Temperature also sets colour. DMR reports P. florida caps light brown at 10-15 C but white to pale yellowish at 20-25 C; P. sajor-caju at 15-19 C is white with high dry matter, at 25-30 C brown with less. Below 100 lux of light caps go pale yellow; in bright light dark brown. Buyer preferences vary with market and product. Agree colour, cluster size and maturity with the intended buyer instead of assuming all buyers want white mushrooms.
Then settle the unit. A seasonal room follows the weather and changes species by season. A controlled room holds one band all year at much higher cost. The folder says an 18 x 15 x 10 foot room holds about 300 bags; start with one room and one species.