makes the choice of cooling technology one of the most consequential decisions a data center operator in India will make. The cooling system typically accounts for 30% to 40% of total facility energy consumption. The difference between a cooling approach that achieves a Power Usage Effectiveness (PUE) of 1.5 and one that achieves 1.15 translates directly into millions of rupees in annual energy cost — and, increasingly, into carbon reduction commitments that operators must demonstrate to investors, tenants, and regulators.

Traditional CRAC/CRAH Cooling: How It Works and Where It Falls Short

The conventional approach to data center cooling, still deployed in the majority of Indian data centers built before 2020, is based on Computer Room Air Conditioning (CRAC) or Computer Room Air Handler (CRAH) units. A CRAC unit contains a direct-expansion (DX) refrigeration circuit — compressor, condenser, expansion valve, and evaporator — packaged in a downflow or upflow air handling unit that sits on or beside the raised floor in the data hall. Air is drawn from the hot aisle, cooled across the evaporator coil, and delivered to the cold aisle through perforated floor tiles or overhead ducting.

CRAH units are similar in form factor but use chilled water from a central chiller plant rather than a self-contained refrigerant circuit. The chiller plant — typically a set of centrifugal or screw chillers with cooling towers — provides chilled water at 7°C to 12°C, which is circulated to the CRAH units via a piping network. CRAH-based systems offer better energy efficiency than CRAC units at scale, and they are the standard approach for data centers above 2 to 3 MW of IT load.

The limitation of both approaches is fundamental: they rely on mechanical refrigeration — the vapour compression cycle — to move heat from the data hall to the outside environment. The energy consumed by the compressors in the chiller plant, the condenser fans, the cooling tower pumps, and the CRAH fan motors adds up to a significant fraction of the total facility power draw. A well-designed chiller-based cooling system can achieve a cooling PUE contribution of 0.4 to 0.6 — meaning that for every watt of IT load, 0.4 to 0.6 watts are consumed by the cooling infrastructure. When you add lighting, security, UPS losses, and other facility overhead, the total PUE lands in the range of 1.5 to 1.8 for most conventional Indian data centers.

India's Tropical Climate Problem: Heat and Humidity Together

The challenge with conventional chiller-based cooling in India goes beyond simple energy consumption. India's climate imposes two simultaneous loads on the cooling system: sensible heat (the temperature of the ambient air) and latent heat (the moisture content). A chiller cooling tower operates by evaporating water to reject heat to the atmosphere. The theoretical limit of this process is the ambient wet-bulb temperature — the lowest temperature that can be achieved by evaporative cooling alone. In Indian cities, the wet-bulb temperature ranges from 24°C to 28°C during the monsoon and 18°C to 22°C during the drier months.

When the wet-bulb temperature is high, the cooling tower cannot reject heat as effectively, and the chiller must work harder — consuming more energy — to maintain the required chilled water temperature. During peak monsoon conditions in Chennai (wet-bulb 28°C, dry-bulb 34°C, RH 80%), a chiller plant that consumes 0.6 kW per kW of cooling at design conditions may consume 0.8 or 0.9 kW per kW. The PUE spikes during exactly the months when electricity tariffs are often at their highest due to peak demand on the grid. Water consumption is also a concern: a 10 MW data center with conventional cooling towers can consume 400,000 to 600,000 litres of water per day, a significant draw in cities facing water stress.

Munters Indirect Evaporative Cooling: A Different Approach

Munters indirect evaporative cooling (IEC) technology takes a fundamentally different approach to data center cooling. Instead of using a vapour compression cycle (chiller) to cool the data hall air, an IEC system uses the evaporation of water in a secondary air stream to cool the primary (data hall) air stream through a heat exchanger — without the two air streams mixing. The data hall air is cooled without adding moisture to it, and without requiring a compressor.

