I'm a complete newbie here so, apologies and thanks in advance. Extended family member is considering retrofitting a multi-family residence using GSHPs. I'm a big champion of this technology even though my experience is limited to what I've read so far. They're pretty much sold on the concept but, they want to bill each tenant (there's 3) for heating/cooling used. I suggested using some kind of BTU meter; a friend suggested metering the electrical usage of the heat pumps and multiplying by the COP or SEER. Is this valid? Or can some suggest a better approach? Again, thanks in advance.

Not sure what the laws are where you're at, but in some areas, to bill for utilities they must be seperately metered. The easiest way around that is to provide free heat/cool but charge an extra 100/mo (or so) in rent.
Good luck,
J

Thanks Just a Mechanic. Pretty sure provisions have been made for separate metering so, the question remains: is there a straight-forward method of billing for heating/cooling? Is it kWh used for the heat pumps x COP? would SEER figure into it?

kwh times cop times electric rate would give you a price that would be equal to electric heat
but cop is not constant , but a good start , if the conversion is from gas or oil different numbers would have to be used so let us know what the fuel source is now and what that price is

Teh seperate metering I referred to would require 1 meater and 1 heat pump per apartment.
j

scuse....the.......meter....

I would increase the rent in order to recover the capital cost of the new system. On the other hand, the tenants would enjoy the lower operating expense, by them paying their actual electric bills to the utility company. Good marketing, promoting the benefits of geothermal would be essential in successful implementation of this plan.

Regards, Masoud

thanks to everyone who's responded so far. Geo Fan, thanks for the clarification. right now each large apartment in this house has a gas furnace and window unit ACs. i'm trying to convince my cousin that it would be worth it to replace both with GSHPs. this is in MA, near Northampton. Very cold winters; hot and humid summers. The house would be retrofit to tighten the thermal envelope. He's quite adamant about separate metering--if it can be done (maybe its a local ordinance?). Given this info, can you suggest a more accurate approach that accounts for heating and cooling? Someone else suggested using the GSHPs rated COP and SEER x kWh, but I'm not an engineer. Thanks in advance.

Often best to model your charges after your actual expenses.  This would suggest a monthly "HVAC capital cost" plus a variable KwH used.

Ok, again- seperate meter, seperate heat pump for each apartment or raise the rent sufficiently to give "free heat and A/C". Many landlord tennant laws will not let you bill for fuel for common appliances. Imagine one neigbor saying that don't like A/C and therefore do not wish to pay all summer while others want 72* not 68* in the winter..... If you don't call it "free" or put everyone on their own appliance with their own electric or gas bill, you're asking for trouble.
Honestly, the real problem here is that you may not be giving your family member great advice or at the very least we are approaching it the wrong way. Nothing is cheaper for a landlord than what is already there. To spend a great deal of money to save the tennants money doesn't make sense (yeah I get the safety and durability arguments).
What you really need to do is see if there is a green tennant market that will let him/her charge the kind of rent that will pay for the system.
J

A fixed heat/cooling charge creates no incentive to avoid waste, so I agree on the separate metering.

If you do "KwH x COP", what happens during spring/fall/vacations when there are no KwH used? You get nothing and yet still have a GSHP loan payment to make.

There may be a market for a air/water heat flow metering system that would correctly track energy used by different parties from a single large heat pump. Just need to know temperatures and flows.

A lot depends on how the electrical service and metering is now...or will it be changed?...and DO check the legalities of reselling utilities.

Will there be a separate HP for each unit with a common condenser field?

I think you definitely want to meter things separately, ideally with separate electrical services, if possible.  If there is a single service but individual HPs, it should be relativey easy to submeter the electricity consumed by the HPs and a common area charge can be allocated based on HP use for pumping.  That is easier tham putting a BTU meter on the water side of each unit.

If there are not separate HPs for each unit, then the only way is with a BTU meter on each of the fancoils...I think that is possible with commercial VRV mini splits, but don't know about GSHPs.

I would not try using hour meter run times because you do not know how much energy each tenant uses.

Bruce

 

We installed meters that measured how much time the circulator motors ran and charged each unit a prorated amount. This was for a oil heat system so figuring out the total cost was easy not as easy with a Geo system. I guess if you know how much power the unit uses per time period, minute, hour or fortnight mulitipy that by your rate and you should be pretty close.