Restricted Shutdown KVM HOST

Dear All,

I have install RHEL-6 KVM Host, two guests are also installed on KVM Host.
Both Host and Guests are running well.

We need to start Host & VMs at morning and stop at night regularly.
If I shutdown the host without shutting down guest, it may corrupt guest and may loose unsaved data on guest OS.

My question is that how to prevent shutting down Host accidentally while guest are running ?

Currently I am using shutdown -h command on guest and host to turnoff the machine.