Good Question.
To start, odds are, you do not have enough power to convert the units to electric heat. The reduction is not proportional and as you get closer and closer to 50% of the units off of the boiler, the boiler will have issues. You can not expect a boiler to do this, 80% reduction might get you thorough, but 50% will cause issues unless the boiler is a high efficiency 95% boiler with a 20 to 1 turn down. What turn down means is it would have a range some thing like 50,000 BTU to 1,000,000 BTUs. Even at that, you will have pump issues as the pump will be greatly over sized.

Now to suggest savings.... A hydronic boiler is one of the best ways to heat any building, the larger the better. If your gas bill on the boiler was $6,000 per month, expect the electric to be around $20,000 per month. Now you may suggest that each tenant would be paying their own electric bill, but when they go from a $30 electric bill to a $200 electric bill you may hear a few complaints. Electric heat is the most expensive way of heating your home.

You location is near the Windy City, I am just North of you near Milwaukee. A ex-GFhad a small apartment with electric heat, and the electric bill in the winter time exceeded $200 per month on a 860 square foot apartment. Just so you get the idea of the actual cost of operation. Now look at cost of installation: If each unit had its own power meter, You would need to run a new service to each unit, tear open walls to run new wire which costs a fortune now a days. As a wild guess, you could expect $6,000 to $10,000 per unit to convert.

STRONGLY suggest not doing this, leave the hydronic in the units. Baseboard covers are easy to install and not very expensive. There are ways to make the hydronic system more efficient and even ways to calculate usage of the demand per unit.

With all that said, if this apartment was located a few hundred miles South, the heat demand is reduced drastically, thus electric heat makes sense.

You should do more homework on heat calculations per unit, see what you are really getting into.

 

Appreciate your reply eggs. I have 12 unit buildings where tenants anre individually metered and they have 240 electric hydronic baseboards for heat (i.e. not on a boiler system) and their bills are tolerable. I can run electric if needed but that’s why I said let’s assume electric capacity is not an issue.

you did address the main question, which is whether proportional decreases in cost can be realized by migrating tenants off the boiler. Every dollar in expenses that can be offloaded to tenants increases the value of the asset. Typically, landlords just charge x dollars to each tenant for common expense billback, which accomplishes the same thing but isn’t as clean as each tenant paying for their own usage. Maybe others have ideas…I’ll see what others add. But again, much thanks! I’ve never had to deal with boilers and readily admit my ignorance.

 

So, back to one of my statements....
There is a way to meter hydronic heating in a unit, then billed as an internal utility. This solves your off loading to the tenant.
What is required is a PLC module per unit. It would read the total loss of temperature from inlet to outlet of the hydronic piping in the unit along with the GPM, then meter starts when the thermostat call for heat, then stops the meter when no call for heat. I have seen this done, not a huge deal, yet saves your hydronics letting you bill the tenant.
Also, I'm sure you realize that just because a unit has 240 VAC to the apartment, does not mean there is enough power to run electric heat. Nearly every breaker box ever manufactures for residential - light commercial is a 240 VAC break panel. It is the wire size entering it, the size of the main break, and room for multiply 2 pole breakers.

As you can see, after 40 years in the trades, I absolutely hate electric heating systems, way too expensive to run, more dangerous and materials needed to expensive. At least you now have option to do as you believe. There are also ways to down size pumps as you convert, but it is also not a cheap ticket.

Good Luck

Eggs