You can usually improve insulation by popping down to the local DIY store and buying some rolls for your loft making a big difference.
Of course you can only do that once. And if you’re a landlord why would you pay your money to insulate when you wont save any money as your tenants are the ones paying the bills.
Have you ever heard of mould? Moisture in the walls? Caused by shifting dew points. Your "just pop down to the hardware store" DIY insulation will do a lot of damage.
In some countries, you can't rent out homes that fall below a certain standard for insulation, and the efficiency is rated as part of every property sale, which internalises the cost savings and makes it worthwile.
