TRACE 700 Case study
LEED FAN calculations Demystified
About Instructor
What This Course Covers
After this course
Tools for the Job
Key details
Why is this important
What are we modeling?
Baseline Building
Comparing the two buildings
TRACE 700
Let’s take a trip in TRACE
How does the Fan calculation Work?
=
Total
SYSTEM FAN POWER
Complicated PROCESS?
But it takes it one extra step
Total System Fan power?
Algorithm yields power for ALL Fans in the baseline
What does the Proposed look like?
Baseline Fans
Let’s Look in TRACE 700
Exhaust Fans
Are exhausting…
This webinar we are going to cover LEED fan calculations. The goal is to cover them thoroughly, using Trace 700 as a demo. Like I said, we have a lot to cover and we’ll reserve questions for the end. In fact, that’s probably the best time to address questions as we hope to answer most of them.
Let’s get my least favorite slide out of the way. We can use it as a slide for you to adjust your audio. My name is Bob Fassbender. I’m a LEED AP with a with a BD+C specialty. I spent three years working with CDS??? and afterwards I co-founded energy-models.com with some colleagues. I did write the LEED fan calculator at energy-models.com. As far as I’m aware, it is the only publically available LEED fan calculator, at least at the moment. But I’m proud to say that there hasn’t been a single bug reported since its initial launch. That’s pretty exciting considering I’m not really a programmer. Let’s move on and get these other formalities out of the way. This course covers LEED fan calculations using ASHRAE Standard 90.1 2007, which is still, according to most of our feedback, the most commonly used version of ASHRAE Standard 90.1 Of course that will probably change soon to the 2010 version. We are also going to cover proper set up in Trace 700, as well as common mistakes. A little history on this topic- when I was working at CDS??? A few years ago, we would receive e-mails from users who had submitted to LEED, and LEED reviewed comments said, “Sorry, Trace 700 does not calculate the LEED fan power correctly,” and then proceeded to tell them that they had to re-do it by hand and re-do your model. I should note that the LEED reviewers weren’t really at fault because at the time, the calculations were not very transparent. We’re going to start with an example of why this rumor had started. We’re going to avoid it. Long story short, I think out of hundreds of e-mails, there was only ever maybe one or two real bugs, and the rest were just misconceptions, misunderstandings, or an error in the reporting. So, today I hope to put those misconceptions to the rest, and also, to cover (if you’re not using Trace) LEED fan calculations and how to proceed with them. So, in short, after this course you should be able to set up LEED fan calculations in Trace 700, use the fan calculator at energy-models.com, and assuming you have 8th grade math skills, calculate the LEED fan power manually. Finally, you should also have a reasonable understanding of when to use the LEED fan credits. Just like any job, we need to establish our tools at fist. Obviously here we’re using Trace 700, and you should typically have a printed copy of that for Standard 90.1. For those of you who are really new to this, ASHRAE Standard 90.1 is a book. It’s not some strange topic, it’s just a little book, about 200 pages long. Another good thing to have is some sort of fan calculator to verify your calculations. We have one available for free. We’ll cover that in a minute. It’s at energy-models.com. Or many people have built their own spreadsheets to verify their own numbers. It’s not really an alga rhythm that you can do pen and paper because there are some numbers. You still can do it pen and paper but not consistently. Before we can ever begin running through the fan alga rhythms, we need to know a few key details. We need to know the system type, whether it is constant volume, VAV, or if its residential weather, it’s a P-Tack???, or PTA2P???. We need to know the design CFM calculated using Standard load methodology. We might also need to consider whether we have any additional pressure drop considerations, which we’ll get to that. Why are the fan calculations so important? I apologize for all these intro slides, but we do need to establish this. The fan energy is actually pretty tough to beat in LEED buildings, and since fan energy can be approximately (of course this could vary) 20% of the total cost, if you don’t beat the fan power by your targeted savings percent, you are likely losing LEED points. So, it’s important to know what you’re going to need up front.