The physics are straightforward. Water evaporation is an endothermic process — it absorbs heat from the surrounding air, cooling it. In an IEC unit, outside air is drawn through a wetted media section, where evaporation cools the air toward its wet-bulb temperature. This cooled air then passes through one side of an air-to-air heat exchanger. The data hall return air passes through the other side of the heat exchanger, transferring its heat to the cooled outside air stream without direct contact. The result is that the data hall air is cooled to a temperature approaching the outside wet-bulb temperature, without any mechanical refrigeration.

In Indian conditions, this means the IEC can cool data hall air to within 2°C to 4°C of the ambient wet-bulb temperature. During drier periods (wet-bulb 18°C to 22°C), this provides adequate cooling for data halls operating within ASHRAE A1 or A2 thermal guidelines (18°C to 27°C inlet temperature). During the monsoon, when wet-bulb temperatures rise to 26°C to 28°C, the IEC alone may not achieve the desired inlet temperature, and a small trim cooling system — a DX coil or a small chiller — supplements the IEC output. The critical difference is that the trim cooler only handles the gap between the IEC output and the desired inlet temperature, not the full cooling load. In a typical Indian climate profile, the IEC handles 70% to 85% of the annual cooling load without any mechanical refrigeration.

Adiabatic Cooling: When and Where It Applies in India

Adiabatic cooling is a related but distinct approach that Munters also offers for data center applications. In adiabatic cooling, water is sprayed or evaporated into the condenser air stream of a conventional or hybrid cooling system, pre-cooling the air before it enters the condenser coil. This reduces the condensing temperature and pressure, improving the efficiency of the refrigerant cycle. Adiabatic pre-cooling is particularly effective in hot, dry climates where the difference between the dry-bulb and wet-bulb temperature is large — a 10°C to 15°C wet-bulb depression provides substantial pre-cooling benefit.

In India, adiabatic cooling is most effective during the pre-monsoon summer months (March to May) when dry-bulb temperatures are highest (38°C to 42°C) but humidity is relatively lower (30% to 50% RH), giving a wet-bulb depression of 8°C to 15°C. During the monsoon, when dry-bulb and wet-bulb temperatures converge, the adiabatic benefit diminishes. For inland cities like Bengaluru, which have a more moderate climate with lower peak humidity, adiabatic cooling provides benefit for a larger fraction of the year compared to coastal cities like Chennai or Mumbai.

PUE Comparison: Munters IEC vs. Conventional Chiller-Based Systems

The PUE advantage of Munters IEC technology over conventional chiller-based cooling is substantial and well-documented. A conventional chiller plant with cooling towers in Indian conditions typically contributes 0.4 to 0.6 to the facility PUE, resulting in total PUE values of 1.5 to 1.8 (including all facility overhead). A Munters IEC system, by eliminating the chiller compressor for the majority of operating hours, reduces the cooling PUE contribution to 0.08 to 0.15, resulting in total PUE values of 1.1 to 1.2.

To put this in financial terms, consider a 10 MW IT load data center operating at an average PUE of 1.6 (conventional) versus 1.15 (Munters IEC). At a blended electricity tariff of INR 8 per kWh, the annual energy cost difference is approximately INR 30 to 35 crore per year. Over a 10-year facility life, the cumulative energy cost difference is INR 300 to 350 crore — a figure that dwarfs any capital cost difference between the two cooling systems. Even at more conservative assumptions (PUE improvement from 1.5 to 1.2, INR 7/kWh tariff), the 10-year energy saving exceeds INR 150 crore for a 10 MW facility.

Water Consumption: The Trade-Off

Evaporative cooling uses water — this is inherent to the physics. A Munters IEC system for a 10 MW data center may consume 200,000 to 350,000 litres of water per day during peak cooling periods. This is less than a conventional cooling tower system of equivalent capacity (which typically consumes 400,000 to 600,000 litres per day, including blowdown) but still represents a significant water demand. In Indian cities facing water stress — Chennai, Bengaluru, and Hyderabad are all classified as water-stressed — this is a material consideration.

