HVAC System Screenshots
Overall HVAC system strategy
The architecture of my building is such that my building is easily divided into four zones:
- Level 1, South Building
- Level 1, North Building
- Level 2, South Building
- Level 2, North Building
As such, my strategy was to design four distinct HVAC systems with four separate air handling units. This allow for more greater efficiencies and comfort control for each zone. The fact that my mechanical room is attached to the exterior perimeter of the building allows for a louver so that natural air can be taken in. Furthermore, I have attached a VAV to every supply zone that I believe requires similar temp/humidity/air flow controls (i.e. restrooms versus offices). This is consistent with the goal of having greater control & efficiencies for each space in my building.
I sought to achieve a balance between form and function, as always. What this means is that my MEP systems should not block any of the natural daylighting features of my building (i.e. skylights) and be as close to the ceiling as possible. Thankfully, a floor to ceiling height of 15’ gave me plenty of room to install my HVAC system.
And lastly, I want to incorporate passive design strategies as much as possible. The way my building is situated is such that wind blows from West to East in the separation between the North and South buildings. That wind will be utilized through the use of windows and louvers, which I plan to further incorporate in future modules.
Heating strategy and how you implemented it in your design
Through Climate Consultant, I discovered that direct heating is needed for 30% of the year, but internal heat gain is responsible for nearly 57% of the heating needs for my building’s location. This means that high insulation flooring, walls, and ceilings, in addition to glazing on windows, would be a great design strategy for keeping the heat gained from internal sources within the building. Furthermore, I incorporated as much curtain walls as possible to allow not just greater daylight, but also greater heat from sunlight as well.
For the 30% of the direct heating, I utilized a split system, vertical air handling unit. My strategy for heating was to size every supply duct appropriately to the needs of the zone it is serving, per the analytical space schedule. Furthermore, having a high efficiency appliance would also increase the efficiency of heating.
Cooling strategy and how you implemented it
Per climate consultant, direct cooling is not needed for my building. As such, each supply duct would only need to provide fresh air and heating in terms of HVAC services. Nonetheless, it may get warm in some rooms simply due to density of people, so natural ventilation is a must. My strategy for cooling, besides the supply ducts appropriately sized to each zone, is to make use of the atrium that I incorporated in the southern building. Hot air can be sucked up from the first floor then expelled in the second. I would like to replicate this same strategy for the northern building as well in future modules.
Having a higher efficiency split system, as always, would help reduce energy demand for cooling as well.
Any special HVAC system challenges that you encountered
- One of the most difficult challenges with HVAC was ensuring a supply and return duct can fit in the zone of interest. Some of my rooms are fairly small, so putting two diffusers, plus a VAV unit, and ducts, took some intentional thinking. There were multiple times I had to reconfigure the way I implemented “trunk-branch-leaf” in the design of my HVAC system because of lack of space. Besides horizontal space, there was also the issue of vertical space. The supply run and the return run shouldn’t be criss-crossing each other at the same height, so I had to be careful about the elevations of each element. Same goes with the diffusers—the diffuser had to be a lower elevation than the duct it’s connected to. Being aware of the vertical clearance between different components was also a challenge.
- I had to always keep in mind where my natural daylighting areas and columns were located in my building. I couldn’t have a duct run through a column nor a space where sunlight was supposed to go through. This kind of in line with space, albeit specific to ensuring that mechanical is not adversarial to the work I had already completed in my architectural and structural module.
- Having the supply and return duct connect into my air handling unit was quite troublesome actually, and although Revit has great features that makes things “automatic,” I still had to tinker a lot. There are just so many options to choose from too, it becomes a bit of an art when it comes to determining out the outlets & inlets connect back into the AHU.
- HVAC System Loads
- Lastly, and this may have been the greatest challenge of all, was working with Revit’s “Systems Analysis” tool. I lost a lot of time trying to make it work and in the end, I had to use Glenn’s output (which thankfully worked) to determine airflow for each of my spaces.