We’re going to run through some examples today, and the first thing that we want to do is establish what we’re modeling and become familiar with the project. So, here’s a building that’s drawn up in Google Sketch Up that we kept really simple. This is what is known, if you’ve never done a LEED model, this is our proposed building, or the building that is either already built or going to be built. In this case, it is a simple office building with a completed design and for simplicity’s sake, we gave it five thermal blocks, or rooms, zones, etc, which totals 13,500 square feet. It has a single VAV air handler with the fan horse power already determined and designed. That’s key here, as well. What we can determine from the proposed building is the Baseline building. Because of the size and type of the proposed building, this would correspond to a Baseline building to what is called System 3, or package single zone systems. So, constant volume, package single zone systems, and this is approximately what it would look like with the roof up. Each thermal block get its own single zone unit, and the fan horse power for each unit is what we’re calculating, and so there are five separate calculations and it’s based on the alga rhythms defined in ASHRAE Standard 90.1. If we just look at the buildings side by side, on the left we have the building that’s going to be built, on the right we have the building that we have to compare to in order to get our LEED points. There are several key differences, as you may note, of course in the systems, but the envelop and the glass are also different- in which case, seeing some of the names that signed up, I know that most of you know this, but for the folks that are new we do want to cover this important topic. Let’s take a trip in Trace, and we’re going to look at a common file. Keep in mind we are starting with a file that is modeled with actually a conventional mistake that is made, and we want to address where the rumors came from.
Let’s launch Trace here, so here we have the file- we have the proposed and alternative one, and Baseline and alternative two. Some people may argue that they do this the other way around. This is the more common way that this is done, though it certainly is not the right way. We have the proposed building, this is design, and we have the Baseline building. As we mentioned, Trace automatically does these calculations for you. The way that it does that is that we have to go to actions, change energy parameters, and we have to tell Trace to apply this and apply ASHRAE Standard 90.1 2007. Notice, the common confusion here is “ok we’re applying this, but which one of these is it going to apply to?” When we go to calculate and view results, there is this option to select the performance rating method. That’s the method used to establish your LEED Baseline building- is the performance rating method. So we say the LEED building is alternative two, and for simplicity’s sake, we’re not going to rotate it, though Trace also would rotate this automatically four times. For simplicity’s sake, and this is actually how we’d recommend starting a file because you can calculate it much more quickly using this method. This is already calculated. We’ll save the minute and a half of running through calculations. When we calculate this, the typical report is the PRM fan power, and so this must have erased my results. If you saw earlier, I re-ran a different file. I can’t say why it would be that. But anyways, we’re not to that point yet. We just need to know that we go to change energy parameters, enable it, and then we have to tell it which alternative it’s enabled for.
We need to know what happens when we select those options. Well, it follows a very standard procedure. It takes the supply CFM, calculates it for each one of those thermal blocks in the Baseline building, and calculates the total system fan power. Of course, this needs to be calculated at a 20 degree Delta-T??? for the Baseline building. This is very specific. So, in short, our proposed building is already designed. We are not sizing the fan power for the proposed building because it’s already be determined. Then, Trace follows in the Baseline, the steps in 90.1 2007, which is a reasonably long alga rhythm that is built into Trace. Actually, Trace takes it an extra step and I think this extra step causes most of the confusion. Let’s just quick walk through this calculation. It’s something that I find that most people may or may not have taken the time to do. We’re going to start 90.1 2007, and we start with G3129, as if that’s something that you can remember. This gives a list of items that we need and if we follow through the logic, the first thing we need is the brake horse power. If we calculate fan power in lot, we have to start out with the brake horse power. If we follow through the logic (unless we’re using systems one and two where the equation is super simple), we’re in system three, and so we need this equation, and the next thing we have to define is the brake horse power which low and behold, brings up another table. This is table G3129, again, not that you’d expect it to remember these numbers, but if you do follow through it, it’s not that difficult. So, we decipher which equation we need to use, and here we have per constant volume or variable volume, but system three is constant volume so we know we’re using this equation. There’s another variable here, and if you read the notes it sends us to section 6531. You don’t always have to use this section. This is in case you have this A-value to find, would to be finding A is the sum of the pressure drop, times the CFM divided by a conversion factor. That pressure drop is basically a credit that we’re allowed. A typical scenario is if we have things like a Mer-13??? or better filters in our actual design, so what it’s saying here is that we know 90.1 is saying this, and we know that it costs more energy to put in Mer-13??? or better filters, but we also believe that those filters are a good thing. Thus, we are going to let you use a little bit more energy if you choose to implement high quality filters. So, if you did have those filters, we’re allowed this credit and that credit propagates to the equation and changes our horse power. Finally, we have all the variables to find and we can determine our horse power. We still need to know one more thing. This is based off of Table 10.8 and the column that is specified is highlighted. We need to define the efficiency based off of this table, and that finalizes our equation right here. This is exactly what Trace does. This equals the total system fan power. That’s the key here- the total system- it’s not necessarily talking about one fan, though it could be talking about one fan. Trace 700 does this whole process in the built in alga rhythm but it takes one extra step.
