We have a fairly complex and large office building. I am going to show you how to input the HVAC system for this building. But first, I will show you a Building Component Library measure that works very well for inputting a common HVAC system. It will not directly apply to this building because this building is older and has an older type of system, but I want to show you the shortcut first just to demonstrate some of the power of the Building Component Library measures. Go to your model and go to the Measures tab. Let us take a look at the Building Component Library and check to see if this measure needs any updates. This measure is under HVAC – Whole System. It is part of the Advanced Energy Design Guide series of measures, so we will use AEDG as a search term. The measure we are going to use is called AEDG Office HVAC VAV with Chilled Water System. It looks like it is up to date. If it was not up to date, it would say that the measure is not up to date and give you the option to download the latest version. In this case, it looks fine. The other thing I wanted to show you is that the Building Component Library contains a whole new set of measures that can modify building systems or even install entire systems into your model. These measures were created by the National Renewable Energy Laboratory and are based on the ASHRAE Advanced Energy Design Guide recommendations. You will see many different options to choose from, but we are going to select the office building VAV system with a chilled water plant. Go to Components and Measures and click Apply Now. Go to HVAC and select a Whole System. Choose the VAV system with chilled water. The first input asks whether the building has ceiling return air plenums. We do have ceiling cavities, but all of the return air is ducted, so we do not have ceiling return plenums. You can assign a space type to a return air plenum if applicable, but in this case we do not need to apply that. The next input asks for the cost of the system. There is a checkbox to apply recommended availability and ventilation schedules for air handlers, and we will leave that checked. Click Apply Measure. The measure runs successfully. We started with zero air loops, zero plant loops, and zero conditioned zones, and we ended up with ten air loops, two plant loops, and sixty-nine conditioned zones. This measure applies one VAV air loop per building story, so you must have stories assigned in your building model. You can see that several stories have been assigned, and if we render by building story, each story has been assigned an HVAC air handler system. The information panel shows zero errors and zero warnings. Sometimes you may see errors or warnings if key information is missing, in which case you would need to troubleshoot the model. In this case, the measure applied successfully. We will save this model as a new version. Next, we can go to the Air Loops tab and use the drop-down menu to view the air loops that were created. You will see that air loops were created based on each building story and assigned to the spaces on that story. Each air loop consists of a VAV air handler with an air-to-air heat exchanger for heat recovery, a chilled water cooling coil, a hot water heating coil, and a variable flow fan. It also includes a setpoint manager based on outdoor air reset. There are multiple VAV terminal boxes without reheat serving the zones. If we go to the Thermal Zones tab, we can see that each thermal zone has been assigned a VAV terminal box. Each zone also has a convective hot water baseboard heater for zone-level heating. Going back to the HVAC Systems tab, we can see that a chilled water plant and a heating water plant were also created. The chilled water loop includes an air-cooled chiller, a variable flow pump, and all of the chilled water coils serving the air handlers. The heating water loop includes a variable flow pump, a boiler, a setpoint controller, and all of the air handler heating coils and baseboard heating coils. Finally, we can run the simulation to confirm that the system works. First, we go to the Simulation Settings tab and shorten the simulation run to a single day so that it completes quickly. To speed it up even more, we can reduce the number of timesteps per hour to one. Click Save. There are additional advanced settings that can be adjusted to improve simulation speed related to shading and convergence, but we will proceed with these settings for now. The simulation runs and completes successfully. There are some output warnings, but overall the run is successful. I did have some output variables selected, which increased the post-processing time for the SQL file. Even so, the EnergyPlus simulation completed in about one minute and thirty seconds. This demonstrates how you can quickly assign a complete HVAC system to an energy model that previously had no systems defined. In the next video, we will go over how to manually input a dual-duct VAV system for this building. Thank you, and please like and subscribe.

