Glenn KatzYour Design Journal entries for this module should highlight your design thinking and analysis results that influenced your decisions about:
- your overall HVAC system strategy
- your heating strategy and how you implemented it in your design
- your cooling strategy and how you implemented it
- any special HVAC system challenges that you encountered
- your overall HVAC system strategy
My overall strategy of designing the HVAC system is to first determine the number of air terminal units needed for each room according the CFM calculation results generated by Revit. Once the number is known, the rest is about situating them in positions that have least interference with the architectural model.
Some people might choose to have the ductworks running vertically from the top of the roof and spreading out on each floor, similar to the root of a tree. However, my intention is to have the main ductworks circle around the building so that they would have the least interference with the existing architectural model when it comes to the elevator in the center of the structure. The supply and the return ducts on each level are linked by two respective main ducts that run vertically from level 1 to the roof and connects to a AHU. I used 24” x 13” for all the main ducts and mostly 12-14” of either flex ducts and rectangular ducts for the ones that branch out to each room.
- your heating strategy and how you implemented it in your design
My heating strategy is mostly reliant on the thermal mass and sufficient area of glazing surfaces implemented in this design. Although the HVAC system is able to provide thermal comfort to the individuals in the building even without the implementation of large glazing surfaces, my initial purpose of this design is to make the best use of solar energy to offset the need of using energy by the HVAC system.
- your cooling strategy and how you implemented it
My cooling strategy also aims at taking advantage of energy efficient designs rather than HVAC dependent. As previously mentioned, there is a good amount of glazing surfaces on the building. They can greatly contribute to reducing heating load during the winter but mount pressure on cooling loads during summer. My solution to this is just install directional-varied mullions so they can protect the building from overheating during the summer when rotating to a certain angle. additionally, the green roof on the top can also protect the building from excessive infiltration of heat from the top.
- any special HVAC system challenges that you encountered
Of course, the routing and connection of the ductworks are the most tedious and challenging when it comes to modeling work. The duct height offset from the top can sometimes be easily overlooked and causes the duct run to be placed at an incorrect level. Additionally, it is very challenging to incorporate this with the modular construction design
- Lesson learned:
A very valuable lesson learned in the process of designing mechanical system is that I did not reserve enough space in the mechanical shaft for the duct runs in the initial space planning phase of the design. This has resulted in not having ambient space for a certain portion of the duct that requires large cross-section area to meet the required CFM at that specific location. This has put me in quite of a predicament since the only place sufficient enough to house that portion of the duct is outside of the building. However, the approach of putting main ducts outside of the building would not be viable since the ambient environment (temperature, moisture, etc.) will have drastic impact on the energy efficiency of the ductworks.
The following are mechanical floor plans:
Space Schedule associated with airflow calcs:
