Ice Storage, Chilled Beams, and Title 24 Compliance
Ice Storage, Chilled Beams, and Title 24 Compliance
(OP)
I am currently working on a project in California required to perform 20% better than a title 24 baseline as well as gain as many LEED points as possible beyond that point within a reasonable life cycle cost because silver certification is a goal as well.
I am creating models myself (in Trace 700) specifically to compare different system alternatives and evaluate life cycle costs, while an outside consultant is using eQUEST/DOE2.2 to do the same but moreso to handle the title 24 compliance. Basically they will model the system as I tell them to and will then provide me results regarding what they see the life cycle cost to be and where I am at compared to my 20% goal. My building model i.e. zoning, windows, etc. is much more crude than what they have made with the CAD files and other information I have provided them so they should be able to output the most accurate results, but as I said, they are simply there to input what I tell them and give me whatever comes out.
The problem that bothers me the most as I review their results is with the ice storage that I am trying to incorporate into the project. I have provided them storage size, scheduling, and associated chiller efficiencies while making ice, while making normal LWT etc. and can see % reductions in energy cost with my own model, but they are not even close to what is coming from theirs. I should also note that my output, hour by hour over for every month of the year, looks to be exactly what I would expect and I am happy with my results. Browsing their data over a whole year the output results look sporadic and as though something is very wrong with the input. At this point I am wondering if I will be able to use what they are giving me at all. I have been told by multiple experienced people that you cannot model ice correctly using eQUEST/DOE2.2 but. Does anyone have a take on this? Additionally I am trying to model chilled beams which I know requires some sort of cheat (induction or fan coil units minus fan power etc.) regardless of the software used and their results for those look incorrect as well. For example, the pump power decreased while the fan power increased. That is obviously the exact opposite of what should have been reflected in the results. Any take on either of these? I have to use these guys' results regardless and if I have hold their hands the whole way through getting me what I need I will, but please if anyone has any tips on pointing them in the right direction let me know.
Thanks,
Kevin
I am creating models myself (in Trace 700) specifically to compare different system alternatives and evaluate life cycle costs, while an outside consultant is using eQUEST/DOE2.2 to do the same but moreso to handle the title 24 compliance. Basically they will model the system as I tell them to and will then provide me results regarding what they see the life cycle cost to be and where I am at compared to my 20% goal. My building model i.e. zoning, windows, etc. is much more crude than what they have made with the CAD files and other information I have provided them so they should be able to output the most accurate results, but as I said, they are simply there to input what I tell them and give me whatever comes out.
The problem that bothers me the most as I review their results is with the ice storage that I am trying to incorporate into the project. I have provided them storage size, scheduling, and associated chiller efficiencies while making ice, while making normal LWT etc. and can see % reductions in energy cost with my own model, but they are not even close to what is coming from theirs. I should also note that my output, hour by hour over for every month of the year, looks to be exactly what I would expect and I am happy with my results. Browsing their data over a whole year the output results look sporadic and as though something is very wrong with the input. At this point I am wondering if I will be able to use what they are giving me at all. I have been told by multiple experienced people that you cannot model ice correctly using eQUEST/DOE2.2 but. Does anyone have a take on this? Additionally I am trying to model chilled beams which I know requires some sort of cheat (induction or fan coil units minus fan power etc.) regardless of the software used and their results for those look incorrect as well. For example, the pump power decreased while the fan power increased. That is obviously the exact opposite of what should have been reflected in the results. Any take on either of these? I have to use these guys' results regardless and if I have hold their hands the whole way through getting me what I need I will, but please if anyone has any tips on pointing them in the right direction let me know.
Thanks,
Kevin





RE: Ice Storage, Chilled Beams, and Title 24 Compliance
Chilled beams: They are just ceiling mounted induction units and the pumping power for an "induction unit" system in Trace should be the same. Whether an induction unit is mounted on the perimeter in a console or in the ceiling, it's still just an induction unit. "Chilled beams" are just fancy marketting words. There is very little radiant cooling from them due to the small surface areas involved.
Can't help you on the ice storage, a technology that's been around for at least 30 years, and we still can't model it properly? Crazy business.
From my limited expereince with E-Quest- it's more of a screening tool, and is not an accurate system modeling tool, and any output from that software would be suspect. As a former Trace user (Trace 200-500), I'd be more inclined to trust the Trace modeling as you should have better control over the defaults and operating parameters.
RE: Ice Storage, Chilled Beams, and Title 24 Compliance
When you think of it, it makes sense too: If you manufacture colder water, you are using more energy, it is just cheaper energy.
Now, if you bring in load shading during peak, sponsored by your local utility and giving you a preferred rate schedule, you ought to consider it.
Why LCC for energy compliancer? It should be the ENERGY Savings, Not the Dollar savings.
From an energy stand point - you do use more energy with ice storage than conventional system.
RE: Ice Storage, Chilled Beams, and Title 24 Compliance
As far as beating up the architects I agree, but they like using lots of windows so mechanical gets to contribute a little more which is fine with me. On the chilled beams I haven't heard that about the surface area being too small, but then again the main people I have spoke with are sales reps. Since I was sitting here thinking about it though, I made a quick hand calc/estimation and the radiation I estimated assuming a temperature difference and surface area is worth laughing at with the way they market those things.
I would argue that ice storage uses more energy as well but there are people out there that would disagree addressing lower night time temperatures and the effects of that on cooling equipment as well as increased efficiency/reduced emissions at the energy production site. Overall I don't think the difference is that significant but drawing system boundaries around the building definitely means higher kWh on the meter. I am considering both compliance and life cycle cost; for LEED the costs matters and for compliance the consumption matters. The Title 24 TDV performance compliance method does include multipliers for all utility types, for all regions in the state, for every single hour of the year that assigns a different "value" to different usage depending on relative demand (that's something I need to look into a little more). Also, the rate structure will be Southern California Edison TOU-8 which is quite agressive when it comes to peak usage and if you take a look at it you'll see why I am considering storage; I think the savings should be significant and the payoff should be pretty good, but we'll see if I can get a model that reflects that....
Thanks again,
Kevin
RE: Ice Storage, Chilled Beams, and Title 24 Compliance
And that is the fundamental problem. We engineers MUST educate them on proper fenestration design to meet reduced energy use. Somebody has to do it, and in my opinion, the attitude that "doing the energy modeling" is the Mechanical and Lighting engineers' job is a crock, and has to change. I get sick and tired of hearing from project managers and architects alike that I'm the one rocking the boat because I'm making THEIR life miserable by trying to get them to meet "MY" energy performance standards. They are NOT MY STANDARDS !! It's the friggin' CODE, and it starts with the overall building design.
A great quote from another source:
"Air conditioning is the most poisoned "gift" inherited from the Industrial Revolution. It leads to the following excuse: "Whatever the lack of intelligent environmental design, there will always be a bunch of engineers and industrialists to offer their services and their products to fix the shortcomings". It opens wide the door to an enormous waste of energy, irresponsible costs and unhealthy environments."
EccaCoil website 2004