Transcript

So today we're talking about plant loops, so these are our water-side systems in EnergyPlus.
On the agenda, what is a plant loop?
And then we have some more connector objects that we're going to talk about, that's branches,
splitters, and mixers, and we'll talk about set point managers on loops and availability
managers and operation schemes.
So all of these together help us control how the plant loop is, how it operates, what
temperatures it maintains, what equipment is on and when, and you can also turn entire
plants or systems on and off with availability managers.
Okay, so HVAC systems in EnergyPlus, and I think we've been over this a couple of times,
so just real brief.
These are water loops, this is representative of central plants, so we have a boiler on
a hot water loop and a chiller on a chilled water loop, we both have pumps, and this right
here is a bypass, we'll talk about that in a little bit.
We have our air systems, which we talked about yesterday, and we have our zone HVAC systems,
so they all work together to condition a building.
They were concentrating on water loops today, plant loops.
So plant loops represent a closed loop hyping system, this is kind of a big deal if you
want to get into the physics of it in EnergyPlus, even when they're, even when you're simulating
domestic systems or systems that lose water somehow, EnergyPlus on the inside represents
it as a closed loop hyping system, so just keep that in mind with your modeling, because
they're sort of somewhere in the loop where EnergyPlus is going to be inputting fresh
water or kind of drawing water in from somewhere so that they can represent kind of like a closed
loop system.
The plant loops are for fluid circulation, so generally water, but you can actually specify
other fluids that have different thermal mass and heat transfer properties.
Plant loops have a supply side where you have your boilers and chillers, you can have water
to water heat exchangers, pumps, cooling towers, and then there's also a demand side,
which is not shown at the moment, but that's where our hot and chilled water coils, the
other side of water to water heat exchangers, service water heating equipment, etc.
There's a lot of stuff.
They're controlled by set points and operation schemes, so operation schemes are specific
to plant loops, and they interact with other loops through their supply and demand equipment.
Okay, branches, splitters, and mixers, and then also branch list and connector list.
So yesterday we talked about, in some detail, about branches and we analyzed the structure
of an individual branch, so today we are going to talk about how branches get put together
in plant loops, because in the air loop we just had one single branch here, and in these
plant loops we have one, two, three, four.
So we have an inlet branch, two parallel branches, and then an outlet branch.
So on the inlet branch we have a pump.
You can, and you'll see some examples later on today where the pump is not on the inlet branch.
That's kind of the, this is the simplest operation if you just have one pump on a branch, but you
can put them on parallel branches and have them coupled to particular equipment.
Then the parallel branch, we have a boiler, and then this guy right here, this is called
pipe adiabatic, and we'll talk about that in more detail, but this basically allows the plant
algorithm to resolve if the flow through the pump and the flow through the water heater
are not aligning absolutely perfectly.
It can shunt a little bit of extra flow around the side, if it needs to.
This was more necessary in older versions of Energy Plus than it is now, internal algorithms
are a bit better, but sometimes you'd have a rounding error of a one hundredth of a gallon
per minute, and that extra mass would sort of build up somewhere and cause a lot of heat,
and then eventually the whole system to fail.
So this would kind of help deal with that situation in Energy Plus.
And then on the outlet side, again, we have the pipe adiabatic, and so this allows us
to actually have a branch here, because you can't have a branch without any equipment on it.
You need to have at least one piece of equipment on the branch.
So in order to come in and then split and then mix again, we need something here,
even though there isn't anything actually useful on that branch.
Okay, same thing on the chilled water side, there's a pump, a chiller, and adiabatic pipe
in parallel, and then another pipe on the outlet side.
And what's tying them all together, so I said split and mix, but there's actually an official
Energy Plus object called a splitter, and one called a mixer, which is right here.
And again, on the chilled water side, splitter and mixer.
And this is Energy Plus, so we can't have HVAC structure without redundant objects.
So in addition to having each branch, which is an Energy Plus object, plus a splitter,
plus a mixer, we have two more sort of redundant objects, and those are a branch list.
And then we also have a connector list.
So branch list lists all of these branches, and the connector list lists these two connectors.
Okay, so we're going to take a look at the structure here.
So here we have, for the hot water loop, the, and this is the naming convention that we use
in EP3 is we'll name the inlet branch for the loop. So this will be the inlet supply inlet
branch. So we name it for the loop, the side of the loop that it's on, and then if it's an inlet.
So this is a naming convention that you'll see in EP3 all the time. So this branch right here on
the chilled water side would be a chilled water loop supply inlet branch.
Then we have the boiler branch. And the naming convention here, it gets a little bit long,
but we use hot water loop. So the name of the loop, then the name of the equipment,
and then the name of the node that it's connected to, or rather the field name of the node that
it's connected to. We need to use the field name. All of this equipment has just one paired node,
but there's some equipment that you can connect to the same loop multiple times.
And so if you just name for the loop and the equipment, you will have some naming conflicts.
So on the bypass side, we have hot water loop heating supply side bypass. So
the heating supply side bypass is the name of this object right here, this pipe, and then inlet node name.
And the last one, so again, this is the outlet branch. So we can just call it for the hot water
loop supply side and outlet. Now these list objects tell you how everything is connected,
because if we go here, so yesterday when we were looking at branch connections, we looked at one
object and the next object and the next object, and you could trace the inlet and outlet node names
from one to the other. But here we go back to this branch. Our inlet name is hot water
circ pump inlet node and our outlet node name is hot water circ pump outlet node. And that node
doesn't appear on any of these other branches. That node is right here. It doesn't actually
connect that node is sort of on this splitter object. So if we look at the
the splitter,
so the splitter appears on the connector list, and it's right here between those branches.
And it has a name and then a name of an inlet branch and a name of
two outlet branches. So it's not actually using nodes here, but it's telling it,
okay, this branch is coming in. You can think of this as sort of like a place where,
I mean, it's just I drew it as a T in EP3 because it's literally it's just a pipe where flows get
distributed. There's no intelligence to this. It just water flows in and water flows out and
the flows are actually determined by how much the the other equipment on the loop is allowing
it to flow and how much it's calling how much the other equipment is calling for flow.
And then again on the connector list, we have the mixer and the mixer is just sort of the
opposite of the splitter. It has an outlet branch. So hot water leaps supply outlet branch is this
branch here. And then it has two inlet branches or two parallel branches are boiler and our bypass
branch are in the branches. So here we go. So the connector splitter, we see we have the inlet branch
which showed up on the branch list. We have our outlet branch,
which is an inlet branch for the mixer. Same with the bypass has the same structure.
And then we have our outlet branch, which shows up on the mixer as the outlet branch,
but not the splitter. So it's again, this is helpful information to understand so that you
can understand the structure when you need to look at energy plus individual energy plus files.
All of this, like because the branch list needs to be in order, you could actually
do all of this figuring out without the connector list, the connector splitter or the connector
mixer, but energy plus requires all four and they all need to be coordinated.
Okay, so how do we connect branches to the loop? So here is our hot water loop and our inputs over
here. So we have the plant side inlet and outlet names. So inlet and outlet, I didn't actually
highlight them on the drawing today. These inlet and outlet names are going to coordinate with
the inlet and outlet branch.
And then we have a plant side branch list name and a plant side connector list name.
So the plant side connector list name, technically in energy plus, you can have just
one branch on the plant side. We've sort of made it our requirement to have at least three
an inlet one middle branch and an outlet branch. If you just want to have things go straight through,
you can use some adiabatic pipes to create that. And you will see some examples when we do the live
modeling portion where we go through a couple of models that have just one branch. So
inlet and outlet nodes align with the branches and then we have a branch list name and a
connector list name which tie us back to these two pieces of equipment or these two objects,
which describe the actual architecture of how everything comes together.