Munters addresses this through Water Usage Effectiveness (WUE) optimisation in system design. The IEC control system can modulate water consumption based on ambient conditions, using water only when the wet-bulb depression provides meaningful cooling benefit and operating in dry mode (air-to-air heat exchange only, no water evaporation) when ambient conditions are cool enough. In mild weather, the system may operate for extended periods with zero water consumption. The annual WUE for a Munters IEC system in Indian conditions is typically 0.5 to 1.0 litres per kWh of IT load — compared to 1.5 to 2.5 litres per kWh for conventional cooling tower systems.

Munters for High-Density AI Racks and the Geoclima Acquisition

The emergence of AI workloads — with rack power densities of 40 kW to 100 kW and beyond — has introduced cooling challenges that neither conventional CRAC/CRAH systems nor air-side IEC systems can fully address on their own. At these densities, air cooling alone cannot remove heat fast enough from the rack, and liquid cooling (direct-to-chip or immersion) becomes necessary. Munters' 2024 acquisition of Geoclima, an Italian manufacturer of precision chillers and dry coolers, was a direct response to this market shift.

The combined Munters-Geoclima portfolio now spans the full spectrum of data center cooling: air-side IEC for facility-level thermal management and conventional compute racks, precision liquid cooling for high-density AI clusters, and hybrid systems that integrate both approaches. For a data center operator planning a facility with a mix of conventional and AI workloads — the most common scenario — the ability to source both air-side and liquid-side cooling from a single vendor simplifies design integration, reduces interface risk, and provides a single point of accountability for system performance.

Indian Standards and Green Data Center Policies

Indian data center operators are increasingly subject to energy efficiency and sustainability requirements. The Bureau of Energy Efficiency (BEE) has introduced a star rating system for data centers that includes PUE as a key metric. Data centers achieving PUE below 1.4 qualify for higher star ratings, which may become mandatory for government and public sector tenants. The Indian Green Building Council (IGBC) offers green data center certification with criteria that include cooling system efficiency, water conservation, and renewable energy use.

Several state governments — particularly Karnataka, Telangana, and Tamil Nadu — have introduced data center policies that offer incentives (land allocation, power tariff subsidies, single-window clearance) contingent on meeting specified PUE and sustainability targets. For operators targeting these incentives, the PUE advantage of Munters IEC technology is a significant enabler. A facility designed around Munters cooling can more easily meet a PUE target of 1.3 or below — the threshold increasingly expected by both regulators and hyperscale tenants.

Total Cost of Ownership: A 10-Year View

The total cost of ownership (TCO) comparison between conventional chiller-based cooling and Munters IEC technology is decisive for most data center operators when evaluated over a 10-year horizon. The capital cost of a Munters IEC system is typically 10% to 20% higher than a conventional chiller plant of equivalent cooling capacity. However, the operating cost — dominated by energy consumption — is 40% to 60% lower. The crossover point, where cumulative TCO favours the IEC system, typically occurs within the first 18 to 30 months of operation.

Maintenance costs also favour the IEC approach. A conventional chiller plant contains compressors, refrigerant circuits, cooling towers with chemical treatment systems, and extensive chilled water piping — all requiring regular maintenance, periodic overhaul, and eventual replacement. An IEC system has fewer mechanical components (primarily fans and water distribution systems), lower maintenance complexity, and longer intervals between major overhauls. Over 10 years, maintenance costs for IEC systems are typically 30% to 40% lower than for equivalent chiller plants.

For data center operators in South India evaluating cooling technology for new builds or major retrofits, the technical and financial case for Munters IEC is compelling. Arvi Fluid Systems, as the authorized Munters distributor in Karnataka, Tamil Nadu, Kerala, and Pondicherry, can provide detailed PUE modelling, energy cost analysis, and water usage projections based on your specific site conditions and load profile. Contact us to schedule a technical consultation with our data center cooling specialists.