To provide an equivalent argument,

If you visit https://www.tenancy.govt.nz/rent-bond-and-bills/market-rent/ you can evaluate the rental value of your property. Say a 3-bedroom in Hokitika. It only offers a minimum, average and maximum rental value based on recent activity.

Notice the point however. It doesn’t matter if its a 1950’s home or a 2020’s home. Instead, How many bedrooms, does it have a garage? Perhaps for council utility needs, add in, how many bathrooms. Not, you rebuilt a more ecologically friendly home with a higher value so your rates go up.