The best ASIC miner for those with an energy cost of $0.20 per kWh is the Bitmain Antminer S19 Pro. It offers a high hash rate of 110 TH/s and an efficient power consumption of 3250W, making it one of the most profitable options despite higher electrici.
How much space is available for ASIC placement (eg, are there temperature or ventilation limitations)?
Um, at $0.20 per kWh, regarding ANY miner 'most profitable' is a misleading term. Unless you are running solo and quickly get VERY lucky there will be NO profit, just lower losses. To generate sustained profit at current difficulty you need power to be less than $0.06