My theory on this and why it's so complicated is that I think originally in energy plus,
they were going to allow more complex architecture with multiple levels of branching
and mixing splitting and mixing, but it just it doesn't actually work. So we have this architecture
where it's one branch in a splitter parallels and then a mixer and an outlet. If you want to do more
complex plant loop architecture, you can achieve that by using multiple leaps with heat
exchangers between them. So we'll look at I think one example with a water to water heat exchanger.
And so you get started to get an idea of how those components work.
Okay, so the the demand side uses the same architecture. So on the demand side, we have
the heating demand inlet pipe inlet nodes, we have the demand inlet node, demand outlet node,
the branch list name and the connector list name.
All right, so let's take a look at the actual inputs for the loop.
This right here, this is an EP3 specific input.
Were there actually were there questions on architecture before we go on to loop inputs?
A question just came in. It said, would you need another loop and HX to model
a common primary secondary pumping system? Yeah, yeah, that would be the best
that would be the best way to do it. There are some other ways like you can put a pump on the
demand side of a loop and sort of model. I don't recommend it. Yeah, I would use a heat exchanger.
Okay, and then we had some other questions that just they came into chat.
I think we will have to save them for tomorrow because it's a request for examples that fit into
some of the things we're doing tomorrow. And I was just going to say, anyone using the chat,
if you use the Q&A function instead, I can respond to you directly.
When the questions come in through chat, I cannot respond to them to the person asking. So if you
use the Q&A function instead, then I can respond while Karen's speaking.
But these other ones are looking at geothermal pumps or geothermal heat pumps and the associated
loops and we're covering that tomorrow. Yeah, we actually will look at an example file today
that uses a geothermal heat pump with water to water, I'm sorry, a geothermal system with
that connects to water to water heat pumps. Okay, I knew it was on the docket and we'll cover
that then. And then some of these are just examples that fit better tomorrow. So I did log
them and we'll get to it then. Yeah, the main question relevant to the architecture was the
primary secondary system and it sounds like our guests had inferred the correct way to do that or
the most efficient ways to do that. Yeah, yeah. Okay, so we'll get to loop inputs. So the first
input right here, the loop conditioning type, this is actually an EP3 specific input. If you
remember when you're connecting nodes in EP3, you'll click on a node. The nodes are color-coded
and it will only allow you to connect to objects that are appropriate for the loop type and the
side either supply or demand that you're on. So you can kind of restrict this by selecting your
loop conditioning type. So if you're ever in EP3 and you're trying to connect something to a loop
and it doesn't want to connect, go in and just check your your loop conditioning type. The choices
are heating, cooling, condenser, or bulk. So you can just say, please don't give me any conditioning
restrictions. I want to be able to connect everything so that, you know, you would still be restricted
to water side equipment and you're still restricted for the supply and demand side.
We just do that so that you have fewer errors when you get to energy plus.
Hopefully make your life a bit easier. Okay, so that's an EP3 input.
Then fluid type, so generally water, but you can do other systems, you can do other fluid types.
Energy plus supports steam as well, but we are not currently supporting steam in EP3.
If you become an EP3 customer and you really need steam, let us know. We can implement it,
which is never really had a need.
Okay, then there's the plant equipment operation scheme name. So we'll get into this in a little
bit more detail, but each plant has an operation scheme. So it's also a list of objects. Often
there's just one and it will tell you how to turn on the supply side equipment.
You have a loop temperature set point node name. EP3 always makes this node the loop outlet node.
So sometimes when you import files, just double check the loops and see where the set point
node is. You can always kind of add often on a loop like this. They'll put the set point at the
boiler output and you can also put a set point node at the plant outlet. The loop, yeah, we just
set it to the loop outlet. Okay, then there's a maximum and minimum temperature. This doesn't
limit the loop operation so much as provides some limits for energy cluster to give you some
warnings and errors about your loop operation. Then there's maximum loop flow rate and
well, that one is popping up twice. I'm not sure why, but yes, maximum loop flow rate,
very important input. There's the plant loop volume. This one's actually quite interesting and
early on when I was modeling with energy plus, the auto sizing on the plant volume wasn't very good
and so I had really low energy use on a building that was using water to air heat pumps and after
days and days and days of trouble shooting, I realized that the plant loop volume was
absolutely enormous and it was essentially like a huge thermal mass battery and so there wasn't
any central plant energy used required to heat the building because over the course of the year
so much energy was going into the plant loop. This is also a very simple way to model
thermal storage is to change your plant loop volume. So treat it with caution,
but that's a little hack for you instead of having tanks stored somewhere on your loop.
Okay, loop sizing. So loop sizing is pretty simple compared to air loop HVAC. It's just
the loop type. So if you don't set a loop conditioning type here,
EP3 will look at your sizing loop type and use this sizing loop type.
You have an exit temperature and a temperature difference and then you can size for coincident
or non coincident loads and then there are a couple other inputs here, but these are the
big ones and it's far, far simpler than the airside systems.
Okay, so we're just getting a little introduction into operation schemes. So here in EP3 we have
again this hot water loop and I've just, so I'm in the selected object dialogue for the hot water
loop and I've just collapsed the plant loop in the sizing plant objects. So here also
right now we're looking, we have the plant loop selected and I've just scrolled down to the sizing
object that's connected to the plant loop. We don't, in energy plus all this stuff is sort of all
over the place. It's not necessarily next to each other, but because these objects are
required, there's some caveats we'll talk about later, but these objects are needed to
run a simulation with a plant loop. So we make sure that you have them
right there with your plant loop. Okay, so equipment lists.
These are again energy plus, they love lists. These are lists of equipment attached to your
supply side and EP3 will filter out, it will filter just for equipment that can actually
respond to a load. So those, the adiabatic pipe cannot respond to a load, so it is not allowed
on a equipment list, but boilers, chillers, cooling towers, water heaters, heat exchangers,
all of that equipment is allowed and capable of responding to a load so it can go on an equipment
list. Then you have an operation scheme and there are a bunch of different types of operation schemes.
So the simplest are heating plant equipment operation heating load and then there's plant
equipment operation cooling load. There's also a plant equipment operation uncontrolled, which is
what's often used for geothermal systems. They're just putting flow, you know, a geothermal system
is on the supply side of a loop, but it can't, it's not a boiler, it can't really respond to a
load. All you can do is vary the flow. So here we have a plant equipment operation heating load.
We have a name and then we have a control scheme schedule. So this says when is this
operation available?
For a central heating plant it could perhaps be,
you could, you could perhaps be limiting it with a schedule related to the time of the year.
You could create a schedule file based on outdoor air values in order to turn this on and off
based on outdoor air temperature. Then you have a load range, so lower limit and an upper limit.
So if you, you can have multiple load ranges. So let's say you have a very small piece of
equipment that you want to use at low loads and then when the loads get higher you could switch
to a different, so like let's say you had a, I don't know, 100,000 BTU per hour boiler
and a,
and maybe a, and a 20,000 BTU per hour boiler. So maybe the 100,000 BTU per hour boiler at
low part load ratio is very inefficient. So you're, you use the 20,000 BTU per hour boiler up to
just about its maximum capacity. So maybe from zero to 20,000 you would have the small boiler
and then from 20 to 100,000 you would have the large boiler and then from 100 to 120
you would have a list that, that referenced both boilers.
So you can just, you can add and remove equipment lists and, and create more equipment lists. You
can also have different operation screens as well. You can have multiple.
So the operation schemes define how plant equipment operates under different conditions.
It will control to meet a set point. So it's looking at that loop set point temperature
and it operates on a group of equipment. So here, and they all operate a little bit differently.
