My reference scenario starts in 2020 and I have 100% of households having the inefficient appliance and the number of households with the appliance grow from 2.5 million to 8 million by 2050.

In the scenario I am attempting to model I need to introduce the efficient appliance in 2020 with the efficiency standard coming into effect in 2035.

I know I can interp(2020,0, 2035, 15) to show the % change in households with the efficient appliance. However, I am unsure how to ensure post 2035 no new appliance introduced to the system will be the inefficient one.

The main issue I am having is how do I tell LEAP, post 2035, as more and more households gain the appliance that new appliances added to the system have to be the efficient one.

I do not want to get rid of all the inefficient appliances because purchases made up until 2035 will still be in the system come 2050.

Hope this makes sense!

Thank you