The first question is, what do we mean by the total system fan power? This is the total power that the alga rhythm yields for all fans in the Baseline thermal block, or the Baseline system. It’s all of the fans, and then the obvious question is “how many fans are in the Baseline?” For most scenarios, this is the same as the proposed and actually this is to find officially in 90.1 2007 G31 2.10.1, as if that’s something that’s easy to remember, but it’s independent, it’s G, and it’s actually officially defined. So Trace basically had the foresight to go ahead and implement this. So, if you follow my logic so far, the next question is “how much fan power does each fan get?” If we’re determining, one equation yields kilowatts- it yields 5 kilowatts for all of your fan- well how much does each fan get? It’s defined as the same ratio as the proposed. The answer is simple and confusing at the same time. But it should be made simple in a minute. Let’s take a look at the proposed. In this particular case, the proposed is two fans, a supply fan and a return fan. Of course the proposed can have as many fans as there are in the design, so we could also have an exhaust fan, and however many fans, but that’s the number of fans that we’re starting with. And in this case, the proposed is the supply fan of 5 horse power and a return fan of 3 horse power. So for the Baseline system, each one of these single zone systems will have two fans with the same ratio. The total power is calculated based on the supply CFM of each of these five zones. If we consider what’s the CFM again, remember the Baseline building has a different CFM than the proposed because it’s calculated using the many specifications of Appendix G???, such as a different envelop, or lighting loads, or building mass. For most (and I have to put that in) for most buildings, it’s not the proposed design CFM. In fact, if you’re designing something such as an office building, and you set up your insulation, your Baseline building should actually have more CFM than the proposed. Now that we specified all of that, now we can look at our example in Trace. We had Trace run it in the meantime, and so we set up the proposed and let’s just look at this.
