ASHP uses much
than a conventional heating system to provide the same amount of heat. ASHP has
CO2 emissions.
A well designed system, running on standard mains, causes
  fewer CO2 emissions than an equivalent oil boiler.
A heat pump running on genuine `green´ electricity qualifies as
and produces zero local pollution.
Planning permission is
to install a ASHP.
ASHP are low maintenance and
as well as free from safety and regulatory obligations of gas appliances.