Most, the most common operate on groups of equipment like this, but there's,
there's some others that operate on individual pieces of equipment.
There are lots of different types of operation schemes.
Okay, plant late supply equipment. What is available? There's this big, big, big long list.
We'll talk in detail about some of these categories.
And again, in energy plus, there's tons and tons of options and my recommendation for you is to
do some experimentation, figure out a workflow and, and objects that work for you and develop
libraries of those objects and don't worry about the rest. So to a point where something
that you've been using for a long time isn't serving for a particular project, go exploring,
but don't worry about learning all of these different objects. I mean, there's just,
there's too many and a lot of them have, I mean, how many different chiller models are there?
Like electric chillers, there's one, two, three, four different types of electric chillers and,
yeah. Okay. Questions?
We had one question that came in. Let me find it.
A couple of comments for you to go over that you'll find interesting, but not necessary right now.
Okay. So if we wanted to model a failed or broken control valve or three-way valves,
could we just change the loop minimum flow rate to a higher number? Or would there be a
different approach to modeling a broken valve? This is assuming someone's modeling an existing
building? Yep. Yeah. So I think that depends a little bit on the piece of equipment. So yesterday
we talked about, well, two days ago, let's see, last week on Thursday, we talked about
zone HVAC equipment and with the fan coil, you have the option to simulate it as
constant flow. So you could directly simulate a fan coil using the fan coil
controls as a constant water flow fan coil. Let's see. Can you force? I may have to answer that
question in a bit more detail tomorrow and see if I can come up with an example that actually
shows that. Yeah. A lot of the stuff you can do, whether or not you can do it with normal
energy plus controls or you have to do it with some, a little bit of programming. I'm not 100%
sure on that one, but let's, oh, look, you can make a note of that because that would be a great
thing. That particular use case would be a great thing to talk about tomorrow. Yep. We've got it
noted. And then so it sounds like if the valve is broken on the FCU, the fan coil unit, it would be
simple to switch it to constant volume and just assume a broken valve on that particular piece
of equipment. Yeah. But it would be a different flow if the valve is at the loop level.
Yes. Yeah. And same thing with water to air heat pumps. There is,
there is an option to specify how the water flow is modeled in water to air heat pumps. So whether
it's, I have to take another look the way that simulated when I first started using energy plus
actually doesn't reflect any, anybody's reality. So, you know, we need to take another look and see
what, what those options are. But yeah, there, there are some options at the coil or at the
packaged unit level. And then if you need to force flow through an object, you might need to do that
with, yeah, if it was like a zone coil, you might need to do that with energy management system,
because those, those packaged units have control, that control how much
flow goes through the coil, whether it's constant volume or kind of turns on and off with a fan that
cycling or variable volume. So yeah, I think, I think it's a bit tough to override those.
Okay, we had another question that came in that's really practical use case.
You showed us how to stage the equipment based on the load. Can we change the heating source based
on outdoor temp instead of the low and higher limit, presumably on loads?
Okay, based on outdoor air temperature.
Yeah, it's a different way to stage the equipment, yes.
Yeah, so I think I would need to take a look at the control scheme. The first way that comes to
mind to do that would be to create a schedule using schedule file based on outdoor air temperature.
And what you would do is you would have multiple plant equipment operation, you know, heating
load or cooling load and you would have one that was on when your temperature was below a
certain set point and a different one that referenced different equipment when the, when
the temperature was above a certain set point. There are, there are some more complex controls
plant equipment operation in energy plus, but sometimes it's better to do a bit of
preprocessing and create a schedule file and use the simplest ones. Because the complicated ones
can be a bit of a headache to troubleshoot, but there are some more complex ones that exist.
But that's another use case Bob, make it make a note and I'll see if there's one that does exactly that.
Yup, it'll be saved in our Q&A.
The other, the other thing about getting back to this question about a valve, so you can push
excess flow around in a bypass. So you could, you could definitely force flow in a loop,
but you couldn't, but it would be more difficult to force flow through a coil.
Does that make sense?
Yeah, that makes sense.
Okay. Yeah. Yeah. And if you did not have a bypass, you probably could force flow through
coils as well. There, you can actually set a flow set point with set point manager. So you could
actually say, this is what the flow needs to be. Yeah.
Yeah, sounds like there's more than one way to approach that.
I mean, that's the thing. There's so many ways to approach this. There's so many ways to approach
this. And so I think the, the, the advice for all of you getting, getting going with EP3 and Energy
Plus is to kind of start small, start with example files or existing building models and
build off of them a little bit at a time and really work from, work from small test models,
like we were doing the past couple of days where you can simulate and look at changes and
understand what's going on. Agreed. 100%.
Should we chat about plant equipment?
I think so. We cleared out all the questions, all the burning questions and I saved the other ones.
Great. Okay. So plant equipment. So this is equipment that go on the supply side of the plant
loop. Or I'm sorry, there's some things in here that don't go on the supply side. This is equipment
that can connect to a plant loop. Okay. So pipe adiabatic, we talked about it earlier. It represents
a perfectly insulated pipe and it provides a way to connect branches without changing thermodynamics.
It doesn't place any load. It doesn't request any flow. It doesn't change any temperatures,
basically whatever the conditions at the node coming in, it will just, it just passes the
conditions along. It doesn't change the conditions at all. It doesn't do anything.
Then we have a pump and I'm sort of going in order somewhat of, of complexity. So pumps,
they are what create flow. We have constant speed, variable speed, and then headed pumps,
which allow you to model kind of multiple pumps, but you would still have just one inlet and outlet
node with a headed pump. Boiler hot water is fairly self-explanatory. You can choose multiple
different, you can choose different fuel sources with the boiler hot water and set
efficiency parameters and turn down ratios and all that sort of stuff with the hot water boiler.
Load profile plant. I really like this object and it's used to simulate a scheduled demand
profile on a loop. It's really useful for simulating central plants when, when the loads are known.
It's a great tool for fast simulation when you're setting up new systems. You don't have to create
full building. It won't really help you if you need to do, run some troubleshooting on an
early beach BAC system, but if you're running troubleshooting on some complex branch and loop
and heat exchanger connections, you can definitely drop in a load profile and run some experiments.
And this is, this is based on a schedule as well. So if you're looking at different,
um, looking at for your, your system to respond to different amounts of load,
you can just schedule the loads that you need and see the data that you're looking for in one
simulation. Then we have district cooling and district heating. So this provides heating or
cooling without simulating a plant. It's kind of like the zone HVAC ideal loads air system. It's,
it's a bit of a magic box and it will just meet the loads. It's also quite useful for simplifying
models or for troubleshooting. So if you're trying to troubleshoot an air loop HVAC system,
you can drop some district cooling and heating and you just get the water temperatures that you
need to simplify your system and just work on a piece of the model.
A little bit more complicated. We have chillers. As we saw, there's many different configurations
and models. They can be air, water or evaporatively cooled. A lot of them have three sets of node
connections. So there'll be a chilled water node connection, a condenser node connection, which
will be left blank if there's, if the chiller is air cooled. And then there's heat recovery node
connection. The node connections that go this direction are generally supply, supply side
connections. And that go this way are generally demand side connections because we're kind of,
our loops are going clockwise and supply is on the left, demand is on the right. You can set it up
however you want. But that's the convention that we've established in EP3. And then we have
cooling towers and fluid coolers. They have single to two speed and multi-speed options
and they provide a rapid of cooling to a water loop. Energy plus actually has
plant loops and condenser loops in energy plus. Condenser loops used to be different.