And we have this set up and to be honest, this is basically a completed LEED building but it’s not entirely complete. If anybody is noticing that something is missing, our main objective here is just to identify the fans. Here we have our fans and we have the horse power (5 horse power and 3 horse power) and we have the fans specified as well as the static. One big misconception in Trace is that changing this number, say to 5, will actually change the horse power. The static here is not going to change anything. So we can leave the static at whatever, but what it does is that it won’t change the horse power in this case. If you want more information on that you can see the Help file, but basically the fan adds some heat to the airflow. So it’s based upon the static and friction, and therefore we have some more heat in the airflow. Of course this often causes confusion among designers because they know that the horse power is actually based on the static and on the CFM. Thus, the confusion. But if we lock in this at 5 horse power, its 5 horse power no matter what. That’s the key take away here, and a common misconception. So we have 5 and 3- this is built into our design documents. Of course if the designer was being LEED conscientious, the designer would make sure that this value was already beating the values in 9.1. In fact, they would have to. We have our proposed system set up, and so the common thing in the Baseline is that people say “let’s set up our single zone system” and we’re setting this up for system three, and we have the fans, and the best thing to do is to start with the fans identical to the proposed. We don’t need to do anything here because Trace is going to recalculate the numbers. But we do need to tell which fans are running, so if there was no primary fan, it would not calculate a primary fan. The best thing to do is to say “ok, we have a primary fan in the proposed- let’s keep a primary fan in the Baseline- and we have a return fan in the proposed so let’s keep a return fan in the Baseline.” The ratio is very important. Trace gets the ratio from these two numbers. So, follow with that, and the common way of modeling this for people that are intimately familiar with Trace, is just to take each one of these thermal blocks and assign your room to each one of these. In Trace, you have zones and systems and so we can assign the system to the zone, and what this does is Trace knows now that each one of these gets its own unit. This has been the common way to model this in Trace, pre-LEED. There’s nothing wrong with modeling it this way, technically, but when you model for LEED we’re going to want to consider modeling this differently. This is basically what caused the misconception, is modeling it this way which technically isn’t wrong, it just causes a misconception. Let’s go ahead and let’s look at our reports, and so the common report to show what happened with the fan energy previously, was this PRM fan power was not here, so there’s this equipment energy consumption report, which is still a great report especially when working with LEED models. Here we have alternative one and we’re using the group tree here just to hop around, and we have our fan which we entered 5 horse power and 3 horse power, and we can work that to kilowatts. We have our 3.73 kilowatts which is just a direct conversion. If we look at our system in the Baseline alternative and alternative two, it tells us “hey, you entered the same thing, 3.73 and 2.24, which is 5 horse power and 3 horse power respectively, you entered that but this is what we calculated.” We calculated 8800 CFM and we calculated this CFM for each one of those fans. Notice the ratio is the same, for instance, if we took 3.73 divided by 2.24, we’d get 1.66. If we take 4.58 divided by 2.75, we get 1.66. So, it’s the same ratio as 5/3. The ratio holds, but right here is where the rumors started that Trace does this wrong. Let’s just keep this number in mind. Let’s add up the total- 4.58+2.75 which equals 7.33. Keep that number in mind, along with 8,859. Let’s go to the fan calculator. There’s no fan filter credit that we’re considering, and it’s constant volume non-residential, so this is just if you go to energy-models.com, and go to tools and LEED fan calculator. Here, just fill this out, it’s pretty basic. We calculate the fan power. It returns all of the numbers from the tables that we looked at. Here we have 6.94 kilowatts and so Trace calculated 7.33 total, according to this report. Well, this report is just a summary for energy, it’s not reporting what’s actually happening, because it’s showing that there’s only 2 fans in the Baseline building. What Trace is really modeling, each zone in the single zone system gets its own fan. There’s actually 10 fans in this particular file. The correct report to go to would actually be the PRM fan power. Here if we look, sure enough, there is actually 10 fans- a primary fan and a return fan for each one of these. Let’s just look at one of these as an example. We’ll look at the southwest system. It was 2,099 CFM and we had a total of 1.76 kilowatts. Here it’s 1.75 kilowatts. What happens is of course Trace rounded two numbers and they both happened to round up, so obviously the calculation is just based on a difference in rounding. We have 1.75 vs. 1.76. If we ran through all of these we’d found out that it’s the same. If we looked at every single one of these ratios, they all hold the 5:3 ratio. The confusion again was caused by the fact that it appears, according to the equipment energy consumption report, that Trace is really only modeling two fans. If we went through and added up all of the individual powers, of course it would add up to this. But since the equation is non-linear, it doesn’t add up to be the same. The conventional way of modeling, pre-LEED, caused the misconception because of this report. There’s other reasons in LEED where you should no longer model this way, and one of the reasons is that a lot of LEED review comments require separate unloading, and so that means that you have to have a plant for each one of these single Baseline units. The correct set up is that instead of having 5 zones in one system, we have 5 systems and we put one zone in each system. Now if we look at this report, we have five systems here, and each system is going to have two fans. So right here we have 1.17 and .70 so we have 1.87 total kilowatts. If we look at the supply as being 2,326, we have 1.86. Again, Trace, when it reports the numbers, just common math if we take a number and divide it by 2, typically one of the numbers is going to round up and one is going to round down. But often we can have them both round up. Here Trace uses these two numbers that rounded up 1.87, but actually the numbers used to calculate the true energy probably had 10 decimal places. The reports round up just slightly, but the true number that was used is actually the float number with probably 10 decimal places. I don’t know the number of decimal places it uses in the alga rhythm but it’s a lot. You can see now the fact that we have all 5 systems labeled in this report, we can see in every single one of these that we entered 5 horse power and 3 horse power and it recalculated those.
