The humidity excursion you didn't see.The product you can no longer ship.
For tropical warehouses storing tobacco, dried foods, grains, paper or any hygroscopic product. Standard split air conditioning physically cannot hold 22 °C / 60% RH in Manila ambient. Karnot AHU + iSTOR + iHEAT R290 + iVOLT solar holds the warehouse at spec continuously, year-round, while taking ~89% off the electricity bill.
Why standard split AC always fails for tropical product storage.
The engineering reason your warehouse RH climbs above 65% every wet season is structural — not a fault, not bad operation, not undersizing. Split AC is the wrong machine for a latent-dominated tropical load. Four ways the existing plant fails, and what each one costs.
SHR Mismatch — sized for the wrong job
A standard split AC has a Sensible Heat Ratio of 0.70–0.85 — 70-80% of capacity goes to lowering temperature, only 20-30% to removing moisture. Your tropical warehouse needs SHR 0.40–0.50 — the load is dominated by latent moisture from infiltration, ventilation and product respiration. Specifying the wrong SHR is a fundamental engineering error, and it cannot be corrected by adding more split AC.
Short-Cycle Compressor — humidity spikes silently
The room hits 22 °C in five minutes (low sensible load). The thermostat is satisfied; the compressor cuts off. Dehumidification stops. Moisture continues to enter through loading-bay doors, ventilation, product respiration. RH spikes to 75–80% within the hour. Mould in 3–6 days; cured tobacco can be irreversibly spoiled inside one week. The damage compounds silently — it does not show up on the BMS dashboard.
Electric Reheat Workaround — illegal under ASHRAE 90.1
The lazy operator solution to humidity creep is to add an electric reheat coil: overcool the air to drop the dewpoint, then electrically reheat it. This is explicitly forbidden under ASHRAE 90.1 §6.5.2.3 (simultaneous heating and cooling) and triples the electricity bill. The only compliant path is hot-gas reheat from recovered condenser heat — which standard split AC cannot do, but a Karnot AHU + iSTOR system does by design.
Product Loss — the cost nobody puts on the spreadsheet
PHilMech (Philippine Center for Postharvest Development) documents average 12.7% storage loss on corn alone; broader agricultural loss across PH supply chains routinely reaches 50%. Tobacco operators face the same physics — once mould begins on cured leaf or finished cigarettes, the entire affected pallet is unrecoverable. Inadequate warehouse HVAC is universally cited as the primary driver.
One AHU. One reversible heat pump. Two iSTOR tanks. One iVOLT solar package.
Four products that work as one continuous system — the AHU conditions the warehouse air, the iHEAT R290 charges either iSTOR tank on demand, the iSTOR tanks buffer the AHU through every heat-pump reversal, and the iVOLT solar + Li-ION package powers the whole thing from the warehouse roof.
iHEAT R290
Reversible R290 heat pump 9.5–105 kW. Heating COP 4.14–5.59 / Cooling EER 3.51–4.16. Outdoor packaged unit, ambient −25 to +45 °C. Charges either iSTOR tank on demand.
iSTOR PCM × 2
Two phase-change thermal batteries — hot tank @ 44 °C, cold tank @ 22 °C. Patented PCM, natural fluids sourced in PH. Buffer the AHU through HP reversal — no warehouse interruption.
Karnot AHU
Fully inverter-controlled Air Handling Unit with hot coil + cold coil + ECM fan. Conditions the warehouse air directly through ductwork. Runs on humidistat for continuous RH control.
iVOLT solar + Li-ION
Roof-mounted PV array + Karnot inverter + LiFePO4 lithium-ion battery. Sized to power the entire AHU + iSTOR + iHEAT system through any grid event. Eliminates diesel-generator OPEX.
One zone. ~89% off the bill. ~2.9-year payback.
First-principles ASHRAE Heat Balance Method calculation on a 200 m² tobacco-product warehouse zone at 22 °C / 60% RH spec. Existing setup: 5 × 3 HP + 1 × 2 HP split AC running 24/7. Tariff: ₱14/kWh including 3-phase service premium. Existing annual electricity cost: ~₱629,000. Replaced with Karnot iHEAT 18.5 kW R290 + iSTOR PCM thermal storage + dual-coil AHU + 15 kWp iVOLT roof solar: ~₱65,000 annual cost. Net annual saving: ~₱564,000 per zone. CO₂ avoided: ~28 tonnes per year per zone. Customer name withheld. Real numbers from a free site audit on your specific warehouse.
Capital purchase. ~2.9-year payback per zone.
Karnot equipment is sold outright with a 3-year warranty on the heat-pump core. Per-zone payback figures are from a worked first-principles 200 m² warehouse case study. Energy-efficiency capex may qualify for BOI incentives under RA 11285 — Karnot supports the registration paperwork; the final package is confirmed by BOI on a case-by-case basis.
From the day it's commissioned, the bill drops.
Energy Efficiency & Conservation Act incentives.
Most hotel installations qualify. Karnot supplies the BOI registration paperwork as part of the project handover.
- RA 11285 framework — codifies energy efficiency as a public-policy priority
- DOE classification support — Type 1 / Type 2 designated establishment
- BOI registration — Karnot supports application paperwork as standard project scope
- Final incentive package — confirmed by BOI based on project profile and Strategic Investment Priority Plan
- Verify with your tax adviser before commitment — incentives are not guaranteed
Download the Warehouse Climate Control Application Brief
The full slide deck and the single-page summary — both ready to share with your facilities team, your CFO or your board.
Engineering Tools for Hotel Projects
Free calculators to size your hotel heat pump system.
Frequently Asked Questions
Why does standard split air conditioning fail in tropical warehouses?
A standard split AC has a Sensible Heat Ratio (SHR) of 0.70–0.85 — designed to remove sensible heat. A tropical warehouse load is dominated by latent moisture (SHR around 0.40–0.50). The split hits its temperature setpoint in minutes, the compressor cuts off, and humidity continues climbing through loading-bay door cycles, ventilation infiltration and product respiration. RH spikes to 75–80%, mould forms in 3–6 days, and stored hygroscopic product is irreversibly damaged.
What is the payback period for a hotel heat pump?
DHW retrofit (replacing an LPG or diesel boiler with iHEAT) typically pays back in around 24 months. Full thermal retrofits including pool, spa, kitchen cold storage and chiller upgrades pay back in 3 to 5 years. Most installations qualify for BOI tax incentives under RA 11285 — Karnot files the registration paperwork as part of project scope.
Can iHEAT heat a swimming pool?
Yes. The iSPA range (6.5-39kW) is specifically designed for pool heating with COP up to 14.05 and titanium heat exchangers for saltwater resistance. For larger resort pools, iHEAT R290 units provide efficient year-round heating and can be integrated with the hotel domestic hot water system.
Does switching to heat pumps help with SEC PFRS S2?
Yes. Replacing diesel boilers eliminates Scope 1 combustion emissions from your hotel. R290 refrigerant has a GWP of just 3, avoiding the HFC-related Scope 1 disclosures that affect hotels using conventional DX cooling systems with R410A (GWP 2,088).
What happens during a power outage?
iSTOR phase-change thermal batteries store up to 80kWh of hot water energy, providing hours of backup without electricity. When paired with generator backup, the heat pump restarts automatically and the thermal store bridges the transition period seamlessly.
Ready to Hold Your Warehouse at 22 °C / 60% RH Year-Round?
Book a free site survey. Our engineers will model your warehouse load using the ASHRAE Heat Balance Method, size the AHU + iSTOR + iHEAT + iVOLT package, and show you the exact payback.