Archive and warehouse humidity held at 50%
How a 3,000 m² archive store can hold 22–25 °C and 45–55% relative humidity through the monsoon with heat pump dehumidification, and what it saves against electric-reactivated desiccant dehumidifiers.
▶Video: Industrial drying and dehumidifying
V09 · 2–2.5 minSludge, green-ware, pharma granules and storage rooms
Video coming soon01Problem statement
- Mould and paper damage. Above about 60% relative humidity, paper, leather, textiles and packaging grow mould and foxing within weeks.
- Moisture comes in all the time. Humid air leaks in through doors, docks and the building fabric, and stock itself releases moisture.
- Desiccant units use a lot of heat. Electric heaters regenerate the desiccant wheel and add heat to the room, which then needs cooling.
- Electric heating is expensive heat. Resistance heaters turn one kWh of electricity into one kWh of heat, at the full commercial tariff. A heat pump moves two to four kWh of heat for the same unit.
- Large connected load. Heater banks take a big share of the sanctioned load and push up maximum-demand charges.
02Use case
The reference building is a 3,000 m² archive and records store with 6 m clear height on the west coast. It holds paper files, books and packed goods, and outside air in the monsoon stays above 80% relative humidity for months.
| Product | Drying | Basis | Water removed, kg/day | Conventional heat, kWh/day |
|---|---|---|---|---|
| Daily moisture load (infiltration, doors, stock) | Room 22–25 °C, 50% RH | 18,000 m³ × 0.15 air changes/h × 1.2 kg/m³ × 8 g/kg × 24 h = 622 kg, plus doors and people 78 kg, total 700 kg/day. Entered as a notional 1,400 kg/day at 50% moisture dried to 0%, which gives 700 kg of water removed. | 700 | 1,260 |
| Total | 700 | 1,260 | ||
Conventional hot-air dryers use about 1.8 kWh of heat per kg of water removed. That figure is the baseline the savings are measured against.
03P&ID
Tags: HP heat pump, TK tank, SG steam generator, P pump, PHE plate heat exchanger, TCV temperature control valve, TIC temperature indicating controller (panel), TT temperature transmitter, MT moisture transmitter, PT pressure transmitter, LT level transmitter, FS flow switch, NC normally closed. Process fluids are heated through their own exchanger, coil or jacket.
04Solution
System description
- 3 × SE-AA-DR-11 (32 kW total) heat pump drying modules, removing about 700 kg of water a day in roughly 19 running hours.
- The electric-reactivated desiccant dehumidifiers stays connected behind a normally closed valve as standby.
- Heat pump dehumidifiers draw room air over a cold evaporator, condense the moisture and reheat the dried air over the condenser before returning it to the store.
- Ducted supply runs along the aisles so air moves gently through the shelving.
- Doors and docks get strip curtains or air locks to cut the moisture load at source.
- Condensate is collected and drained, and the volume removed is logged as a check on performance.
Selected equipment
| Model | 3 × SE-AA-DR-11 |
|---|---|
| Heating capacity | 10.5 kW each, 32 kW total |
| Dehumidifying | about 37 L/h total (pro rata to the published 12–120 L/h range) |
| Drying air | rated 70 °C, 75 °C maximum |
| Refrigerant | R134a |
| Ambient | −5 to 43 °C |
| Water removed per kWh | about 2.4 kg |
Ratings from the Sunniva TDS 2026 data sheets.
Control philosophy
Humidity sensors across the store hold 50% relative humidity, staging the heat pump dehumidifiers in turn. TIC-201 limits supply air to 35 °C and room temperature to 25 °C. If humidity rises above 60% the BMS raises an alarm and the existing desiccant units can be started.
05Energy saving and ROI
Change any input to match a customer's site. Defaults are typical Indian prices for October 2026. The installed cost is a placeholder; replace it with the actual quotation.
| Existing | Heat pump | |
|---|---|---|
| Daily consumption | – | – |
| Annual energy cost | – | – |
| CO₂ per year | – | – |
06Benefits
Stable conditions for collections
Steady humidity and temperature slow decay of paper, textiles and objects.
Less energy per kg of water
Heat pump dehumidification uses a fraction of the energy of electrically regenerated desiccant units at these conditions.
No added room heat
The condenser only reheats air back to room temperature, so no extra cooling is needed.
Heat recovered from the moisture
The evaporator condenses water out of the air and the condenser puts that latent heat back into the drying air, so about 2.4 kg of water leaves per kWh of electricity.
Closed loop, clean product
Air recirculates inside the chamber. No dust, smoke or outside humidity reaches the product, whatever the weather.
Built-in redundancy
Several machines share the load. If one is serviced, the others and the storage carry most of the day, with the existing heater in reserve.
07Engineering pointers
Site data to collect
- Store floor area, height and construction
- Target temperature and humidity
- Door and dock openings per day
- Current dehumidifier ratings and running hours
- Records of humidity and any mould problems
- Present fuel or electricity use and monthly bill
- Sanctioned electrical load and spare capacity
- Space for the heat pumps and storage, with service access
Design notes
- Seal the building first. Most of the moisture load comes through gaps and doors. Sealing and door control can halve the load before any equipment is sized.
- Low dew points. Below about 40% relative humidity at 20 °C, condensing units lose capacity. Combine with desiccant only if very dry conditions are needed.
- Air distribution. Keep air moving through all aisles. Dead corners behind shelving are where mould starts.
Service and warranty
Sunniva has supplied 5,000+ heat pumps since 2012, with nine service technicians across India, including remote sites such as Leh. All components carry a one-year warranty.