Again we’re just using one system for simplicity here. But here we set this one up with 500 horse power and 300 horse power. We calculated this and to jump to the reports, you can just click the magnifying glass. We’re looking at the equipment energy consumption, here you can see the original power was 500 and 300 horse power and the total comes out exactly the same as it did in the original file. The key factor in all of this is to enter the same fans as the proposed. So we had a return fan and we had a supply fan and the key factor is that the ratio stays the same and this is in fact defined in 90.1 2010. If we went ahead and we added a system exhaust fan to this and gave it some power, the total kilowatts would be the same but of course we would screw up our ratio. I’m going to have to re-do this now that I selected the fan. We recalculate this, it just will take a minute. We entered a supply fan, a return fan, and an exhaust fan. We’ll look at the equipment energy consumption. If you’re wondering why my report keeps sneaking off to the side, it’s because we change the resolution when we do a webcast. That’s not typical behavior of Trace. Let’s just look at alternative two here, and sure enough we started out with 1 horse power each which is .746 kilowatts, rounds to .75, and each one is recalculated accordingly. If we take 2.44 times 3, it comes out to 7.32 and so if you remember in our initial model it was 7.33. The total power stays the same as long as the CFM doesn’t change, but the number of fans can change and it’s just the amount of power attributed to each fan will change. Some people are asking about exhaust fan power and we are going to get to that, in fact it’s the last thing we’ll talk about because it’s such a common question. By the way, thanks to the folks that let me know the sound was still working. I was getting some funny feedback on this end. Just looking at a few other questions to see if there’s anything else that we should address before we move on. Let’s go ahead and continue. We’re saving some time for questions because there’s quite a few so far. One other thing I wanted to point out, because these are two different buildings and the number of factors, let’s just look at the system check sums, this is just the total system CFM and so for the proposed building we have a total diffuser CFM of approximately 6500 and in the Baseline building we have a block CFM because this is 5 supply fans supplying 5 zones of approximately 9000 CFM. It should be more in the Baseline building because if we’re designing for LEED we should have a better envelop and better lighting power density, and all of those things drive the airflow down in the proposed building. The equation is based off, not on this CFM because there’s 5 systems, but actually it would be based off of the zone check sums. We looked at those here. The equation in alternative two is based off of 481 here, 270 here, and we calculated the southwest here to 2,099. We’re getting some really good questions and I’m going to save those for the end because we’re right on schedule here, we should have a few more minutes of slides and then all questions. Some of the slides are going to answer some of the questions. We already looked in Trace, if we took our model and we took our VAV system here, so this is what we started with here, and this was designed. I left the scale out to not confuse anyone. We have our additional five roof top systems. If we added all of those up, you can see that the total sum of these is larger than our proposed fan power, which is of course a good thing. Since this is VAV we don’t always see that in our design because there are other factors that play, but in reality the total power should be less in the Baseline building. In fact, that’s actually built into some of the prerequisites.
