The longer the amount of time a bulb is in use then the greater the economic advantage and the smaller the carbon footprint. Traditional bulbs lifespan finishes when the filament breaks, LED bulbs however behave differently. The decrease in the amount of light produced by an LED over time is a normal process so by slowing this process down you will get the maximum benefits and use out of the bulb.
Operating above a fixtures recommended power requirements will reduce the life time of the LED due to the electrical stress being put on the bulb. An example of this would be using the wrong driver for the fixture such as a driver that produces 700mA when the LED only needs 350mA. Using higher currents than necessary will not only shorten the lifespan of the driver, but also shorten the life of the LED itself.
High temperatures will affect the life span and the quantity of light that your LED bulb is producing. If you are buying an LED knowing it will be exposed to high temperatures then a Heat Sink is the answer for you. They provide a path for heat to travel from the bulb to outside elements. They dissipate power in three ways: transferring heat from a solid to a solid, transferring heat from a solid to a moving fluid (air for the most part) and transferring heat from two bodies at different temperatures through thermal radiation. The cooler the bulb temperature, the longer the LED works effectively and the lighting quality remains at a high level.
The LED element itself is very resilient to damp surroundings; it is the metal elements, connections and electronic device that will get damaged and corrode very quickly. If you are buying for such an environment then there are certain things that you can look out for. You need to select LED lights that are IP rated against water and wet conditions which will be rated IP65-IP68. This rating means that they are specifically intended for use in wet surroundings.
Aside from the factors that are mentioned above, mechanical stress, vibrations and extreme ambient temperatures can all contribute to reducing the lifespan of an LED bulb. To ensure that you get the maximum use out of your bulb you need to make sure that they are placed in a dry and stable environment. If you know that the environment is going to be different however, then you need to make sure that you get a bulb or fixture suitable to withstand those conditions. For example for a wet or damp environment you will need to look out for an IP65-IP68 rated LED bulb, this rating means it is water proof.