About $115K/annum working remotely—probably about the same as if not. As @stephencanon said, an employer that suspected there was a downside in productivity for remote workers (and I'd say it's at least equally likely that working remotely results in higher productivity on average) could assuage their own concerns by remembering the significant (~50% of salary?) savings from not having to pay for air conditioning, heating, security, probably some office equipment (I provide my own printers, for example, since they're not terribly useful for remote work anyway), and various other bits of overhead.