Like years ago, condenser loops were kind of a different thing. And there is, there's a whole
group of equipment operation schemes and sizing objects that say, you know, they say condenser
equipment list and condenser, et cetera, et cetera. Under the hood, a couple years ago, it all became
exactly the same thing. And when we import files from energy plus into EP3, we convert from a plant
loop to a condenser loop and all condenser equipment to plant equipment. And there is
absolutely no change in the functionality or the energy use of the program. But just as a,
as an aside for you to know, if you're modeling existing files and you've brought them into EP3
and all of a sudden you have a plant loop instead of a condenser loop, that's why. But the EP3 import
report will tell you this, but this is just a little bit more background is that under the hood
they're, they're the same. Okay, then we have a heat pumps. Lots of different types of heat pumps
can be connected to loops. So there's water to water, water to air actually been listed here,
but there are air to water heat pumps as well. There are separate modules for seeding and pulling.
So you will always, I think there's one exception, but you'll always have a separate
object for the heating side versus cooling side. But some heat pump models, actually the ones that
say heat pump, have heat pump in the name, they can be coupled. So you can assign kind of like a
pair. And that can help with some, some of them, like they're a couple different models. So some
of them have controls that can say lock out the other one when like lock out heating mode when
the cooling mode is operational. So it's not actually the same piece of equipment, but they're
kind of connected. Then we have generators. So combustion electric generators or a fuel cell,
which can reject heat to plant loops. We've got a swimming pool object. So yeah, we can simulate
an indoor swimming pool on this would, this would be a heat for the swimming pool.
Finish my sentence there. And then there's solar collectors. So they simulate hydronics.
But we'll look at it an example today. Hopefully we'll get to it where they're simulating flat
plate solar collectors. Solar collectors, I find really fascinating. And it took me a while to get
my head around the solar collector example file, because I always think of solar collectors as
something that is should be on the supply side, it's supplying heat and harvesting from the solar
collector. But solar collectors are passive components. And as I think in energy plus,
it would be a little bit more accurate instead of saying supply and demand to say active and passive
components. So the solar collectors are passive components and they go on the demand side.
Yeah, so the demand side of the loop is in general for components that don't have a lot of control.
They can't provide, they can't provide heating or cooling on demand.
Okay, so we have six models that we're going to look at in the second half of our session.
I'm going to kind of introduce them to you.
So we have our five zone air cooled model that we've been using for a while.
So we can look at in more detail at the plant connections and explore this. I want to start here
because this is a model that we've been working with and you can see that we've been working with
and you're familiar with it. We have an air source heat pump model. So we have a hot water loop
and a chilled water loop. And right here these are, what is it called? You just look at it.
Load profile. These are load profiles right here. So this model is just
modeling the central plant providing heating and cooling to two different load profiles
with air source heat pumps, air to water heat pumps. Then we have water source heat pumps.
So essentially this file is the same as the previous one. We have the two loops except
we have some, we have a geothermal system which is providing our source. So it's water
to water heat pumps. Again using load profiles as our load to simplify everything.
We have a fluid to fluid heat exchanger. So that is a bit hard to tell which is which, but
one of these is a chiller. One of these is a fluid to fluid heat exchanger that provides
free cooling to a chilled water loop. We have a model that has solar collectors. So these are
each solar collectors with domestic hot water. And in this model we can also look at the domestic
hot water architecture and some of the objects associated with domestic hot water.
And then I've dropped in a VRF system because it doesn't fit super cleanly in any of our other
categories, but here it is. So we can take a look at that. So it's a VRF system and this is a DOAS
Aerylip HVAC object. So I think what I'd like to do is let's start with our five zone HVAC model
and then we'll take a little break. And while we're taking a break maybe you all can drop in
the chat and say which ones of these systems you want to start by looking at. So we probably won't
get to all of them. So I'd like to kind of start with the ones that have the most interest.
I will share these files with all of you at some point in the next couple days though,
like I did with the homework yesterday.
Any questions before we take a look at the
Yeah, we had a question come in. I was wondering the same thing.
Are there other types of pipes besides adiabatic in the EP3 library?
Something to represent heat losses from old buildings with damaged installations, etc.
Yeah, I'm not sure it's in the EP3 library, but that would be a very small ask for us to add it.
So if, yeah, those sorts of really simple equipment we can get push out in like a couple days.
Yeah, okay, and then you would have to say where that heat is going, I assume.
Yeah, yeah, yeah. Yeah, I think generally there's like an R value and then it's associated with a zone.
But a lot of the regulation models don't allow that sort of thing.
You know, ASHRAE says, you know, don't model heat loss from piping systems.
There is actually also a ductwork object on the air side, which allows you to model heat loss that way as well.
Got it. Okay, yeah, makes sense.
Anything else before we move on to our two just came in. Oh, great.
Okay, we'll just a reminder about the heat pumps, air source and geothermal.
And then a note about with regards to pumps and E-Quest pumps had both pump and motor efficiency
and EP3 slash EP, there is fan efficiency and motor efficiency for fans. However,
for pumps, I only see motor efficiency. Does EP3 have pump efficiency or pumps or does this go by a
different name, i.e. fraction of motor inefficiencies to fluid stream?
Okay, that's a good question. I'm going to have to take a look at that one.
Yeah, Bob, if you can note that one for me to take a look at.
Yep, I have to save all of these. And they should be saved with the webinar,
but I copy them just in case.
Okay, let's see what else that looks like everything that came in. Okay, got that.
Okay, great. All right, let's go to
let's go to beach. Let's go to five zone air cooled.
Okay, so here we are in our five zone air cooled model and we actually are looking at
our plant systems finally. So on the hot water loop, we have
we have it broken down by so similar to the VAV system where we had set point
managers supply side, demand side. On the plant loop side, we have set point managers.
And here we have two. I think they're probably controlling to the same
temperature. What a loop time schedule. What a loop time schedule. You could do exactly the same
thing here by just adding a node. So set point managers, most of the set point managers
have up to six set points available. And you can just keep adding nodes.
And you can get rid of one if you if you want to. So
yeah, so you don't need to make a separate set point manager, you can add a separate
point, you can it will control to the same temperature on all of these nodes.
Okay, then on our supply side, we have those four branches we were talking about.
So inlet branch,
bypass branch, boiler branch and the outlet branch. And on the demand side, we didn't really look
at it because it's it's a little bit messier with all of these coils. But on demand side,
we have an inlet branch. And then we have a branch for each of these coils that are connected.
So usually with
and then outlet outlet branch, usually with plant loops, you'll have maybe four or five branches
on the supply side, and you'll have 20 or 100 on the demand side. So when you're looking at
when you're looking at actual energy plus files, you can it can get a little bit overwhelming
having that many branches on the demand side, but that's it's it's expected.
Okay, so let's let's just do a real simple example and add another boiler. So I just
hit the space bar for the select key, clicked on the boiler, and then M, which gives me my
move tool, and I can click. And if I click control, it puts me in copy mode. So I just copy this
boiler over. And I can connect it to my plant leap, I can either connect it here and here,
which will put it in series, or I can connect it here. And here, which will put it in parallel.
And if we look at our water loop,
and we look at our plant equipment list, I now have two objects available on the plant
equipment list. So I can add a second boiler to that list. And order here is important. This is
exactly the same as the zone HVAC, where we were clicking and dragging to change the order
of simulation of equipment. So we do the same thing here. So anytime you see a list in EP3,
where there's gray boxes, and you click them on and they turn gold, that makes it a
that means it's like a click and draggable list.
If we want to, we can check out the IDF for the this entire looking at the IDF for the plant
loop will give you all of the information for everything connected to the plant loop. So it's
quite a lot, but we'll just price it real quick piece by piece. So this is the actual hot water
object. Then we have the sizing object.
We have our plant equipment list here. So we have paired object type and object names.
