ASHRAE 90.1 System 5 Baseline Packaged VAV Walkthrough скачать в хорошем качестве

ASHRAE 90.1 System 5 Baseline Packaged VAV Walkthrough

Get the full course and learn how to model other baseline systems at https://energy-models.com/content/equ... Here we're going to model ASHRAE 90.1 baseline system 5 packaged VAV with reheat. The first step we're going to take is we're going to import system imports for VAV 5 through 8 which includes supply or reset, optimum start, and VAV fan we made in other videos. Yes, and it skipped them because I had already imported them into this file. The steps are the same. We're going to follow the template we've modeled in the other videos and start by a file that we created in the wizard. We're going to edit the first system and the first system only. From the wizard we have the correct system type packaged variable volume. We set the system sizing ratio to 1 here because we're going to edit the coil sizes. The next thing we're going to do is we're going to go to the coolant tab and ensure the cool sizing ratio is 1.15. We have to have a 20 degree delta T from our set point in the rooms which was 75. It just so happens that this is 55 degrees which is brought in from the wizard. One of the things that we have to do is we have to model a specific type of cooling reset per ASHRAE 90.1. We have the supply air reset temperature that we made in the other video and we imported that in the beginning of this lesson. The next thing is the heating tab. We have to change the heat source to the hot water loop and set the heat sizing ratio to 1.25. Again this is per ASHRAE 90.1 baseline requirements. We did the cooling tab, the heating tab. Next thing is the outdoor air tab. Depending on your system type and the climate zone you may have an outside air economizer. We've been modeling Chicago and that requires an outdoor air economizer with a dry bulb limit of 70. It has no compressor lockout and there should be no enthalpy high limit. Next thing is the fans tab. It's a variable speed fan that follows a defined fan curve. From another video we created this fan curve and put that into a file and now we have the curve for the 90.1 VAV fan. The fan follows a specific unloading curve. Systems of 10,000 CFM or more require optimum start. So far this is what we can model for the system before we require any calculations. We are going to require one system per floor for system 5. That was brought in from the wizard. We also are required to set up the minimum VAV flow per zone. Depending on the standard many of the standards require a ratio of 0.3 which is brought in from the wizard. The ratio of 0.3 means the VAV box can close down to 30% of the flow of the room. The minimum design flow is unrelated to that and is probably going to end up closer to 1 CFM per square foot for most rooms. So that is unrelated and then of course we'd want to look at our other zones and ensure that they follow the same thing. Most of the time all of the zones will be the same. We have the minimum flow for the VAV box defined. The next thing we have to do is define the efficiency and the fan power. We can't define those without knowing how big our system is. This is a step that you would take when you're closer to the end of your model where you have the lights updated, insulation, and the glazing defined per 90.1. We will assume that the envelope and the internal loads are defined. Let me go to simulate. We'll view the detailed simulation output file. And we want to jump straight to the SVAV report like we've done in our other videos. Right here we can see that the cooling capacity is 406 kbtus. The supply CFM is 10,300. That would mean that we need optimum start for the system. The two important numbers are going to be the cooling capacity and the supply CFM here. We need to take the cooling capacity and look at table 6.8 in your version of ASHRAE 90.1. We're using the 2010 version for simplicity as it's still relatively common and it's very similar to other standards. Navigating to ASHRAE 6.8.1a, we look at air conditioners, air-cooled, and it was 400,000 BTUs per hour approximately. And the heating type is all other. And that brings us to a 9.8 EER. Going back to EQUEST, we want to enter the EER and we find that under unitary power, EQUEST requires this electric input ratio EIR There are several ways to calculate this. I calculate the ASHRAE 90.1 fan power using a tool that I wrote. I wrote it specifically for EQUEST. So you go to energymodels.com. SHRAE 90.1 fan power, 10,300. The fan filter credits are another topic that you can add that are outside the scope of this course. Basically, if you have extra filters in your proposed model, you're allowed to take extra fan power to offset the power that the proposed requires. Select variable volume and calculate. It gives us the total brake horsepower. The last step is defining the heating efficiency and the heating is provided through hot water heating and therefore through a boiler. Per 90.1, it should be a natural draft boiler.