Let’s look at a few common mistakes. The first one is single zone system with zones, verses multiple systems- it’s not that it’s wrong if you were doing a life cycle analysis, it’s just wrong because for one, it’s confusing in the equipment energy consumption report, and two, LEED has made it quite clear in a number of reviews that I’ve seen that they want to see for each one of these rooftop systems, they want to see a cooling plan. The only way to do that in Trace is of course to model the systems separately. You can’t design zones to plants in Trace. We’re going to jump back into Trace after we go over a few of these. Another common problem is in the proposed building, there’s no true fan selection. So in our case we had a 5 horse power fan and a 3 horse power fan, and it’s based off of a true fan selection. Sometimes of course because fans only come in certain sizes, and let’s just say we rounded up and now we had a 10 horse power fan that we had selected for our proposed building, well people put in 10 horse power but in fact that fan is never going to operate at 10 horse power because of the BVD. That’s something to consider. I’ll show you where that causes a problem in a minute. The other mistake is assuming fan static impacts the fan horse power when you enter units of horse power kilowatts. It simply is just a friction that causes heat. In reality, of course yes, it does affect the horse power, but in Trace the bottom line when you enter horse power or kilowatts, is whatever you entered- that’s the bottom line. Let’s go back into Trace. There are two things I want to address. Let’s go into the correct set up. What I mean by separate unloading, is so here we have 5 systems and we have some plants. When we have to assign the systems, separate unloading means that for the northeast system, we have to put this into the north upped plant, that’s specific to the northeast system, and so on. That’s what we mean by separate unloading and that is something that LEED reviewers has requested not really part of this training.
Another problem is often because Trace is used for design and for LEED, people forget that your design model is typically different from your LEED model. In a VAV system, it’s common to enter the block CFM, and let’s just say I can’t remember exactly what it was, maybe 6500 CFM, and so we lock this in, this is the number that will show up. When we enter the horse power here, what Trace will do is now it will say whenever we’re at 6500 CFM, that’s when we’re at 5 horse power for the supply fan, the primary supply fan, and we’re at 3 horse power for the return fan. Of course we know that often these fans, for instance if it is in fact operated at 5 horse power, we might have put in a 10 horse power fan here, this is going to cause problems because now Trace is going to start this operating at 10 horse power even though the fan truly is operating at 5 here. It’s something that’s very important that if you enter the block airflow that you’ve down a fan selection, that the fan horse power matches that. And that you can document it because the LEED reviewer is going to want to see it.
The last thing is exhaust fans. What I can tell you about exhaust fans is that they are exhausting. Yes, that’s a pun. It’s true. Let’s just look at this. There are several factors that we have to consider. One is restroom fans. They’re generally small and to be conservative they should just be include in the calculation. It’s not actually quite clear. What has been made quite clear is that unconditioned spaces, such as garages, are considered process loads. If you have a garage with an exhaust fan, that’s considered a process load. This has nothing to do with this equation at all. We’ll cover where we should put that in Trace because that number itself, the garage exhaust fan, should be identical in the proposed and the Baseline because it’s a process load. We actually have to model that in a different place. For those of you familiar with Trace, that’s in the base utilities.
The question is, “If we have dedicated outdoor air system, is it considered part of the whole?” This is a common confusion point for a lot of people. Here’s why- let’s go into our Trace model. If we have dedicated outdoor set air, that means that we do have an optional ventilation fan. If we have an optional ventilation fan, we do have an additional fan, and since it’s based on the total fan power, yes, that’s included because if you have an optional ventilation fan, for say, a fan coil unit, the fan coil unit can then use less CFM and less static because it’s not providing the ventilation air. The optional ventilation is lumped into your whole thing, but however, that never really happens in the equation. It’s just in the number that you need to beat because in the Baseline model you should never have optional ventilation. There is never a case when you need dedicated outside air in your Baseline building, unless I’m unaware of some credited interpretation ruling. Since the Baseline building should never in fact have optional ventilation fans, this is in fact one of the exceptions where the number of fans would differ in the Baseline building verses the proposed. In order to keep the ratio the same as we discussed, one may want to take the total power of the supply fan and the optional ventilation fan in the proposed building and add that into one fan because that's the equivalent supply fan for the Baseline building. So again, the Baseline building should never have optional ventilation modeled in it. But I’ve seen a lot of people try to sneak it through, and I’ve seen it flagged a lot as being incorrect. You should not have optional ventilation in the Baseline building anyway, but if it is in your proposed it counts as your total fan power, and therefore that number also needs to beat your Baseline number if you’re hoping to get any LEED points.
