HIV is fragile by nature and is also extremely sensitive to even small fluctuations in temperature and the presence of oxygen. Outside of strictly controlled laboratory conditions, HIV will only survive for a couple of minutes at the very most.
The one place that HIV has been shown to survive for extended periods of time (several days) is in needles used with syringes; the needles frequently contain enough blood to prevent the HIV from drying out.
In the almost twenty-five years that scientists have been studying HIV, there has not been a single known instance of HIV being transmitted trough casual contact in the environment.