Equipment operation scheme. So this is a list of our equipment operations as well.
So
control scheme one name
and schedule name. Okay, let's see type name and schedule name.
And then our operation connector lists, branch lists, etc. We don't need to go
and look at that again.
Any questions on on this?
No current questions.
Okay.
So we take our five minute break and then drop some in the chat.
Oh, we just had a question. I was thinking the same thing, although I'm pretty sure I
saw how you did it. Okay. Copying the boiler. Yes. How could you go through a little slow
motion on how you got the loop to extend? Maybe click by click. Yes. So let's let's erase a branch
and then let's draw it again. So you have two tools up here. One is erase branches and one is
draw branches. So if you erase branches, it will highlight all the branches in the in the model
for you. And when you mouse over it will show you, okay, this is the branch you're going to erase.
So if I go next to this boiler here, and it's showing me that it's highlighting it kind of all
the way back to the the splitter and the mixer. But if I erase it, there we go, it goes away. So now
I'm back to where I started. So I go to my draw branch connections tool. This highlights all of
the nodes in my model that I can connect something to and they are color coordinated. So the hot water
nodes are red. The chilled water nodes are light blue. And yeah, and then the air nodes are this
darker blue. So I can select
a point on the boiler or you can select a node on the splitter and the mixer. And these two
points are kind of close together. But if I select this one that's on the parallel branch side,
it will give me another parallel branch. If I select this one down here, it will actually
would put the boiler on this inlet branch. So I'm going to select this one here.
And then here. And it will automatically draw the connections for me.
It completes the loop on the other side. It completes the loop on the other side. Yep.
The the lines, the lines are just for you. The lines are not actually used by EP3. The lines are
to help the user understand what's going on that the actual data is is just data about what's
connected. So all these lines are just are just for you. So if you ever kind of move something,
and the lines don't update right away, one thing that will always trigger the lines to update is
if you go outside of the HVAC group, I click outside, it will always update.
And you can get back inside just by going back to your HVAC outliner. So let's just draw a couple
other configurations. We can just use this. This file is an example to mess with some of these
configurations. So let's erase this branch again, and we can do the two boilers in the series instead
of parallel. So I'm going to give myself some room. I'm going to move this boiler down a bit.
And then I'll use erase branches and erase this branch. And then I'm going to move this boiler
up and go to draw branches. And I can go from here to here. And it draws that.
Now, questions on that before I do the next thing, because this is going to look a little bit
this might be surprising. But yeah, any questions before I do the next piece?
Yeah, do you want to take a break now, or should we do this next piece first?
No, let me do this next piece, because it's in the same model. And then after the break,
we'll go to a different model. So I really like to have clean drawings. And we do our best in
EP3 when we import to have everything come up nice and clean. Like this, what we saw before
we added this boiler is exactly what EP3 drew when it imported this file. So that's, you know,
I consider that pretty good. But sometimes, and we'll see this with some of the later models
that we're looking at today, they came in and they were a bit messy when they came in, like
the lines weren't really going in the directions that you want. And there wasn't really enough
space for all the equipment. So if you ever need to, you can
you can move equipment around, and you can you can rotate it as well. So if you click M,
and you'll see the there's this protractor and the little red cross marks here.
Whoops, I didn't actually grab cross mark. You can grab a cross mark and you can and you can
rotate it. And so sometimes this will give you a better drawing if you rotate it. So this one,
you know, you could and you can put it at any angle. But here,
what I really want is to give myself a little bit more space.
So I can move, it says two steps, but I'm going to move these two pipes up.
And then I'm going to double click into this loop. And I'm going to move these objects up as well.
And don't worry about the lines getting weird,
because EP3 will redraw it for you and that makes it much, much cleaner. So if you have a lot of
stuff and you don't really have room for it, you can just go into your loops and you can move
these objects and they will, EP3 knows where they are inside the loop.
I did see there was one question about geothermal. So we will do geothermal, but before we do
geothermal, we'll do the air source heat pump because the geothermal is
the logical progression from the air source heat pump. Perfect. There was a question earlier
about air source heat pumps. Yeah. Yeah. Okay. So this is an incredibly simple model. If we go to
the building geometry, there isn't even any building geometry whatsoever.
There is just a very, very simple HVAC system.
And remember I said, EP3 kind of forces you to have three branches,
even if you only have equipment on one branch. So this is what it looks like. You would have an
adiabatic pipe, mouse over here. You would have an adiabatic pipe on the inlet and on the outlet
and you just have your other. You have to show your screen again.
Oh, I thought I said share screen. Maybe it's my. I didn't click the last button. There we go.
Okay. In the meantime, somebody mentioned while we're talking,
that VRF might be a good topic. I don't know how long that fits in.
Yep. It's not plant, but I'm not really sure exactly where it fits in. So we can talk VRF.
It's actually not that the objects are not that complicated. I think what's complicated about
VRF is if you're generating curved software data, that can be complicated. But that's
yes. And they mentioned that they're not confident in the equest VRF
models. And I would add that neither am I. And I don't think that Karen would be either.
Yeah. I'm not I'm not saying equest VRF systems for sure. So, okay. It's a lot of statistical
it's a lot of statistical noise in equest. And I think we'll get to the sharing on that.
Obviously, the data is complicated to obtain. I assume that there's some reasonable default
curves in EP3 or energy plus. Yeah, I think that I think the default curves are pretty good
in energy plus. So I have generated my my own curves as well, which is which is a bit
of a headache, but the others. I've done that and I've compared them to the existing curves.
And they are surprisingly not that different in the standard temperature ranges.
Yep. Yeah. Yeah, I think what what the default curves and energy plus, I think at like the lower
part load ratios, they are we use more energy than some of the manufacturers claim. But anyway,
so yeah, okay, great, great, great stuff. So we are looking at air source heat pumps now.
Okay. Yeah. So air source heat pumps. This is a very, very simple model. I will show you
because you couldn't see my screen. There is no building. There is absolutely no building.
Let's see what we've got for object types. I mean, there's a couple of curves.
There's an outdoor air node. There's some outputs. There's a whole bunch of outputs and a few
schedules and simulation control. But like this is a very, very small model that allows you to do
air to water heat pumps, which you can't do in most energy simulation programs,
or maybe not most, but a lot of energy simulation programs, you cannot do air to water heat pumps.
So here we are. Let's see, I do want to show you another trick because when we looked at
the five zone air cooled model, the loops are nicely colored, and here they are not. So
these are colored just with sketch up materials. So if you want to have a color of your loop that
aligns with what type of loop it is, so it's a little bit easier to read the one line diagram,
you can. So there's this default tray here, and you open it by mousing over,
and it's a little bit annoying, and then you can pin it, and there should be materials as an option.
If there's not, you can go to window, default tray, but if you don't see it at all, you can up here
would say show tray instead of hide tray, and you can check which options you want. So if you
don't see materials, you can check materials. And then if you go to here, to solid colors,
you can choose a nice and dramatic solid color. And when you choose a color, you'll get your
paint bucket tool, and you just click on your splitter or your mixer, and then the lines will
change color. And let's do the same for cooling loop. So there we go. So now we can tell which
is cooling and which is heating. These two objects are going to look pretty similar to each other,
and there's output data that I want the inputs. So we have a load side inlet and outlet node.
The condenser type selected is air source. EP3 will do the best to correct these condenser
types for you if you select the wrong one. And there's a source side inlet and outlet node,
and a heat recovery inlet and outlet nodes, which are not being used here. This right here is an
important field. This is your companion heat pump field. So the companion heat pump is used by the
sizing algorithm to make sure that the sizing between the two aligns. Sometimes you have a much
higher heating load than cooling load, and that drives the sizing of the chiller side or vice
versa. And then this will also allow EnergyPlus to warn you and check about simultaneous operation.
