Platt’s Black Flax

Evergreen Plant, Prune unsightly fronds in spring. Phormums don’t like excessive cold weather, so many people cover them with packing material, or a large pot for winter months (I noticed the people at the end of your street have a huge phormium that was covered earlier this year).

https://www.monrovia.com/plant-catalog/plants/495/platts-black-new-zealand-flax/