Talk to us
Archive and warehouse humidity held at 50%
How a 3,000 m² archive store can hold 22–25 °C and 45–55% relative humidity through the monsoon with heat pump dehumidification, and what it saves against electric-reactivated desiccant dehumidifiers.
▶Video: Industrial drying and dehumidifying
V09 · 2–2.5 minSludge, green-ware, pharma granules and storage rooms
Video coming soon01Problem statement
- Mould and paper damage. Above about 60% relative humidity, paper, leather, textiles and packaging grow mould and foxing within weeks.
- Moisture comes in all the time. Humid air leaks in through doors, docks and the building fabric, and stock itself releases moisture.
- Desiccant units use a lot of heat. Electric heaters regenerate the desiccant wheel and add heat to the room, which then needs cooling.
- Electric heating is expensive heat. Resistance heaters turn one kWh of electricity into one kWh of heat, at the full commercial tariff. A heat pump moves two to four kWh of heat for the same unit.
- Large connected load. Heater banks take a big share of the sanctioned load and push up maximum-demand charges.
02Use case
The reference building is a 3,000 m² archive and records store with 6 m clear height on the west coast. It holds paper files, books and packed goods, and outside air in the monsoon stays above 80% relative humidity for months.
| Product | Drying | Basis | Water removed, kg/day | Conventional heat, kWh/day |
|---|---|---|---|---|
| Daily moisture load (infiltration, doors, stock) | Room 22–25 °C, 50% RH | 18,000 m³ × 0.15 air changes/h × 1.2 kg/m³ × 8 g/kg × 24 h = 622 kg, plus doors and people 78 kg, total 700 kg/day. Entered as a notional 1,400 kg/day at 50% moisture dried to 0%, which gives 700 kg of water removed. | 700 | 1,260 |
| Total | 700 | 1,260 | ||
Conventional hot-air dryers use about 1.8 kWh of heat per kg of water removed. That figure is the baseline the savings are measured against.
03P&ID
Tags: HP heat pump, TK tank, SG steam generator, P pump, PHE plate heat exchanger, TCV temperature control valve, TIC temperature indicating controller (panel), TT temperature transmitter, MT moisture transmitter, PT pressure transmitter, LT level transmitter, FS flow switch, NC normally closed. Process fluids are heated through their own exchanger, coil or jacket.
04Solution
System description
- 3 × SE-AA-DR-11 (32 kW total) heat pump drying modules, removing about 700 kg of water a day in roughly 19 running hours.
- The electric-reactivated desiccant dehumidifiers stays connected behind a normally closed valve as standby.
- Heat pump dehumidifiers draw room air over a cold evaporator, condense the moisture and reheat the dried air over the condenser before returning it to the store.
- Ducted supply runs along the aisles so air moves gently through the shelving.
- Doors and docks get strip curtains or air locks to cut the moisture load at source.
- Condensate is collected and drained, and the volume removed is logged as a check on performance.
Selected equipment
| Model | 3 × SE-AA-DR-11 |
|---|---|
| Heating capacity | 10.5 kW each, 32 kW total |
| Dehumidifying | about 37 L/h total (pro rata to the published 12–120 L/h range) |
| Drying air | rated 70 °C, 75 °C maximum |
| Refrigerant | R134a |
| Ambient | −5 to 43 °C |
| Water removed per kWh | about 2.4 kg |
Ratings from the Sunniva TDS 2026 data sheets.
Control philosophy
Humidity sensors across the store hold 50% relative humidity, staging the heat pump dehumidifiers in turn. TIC-201 limits supply air to 35 °C and room temperature to 25 °C. If humidity rises above 60% the BMS raises an alarm and the existing desiccant units can be started.
05Energy saving and ROI
Change any input to match a customer's site. Defaults are typical Indian prices for October 2026. The installed cost is a placeholder; replace it with the actual quotation.
| Existing | Heat pump | |
|---|---|---|
| Daily consumption | – | – |
| Annual energy cost | – | – |
| CO₂ per year | – | – |
06Benefits
Stable conditions for collections
Steady humidity and temperature slow decay of paper, textiles and objects.
Less energy per kg of water
Heat pump dehumidification uses a fraction of the energy of electrically regenerated desiccant units at these conditions.
No added room heat
The condenser only reheats air back to room temperature, so no extra cooling is needed.
Heat recovered from the moisture
The evaporator condenses water out of the air and the condenser puts that latent heat back into the drying air, so about 2.4 kg of water leaves per kWh of electricity.
Closed loop, clean product
Air recirculates inside the chamber. No dust, smoke or outside humidity reaches the product, whatever the weather.
Built-in redundancy
Several machines share the load. If one is serviced, the others and the storage carry most of the day, with the existing heater in reserve.
07Engineering pointers
Site data to collect
- Store floor area, height and construction
- Target temperature and humidity
- Door and dock openings per day
- Current dehumidifier ratings and running hours
- Records of humidity and any mould problems
- Present fuel or electricity use and monthly bill
- Sanctioned electrical load and spare capacity
- Space for the heat pumps and storage, with service access
Design notes
- Seal the building first. Most of the moisture load comes through gaps and doors. Sealing and door control can halve the load before any equipment is sized.
- Low dew points. Below about 40% relative humidity at 20 °C, condensing units lose capacity. Combine with desiccant only if very dry conditions are needed.
- Air distribution. Keep air moving through all aisles. Dead corners behind shelving are where mould starts.
Service and warranty
Sunniva has supplied 5,000+ heat pumps since 2012, with nine service technicians across India, including remote sites such as Leh. All components carry a one-year warranty.