This on its own doesn't necessarily stop simultaneous operation, but it will help you achieve that.
There are some curves. You can choose sizing method. You can choose
whether you're going to control to a load or set point. So default is load, and that I recommend
that because that allows the operation scheme to control the heat pump, but there might be times
when you want to have it control to a particular set point. We're not going to go into all of these
different curves. I think the more important thing is that these objects exist, and that,
yeah, they exist, and this is how you connect them up. In this particular file,
I think they're just allowing the loads to determine when they're operational.
So the other thing they've done in this file is
they're only simulating it for the sizing periods, and they have two sizing days
specified. So when you simulate this file, it's lightning, lightning fast, and that allows you
to really dig in and troubleshoot and figure out your operation.
Yeah, I had some results. Data figured out here. So this is doing our winter sizing period,
and our summer sizing period. So it's just double checking the mass flow rates against
one another and seeing if there was simultaneous operation. We need to simulate for
like a shoulder season to check for simultaneous operation, but let's
we can move on to the next example, unless there are pressing questions about this one.
Any pressing questions?
Nothing's come in. Okay. So this one is a little bit more exciting. So this is one of those cases
where I've done some rearranging to make things a bit prettier for us. This line going from here
to here is a little bit unfortunate, but you know, we could.
Yeah.
Oh, it's a little bit better on an angle. So we can see the connections. We have a
geothermal system. So the person who was asking about geothermal system, this is the
little diagram for a geothermal system. And again, they're just doing a single branch
systems. So on the heating coil loop, we have a single branch, which has the pump
and the heating. They're calling it heating coil, but this is a heat pump. And the demand side,
again, we just have this kind of one branch. We have an inlet and an outlet branch as well,
but there's just one path. I should say instead of one branch, there's one path.
On the cooling side, you have inlet, one path, and one path. And with the inlet,
the parallel branch and the outlet, and same thing on demand. If you don't have any bypass
pipe, that's one way you could probably push extra flow through a water coil with the broken
mixing valve example. And then the condenser loop, we have the condenser loop pump and the
ground heat exchanger as well. So the ground heat exchanger object,
it's a on a service, it looks pretty simple. It just has an inlet node and outlet node
design flow rate, which I don't think I think one of the things that's a bit of a pain about
the ground heat exchanger system is it's not auto sizable. So if I'm
doing early version models of buildings where I need to do a lot of work, and I'm trying to
simplify the system, I will sometimes use district heating and district cooling on the supply side
of a loop to provide a constant sort of ground ish temperature for the early portion of the
portion of the modeling. And then once the once the building's a little bit more
once it designs a little bit farther along, and I can size
the ground heat exchanger with a little bit more precision, then I will go in and actually add a
ground heat exchanger with some flow rates. But that's also a trick that can work decently well
in some of the areas that I work because in Vermont, sometimes there's so much water flowing
through the ground that even if you have a geothermal system that's active for a couple of
years, the ground temperature doesn't really change because there's so much water coming
through that just dissipates any heat rejection. So it's a technique that works in a particular
location, but is it necessarily large scale applicable to other places, but it can make
this process a little bit easier. Okay, so then there's this undisturbed ground temperature model
type and name. So there are a lot of different geothermal models, kind of mathematical models
that are available in energy class, but
okay, actually this one is a relatively simple one.
There we go, there are all the numbers. Okay, the ground temperature, and then we have response
factors, the g-function numbers, and the vertical line properties. So you can model various types
of ground heat exchangers, vertical boreholes or horizontal or whatever you like. There are
a whole bunch of different models available in energy class, and I think we've got a lot of that
stuff supported. Ground heat exchanger may need to add some of those, but there we go. So ground
heat exchanger, and it's just going directly through our chillers. I think a really good thing
to do tomorrow for special topics would be to do a primary secondary loop potentially with
the ground heat exchanger, where we can actually vary the flow through the ground heat exchanger
separate from the flow through the heat pumps in order to minimize pumping energy and provide a
stable flow. So you're kind of just recirculating through heat pumps if the heat pumps are balancing
each other out, and you're only going to the ground when you actually need to add and remove heat,
you're not right default going to the ground all the time. So let's see, I ran my simulation here.
Now we didn't,
we could take a look at some of these temperatures if you're interested or we can move on to the
next example, but I'll let look the group decide at this point questions or comments.
One question came in, can we model borehole heat storage slash recovery in EP3?
Borehole, can you expand on what you mean by that?
I will, I will wait for an expansion on that. Okay, okay.
There is one thing that, and again, I might be asking a very dumb question. I'm coming from
I've modeled a lot of geothermal and a lot of that has been an equest and trace 700. So
my question is, you mentioned that this shouldn't be in simultaneous heating and cooling
earlier.
Yes. So that is specific to these being coupled heat pumps, water to water heat pumps that
essentially often it's a packaged unit that provides either heating or cooling.
I think that's a good question.
Heat pumps, water to water heat pumps that essentially often it's a packaged unit that
provides either heating or cooling and it can't provide both at the same time. So what you're
simulating, what exists in reality is a packaged unit and it's never going to be providing heat
and cooling at the same time.
Yes, some of them can't, but some of them can.
Some of them can, but it would be through the, it would be through like heat recovery.
So, yeah, so what I would do is a little bit more complex system where you would
see if we can do it heat recovery.
Oh, I understand because the compressor is only running in one direction at any given moment.
Yeah. Oh, I don't think these nodes set up, I don't think.
No, okay. Yeah, those nodes should be, those nodes look like they're not set up to connect,
but the, what you would do is you would connect to these nodes here on the heating side and that
would be like passively adding heat to your heating loop.
Right. Okay, right. So, okay, I understand what you were saying now.
I think the question regarding the boreholes.
Yep.
Uh, borehole heat storage recovery, I think that is at least a common application
is when you put the boreholes into the ground and then say they're in cooling all summer
and you reject heat into the borehole, so the borehole heats up.
Yep. And then you recover that over the winter, especially in the shoulder months when the water
is really warm. Yeah, so let's see. And I would imagine that's what that means because that's
what I've seen frequently applied. Yeah, exactly. Yeah, so I think maybe what we could do for
special topics tomorrow is do a detailed and more complex version of this system where we have
heat recovery. We have, because that is exactly what is happening with the geothermal system.
And it's these big long lists of response factors and borehole factors,
like the grout thermal conductivity, grout thermal heat capacity. And then there's
these response factors dictate information about the actual borehole.
And these are generated often off of borehole test data, which you don't always have for every
single project. But yeah, I think there's, it's been a while since I've modeled a lot of geothermal,
a lot of people are going to air to water heat pumps because they're just so much less expensive.
But yeah, these are like outputs from a different program that does all of those
calculations about how the ground responds to your inputs and how the heat and cooling gets stored.
But yeah, we could, for special topics tomorrow, I'll put together a model,
I'll slash this model out a bit, and then we can track the, we can use this output variable here,
ground heat exchanger, average borehole temperature, and we can track that versus the
ground temperature, like the,
yeah, because NAD plus has like a regular ground temperature,
yeah, site ground temperature deep. So we can track
this temperature against these ground temperatures and see what the difference is, and we'll see a curve.
Yeah, okay. And I guess that in Vermont, things don't, the heat does not store as well.
