BMS Retrofit payback
BMS Retrofit payback
(OP)
Does anyone know a rough payback to retrofit an existing pneumatic control system with a new DDC BMS system? The building is a water treatment plant with offices, lab, maintenance, etc approximately 10,000SF. The building has a central hot water heating system with cast iron boilers. There are multizone air handlers with hot water coils (I am replacing with VFD AHU's & VAV boxes) and DX cooling.





RE: BMS Retrofit payback
I am in the process of having another contractor retrofit another City of Toronto water plant as we speak. That plant has 550 points and it is a Johnson control system that is going in there also
From my experience working in the US if it costs $100 Canadian to do the job in Toronto it will cost $100 USD to do the job in the US
RE: BMS Retrofit payback
just a pneumatic to DDC conversion based on energy payback alone is long(15 to 20 years if not longer) and difficult to calculate. there are lots of good reasons to convert from pneumatic to DDC but even with advanced control strategies and tighter temperature control the senergy savings alone does not justify it. What I am finding though is the cost to correctly recalibrate/repair the pneumatics to get them working again is 1/2 to 2/3 of the cost to just replace with DDC depending how many and how bad the pneumatics are(dual duct boxes vs single zone, is there oil/water in the system, etc.)
if you look at doing the VSD, VAV and DX along with conversion to DDC controls(ddc is the only way to go) it will be a much better payback than having to break out the DDC controls seperately.
A VAV conversion on a 10,000 cfm air handler in a waste treatement plant that has long operating hours will most likely have a "decent" payback. with out more info it would be silly of me to SWAG a payback in years.
RE: BMS Retrofit payback
Obviously you want to do DDC as smart as possible to get most savings. Scheduling, water temperature setback etc. All the things you never could do with a dumb pneumatic system.
Occupant comfort is another benefit. Just tell the building owner what the annual salaries of the employees are and how much they could when they have better temperatures.
RE: BMS Retrofit payback
RE: BMS Retrofit payback
Having said that there are good reasons pneumatics has gone bye-bye. decrease in installation costs, increased reliability, younger operators familiar with computers, better temperature control, easier trouble shooting all make DDC the way to go. once you have a DDC system it is difficult to go back to pneumatics.
havings oil or water in your system even once can cause problems for years. I still see no air dryers, shop air compressors(to much oil), water filters full of water.
Occupant comfort is a great benefit of DDC. the problem is that occupant comfort sometimte comes at increase energy costs. thermostas that are totally our of whack, pneumatic dual duct boxes that die between heating and cooling so the temp is ok some of the time, , closed OA dampers, cooling discharge air temps at 65 F when improved with DDC(or recalibrated pneumatics) add up to increased energy costs.
sorry just don't automatically fall into the just change to DDC and you will save lots of energy.
RE: BMS Retrofit payback
RE: BMS Retrofit payback
I am looking into a green project of that nature (New York City area)but wold advise you to be careful in this area concerning national and local fire code. Most dampers (in my field) are used for fire or fire smoke applications. Make sure you replace any system with code compliant equipment. All systems for control also utilize default "on" position for your heating applications to prevent freezing in the event of air failure.
%
RE: BMS Retrofit payback
I would not discount electronic analog if this is a standalone facility. It would be a lower upfront cost.
The EPA EnergyStar Building Manual-Stage 2 Building Tune-Up gives some rules of thumb; as it is generic, the numbers can be fudged toward the results you want.
RE: BMS Retrofit payback
Interesting you mentioned geothermal heat pumps. I have another new plant where we are trying this design for the first time. Did you use a shell and tube HX or plate frame?
Are there any known DEP issues with using water supply for hvac? Lastly, did your condenser loop have glycol? I'm in the northeast we always use antifreeze in geothermal systems.
in the winter I think we will need supplemental heat when the water is 40F.
Your comments?