Mushroom Grow Room Tonnage (TR) Calculation
Cooling tonnage for a button mushroom grow room: TR per sq ft, compost respiration load, room volume and the TR table for 18×30 to 18×70 ft rooms.
How many tons of cooling does a mushroom grow room need?
A commercial button mushroom grow room needs roughly 1 TR per 100–120 sq ft of floor area — far higher than comfort air-conditioning — because the compost itself releases heat continuously. In MushroomWale's standard rooms an 18×30 ft room is sized at 6 TR, 18×40 ft at 8 TR, 18×60 ft at 10 TR and 18×70 ft at 12 TR.
Estimate your own numbers
Pick a room size and count — the tool applies the same engineering constants used in MushroomWale BOQs and returns a recommended plan summary.
Total built-up area
~1,440 sq ft
720 sq ft per room
Cooling requirement
~16 TR
8 TR per room
Bag capacity
~3,200 bags
1,600 bags per room
Phase-III compost
~80–96 T
per full filling (25–30 kg/bag)
MS racking material
~4,100 kg angle
+ ~450 kg jali (incl. wastage)
PUF doors
2 nos.
insulated cold-room doors
Yield per cycle
~6,400 kg
~106 kg/day at peak flush
Annual yield @ 5 cycles
~32,000 kg
fresh weight, all flushes
Recommended plan summary
Climate unit per room: Daikin 8 TR (~28 kW Outdoor Unit)
2× Outdoor Unit (4 HP ea., R32 3ph HMT) + 1× Indoor Unit (HMT Dual-Circuit Evap, 550mm fan)
Compost planning: ~80–96 tonnes of Phase-III compost per filling, staggered across rooms so tunnel turns stay continuous.
Indicative engineering estimate only — not a price quotation. Final sizing depends on site conditions, climate zone, ceiling height and grower practice. GST and transportation are extra; any additional client requirement is charged extra.
How MushroomWale calculates it
- 1
Take room volume, not just floor area
Cooling load follows enclosed volume and rack density. Standard MushroomWale rooms are 18 ft wide with an internal height of 12–14 ft, so a 18×60 ft room encloses roughly 13,000–15,000 cu ft. Two rooms with equal floor area but different heights do not carry the same load.
- 2
Add the compost respiration load
Colonised Phase-III compost is biologically active and releases heat throughout cropping. This is the load ordinary AC sizing ignores and the reason a comfort-AC-sized unit fails in week two. Budget the respiration load in proportion to compost tonnage in the room, not to the number of people or lights.
- 3
Add envelope gain across the PUF envelope
With 60 mm PUF on common walls, 80 mm on external walls and 80/110 mm on the roof, envelope gain is small but not zero — it rises sharply in May–June in plains districts and on roofs without a shade shed.
- 4
Add fresh-air and door-opening load
Fresh air is mandatory for CO₂ control, and every cubic metre admitted must be cooled and re-humidified. Picking and door traffic during flushes add a repeated transient load.
- 5
Size for the cropping set point, not the average
Design for a 16–18 °C room air temperature at 85–90% RH held against the worst ambient month at the site, then select the nearest standard machine above the computed figure. Undersizing shows up as a lost third flush, not as an immediate breakdown.
Reference data
Standard MushroomWale room sizing (Daikin HMT stack, ex-GST, transport extra)
| Room | Floor area | Compost bags | Cooling | Indicative BTU |
|---|---|---|---|---|
| 18×30 ft | 540 sq ft | 1,000 bags | 6 TR (~21 kW Outdoor Unit) | 72,000 BTU |
| 18×40 ft | 720 sq ft | 1,600 bags | 8 TR (~28 kW Outdoor Unit) | 96,000 BTU |
| 18×60 ft | 1,080 sq ft | 2,500 bags | 10 TR (~35 kW Outdoor Unit) | 1,20,000 BTU |
| 18×70 ft | 1,260 sq ft | 3,000 bags | 12 TR (~42 kW Outdoor Unit) | 1,44,000 BTU |
18×30 ft
- Floor area
- 540 sq ft
- Compost bags
- 1,000 bags
- Cooling
- 6 TR (~21 kW Outdoor Unit)
- Indicative BTU
- 72,000 BTU
18×40 ft
- Floor area
- 720 sq ft
- Compost bags
- 1,600 bags
- Cooling
- 8 TR (~28 kW Outdoor Unit)
- Indicative BTU
- 96,000 BTU
18×60 ft
- Floor area
- 1,080 sq ft
- Compost bags
- 2,500 bags
- Cooling
- 10 TR (~35 kW Outdoor Unit)
- Indicative BTU
- 1,20,000 BTU
18×70 ft
- Floor area
- 1,260 sq ft
- Compost bags
- 3,000 bags
- Cooling
- 12 TR (~42 kW Outdoor Unit)
- Indicative BTU
- 1,44,000 BTU
Rule-of-thumb check
| Check | Target band |
|---|---|
| Cooling per floor area | 1 TR per 100–120 sq ft |
| Cropping air temperature | 16–18 °C |
| Relative humidity (cropping) | 85–90% |
| Spawn run / case run air temperature | 22–24 °C / 24–25 °C |
| CO₂ during cropping | under 1,000 ppm |
Cooling per floor area
- Target band
- 1 TR per 100–120 sq ft
Cropping air temperature
- Target band
- 16–18 °C
Relative humidity (cropping)
- Target band
- 85–90%
Spawn run / case run air temperature
- Target band
- 22–24 °C / 24–25 °C
CO₂ during cropping
- Target band
- under 1,000 ppm
- Carrier (Haier-CCR, R-404a commercial refrigeration) is offered as an alternative brand on 18×40, 18×60 and 18×70 ft rooms.
- Machine prices are quoted ex-GST. GST @18% and transportation are extra. Civil work and boundary remain client scope.
Frequently asked questions
Related engineering pages
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