It really doesn't. It's shocking. It really doesn't. So, but because most of the geothermal
systems that I've done have been in Vermont, I've gotten quite lazy because I mean, you drill down
and there's like just 500 gallons a minute coming out of a well and that water is moving,
you know, it's not just like, it's moving through the aquifer. Yeah, it's moving through the aquifer,
and so it just, there's not really much storage. We don't have the same effects that you have
in other places where it's dry. Yeah, that though, that prevents you from having
a problematic buildup of heat or heat loss over a 10 year period. And that's the typical problem
that, that's the typical problem that you run into with heat pumps. So it's probably not the
worst problem to have. So it's, it's not, and honestly, I mean, this is a small aside, but
a lot of projects, when there's that much water, you can, you don't have to drill nearly as much,
you drill down a certain amount, a couple hundred feet, and then you move the rig over,
and if you hit the same aquifer, you can have an open loop geothermal system and just dump water
in one and pull it out of the other. And you don't, and you have, it's saves, the clients love it
because they save some kind of money and because they don't have to drill as much well, and they
don't have to put all the insulating grout in and all the other things. So anyway, it can be an
interesting alternative for geothermal where, which has made me lazy as an energy modeler.
As an aside there, I am working on the, the world's largest open loop
geothermal well at the moment. Oh, wow. Yeah, and, but interestingly enough,
if you pump enough heat into it, it will change the temperature of the aquifer.
Yeah, eventually, eventually it will. So we're working on balancing that, and so that's a great
topic for me. And then we had some additional information, the borehole thermal energy storage,
which uses boreholes to store and retrieve heat for heating and cooling buildings. Okay,
it sounds like it's the same thing that we're talking about. Okay. In a drier area where the
aquifer is not, has a secret cross flow that's not monitorable. Yeah. That, that strategy is the
conventional strategy. Yeah. Yeah. Yeah. So I will build this model out for tomorrow. I think we
can spend a good amount of time talking about some options here. Yeah. And then there were other
questions about making a heat pump from one loop to the other from the cold side return to the
the hot side supply side, something like that.
Was that a question? I don't quite understand. Yeah, it was a question somewhere. And
one of the other lessons that I have archived. Okay, okay. It's not related to geothermal,
it's just a heat pump water to water heat pump. In order to, I believe,
optimize the amount of heat transferred to optimize the temperatures on the return water
for the cooling side and then increase the heating temperature on the hot supply side. So
I'll send you those notes. That's what these are. These are water to water heat pumps.
One is optimized to provide heating, this one here. And this one is optimized to provide cooling.
And then it will, you know, so then it then it has the source and I will activate these
nodes for the for the tomorrow so we can actually model the heat recovery portion.
Yeah, I think we'll get to that. I think it's a, it's a separate type of heat pump.
It's not, there's no, there's no geothermal well involved. It's between the dark red loop
and the light blue loop. Oh, between these two loops. Yeah, so yeah, I mean, you could,
you could use one of these as, you can use any loop as a source in energy plus. If I wanted to,
I could connect this source for the this, this EIR cooling heat pump. I could have a hot water
loop as its source. You have to be careful that your equipment is going to be getting
water that is a temperature that's appropriate for its operation. So if this has a high limit
shutoff temperature, that should probably does minimum source inlet temperature,
maximum source inlet temperature. So it will, it will turn itself off if the inlet temperature
is outside of these bounds. Yes. And that equipment would be specialized for the
appropriate temperature. So yeah, yeah, but you, you could use this exact piece of equipment to
do that. You don't want to make sure that your curves were appropriate for, you know, if you
were, if you were generating cooling off of hot water, probably isn't a standard piece of equipment
and you might need some non-standard curves. But you can, yeah, it's doable. It's possible.
Okay, so I will send you those questions. But yes, I assumed the same answer that it really
doesn't matter the supply and the supply loop and the, I don't know, the return loop, would you
call it the condenser loop and the evaporator loop effectively? And as long as your bounds are the
same, I wouldn't see why you could not model that. Yeah, yeah, there, you know, there is another
object that is specific for central heat pump system. There is this central heat pump system
object which has a heating side, a cooling side, and then a heat reject side. So
cooling loop inlet, source loop inlet, heating loop inlet, and outlet. So this is, this is another
option. And it's, the two sides are coupled. Right, okay, so that, in the case where you're using
heat recovery. Yeah, so this, this one, sometimes, sometimes these can be a little bit misleading
where you see, oh, okay, because there's a heating side and a cooling side, it must first send any
heat rejected by the heating coil to the cooling side. You got to verify everything with energy
plus, you got to verify that the cooling coil is actually getting the heat reject before it's
getting rejected to the source loop. But this is an object that's available and I could, I'll add
that to the list for this model for tomorrow. Yeah, there's clearly infinite options here.
Exactly, there's many, many ways to do things in energy plus and that's why the, you know, say it
until I go blue in the face. The recommendation is to develop a workflow, get familiar with
particular objects that serve your particular needs, and don't worry so much about the rest.
Because it can get really overwhelming and you're not going to learn absolutely everything
in energy plus. Yeah, so stick to the workflow that you mentioned earlier
with the creating the nodes and the limits and so on.
Okay, so we, I think we should stop talking about how, how we wish this model would be
because we will, we will see it in a more glamorous form tomorrow. Let's go onto a couple of other
examples and if that's all right. Absolutely. Okay, so
here we go.
We did water source. Okay, so we can do
a fluid to fluid heat exchanger. Let's do that.
Okay, so this model has an actual, absolutely gorgeous building and
on the HVAC side, it's a little bit, you know, it looks more like a complete HVAC system. So this
is an outdoor air loop or I'm not sorry, this is a no outdoor air loop. This loop does not have any
outdoor air. Unless, unless you learn our lesson from yesterday. I'm looking here for something
called zone ventilation, which is a sneaky little thing that doesn't have any
nodes.
But can,
so you can provide ventilation directly with this object that is not really an HVAC object.
It's kind of something in between, although you can, it does sort of have a fan but it sort of doesn't
have a fan. And you can, if you say that the ventilation type is exhaust, it will induce air
from your air loop, even though your air loop looks like there's absolutely no outdoor air. So
that's why I said, I think there's no outdoor air. It's just just verifying that there is no
zone ventilation design flow rate object here.
Okay. So we have an air loop, just got a chilled water coil and then VAB reheat.
And then the hot water loop here. I just zoomed in. If you want to see what type of object it is,
the more you zoom in, that when you get a little bit closer, the labels will pop up.
If you zoom out a bit, it will just tell you the name. You zoom in a little bit
farther, it will tell you the type of object as well.
So this is that district heating object where we just have an inlet node, an outlet node,
and then a capacity which is usually auto-sized.
And condenser loop, which the supply side is actually going in two directions.
I'm sorry, the demand side.
So to the right is just for our bypass. And then on the left here, we have two objects.
So this one, if you look in the outliner, this is the free cooler and this is the main chiller.
This is a chiller constant COP. So this is a really, really simple chiller model.
It's, as the name suggests, it's just a constant COP. It's not responding to any changes in
temperatures. It could actually be appropriate to use if you have a condenser water loop that
is always the same temperature and you're certain that your inlet temperatures are always going to
be the same. Not at all appropriate if it's an air cooled chiller. Okay, and then there's a free
cooler here. This is a heat exchanger. And these are incredibly flexible objects. We have
demand side, inlet, and outlet. So these nodes are connected to the demand side of a loop.
And you have a demand side design flow rate, which can be auto sized, but be careful with the heat
exchanger with auto sizing. You got to verify that it's auto sizing to what you want. And then
there's a supply side loop supply and demand. And you can have a couple different models of heat
exchanger. So there's ideal counter flow, cross flow both mixed, etc, etc, etc. If you're doing a
primary secondary loop, there isn't actually any heat exchanger at all. So you want to use ideal
that would basically models water mixing, but it lets energy plus
maintain its conservation of mass equations in any comfortable ways. You don't upset energy class.