Today we discussed one of the most important features of OpenStudio: space types. Space types are used to apply all required information—such as people, lighting, plug loads, gas loads, infiltration, ventilation rates, and schedules—to spaces, which are then converted into thermal zones and passed to EnergyPlus for simulation. Since EnergyPlus does not use space types, OpenStudio acts as an organizational layer that simplifies modeling. OpenStudio follows a parent–child hierarchy when assigning data. It first looks at information applied directly at the thermal zone or space level. If information is not found there, it checks the Facilities tab for default construction sets, schedule sets, or space types. If it still cannot find the required data, OpenStudio finally looks at the Space Types tab, which is the lowest level. Space types are powerful because they allow standardized data to be applied across many spaces efficiently while still allowing overrides at the space level when needed. We then created a classroom space type based on the Australian National Construction Code 2019 as a reference building example. Since this model is intended to be reusable as a template or library file, we did not assign a default construction set, allowing future climate-specific construction sets to be applied later. We defined a design specification outdoor air object based on Australian ventilation code 1668.2, using 12 L/s per person and 0.35 L/s per square meter, summed together. Next, we created an infiltration design flow rate using air changes per hour, set to 1 ACH, and applied a fractional schedule to modulate infiltration throughout the day based on HVAC operation. This schedule was created to reflect higher infiltration when HVAC systems are off and lower infiltration during occupied periods, and it was assigned through the space type loads tab. Next, we added internal loads to the space type. These included electrical plug loads set at 5 W/m² based on the reference building code, lighting loads set at 4.5 W/m² with appropriate radiant fractions, a people definition using 2 m² per person, and an internal mass definition representing classroom furnishings. The internal mass was modeled using a construction created from a 25 mm wood material to represent furniture thermal storage effects. Each load definition was created separately and then assigned to the classroom space type. This approach allows consistent reuse of load definitions across multiple space types and projects. Finally, we created and assigned schedules for occupancy, lighting, electrical equipment, infiltration, and occupant activity levels using fractional and activity schedules derived from the construction code reference tables. Occupancy and equipment schedules varied throughout the day to reflect realistic school operation. We also created an HVAC operation schedule defining when systems are allowed to run. Instead of assigning each schedule individually, we demonstrated how to create a default schedule set that bundles all schedules together. Assigning this schedule set to the space type automatically populated all schedule fields, saving time and reducing errors. Once completed, this space type can be applied to all classrooms in a project, ensuring consistent loads and schedules. We concluded by noting that multiple space types can be created for an entire school and shared through the Building Component Library for reuse across projects and teams.

We are back and this time we are going to model the Mitsubishi VRF system. First, we save this as a new file and then download the Mitsubishi library from the Building Component Library by searching for Mitsubishi and downloading the zip file. Inside the zip file is an XML description, an OSM file, and a PDF with notes to the energy modeler. We copy the OSM and PDF files into the project folder, then go to preferences and add the downloaded OSM file as a default library. After that, we delete the previously modeled generic VRF system and go to the library tab to locate the Mitsubishi VRF system, specifically the PUHY EP72 option, which provides ducted and non-ducted choices. We review the PDF notes to understand the naming conventions, which include ducted versus non-ducted efficiency ratings and standard versus high-heat options. For simplicity and based on the climate, we choose the non-ducted high-heat option. Next, we add the required terminal units, such as the PFY P30 and PKFY P30, and assign them to the appropriate thermal zones. We also assign the master thermostat location and select an always-available schedule. Once the thermal zones are connected to the terminal units, we run the simulation. After completion, we review the error output file, which contains several warnings. These include fan system discrete speed warnings and airflow-per-capacity warnings, which are common for VRF systems in EnergyPlus. These warnings are mainly guideline checks and are not considered critical, as AHRI standards do not impose strict limits on these values. Some warnings indicate that the VRF heat pump operating temperature limits were exceeded, or that the system appeared to be heating or cooling under unusual outdoor temperature conditions. These issues occurred during the warm-up period while EnergyPlus was performing equipment and zone sizing, not during the actual annual simulation run, so they are not a major concern. There is also a warning about a terminal unit part load ratio exceeding limits, which has been reported as a bug and may occur because terminal units can exceed a part load ratio of one. Overall, despite these warnings, the simulation completes successfully. We then review the simulation reports and compare the Mitsubishi system results with the generic VRF system modeled earlier. The generic system used about 125,000 kBTU per year, while the Mitsubishi system used approximately 118,000 kBTU, indicating slightly better performance. We also compare unmet hours for heating and cooling. Cooling unmet hours are negligible for both systems, while heating unmet hours are similar when looking at unmet degree hours. Occupant-weighted unmet hours are higher for the Mitsubishi system, possibly due to higher airflows or comfort-related factors, but overall the performance between the two systems is quite comparable. Next, we review the notes to the energy modeler for both the terminal units and the outdoor unit. For ducted units, it is important to verify that the static pressure assumptions match the project conditions, and adjustments can be made by editing the fan design pressure rise in the VRF system settings. Additional notes discuss outdoor unit installation considerations, such as adjusting minimum and maximum outdoor temperatures if the unit is installed below indoor units, and limitations in EnergyPlus for modeling certain features like drain pan heaters or waste heat recovery. Several performance curves are shown, comparing Mitsubishi-specific curves to generic EnergyPlus curves, highlighting differences in capacity and efficiency across temperature ranges and part load ratios. Finally, we extend the comparison by modeling other manufacturers’ VRF systems, including Daikin and LG, using the same procedure of downloading equipment from the Building Component Library, installing it, and running simulations. The Daikin system shows annual energy use of around 132–133 kBTU, the LG system about 123 kBTU, compared to 124 kBTU for the generic system and 117 kBTU for Mitsubishi. Performance varies by system and climate, and additional factors such as unmet hours can be reviewed for deeper analysis. This demonstrates how to use manufacturer-specific performance data in OpenStudio and compare it against generic VRF models. Thank you. Please like and subscribe.