Philippine Data Centres Pay Too Much to Cool Servers.
There Is a Better Architecture.
Average Philippine data centre PUE is 1.6-2.0. That means 37-50% of electricity goes to cooling, not computing. CO₂ heat pump + LiBr absorption cascade achieves PUE 1.22 active, with passive thermosyphon reaching PUE 1.02-1.05. Zero water consumption.
Why Data Centre Operators Are Looking at Natural Refrigerants
Philippine data centres face four converging pressures that make conventional DX cooling increasingly untenable.
High PUE: 1.6-2.0 Average
Most Philippine data centres operate at PUE 1.6-2.0, meaning 37-50% of total electricity is consumed by cooling infrastructure. At Philippine commercial electricity rates of ₱10-12/kWh, every 0.1 PUE improvement saves millions of pesos annually per MW of IT load.
Water Consumption
Evaporative cooling towers consume 5-15 litres of water per kWh of IT load. In water-stressed areas of Metro Manila, Cebu, and Clark, this creates operational risk, regulatory exposure, and ESG reporting challenges. CO₂ + LiBr cascade uses zero water for heat rejection.
HFC Refrigerant Liability
Data centres using R410A (GWP 2,088) or R134a (GWP 1,430) chillers face Scope 1 refrigerant emission liabilities under SEC PFRS S2. Typical 5-10% annual leak rates create significant CO₂e exposure. CO₂ (GWP 1) eliminates this liability entirely.
35°C Ambient Challenge
Philippine ambient temperatures of 28-35°C eliminate free cooling opportunities available in temperate climates. Conventional chiller efficiency drops at high ambient, increasing energy consumption. Transcritical CO₂ operates efficiently above its critical point (31.1°C), actually designed for these conditions.
CO₂ Heat Pump + LiBr Absorption Cascade
The architecture uses a transcritical CO₂ heat pump as the primary cooling stage, with a lithium bromide (LiBr) absorption chiller providing a secondary cooling stage driven by waste heat or low-grade thermal energy. This cascade approach reduces compressor electrical input while maintaining cooling capacity at peak Philippine ambient temperatures.
The concept builds on the Calysta/TLK-Thermo 2018 cascade architecture, adapted for tropical operation with optimised gas cooler design and variable-speed compressor control.
Active Mode
CO₂ HP + LiBr cascade at full load. Maintains cooling capacity at 35°C ambient. Zero water for heat rejection. Suitable for all Philippine operating conditions year-round.
Passive Thermosyphon
Two-phase CO₂ loop: liquid absorbs server heat, boils, rises to roof condenser, condenses by gravity return. No compressor, no pump, no moving parts. Transitions to active mode automatically at peak ambient.
Reference architecture: Calysta/TLK-Thermo 2018 cascade concept.
Industry References
Karnot is developing natural refrigerant data centre cooling solutions with leading industry partners.
US Data Centre Consortium
Collaborative research programme with a US data centre consortium exploring CO₂ + LiBr cascade cooling for high-density compute facilities. Focus on PUE optimisation and zero-water heat rejection in tropical and subtropical climates.
Hyperscale Cloud Provider Pilot
Pilot programme with a hyperscale cloud provider evaluating passive thermosyphon CO₂ cooling for edge data centres in Southeast Asia. Target PUE 1.02-1.05 with automatic failover to active cascade cooling during peak ambient conditions.
Recommended Products for Data Centres
Custom-engineered cooling solutions from standard Karnot modules.
iCOOL CO₂
Transcritical CO₂ cooling. 6-350kW modules. COP 3.5-4.0 at 35°C ambient. Scalable rack-level or hall-level deployment. GWP 1.
Custom Cascade
CO₂ HP + LiBr absorption cascade. Engineered to site conditions. PUE 1.22 target. Zero water. Passive thermosyphon integration available.
iSAVE
Smart energy platform. Real-time PUE monitoring, predictive load management, carbon reporting, and BMS/DCIM integration via BACnet and ModBus.
Engineering Tools for Data Centre Projects
Free calculators for data centre cooling system design.
Frequently Asked Questions
How does the CO₂ HP + LiBr cascade achieve PUE 1.22?
The transcritical CO₂ heat pump provides primary cooling while the LiBr absorption chiller uses waste heat for secondary cooling. This cascade reduces compressor electrical input while maintaining full cooling capacity at 35°C ambient, achieving PUE 1.22 — well below the Philippine average of 1.6-2.0.
What is the passive thermosyphon concept?
A two-phase CO₂ loop where liquid CO₂ absorbs server heat, boils into vapour, rises to a roof-mounted condenser, condenses back to liquid, and returns by gravity. No compressor, no pump, no moving parts. Achieves PUE 1.02-1.05 when ambient conditions permit, with automatic failover to the active cascade.
Why does zero water consumption matter?
Evaporative cooling towers consume 5-15 litres per kWh of IT load. In water-stressed Metro Manila, Cebu, and Clark, this creates operational risk and regulatory exposure. CO₂ + LiBr cascade and thermosyphon systems use zero water for heat rejection, eliminating water dependency.
Can this work at 35°C Philippine ambient?
Yes. Transcritical CO₂ operates efficiently above its critical point (31.1°C) — it is designed for these conditions. The LiBr absorption stage provides supplemental capacity at peak ambient. The passive thermosyphon transitions to active mode automatically when ambient exceeds the free-cooling threshold.
What HFC liability do data centres face?
R410A (GWP 2,088) and R134a (GWP 1,430) chillers create Scope 1 refrigerant emission liabilities under SEC PFRS S2. With 5-10% annual leak rates, the carbon cost is significant. CO₂ (GWP 1) eliminates this entirely and avoids Kigali Amendment HFC phase-down restrictions.
Lower Your PUE. Eliminate Water. Future-Proof Your Refrigerant.
Talk to our engineering team about CO₂ + LiBr cascade cooling and passive thermosyphon architecture for your data centre.