I
you factor times area. So this can also auto size based on the temperature differential across
the heat exchanger and the flow rate. And then there's a control type. A lot of different control
types. Cooling set point modulated is what they're using. So that means that
we should see, and there's like a little yellow mark right here, which is telling us where it's
going to look for a set point. But we should see a set point manager.
I should see a set point manager.
Yeah. Okay, actually,
there may not be a set point manager on that. Oh, I'm looking at the wrong loop. Okay, here we go.
Um, chilled water loop. There we go. Okay, there's our, there's our free cooler set point manager.
There it is. Okay, so you need to have a set point manager on that set point in order to use
your, a set point modulated control type.
Uh, there's dual dead band set point. So this would be looking for a dual dead point,
dead band set point manager. And then you can also do operations to be modulated. So this
object will show up on, so now I'm on the chilled water loop here. This will show up
as an option on your plant equipment list. And this particular model, which I imported from an
example file, it has two cooling load operations that reference the same, you know, two different
equipment lists that have the same object on it. And one operates on peak and one operates off
peak, but it's the same equipment. So just, just because it's an example file doesn't necessarily
mean it's going to be logical. It does mean that all the equipment is going to connect and it will
simulate. But it doesn't necessarily mean that what they've done makes a huge amount of sense.
But the point is that the, the free cooler is available on the plant equipment list.
But my advice to you on using heat exchangers is to always, always, always verify that they're
operating the way that you want them to because they tend to be a little bit finicky. So put,
put a note report on those, those nodes and double check.
Let's see. Okay. So I did run a simulation here.
And we have
a bunch of variables that are related to the heat exchanger.
The energy transfer, the supply side mass flow rate, the supply inlet temperature
and the supply outlet temperature. And then
okay, heat transfer rate is aligning with the mass flow rate.
And then our temperatures on the supply inlet and outlet, when there is no flow, the temperatures
are the same. So that is as expected. And when the, when it can supply 50 degree water to meet
its set point, then there's some amount of flow. There's actually, let's see, I think there are
a couple more variables down here. Cooler.
Okay.
Okay. Oh, I guess I had to scroll down a little bit. Okay. So we have a heat transfer,
energy is the same. There's just the one. Now we have the demand mass flow. And I didn't put
supply in, but the green line is supply mass flow. And so we can see that, that they are not equal.
So this, this model allows unequal flows across the heat exchanger.
And we can also track so the, we can see that we're getting an ideal
if we, we know we can't. So the supply inlet temperature and the demand outlet temperature
are the same. So we're getting an ideal heat exchanger model. We can also see that the,
the supply and demand mass flow goes to zero at the same time.
Anyway, I just, I found this one, I find this, this graph with the heat exchanger is super
interesting. And it's very helpful for verifying that the heat exchanger is doing what we want it
to. This object is so powerful for building more complex leak and piping systems. I use it
all the time, obviously, obviously all the time to build. Yeah, well, we'll do a complex example
for tomorrow with the geothermal system on a separate leap from the heating and cooling water
to water heat pumps. And you could, you'll start to see a little bit the power of this particular
object. Questions on this before we got a couple minutes and we can go take a look at
variable refrigerant flow. And it's actually not all that complicated. Any, any pressing questions
here?
No, I was just copying and pasting all of them. So, we have them for tomorrow.
Okay.
Let's see. So,
not open.
Oh, question, question came in. General question for EP three, can we model solar or any renewable
sources to offset the electrical loads in the reports? Yes, you can model solar PV directly
in EP three. And actually one of the other models that I had open that we didn't get to maybe we'll
look at this one tomorrow. This is kind of a good special topic. But this is a system, these are
domestic, or I'm sorry, these are water heaters. And this one is actually operating as thermal
storage between two loops. And then these are solar collectors, which are connected to
some surfaces. So, there are a bunch of surfaces that are oriented. Again, this model doesn't
really have a building other than it has some site shading, which are the surfaces that these
solar panels are connected to. So, yeah, absolutely. You can do both water and little bit of solar
panels. But let's save this model. We can go into this one in more detail tomorrow.
We'll do the geothermal model in more detail tomorrow. I think we still have desiccant wheels
that someone was asking about. And I think there are some other... Oh, someone asked about radiant
systems. I think that might just about get us to...
Yeah, that sounds right, besides all of the heat pump connections.
Yes. Yeah, we'll revisit the geothermal system with heat pump connections.
We'll revisit this with a more complex system and probably add a water-to-air heat pump in there
as well. So, I hope my modeling work cut out for me the rest of the day and tomorrow to get that
ready for me. Yep. Okay. So, the next topic is... Is it VRF or is it the desiccant loop?
So, let me just open real quick. I think I can get that VRF system open. I got all these files open already.
But...
When you open a new file in EP3, it doesn't actually have any of the EP3 intelligence until you start.
Okay. So, this model has the same kind of five zones that we're used to seeing from our five-zone
example files. And on the AQAC system side, this should look relatively familiar. It's an air loop
with a fan and then there's a... It actually has a DX cooling and heating coil.
I'm sorry. DX cooling and fuel for heating.
Did you open this file from the example energy plus files or example EP3 files?
This one, all of these are imported from the energy plus example files. I think this one
imported without any modifications. The others, some of the other ones I had to do minor modifications
after importing them. Okay. Yeah. But I will provide all of these files. I will provide to
the people in the class after the class. I'll probably modify them a little bit and we'll work
with them tomorrow and I will provide all of these files to you. Okay. So, all right. We were just
looking at a standard file from energy plus basically. Yeah. Yeah.
Okay. So, I will just very briefly introduce the structure of this because we've got like a minute
and then if we want to spend more time with this, we can do that tomorrow. But the VRF in energy plus
is actually relatively simple. You have a terminal unit which you see here and then you have your
actual condensing unit here. One of the things that I actually haven't shown all of you much of
yet is that because this object is applied to multiple zones.
So, you can see here a space, our TU, permanent unit is applied to five different zones
and the space 11, this is left over from the import. We can change the name. But if we look,
we have one for each zone. So, this object is replicated five times for each zone.
It has an outdoor air mixer, it has a fan
and then it has a DX cooling coil or a variable refrigerant DX cooling coil
and a variable refrigerant DX heating coil. And these DX heating coil, the variable refrigerant
heating coil models are not available in a lot of objects in energy plus. They're sort of newer
and it takes a while for them to get into all the other parts of energy plus.
The connection between the air conditioner and the terminals is done with energy plus
levels lists. So, we do it like this. This is just a little radio button where we can say
which terminal and there's five terminals, not one, there's five different terminals
and we can select, we can connect them to different terminal lists. So, if I made another
heat pump, so this would be VRF 2. We can call this VRF 1.
So, now we have two lists. So, there's a list for VRF 1 and there's a list for VRF 2 and we
can toggle which terminal is connected to which VRF. Anyway, let's not push
way over like we did last night. I will stop. I'm happy to stay for questions,
but if we want to go over VRF systems in more detail, we can try to find a few minutes again
tomorrow and revisit this. Yeah, okay. Well, it sounds like you have your work cut out for you
together tonight to push through for everything to be cohesive tomorrow. I'm answering these
questions and if anyone has additional material to ask about or to work in,
give Karen some time before the presentation tomorrow and
she will hopefully be able to work that in or answer separately on the forum.
Yeah, I will continue monitoring and responding to questions on the forum for another week or so
and then at some point we'll close it. You all haven't used it a whole hell of a lot,
but I think as you start working with EP3, it might become a very useful resource.
Okay, so if there's nothing else, we can finish up and we'll see you all tomorrow for
our last class and our special topics and looking forward to it.
All right, thank you, Karen, and thank you everyone for all of the useful questions.