Bats are nocturnal animals and are adapted to low-light conditions. This means that most bat species can find artificial lighting to be very disturbing. Artificial lights shining on bat roosts, their access points and the flight paths away from the roost must always be avoided.
If it is considered necessary to illuminate a building known to be used by roosting bats, the lights will need to be switched off at bat emergence time and during peak bat activity times. Or better still, it is usually straightforward to ensure that the light does not fall on the roost access point or the flight line away from the roost used by bats. Celebratory lighting of buildings should be limited to special occasions.
Bats and their roosts are all protected by law and bats should always be taken into account when lighting is being considered.