The final issue is exhaust fans, and there is some CIRs on this, but basically what I can say for certain is if you have an unconditioned space, which is commonly a garage, and you have an exhaust hood for an unconditioned space, and it’s maybe 5 kilowatts, that’s a process load that has nothing to do with the fan calculations. Where you put that in Trace—in other programs it’s basically a direct load—you make room exhaust fans and you would put in 5 kilowatts and also the schedule which would typically be the occupancy schedule, or you might have to make a schedule. Just select some sort of people schedule or a ventilation schedule which might be more appropriate. General scenario is that they need to be identical. Let’s just say it’s available 100%. Let’s give it a label so that we’re clear- garage fans. If the proposed building has 5 kilowatts of garage fans, then the Baseline building has nothing to do with the fan calculation at all since it’s a process load. You should also have garage fans of 5 kilowatts with the exact same schedule, so in other words it’s completely neutral between the two as a process load. They need to be identical because they’re considered process loads. That I can tell you for certain. If you have a funny scenario such as you maybe have some large unconditioned shower rooms and they have significant exhaust fans in the proposed building, you can make an argument and try the same thing, though I can’t guarantee that it will get through. You’d have to do some CIR research. I have seen them get through that way but it’s for unconditioned spaces which exhaust fans. The exhaust fans are just considered part of a process load. Back to the case where if we had optional ventilation fans, our pressure drop would not correspond correctly so what do you do in that case? It would depend on the scenario. You should make the conservative judgment. For instance if we had optional ventilation fans and this had 3 inches of static and therefore we only have 1 inch of static in our primary system. The question here is just about since we never have optional ventilation in our Baseline, what do we do with the static in case we do have it? In this case, you could just be conservative and go with 1 inch of static and that’s costing you a little bit of extra heat. However, it would be inarguably no in your favor. You could say that you did this to be conservative but it’s not serving us any points, because if you went and gave the Baseline 3 inches of static because you had the optional ventilation, you’re actually giving yourself a slight edge in terms of net savings. However, either way it’s probably insignificant and so you could probably opt with either one of those decisions and it’s going to make a difference of less, like 1/100th of a percent, unless the static is really significant. Sorry for those of you folks who didn’t follow through on that. There’s some really good questions here. We’re probably going to go past 10:00 just a hair. I’ll try to answer these and if you need to leave at 10:00, then that’s fine. We’ve got a few more long questions to answer. Some of these I’m going to respond to you privately, and we’ll try to post these. There is a great question about the fan correction—that whole A-factor that we talked about.
Let’s say we have energy recovery that we’re required to have in the Baseline building and thus we have it in the proposed, how do we implement that? Do we have to do it by hand? No. We can actually find the number from this table and that goes into the equation, and where you enter that in Trace is right here. Whatever the pressure drop turned out to be, we were allowed that pressure drop. Now the question was specific to if we’re required to have heat recovery in the Baseline building. Notice I say “required,” because there’s this little caveat that says “do not include pressure drop for heat recovery devices that are not required in the Baseline building.” If you have heat recovery in the proposed and it’s not required in the Baseline, you cannot take credit for it. However, if you have a Mer??? filter, or you have anything else from this list besides what’s referenced in this little caveat, if you have a Mer??? filter then you’re allowed to put in .9 here. Let’s see what happens there. Let’s look at the fan calculator at energy-models here. I like to use this because it gives one number so we don’t have to break it out. Let’s just put in zero here. We were allowed 1.75 kilowatts. Let’s just say we had a Mer??? filter in the proposed and now we remember to take credit for it, a Mer-13 are better, we get an extra 15%, so we get an extra .3 kilowatts out of 1.75 and so we get an extra, maybe, 15% more fan power just because of that fan filter credit. For the rest of these questions, some of you indicated that you’re out of time. I’ll save the chat log and reply to you privately, and then we will post the chat log.
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